Zenas BioPharma, Inc. (ZBIO) Business

Item 1. Business

Overview

We are a clinical stage global biopharmaceutical company committed to being a leader in the development and commercialization of transformative immunology-based therapies for patients in need. With the evolving understanding

6

Table of Contents

of the pathogenesis of autoimmune diseases, along with the expansion of promising immunology-based pharmacologic targets, we are building an I&I focused biopharmaceutical company. Our core business strategy combines disciplined product candidate acquisition with strategic deployment of internal expertise and effective use of external resources. We leverage our experienced executive management team and our established networks throughout the biopharmaceutical industry to identify, acquire and develop product candidates that we believe can provide superior clinical benefits to patients living with autoimmune diseases.

Our lead I&I product candidate, obexelimab, is a bifunctional monoclonal antibody designed to bind both CD19 and FcγRIIb, which are broadly present across B cell lineage, in order to inhibit the activity of cells that are implicated in many autoimmune diseases without depleting them. Based on existing clinical data generated to date, we believe that targeting B cell lineage via CD19 and FcγRIIb can inhibit B cells and has been shown to be well-tolerated. While anti-CD20 or other anti-CD19 targeting agents may effectively deplete B cells in systemic circulation, these agents do not fully impact B cells in relevant tissue, and the intermittent dosing regimens of these agents may not provide optimal benefits for all patients. In addition, anti-CD20 and other anti-CD19 targeting agents may cause prolonged depletion of circulating B cells for six months or longer, placing patients at higher risk of opportunistic infections and potentially reducing their ability to respond to, and receive full benefit from, vaccines. We believe obexelimab’s mechanism of action and chronic dosing regimen may broadly and effectively address the pathogenic role of B cell lineage in chronic autoimmune disease. Across eight clinical trials, including INDIGO and MoonStone, in which 383 subjects were dosed, obexelimab was well-tolerated and demonstrated clinical activity that we believe provides POC for obexelimab as a B cell inhibitor for the treatment of patients living with certain autoimmune diseases and, together with its mechanism of action, positions obexelimab to be a potentially differentiated B cell therapy for the treatment of such patients.

We believe obexelimab holds the potential to provide meaningful clinical benefit for patients in multiple I&I indications.  We are developing obexelimab as a potential I&I franchise for patients in several autoimmune diseases, representing substantial commercial opportunities, individually and in the aggregate. The first three indications we are pursuing include immunoglobulin G4-related disease (“IgG4-RD”) through a registration-directed Phase 3 trial which reported topline data in January 2026, and relapsing multiple sclerosis (“RMS”), through a Phase 2, double-blind, randomized, placebo-controlled trial which reported topline data in October 2025, and systemic lupus erythematosus (“SLE”) through an ongoing Phase 2, double-blind, randomized, placebo-controlled trial for which we expect to report topline results, including biomarker data, in the fourth quarter of 2026. We estimate that each of these potential indications represent a multi-billion-dollar commercial opportunity in the U.S. alone.

In January 2026, we reported positive results from the Phase 3 trial of obexelimab in patients with IgG4-RD (the “INDIGO”) trial. Obexelimab met the primary endpoint, demonstrating a highly statistically significant and clinically meaningful 56% reduction in the risk of IgG4-RD flare compared to placebo (Hazard Ratio 0.44, p=0.0005) and also met and demonstrated highly statistically significant activity compared to placebo on all four key secondary endpoints. Obexelimab was well tolerated with a safety profile consistent with that observed in previously completed clinical trials. Based on these results, we plan to submit the obexelimab Biologics License Application (“BLA”) to the U.S. Food and Drug Administration (“FDA”) for the treatment of IgG4-RD in the second quarter of 2026. We also intend to submit a Marketing Authorization Application (“MAA”) to the European Medicines Agency (“EMA”) in the second half of 2026.

In October 2025, we reported that the Phase 2 trial for RMS (“MoonStone”) met its 12-week primary endpoint, demonstrating a highly statistically significant 95% relative reduction in the cumulative number of new gadolinium-enhancing (“GdE”) T1 hyperintense lesions over week 8 and week 12 compared with placebo (p=0.0009).

In February 2026, we reported the 24-week data from MoonStone trial which confirmed the reductions in total GdE T1 hyperintense lesions observed with obexelimab over weeks 8 and 12 were maintained through week 24; unadjusted mean numbers of new lesions per scan were 0.87 at baseline, 0.08 at week 12 and 0.04 at week 24 for obexelimab indicating a 95% reduction.

In addition to obexelimab, we are developing orelabrutinib, a Bruton’s Tyrosine Kinase inhibitor (“BTK”), for progressive forms of multiple sclerosis. Orelabrutinib is a highly selective and central nervous system (“CNS”)-penetrant, oral small molecule BTK inhibitor. Orelabrutinib is designed to bind irreversibly to BTK with minimal off-target effects, which may potentially reduce certain side effects. We believe orelabrutinib is designed to efficiently cross the blood-brain barrier, reaching therapeutic levels within the CNS to directly target inflammation in diseases like Multiple Sclerosis (“MS”).

7

Table of Contents

We are advancing orelabrutinib in a global, Phase 3, multicenter, randomized, double-blind, placebo-controlled clinical trial in patients with Primary Progressive Multiple Sclerosis (“PPMS”), the (“PriMroSe”) trial, and we plan to initiate a second global, Phase 3, multicenter, randomized, double-blind, placebo-controlled clinical trial evaluating orelabrutinib in patients with non-active Secondary Progressive Multiple Sclerosis (“non active SPMS”), the (“Monarch”) trial in the first quarter of 2026.

We also have two early-development product candidates: ZB021 and ZB022. ZB021 is an oral IL-17AA/AF inhibitor designed to block both IL-17AA homodimer and IL-17AF heterodimer signaling. We expect Phase 1 clinical study initiation in 2026.

ZB022 is an oral, brain-penetrant tyrosine kinase 2 (“TYK2”)-JH2 inhibitor, currently in Investigational New Drug (“IND”)-enabling studies. Subject to the results of the IND-enabling studies, we expect to submit an IND application for ZB022, and if cleared, initiate a Phase 1 clinical study in 2026.

In addition, we have two other programs for the potential treatment of other I&I indications that we may continue to advance and ultimately commercialize with partners. These consist of ZB002 (an anti-TNFα monoclonal antibody) and ZB004 (a CTLA-4-Ig fusion). We retain global rights for both assets. In addition, we hold the development and commercialization rights to one regional program, ZB001 (also known as VRDN-001, an insulin-like growth factor-1 receptor (“IGF-1R”) monoclonal antibody and related programs, which were exclusively sublicensed to a partner in greater China.

To date, we have no product candidates approved for commercial sale in any country and have not generated any revenue from product sales.

Pipeline

We are developing obexelimab, orelabrutinib and other product candidates for the treatment of several I&I diseases summarized in the pipeline figure below:

1. Bristol Myers Squibb & Co. holds exclusive development and commercialization rights for obexelimab in Japan, South Korea, Taiwan, Hong Kong, Singapore, Australia.

2. InnoCare territories

Obexelimab Overview

Obexelimab was engineered to mimic the natural antigen-antibody complex for the inhibition of B cells. By targeting CD19, obexelimab is designed to inhibit a broader B cell population, including plasmablasts and the subpopulation of CD19 expressing plasma cells, each of which produces high amounts of auto-antibodies. Co-engagement of CD19 and FcγRIIb by obexelimab has been shown to inhibit B cell activity, including antibody production, proliferation, cytokine secretion, B cell differentiation, and antigen presentation to T cells. In addition, obexelimab is designed to inhibit rather than destroy or deplete B cell lineage. Other anti-CD19 and CD20 targeting antibodies rely on antibody-dependent cell-

8

Table of Contents

mediated cytotoxicity (“ADCC”), complement-dependent cytotoxicity (“CDC”) and/or apoptosis or programmed cell death as a key component of their mechanism of action. ADCC, CDC and apoptosis activity are generally lower in disease-relevant tissue than the peripheral blood. In addition, in clinical practice other CD19 and CD20 targeted antibodies are typically dosed once every six months which has demonstrated efficacy, but may not provide sustained benefit in all patients due to variability in B cell depletion and recovery. The obexelimab mechanism of action and chronic dosing regimen may more broadly and effectively address the pathogenic role of B cell lineage in chronic autoimmune disease and has the potential to show greater clinical benefits, especially over a longer course of maintenance treatment.

The inhibitory mechanism of obexelimab is believed to reduce the number of B cells in systemic circulation through margination of B cells to other tissues such as the lymph nodes and the spleen, rather than through depletion. The concept of margination is supported by preclinical and clinical data, where the substantial return of B cells in circulation of subjects receiving obexelimab was observed to occur as soon as six weeks after discontinuation of obexelimab administration, contrasted with the much longer period of B cell recovery observed with other CD19 and CD20 targeted depleting agents, which can take six months or longer following the last dose. The risks of prolonged B cell depletion include limitations on a patient’s ability to fight serious and opportunistic infections and on a patient’s ability to generate an adequate response to vaccines such as influenza, shingles, respiratory syncytial virus, and COVID-19. We believe the rapid return in B cell activity following the cessation or pause in obexelimab dosing could allow the patient’s immune system to more quickly return to baseline to protect against infections and allow a patient to receive vaccinations within as few as six weeks of his or her last dose, rather than potentially waiting six months or longer following treatment with an anti-CD19 or anti-CD20 targeted depleting therapy.

Obexelimab has been evaluated in eight clinical trials in which a total of 383 subjects have received obexelimab either as IV infusion (n=158) or as a subcutaneous (“SC”) injection (n=225). Obexelimab was well-tolerated across these eight trials and demonstrated PK, as well as clinical activity providing POC in multiple I&I indications. Based on this clinical data, we believe obexelimab could have potential advantages over anti-CD19 and -CD20 targeted depleting agents.

We are also developing ZB014, an anti-CD-19 and FcγRIIb monoclonal antibody designed to extend half-life, which is currently being evaluated in pre-clinical studies.

Orelabrutinib Overview

Orelabrutinib, also known as ZB020, is a highly selective and CNS-penetrant, oral small molecule BTK inhibitor. Orelabrutinib is designed to bind irreversibly to BTK with minimal off-target effects, compared to certain other BTK inhibitors, which may potentially reduce certain side effects. We believe orelabrutinib is designed to efficiently cross the blood-brain barrier, reaching therapeutic levels within the CNS to directly target inflammation in diseases like MS. This CNS penetration may be important for addressing the underlying disease pathology of progressive forms of MS, which is characterized by compartmentalized neuroinflammation and neurodegeneration. The mechanism of action of BTK inhibitors targets not only pathogenic B cells in the periphery, but also those in the CNS, as well as macrophages and microglial cells addressing the key pathogenic drivers of progressive MS.

9

Table of Contents

Early-Development Product Candidates: ZB021 and ZB022

ZB021 is an oral small molecule IL-17AA/AF inhibitor designed to block both IL-17AA homodimer and IL-17AF heterodimer signaling, ZB022 is an oral small molecule, brain-penetrant TYK2-JH2 inhibitor.

Preclinical studies for ZB021 have shown favorable PK and ADME properties. ZB021 achieved comparable activity in vivo to a reference anti-IL-17 biologic in a rat collagen-induced arthritis (“CIA”) model. We expect Phase 1 clinical study initiation in 2026, with the potential for initial data in patients in 2027.

ZB022 is currently in IND-enabling studies. Subject to the results of IND-enabling studies, we expect to submit an IND application for ZB022, and, if cleared, initiate a Phase 1 clinical study in 2026, with the potential for initial data in 2027

Other Programs

In addition, we have two other programs for the potential treatment of other I&I indications that we may continue to advance and ultimately develop and commercialize with partners. These include ZB002, an anti-TNFα therapy designed to have an extended half-life as compared to existing anti-TNFα therapies and ZB004, a CTLA-4-Ig fusion protein designed to have an extended half-life compared to approved CTLA-4-Ig fusion protein therapies.

Partnered Regional Programs

We also have in-licensed the development and commercialization rights to ZB001 (also known as VRDN-001), an IGF-1R monoclonal antibody, and related programs from Viridian Therapeutics, Inc. (“Viridian”) in China, Hong Kong, Macau and Taiwan (collectively, “greater China”). In January 2025, we entered into a license agreement (the “Zai License Agreement”) with Zai Lab (Hong Kong) Limited (“Zai”), under which we granted Zai an exclusive sublicense to develop and commercialize ZB001 and related programs in greater China.

In addition, in October 2024, we entered into a novation agreement with Tenacia Biotechnology (Hong Kong) Co., Limited (“Tenacia”), under which we transferred to Tenacia our rights and obligations under our agreements with Dianthus Therapeutics Inc. (“Dianthus”) for ZB005 (the “Tenacia Agreement”).

Our Management Team

Our executive management team is comprised of seasoned executives and scientists with extensive experience in the biopharmaceutical industry, leading drug development and commercialization and executing successful business development strategies. Our company is led by Leon (Lonnie) O. Moulder, Jr., our Founder, Chief Executive Officer and Chairman, and the Managing Member of Tellus BioVentures, LLC, an early-stage life sciences investment fund. Prior to founding Zenas, Mr. Moulder co-founded TESARO, an oncology-focused biopharmaceutical company, serving as Chief Executive Officer and Director until its acquisition by GlaxoSmithKline. He previously served as President and Chief Executive Officer of Abraxis BioScience and as Vice Chairman of Eisai Corporation of North America following Eisai’s acquisition of MGI PHARMA, where he served as President and Chief Executive Officer. Mr. Moulder is joined by our team of veteran biopharmaceutical executives, including Joseph Farmer, Jennifer Fox, and Lisa von Molkte, M.D., who together with the leadership team, bring exceptional track records and experiences across the industry at companies such as TESARO, Inc., GlaxoSmithKline plc., Amgen Inc., Nuvation Bio Inc.,  Cubist Pharmaceuticals, Inc., Seres Therapeutics and other biopharmaceutical companies. Our leadership team has collectively been responsible for numerous INDs, and NDAs/BLAs and the associated commercial product launches of several successful pharmaceutical products.

Our Strategy

Our vision is to become a global leader in delivering transformative I&I therapeutics to patients in need. We intend to leverage the experience and capabilities of our executive management team and our established networks throughout the biopharmaceutical industry to identify, acquire, develop and, if approved, commercialize product candidates that we

10

Table of Contents

believe can offer enhanced efficacy, safety and/or convenience over existing therapies and thereby provide superior benefits to patients. We intend to achieve our goals by implementing the following strategies:

Obexelimab (CD19 and FcγRIIb bifunctional monoclonal antibody) Program

We believe that obexelimab has the potential to address key unmet needs in multiple I&I indications due to its mechanism of action and chronic dosing regimen that may broadly and effectively address the pathogenic role of B cell lineage through reversible inhibition of B cell activity without causing B cell depletion.

Obexelimab is a bifunctional, humanized monoclonal antibody designed to bind CD19 and FcγRIIb to inhibit B-lineage cell activity. The antibody variable region of obexelimab has been engineered to bind CD19, whereas the constant region has been engineered to enhance affinity for the inhibitory FcγRIIb receptor. FcγRIIb is the only Fc receptor on B cells and serves as an antibody-sensing down-regulator of humoral immunity that is naturally engaged by antigen-antibody complexes. In addition, FcγRIIb regulates the activity of other B cell stimulators including interleukin-4, lipopolysaccharide and B cell activating factor (“BAFF”) that amplify BCR-driven proliferation and differentiation. By binding CD19 and FcγRIIb, obexelimab mimics the action of naturally occurring antigen-antibody complexes and inhibits B cell activity without depleting B cells through ADCC and CDC.

The mechanism of action of obexelimab shown below in Figure 1, involves co-engagement of CD19 and FcγRIIb, leading to inhibition of B cell activity, including antibody production, proliferation, cytokine secretion, B cell differentiation, and antigen presentation to T cells.

11

Table of Contents

Figure 1: Mechanism of Action of Obexelimab

Through in vitro, in vivo and classical animal models of autoimmune disease, obexelimab’s binding to CD19 and FcγRIIb has been shown to enable the inhibition of B cell activity without depleting B cells. Preclinical and clinical studies have demonstrated that obexelimab rapidly achieved nearly 100% CD19 receptor occupancy, potently inhibiting B cell activity along with a decrease of approximately 50% in circulating B cell levels observed within one to two days. We believe the decrease in circulating B cell levels results from margination of B cells in lymphatic tissues, such as the lymph nodes and spleen, rather than depletion or elimination of the B cells. In contrast, anti-CD20 and other anti-CD19 B cell-targeting agents deplete B cells through B cell destruction. In clinical studies, we have observed substantial recovery of B cell levels in circulation following cessation of therapy with obexelimab within six weeks, as opposed to six months or longer that has been observed with B cell depleting agents. This rapid return in B cell activity following the cessation or pause in obexelimab dosing could allow the patient’s immune system to more quickly return to baseline to protect against infections and could allow a patient to receive vaccination within as few as six weeks of his or her last dose, rather than potentially waiting six months or more following treatment with an anti-CD19 or anti-CD20 targeted depleting therapy.

Clinical Development

Obexelimab has been evaluated in eight clinical trials, including INDIGO and MoonStone, in which a total of 383 subjects have received obexelimab either as an IV infusion (n=158) or as a SC injection (n=225). Across these eight trials obexelimab was well-tolerated and demonstrated clinical activity that we believe provides POC for obexelimab as a B cell inhibitor for the treatment of patients living with certain autoimmune diseases. Our current ongoing and planned future trials of obexelimab utilize a fixed 250 mg, dosed weekly as a self-administered SC injection.

12

Table of Contents

Summary of Completed Clinical Trials for Obexelimab

​

*These clinical studies were conducted by Xencor. The results of these studies are further described below.

**Primary endpoint did not achieve statistical significance.

13

Table of Contents

Obexelimab has demonstrated clinical activity across multiple I&I indications. As described below, we recently announced positive topline data in a registration-directed Phase 3 trial in patients with IgG4-RD and are currently pursuing ongoing

14

Table of Contents

Phase 2, double-blind, randomized, placebo-controlled clinical trials of obexelimab in patients with RMS and SLE. Despite the promising results from the Phase 1b/2a trial of obexelimab in RA, we do not intend to develop obexelimab further in RA due to the competitive landscape in that disease. While we believe that the results from the SApHiAre Trial in patients with warm autoimmune hemolytic anemia (“wAIHA”) patients established proof of mechanism through an increase in Hgb and a positive effect on other clinical markers, we have determined not to progress to a registration-directed trial of obexelimab for the wAIHA indication based on several factors, including the expected length and expense of a potential Phase 3 trial.

Obexelimab for the Treatment of IgG4-RD

We believe obexelimab’s differentiated mechanism of action as an inhibitor of B cell lineage supports its potential to play an important role in the treatment of IgG4-RD. The reported evidence for the role of B cells in the pathogenesis of IgG4-RD, the observed effects of B cell targeting agents in previous trials in IgG4-RD and the data from our Phase 2 IgG4-RD trial with obexelimab support the continued development of obexelimab in patients with IgG4-RD. In January 2026, we reported positive results from the Phase 3 trial of obexelimab in patients with IgG4-RD (the “INDIGO” trial). Obexelimab met the primary endpoint, demonstrating a highly statistically significant and clinically meaningful 56% reduction in the risk of IgG4-RD flare compared to placebo (Hazard Ratio 0.44, p=0.0005) and also met and demonstrated highly statistically significant activity compared to placebo on all four key secondary endpoints. Obexelimab was well tolerated with a safety profile consistent with that observed in previously completed clinical trials. Based on these results, we plan to submit the obexelimab BLA to the FDA for the treatment of IgG4-RD in the second quarter of 2026. We also intend to submit an MAA to the EMA in the second half of 2026.

IgG4-RD Histology and Disease Background

IgG4-RD is a chronic fibro-inflammatory condition that can affect virtually all organ systems, including the pancreas, biliary tract, salivary and lacrimal glands, lungs, and kidneys. Patients with IgG4-RD may present with a single organ involved but more frequently present with multiple organ involvement. As the disease progresses and patients experience new or worsening symptoms (i.e., flares), lesions develop in additional organs and the cellular inflammation characterizing early disease moves toward a more fibrotic stage, which can lead to major irreversible tissue damage and ultimately organ failure. The most common symptoms in patients with IgG4-RD and their relative frequency of presentation are highlighted below in Figure 2. IgG4-RD is a relatively recently described disease that incorporates groups of manifestations that were diagnosed as separate disease entities prior to 2003. We estimate that the currently diagnosed population of IgG4-RD patients in the U.S. is approximately 20,000, with what we believe to be comparable prevalence rates globally. The pathogenesis of IgG4-RD suggests that B cell-targeted therapies may provide therapeutic benefit. Several B cell subsets have recently been shown to be elevated in the peripheral blood of IgG4-RD patients. Moreover, plasmablasts have been shown to actively contribute to tissue fibrosis through multiple mechanisms, including production of pro-fibrotic molecules and stimulation of collagen production by fibroblasts.

15

Table of Contents

Figure 2: IgG4-RD: A Chronic Fibro-inflammatory Disease Characterized by Flares

Current Treatment and Unmet Need

Despite the growing recognition of IgG4-RD and advances in the understanding of its pathophysiology, there is only one approved therapy for the treatment of this disease and there remains high unmet medical need. There are few treatment options, which are often limited by co-morbidities common among patients with IgG4-RD, including diabetes, obesity and hypertension. Glucocorticoid (“GC”) treatment is commonly used, however such treatment often results in various complications. Although GCs are initially effective in most patients, up to 60% of patients with IgG4-RD will relapse within 12 months of discontinuing GC treatment.

IgG4-RD is a disease commonly marked by flares, which can lead to the accumulation of fibrosis, resulting in irreversible organ damage, often involving multiple organs, and past flares are often a strong indicator of future flares. Therefore, patients are in need of long-term maintenance treatment. However, maintenance therapy with GCs has not been shown to prevent recurrence of disease and can lead to significant toxicity and complications, including osteoporosis, hypertension, and diabetes, especially in elderly patients.

In addition to GCs, the pathogenesis of IgG4-RD suggests that B cell-targeted therapies may provide therapeutic benefit. As a result, although not approved by any regulatory bodies to treat IgG4-RD, certain B cell depleting agents (e.g. rituximab) are occasionally used in such patients, and in April 2025, inebilizumab, a B cell depleting agent, was approved by the FDA. However, B cell depleting agents are often associated with infections, including serious opportunistic infections, and can compromise a patient’s ability to mount a response to vaccinations. This was shown in a small pilot study of rituximab, a B cell-targeted therapy, in patients with IgG4-RD. We believe this is due to the fact that rituximab and other B cell depleting agents can cause prolonged depletion of B cells for six months or longer, which places patients at risk of opportunistic infections and potentially reduces response to vaccines.

INDIGO Trial—Our Global Phase 3 Trial in IgG4-RD

In January 2026, we announced positive results from the INDIGO trial. The INDIGO trial enrolled a total of 194 patients, randomized to obexelimab (n=97) and placebo (n=97). Obexelimab met the primary endpoint, demonstrating a

16

Table of Contents

highly statistically significant 56% reduction in the risk of IgG4-RD flare that requires initiation of a rescue therapy compared to placebo (Hazard Ratio 0.443, p=0.0005) during the 52-week randomized placebo-controlled period. The number of participants with flares was 26 (26.8%) in the obexelimab arm and 53 (54.6%) in the placebo arm. Obexelimab also met and demonstrated highly statistically significant activity compared to placebo with respect to all four key secondary endpoints, which were time to first investigator-determined IgG4-RD flare requiring initiation of rescue therapy (p=0.0001), the number of flares requiring initiation of rescue therapy (p=0.0008), the proportion of patients achieving complete remission (p=0.0049) and the cumulative use of IgG4-RD glucocorticoid rescue therapy (p=0.0042).

​

Obexelimab was well tolerated with a safety profile consistent with that observed in previously completed clinical trials. When compared to the placebo arm, incidences of serious adverse events were lower in the obexelimab arm (obexelimab 10% vs. placebo 19%). Additionally, overall rates of infections, including Grade 3, were lower in the obexelimab arm compared to placebo (Grade 3 infections, obexelimab 2% vs. placebo 4%), as well as related upper respiratory tract infections (obexelimab 5% vs. placebo 7%). Lower rates of urinary tract infections and rates of COVID-19 were observed with obexelimab compared to placebo (obexelimab 2% vs placebo 4%). Percentage of doses with injection site reactions were similar across both study arms (obexelimab 3.5% vs. placebo 2.3%). Three malignancies were identified (all deemed unrelated): one renal cell carcinoma determined to be pre-existing before enrollment; one prostate cancer, for which there is no known increased risk with immunosuppression; and one squamous cell carcinoma.

​

Following the positive Phase 3 INDIGO results, we anticipate submitting a BLA to the FDA for obexelimab in IgG4-RD in the second quarter of 2026. We also intend to submit an MAA to the EMA in the second half of 2026.

​

INDIGO Trial Overview

The INDIGO Trial is a global Phase 3 registration-directed, double-blind, placebo-controlled trial to evaluate the safety and efficacy of SC obexelimab in patients with active IgG4-RD in a randomized controlled period followed by an optional open-label extension period. Approximately 190 patients were enrolled in the randomized control period (“RCP”) and all patients from the RCP are eligible for the open label extension (“OLE”) period. The trial is being conducted at approximately 100 sites in 20 countries. The RCP consists of a screening period (Day -28 to Day -1) and a 52-week treatment period, during which 250 mg of obexelimab or placebo were administered as an SC injection every seven days. Following the 52-week RCP, eligible patients had the opportunity to continue in an OLE period where all patients will receive obexelimab.

Figure 3: INDIGO Trial Schema

To be considered eligible for the screening period, patients must have had a clinical diagnosis of IgG4-RD, met the 2019 ACR/EULAR classification criteria for IgG4-RD, as determined by an Adjudication Committee (“AC”), and had active IgG4-RD signs/symptoms (i.e., flare) that require, as assessed by the investigator, the initiation of GC therapy or an increase in background long-term GC therapy. All patients were required to receive three to six weeks of GC treatment at a dose of 20 to 60 mg/day prednisone equivalent prior to randomization. The required GC therapy could either have been newly initiated or an increase in long-term GC therapy (i.e., patient was previously on a dose of ≤ 10 mg/day prednisone equivalent). The exact dose and taper schedule during the screening period and prior to randomization are at the discretion of the investigator. However, on the day of randomization, patients must have had no disease activity and been at a dose of 20 mg/day prednisone equivalent. Patients were randomized 1:1 to receive obexelimab or placebo. The primary efficacy assessment was time to first IgG4-RD flare, as determined by the investigator and the AC. If the investigator suspected an IgG4-RD flare, based on reappearance of previous signs/symptoms or appearance of new signs/symptoms of IgG4-RD, organ-specific diagnostic assessments were conducted, including a physical examination, imaging and/or testing of

17

Table of Contents

biochemical parameters specific to the involved organ(s), to correlate symptoms and to document disease activity. The investigator then determined if an IgG4-RD flare occurred and whether the initiation of rescue therapy was required. The AC independently reviewed these diagnostic assessments to determine if, in their judgement, the signs/symptoms represent a flare. Patients who met the protocol-defined criteria for IgG4-RD flare, by both the investigator and the AC, were counted as treatment failures for the primary endpoint of time to first flare and the key secondary endpoint of proportion of patients who remain free of IgG4-RD flare (i.e., complete remission). Rescue therapy outside of permitted GC therapy would result in discontinuation from obexelimab or placebo treatment, as the case may be. The trial was designed with approximately 90% power to detect a hazard ratio of 0.376 using a one-sided log-rank test at a significance level equal to 0.025.

Summary of the Completed Phase 2 Trial of Obexelimab in IgG4-RD

In August 2023, the results of the Phase 2, open-label, single-arm, trial of obexelimab for the treatment of patients with IgG4-RD were published in The Lancet Rheumatology. Twenty patients with active IgG4-RD, defined as an IgG4-RD RI score of three or more, were enrolled. Fifteen patients received obexelimab 5 mg/kg IV every two weeks for 24 weeks. The protocol was later amended to also provide for the enrollment of an additional five patients who would receive a fixed dose of obexelimab of 90 mg IV or 180 mg IV every two weeks for 24 weeks.

The pre-specified primary analysis of this study focused on the 15 patients enrolled at obexelimab 5 mg/kg. At baseline, the median IgG4-RD RI score was 12 (IQR 7-13). In the primary efficacy analysis, as shown in Figure 3 below, the median decrease in the IgG4-RD RI score was 11.5 points (IQR 7.5-14.5). The IgG4-RD RI score at day 169 had decreased by two or more points from baseline in 12 (80%) patients, eight (67%) of whom had a score of zero (complete remission). These patients included four (80%) of five patients who had achieved remission on previous therapies. Fourteen (93%) patients achieved an improvement on the RI of two or more points during at least one trial assessment at a median of 15 days (range 14 to 90) from treatment initiation. Twelve (80%) patients achieved a combined (secondary) endpoint of a decrease on the RI of two or more points at day 169, with no steroid use after day 57, and no disease flares. All primary responders had sustained responses through the end of the trial. One (7%) patient who did not meet clinical response criteria had a RI score of two at baseline and a score of one before withdrawing from the trial after the Day 71 dose due to lack of efficacy (an IgG4-RD RI score reduction of less than two). Two responders also did not complete the trial: one discontinued after experiencing a disease relapse and one discontinued after an infusion-related hypersensitivity reaction during the fifth infusion. Thirteen (87%) patients experienced adverse events with the most common adverse event of GI infusion-related, including nausea, abdominal pain, and diarrhea.

Figure 4: Rapid and Sustained IgG4-RD RI Response from Phase 2 Trial

18

Table of Contents

Furthermore, as shown in Figure 5 below, circulating B cell counts decreased by approximately 60% throughout the treatment period. However, among seven patients with post-treatment follow-up data, four (57%) demonstrated recovery of circulating B cells to at least 75% of baseline within 42 days of the final obexelimab dose. Circulating plasmablasts also decreased quickly, by approximately 70 to 80%, and began returning following cessation of obexelimab. After the first dose of obexelimab, CD19 receptor occupancy was nearly 100% for most patients and remained at or near complete occupancy until after the last dose of obexelimab at day 155.

Figure 5: Rapid Recovery of Systemic B Cells Upon Discontinuation

Following enrollment of the first 15 patients treated at 5 mg/kg every other week, an additional five patients were enrolled in a separate cohort to explore a fixed dose regimen of obexelimab 90 mg IV every other week. All five patients achieved a decrease of two points or greater in the IgG4-RD RI at some time during the trial; however, three patients required an increased dose of obexelimab 180 mg IV every other week for disease flare, and two patients also received corticosteroids after Day 57. Peak serum concentration for patients who received 90 mg of obexelimab was approximately 25% and at 180 mg were approximately 50% of those patients who received 5 mg/kg.

Safety Summary

One patient experienced pneumonia accounting for two SAEs (initial and recurrence due to non-compliance with antibiotic therapy), and a second patient experienced one SAE (chronic inflammatory demyelinating polyradiculoneuropathy in the setting of small lymphocytic lymphoma (preexisting)). None of these events were considered by the investigator to be related to obexelimab. Certain patients also experienced mild to moderate and transient IV infusion-related GI symptoms. The most common TEAEs were abdominal pain and nausea (4/20, 20.0%), vomiting (3/20, 15.0%), and diarrhea, chills, headache, nasal congestion and upper respiratory tract infection (2/20, 10.0%).

Obexelimab for the Treatment of MS

We believe obexelimab’s differentiated mechanism of action as an inhibitor of the B cell lineage supports its potential for the treatment of MS. The role of B cells in the pathogenesis of MS has been demonstrated through the successful clinical development, approval and clinical use of anti-CD20 B cell targeting therapies of other companies, including OCREVUS (ocrelizumab) and KESIMPTA (ofatumumab), which selectively deplete peripheral CD20-expressing B cells. B cells are thought to play a central role in MS pathology and its concomitant neurodegeneration via multiple mechanisms. In addition to antibody secretion by plasmablasts and plasma cells, B cell functions implicated in MS pathogenesis include antigen presentation to T cells and production of pro-inflammation cytokines. We believe this activity observed from B cells may contribute to both MS relapses as well as the underlying disease progression.

19

Table of Contents

In October 2025, we announced positive results from the MoonStone trial of obexelimab in patients with RMS. Obexelimab met the primary endpoint, demonstrating a statistically significant 95% relative reduction in the cumulative number of GdE T1 hyperintense lesions, which are markers of active inflammation, over week 8 and week 12 compared with placebo (p=0.0009). The adjusted mean number of new GdE T1 hyperintense lesions per scan in the obexelimab group (n=72) was 0.01 (95% CI: 0.00, 0.06) compared to 0.23 (95% CI: 0.11, 0.51) with placebo (n=38). Additionally, over weeks 8 and 12 of treatment, obexelimab significantly reduced the cumulative number of new and/or enlarging T2 weighted hyperintense lesions compared to placebo, which represent the amount of disease burden or chronic lesion load. The safety profile of obexelimab was consistent with that observed in prior completed trials, including cases of infections and hypersensitivity, most commonly mild injection site reactions.

In February 2026, we reported the 24-week data from the MoonStone trial which further confirmed the robust and durable activity of obexelimab. The highly statistically significant reductions in total GdE T1 hyperintense lesions observed with obexelimab over weeks 8 and 12, when compared to placebo, were maintained when evaluating the obexelimab arm patients through week 24; unadjusted mean number of new lesions per scan were 0.87 at baseline, 0.08 at week 12 and 0.04 at week 24 for obexelimab indicating a 95% reduction. Additionally, obexelimab meaningfully reduced serum Neurofilament Light (“NfL”) by 40% through week 24; 15.28 pg/mL at baseline declining to 12.7 pg/mL at week 12 and 9.2 pg/mL at week 24. New and/or enlarging T2 lesions were also lower in the obexelimab arm and the Expanded Disability Status Scale (“EDSS”) scores were stable, indicating a lack of progression in physical disability. No new safety signals were observed at week 24. As we continue to evaluate the MoonStone data and consider next steps for clinical development in this indication, we will consider, among other items, the evolving treatment landscape in RMS, including existing therapies, current pivotal trial endpoints and prioritization of capital.

MS Histology and Disease Background

MS is the most common immune-mediated, chronic inflammatory demyelinating disease of the CNS, affecting over two million people worldwide including as many as 1,000,000 in the U.S., according to the National MS Society and the MS Foundation. We estimate a diagnosed prevalence of approximately 650,000 patients in the U.S. with MS.

MS is characterized by numerous demyelinating lesions of the brain and spinal cord. The magnetic resonance imaging (“MRI”) hallmark of the disease are multiple areas of demyelination in the CNS. The clinical features of an MS attack depend on the areas of the brain or spinal cord involved, thus symptoms may include sensory and visual disturbances, motor, coordination impairment and spasticity, fatigue, pain, and cognitive deficits. Its peak onset is typically in adults between 20 – 40 years old. The most common course of MS is relapsing-remitting (“RRMS”), which affects as many as 85% of MS patients. Patients with RRMS experience episodes of neurological dysfunction followed by complete or incomplete recovery. Over time, the majority of RRMS patients develop disease progression, with or without relapses, referred to as SPMS. Patients with RRMS and SPMS with relapses are typically referred to as having RMS. Lastly, 10 to 15% of patients present with a gradually progressive disease course from onset known as PPMS.

Most patients initially diagnosed with RRMS experience two distinct clinical phases, the relapsing-remitting and progressive phases, each of which is reflected by a distinct pathological process. During the relapsing-remitting phase, inflammation drives disease activity while neurodegeneration, which is characterized by accumulating disability, is predominant in the progressive phase. However, underlying progression occurs in all forms of MS, and obexelimab’s unique mechanism of action has the potential to impact both the inflammation and neurodegeneration aspects of MS pathogenesis.

Currently, the cause of MS remains unknown; however, both B and T cells play an important role in the pathogenesis of the disease, including inflammation and demyelination processes. In addition to producing autoantibodies and inflammatory cytokines, B cells have an important function as antigen-presenting cells (“APCs”) involved in T cell activation. The APC function of B cells is thought to be an important reason for the beneficial effects of anti-B cell therapies in MS. Chronic CNS inflammation in the MS lesion is maintained, in part, with activated pro-inflammatory macrophages, microglia and astrocytes at the rim of chronic active or slowly expanding MS lesions, which are the site of ongoing demyelination and neuronal damage. The continued expansion of chronic active lesions is believed to play a role in the pathogenesis of disease progression in MS.

20

Table of Contents

Figure 6: Role of B and T Cells in Multiple Sclerosis

​

Current Treatment, Limitations and Remaining Unmet Need

Despite various treatments available for MS patients, unmet clinical needs remain, including a lack of an effect on progression independent of relapse activity (“PIRA” or also known as “silent progression”), which has been observed even in patients with early RMS on highly effective therapies. Gadolinium enhancement is a sensitive technique for detecting active MS lesions and confirms the inflammatory activity of the disease. Monitoring the change in these MRI contrast enhancing lesions is routine and decreased MRI activity represents the earliest treatment effects in clinical trials. In many MS Phase 3 trials, including those of B cell therapies, reductions in inflammatory lesions, initially demonstrated in Phase 2 POC trials utilizing MRI endpoints, were often accompanied by clinical improvements. The paramagnetic rim lesion may serve as another important emerging MRI marker of chronic neuroinflammation, with any modification observed in a clinical trial potentially indicating a change in disease progression.

To date, there are a number of therapies that have been approved for the treatment of MS, including injectable, oral and infused medications. Although MS is historically considered a T cell disease, blockade of B cell autoreactivity inhibits neuroinflammation through several pathways, including (i) preventing B cells from acting as antigen-presenting cells that activate autoreactive T cells, (ii) preventing B cells from releasing proinflammatory cytokines, (iii) preventing B cells from transforming into plasma cells that may produce myelin-directed autoantibodies, and (iv) preventing B cells from forming meningeal lymphoid follicles. Despite effective treatment for relapses, there remains a considerable proportion of patients who experience ongoing disease activity and/or accumulating progression of disability. Within 20 years of diagnosis, 30 – 60% of patients with RRMS convert to SPMS with relapse-independent disability progression resulting in severe limitations on quality of life. Despite currently approved therapies, there is an enduring need for additional safe and effective treatments that address the underlying progression seen in MS to potentially alter the course of disability.

Our Global Phase 2 Trial in RMS

The Phase 2 MoonStone trial, which enrolled 116 patients, is a randomized, double-blind, placebo-controlled trial, to evaluate the efficacy and safety of obexelimab in patients with RMS. The trial follows a standard design using magnetic resonance imaging (MRI) endpoints. After an initial screening period, patients were randomized 2:1 to receive either 250 mg of obexelimab or placebo via subcutaneous injection once weekly over a 12-week double-blinded treatment period. The primary endpoint is the cumulative number of new Gd-enhancing T1 hyperintense lesions over week 8 and week 12

21

Table of Contents

as measured by brain MRI. Secondary and exploratory endpoints include using standardized assessments, imaging, and biomarkers to evaluate the impact on disease progression. Upon completion of the double-blinded phase, all patients entered a 12-week open-label period in which those previously on placebo transition to obexelimab treatment, while those originally assigned to obexelimab continue therapy. During the open-label period, secondary and exploratory endpoints will assess obexelimab’s clinical activity through week 24.

Obexelimab for the Treatment of SLE

The crucial role of B cells in SLE pathogenesis is well recognized, from producing autoantibodies to abnormal regulation of immune responses. Moreover, SLE is an autoimmune disease characterized by B cell dysfunction, the production of autoantibodies toward cellular and nuclear components, and multiorgan damage caused by immune complex deposition and inflammation within affected tissues. Obexelimab has demonstrated clinical activity as a B cell-directed agent due to its inhibitory effect on B cell lineage via its binding to CD19 and FcγRIIb, and a prior Phase 2 double-blind, randomized trial we believe demonstrated POC in SLE. In the third quarter of 2024, we initiated the SunStone Trial, a Phase 2, multicenter, randomized, double-blind, placebo-controlled trial, to evaluate the efficacy and safety of obexelimab to reduce disease activity in patients with SLE.

SLE Histology and Disease Background

SLE, the most common form of lupus, is a complex, chronic autoimmune disease characterized most notably by unpredictable flares in joints, skin, kidneys and other vital organs that cause progressive organ damage. The prognosis of SLE varies from patient to patient, with alternating periods of active symptoms and remission throughout their lifetime. SLE ranges from a relatively benign disease to rapidly progressive and even fatal. Comorbidities, such as infections, malignancies, hypertension, lipid disorders and diabetes, increase the risk of disability and death in patients. SLE commonly affects the central nervous system, kidneys, gastrointestinal system, mucous membranes, heart, skin, hematologic system, musculoskeletal system and lungs.

22

Table of Contents

Figure 7: SLE Disease Characteristics

Increased B cell activity and survival mediated through BCR abnormalities is a classic feature of SLE. BCR signals are impacted by several regulatory surface proteins, including CD19 and FcγRIIb. Activation of FcγRIIb is known to effectively dampen BCR signaling and decrease B cell responses to activating signals, which may play a pivotal role in suppressing a patient’s own immune system from attacking cells. In addition, data in both murine lupus models and human lupus studies provide a rationale for targeting CD19 and FcγRIIb as a treatment for SLE.

Current Treatment, Limitations and Remaining Unmet Need

According to the Lupus Foundation of America, at least 1.5 million Americans are afflicted by lupus and more than 16,000 new cases are reported annually. It is estimated that five million people throughout the world suffer from some form of lupus, of which approximately 70% suffer from the most common form, SLE. Lupus affects primarily women of childbearing age (15 to 44 years). However, men, children and teenagers can also develop lupus. We estimate a diagnosed prevalence of approximately 245,000 patients in the U.S. having lupus, with approximately 150,000 having SLE.

The current treatment strategy for SLE is based on treating the affected organ(s) and focuses on achieving a defined state of remission or low disease activity. Targeting B and plasma cells may have positive results in the overall treatment of SLE because of the role autoantibodies play in the pathogenesis of the disease.

23

Table of Contents

Current treatments include non-steroidal anti-inflammatory drugs (“NSAIDs”), glucocorticoids, hydroxychloroquine, Benlysta (belimumab) (FDA approved for SLE in 2011), and Saphnelo (anifrolumab) (FDA approved for SLE in 2021). These limited FDA approved options are modestly effective with improvement in combination with standard therapy versus standard therapy alone in Phase 3 trials of nine to seventeen percentage points. We believe there is an opportunity to identify a clinically-validated biomarker to guide the selection or optimal administration of treatments.

Summary of Obexelimab—Phase 2 Trial in Patients with SLE

Study XmAb5871-04 was a Phase 2, double-blind, randomized, placebo-controlled trial to evaluate the ability of obexelimab to maintain SLE disease activity improvement in patients after brief treatment of active disease with corticosteroids. Patients were randomized 1:1 to receive intravenous obexelimab (5 mg/kg) or matching placebo every two weeks for 16 doses or until loss of improvement (“LOI”). LOI was defined by either a 4-point increase in the hybrid Systemic Lupus Erythematosus Disease Activity Index (“hSLEDAI”) score or at least one British Isles Lupus Assessment Group (“BILAG”) A or B score rated “new” or “worse”. One hundred and four patients were randomized, with 52 assigned to obexelimab treatment and 52 to placebo. Patients completing the trial included 28 (53.8%) receiving obexelimab and 17 (32.7%) receiving placebo. Median months of treatment was 6.9 (range 0 – 7.4) with obexelimab and 3.6 (range 0 – 7) with placebo.

The primary endpoint was assessed as the proportion of patients reaching week 32 without LOI, using an EE population, defined as patients who completed the trial or withdrew for flare or treatment-related toxicity. Twenty-one out of 50 (42.0%) obexelimab-treated patients versus 12 out of 42 (28.6%) placebo-treated patients achieved the primary endpoint. Although the primary endpoint was not achieved with statistical significance (p = 0.183), the ITT population revealed a larger absolute treatment difference of 17.3% (40.4% versus 23.1%, p=0.06) in the obexelimab-treated group versus the placebo-treated group. The ITT analysis is relevant since all patients are considered in this analysis, whereas in the EE analysis a larger number of placebo-treated patients than obexelimab-treated patients discontinued treatment for reasons that removed them from the analysis (10 patients versus 2 patients). Furthermore, the placebo response rate (28.6% in the EE analysis and 23.1% in the ITT analysis) was higher than the 10% rate which was assumed in the statistical assumptions for the trial. Nevertheless, the difference in response rates between the obexelimab and placebo arms in this trial was similar to that observed in SLE registration-directed trials with other agents, although with different trial design and endpoints.

Further, there was an association between obexelimab concentration and time to LOI. PK analysis revealed that quartiles of patients with progressively higher drug concentration had progressively longer time to LOI. In the EE analysis, patients in Ctrough quartiles three and four exhibited a larger absolute LOI treatment difference of 35% in the obexelimab-treated group versus the placebo-treated group. Accordingly, we believe these data demonstrated POC for obexelimab in SLE.

Fourteen (26.9%) patients that received obexelimab and 25 (48.1%) patients that received placebo withdrew for LOI. Adverse events led to the withdrawal of seven (13%) obexelimab-treated patients (most of which were infusion-related reactions) and two (4%) patients that were administered placebo. Withdrawal for other reasons occurred in three patients that were administered obexelimab and eight that were administered placebo. There was no increase in the proportion of patients with infection in obexelimab as compared to placebo treated groups. The most frequently occurring TEAEs in patients who received obexelimab administered IV were nausea (20/52, 39%), headache (12/52, 23%), vomiting (9/52, 17%), back pain and dizziness (8/52, 15%), flushing (7/52, 14%) and pain in extremity (6/52, 12%).

Biomarker analysis identified baseline gene expression profiles associated with increased response to obexelimab. Patients with adequate baseline RNA samples (71 in total) were assigned into one of seven clusters (immunophenotypes) as defined by Guthridge et al. 2020 using the Oklahoma Lupus Cohort. Patients in gene expression clusters three and six exhibited greater prolongation of time-to-flare with obexelimab, whereas in the other clusters obexelimab was not associated with a prolongation in time-to-flare. Patients in gene expression clusters three and six exhibited a larger absolute treatment difference in LOI of 52% in the obexelimab-treated group versus the placebo-treated group. There was a relatively small difference in time-to-flare between patients treated with placebo in clusters three and six compared with patients treated with placebo in the other clusters, suggesting that clusters three and six had higher predictive than prognostic value. Clusters three and six represent 38% of the population tested, which is similar to the 31% of cluster three and six patients in the original Oklahoma cohort. These clusters include patients of African and European descent and share increased expression of B cell pathways and low expression of inflammation pathways. These responsive immunophenotype

24

Table of Contents

subgroups are thus consistent with the drug’s mechanism of action, inhibition of B cell, plasmablast, and plasma cell activity, an impact that was observed in patients treated with obexelimab.

We believe the obexelimab efficacy data in the overall trial population and the increased response in biomarker-defined subpopulations, coupled with the safety data obtained to date, provide support for further clinical trials and the use of a SC obexelimab formulation in patients with SLE.

Our Global Phase 2 Trial in Patients with SLE

We are currently enrolling patients in the SunStone Trial, a global Phase 2, multicenter, randomized, double-blind, placebo-controlled trial to evaluate the efficacy and safety of obexelimab when used to reduce disease activity in patients with SLE. We expect to enroll approximately 190 patients and to conduct the trial at multiple sites worldwide. We expect to report data on the primary endpoint at 24 weeks and biomarker data in the fourth quarter of 2026.

To be eligible for the trial, patients enrolled must have active SLE at screening, as defined by BILAG 2004 and hSLEDAI. Patients will be randomized 1:1 to obexelimab 250 mg or placebo SC injection every seven days over 24 weeks. The primary endpoint is the percentage of responders, defined by BILAG-based Composite Lupus Assessment, with a reduction of SLE disease activity at week 24. Biomarker analysis is planned to be conducted in all patients. This includes baseline RNA expression profiles to immunophenotype patients and evaluation of their differential responses to treatment. Additional biomarker assessments include serum cytokines and chemokines, SLE disease markers (complement C3/ C4, anti-dsDNA), and immune cell subsets (B cells, plasma cells, etc.).

Safety Profile of Obexelimab

In the clinical studies, including INDIGO and MoonStone, 383 subjects have received obexelimab, 158 subjects as an IV infusion and 225 subjects as a SC injection. The majority of TEAEs in the studies using obexelimab were mild or moderate.

The clinically important identified risk of obexelimab, defined by serious and related events observed in obexelimab treated subjects, included unanticipated infusion related reactions which have not been observed for the subcutaneous injection of obexelimab. The clinically non-important identified risks of obexelimab, defined as non-serious and related events, included intravenous infusion related GI events and injection site reactions via the SC administration. The injection site reactions were of minimal clinical impact, non-serious and did not lead to study drug discontinuation. The IV infusion related GI events were non-serious and were not observed with SC injection.

Serious Adverse Events

The only SAEs considered by the investigator to be related to obexelimab or placebo across the clinical studies completed to date were: two IV infusion related reactions, one in each of two obexelimab treated patients, one venous thrombosis in an obexelimab treated patient, one herpes zoster in a placebo treated patient and a post herpetic neuralgia in a placebo treated patient.

Anti-Drug Antibodies

The development of anti-drug antibodies (“ADA”) has been observed in all studies; however, the ADA response did not have an apparent effect on PK or safety parameters (i.e., accelerated clearance), with the possible exception of one subject (in the first in human (“FIH”) study) and the three subjects with hypersensitivity reactions mentioned above.

Safety Summary of Previously Completed Clinical Studies

Study XmAb5871-01

Overall, doses of up to and including 10 mg/kg obexelimab were well tolerated by healthy male subjects. GI-related TEAEs (including nausea, vomiting, abdominal pain, abdominal discomfort, epigastric discomfort and diarrhea) were the most frequently reported (14/36, 38.9%). Eight subjects (8/36, 22.2%) who had received 0.2 to 10 mg/kg obexelimab had their IV infusion temporarily interrupted as a result of the GI-related symptoms. In all cases, symptoms leading to infusion

25

Table of Contents

interruption were transient and subjects were able to continue the infusion after a short break without recurrence of symptoms. Symptom resolution did not require the use of concomitant medications. No infusion-related reactions or hypersensitivity reactions were observed. There were no SAEs reported. No subject was withdrawn and none self-withdrew. There was no consistent dose-response relationship with the incidence of TEAEs and no dose-limiting toxicities were observed.

Study XmAb5871-02

Among the 40 patients who received obexelimab, the most common TEAEs were vomiting (7/40, 17.5%), headache (7/40, 17.5%), nausea (6/40, 15.0%), pyrexia (4/40, 10.0%), and arthralgia (4/40, 10.0%). As in the FIH study in healthy male volunteers (Study XmAb5871-01), gastrointestinal-related TEAEs (nausea, vomiting, diarrhea) were mostly mild to moderate, resolved with interruption of infusion and did not reoccur with reinitiation of infusion.

In general, multiple doses of up to 10 mg/kg obexelimab were well tolerated in patients with RA. Two subjects experienced infusion-related reactions (both at 10.0 mg/kg), one of which was considered an SAE. The other event, associated with the first infusion, was considered of moderate severity. In both cases, the infusion was terminated, and the patients recovered without sequelae. The nature and severity of these infusion reactions were consistent with those reported for other monoclonal antibody therapies.

Study XmAb5871-03

In general, obexelimab was well tolerated in patients with IgG4-RD. The most common TEAEs were abdominal pain and nausea (4/20, 20%), vomiting (3/20, 15%), and diarrhea, chills, headache, nasal congestion, and upper respiratory tract infection (2/20, 10%). Four patients (4/20, 20%) had first dose GI symptoms of nausea, vomiting, and/or diarrhea as described previously with IV infusions. The symptoms were relieved by interrupting the infusion for a short period of time. There was one infusion-related hypersensitivity reaction that was associated with the presence of ADA, that was treated with symptomatic medications and that resolved after obexelimab was stopped. This patient recovered fully and discontinued the trial. There was one case of pneumonia accounting for two SAEs (initial and recurrence due to non-compliance with therapy) in one patient and a second patient experienced one SAE (chronic inflammation demyelinating polyradiculoneuropathy in the setting of small lymphocytic lymphoma (pre-existing)). None of the SAEs were considered to be related to obexelimab.

Study XmAb5871-04

Obexelimab was generally well tolerated in patients with SLE. The most frequently occurring TEAEs were nausea (20/52, 39%), headache (12/52, 23%), vomiting (9/52, 17%), back pain and dizziness (8/52, 15%), flushing (7/52, 14%), and pain in extremity (6/52, 12%). The majority of these events were mild and resolved. There were 8 SAEs in patients administered obexelimab, only one (infusion-related reaction) of which was considered related to study drug. Fourteen (14/52, 26.9%) patients that received obexelimab and 25 (48.1%) patients that received placebo withdrew for LOI. Adverse events led to the withdrawal of seven (7/52, 13%) obexelimab-treated patients (most of which were infusion-related reactions) and two (4%) patients that were administered placebo. Withdrawal for other reasons occurred in three patients that were administered obexelimab and eight that were administered placebo.

Study XmAb5871-05

Overall, the SC administration of obexelimab was well tolerated. The most common TEAEs across all SC dose regimens were headache and injection site reaction (3/40, 8%). The incidence of injections with injection site erythema, induration and/or pain as a total out of all injections was 4/207 (total), or 1.9% of injections. The symptoms involved only one of the possible two or three sites injected on that day, were mild, and resolved within 24 hours.

Dosage and Administration for Obexelimab

Obexelimab has been evaluated in eight clinical trials, including INDIGO and MoonStone, in which a total of 383 subjects have received obexelimab either as an IV infusion at doses of up to 10 mg/kg (n=158) or as a SC injection at doses up to 375 mg (n=225). We believe these trials have demonstrated obexelimab’s PK/PD and tolerability profile.

26

Table of Contents

Our current ongoing and planned trials of obexelimab utilize or will utilize a fixed 250 mg self-administered SC injection dosed weekly. This dosing regimen is supported by the totality of existing clinical efficacy and safety data, PK/PD modeling, and nonclinical data. The 250 mg weekly SC dose is designed to maximize the potential for efficacy by providing maximum PD target engagement, comparable exposure and, importantly, a higher Ctrough when compared with the 5 mg/kg IV every two weeks dosing regimen, which demonstrated clinical activity in the IgG4-RD and SLE Phase 2 trials of obexelimab. In addition, the 250 mg weekly SC dose was designed to maintain a lower Cmax than the 5 mg/kg IV every two weeks dosing regimen to provide sufficient safety margins and an acceptable tolerability profile based on both clinical and nonclinical study data of obexelimab.

Preclinical Characterization

In vitro studies demonstrated that obexelimab has a high affinity for human CD19 and human FcγRIIb. The half-maximal effective concentration (“EC50”) of binding of obexelimab to a human CD19 expressing cell line is 0.3 nM, and the EC50 of binding of obexelimab to human primary B cells is 1.4 nM. The binding affinity of obexelimab for human FcγRIIb (8 nM) has been increased approximately 230-fold relative to human native IgG1 as a result of Fc engineering. In vitro, co-engagement of CD19 and FcγRIIb by obexelimab results in the inhibition of calcium mobilization upon stimulation of B cells from normal volunteers as well as in RA and SLE patients. Obexelimab has shown no antibody-dependent cellular cytotoxicity mediated B cell depletion of complement directed cytotoxicity in vitro.

We are also developing ZB014, an anti-CD-19 and FcγRIIb monoclonal antibody designed to extend half-life, which is currently being evaluated in pre-clinical studies.

Orelabrutinib (Bruton’s Tyrosine Kinase inhibitor) Program

Orelabrutinib, also known as ZB020, is a highly selective and CNS-penetrant, oral small molecule BTK inhibitor. Orelabrutinib is designed to bind irreversibly to BTK with minimal off-target effects, compared to certain other BTK inhibitors, which may potentially reduce certain side effects. BTK is a member of the TEC family and is expressed in B lymphocytes, mast cells, macrophages, monocytes, and neutrophils. We believe orelabrutinib is designed to efficiently cross the blood-brain barrier, reaching therapeutic levels within the CNS to directly target inflammation in diseases like MS. This CNS penetration may be important for addressing the underlying disease pathology of progressive forms of MS, which is characterized by compartmentalized neuroinflammation and neurodegeneration. The mechanism of action of BTK inhibitors targets not only pathogenic B cells in the periphery, but also those in the CNS, as well as macrophages and microglial cells addressing the key pathogenic drivers of progressive MS, as shown in Figure 8 below.

27

Table of Contents

Figure 8

Clinical Pharmacology

In a central nervous system lymphoma (“CNSL”) study, CSF was collected 2 hours post-dose at steady state from 7 patients receiving a dose of 150 mg QD.  The mean CSF concentration of orelabrutinib was 31.3 ng/mL.  Based on the linear PK of orelabrutinib, the extrapolated CSF concentration at 80 mg QD is 16.7 ng/mL.  Based on a cell-free enzymatic kinase assay, the in vitro IC50 was measured as 0.7 ng/mL and the IC90 calculated to be 3.5 ng/mL. Collectively, these data project that the CNS concentration of orelabrutinib exceeds the IC90 by approximately 5 fold.

​

No significant food effects were observed when orelabrutinib was administered with a standard high-fat, high-calorie meal.  BTK occupancy was achieved at doses of ≥50 mg/day for 24 hours after dosing.

Orelabrutinib for the Treatment of MS

A significant unmet need exists in MS for CNS-penetrant mechanisms that address compartmentalized local inflammation and directly impact the biology of progressive disease and neurodegeneration. BTK inhibition could potentially address the underlying biology of progressive disease by impacting peripherally and centrally located pathogenic B cells and macrophages, and directly inhibiting microglia in the CNS. See the section titled “MS Histology and Disease Background” for more information.

Over time, the majority of RMS patients develop disease progression, with or without relapses, referred to as SPMS. SPMS is an advanced manifestation of RMS where relapses become less frequent or stop but gradual worsening of disability occurs. There are three subtypes of SPMS: active SPMS, non-relapsing SPMS and non-active SPMS.  Non-active SPMS is a progressive disease with no new relapses or MRI activity.  Ten to 15% of patients present with a gradually progressive

28

Table of Contents

disease course from onset known as PPMS, which characterized as a steady increase in disability without relapses or disease flares.

We estimate a diagnosed prevalence of approximately 90,000 patients with non-active SPMS and approximately 60,000 to 100,000 patients with PPMS in the U.S. SPMS and PPMS have the highest unmet need across MS subtypes, with limited therapeutic options. Currently no treatments are approved for non-relapsing/non-active SPMS and there is only one approved treatment, Ocrevus, for PPMS. We estimate that the commercial opportunity for MS could exceed $30 billion, over $12 billion attributable to non-active SPMS and PPMS combined.

Phase 2 Study of Orelabrutinib in RMS

In late 2024, the results of the Phase 2 trial of orelabrutinib for the treatment of RMS were announced. The Phase 2 trial was a global, double-blind, placebo-controlled trial. The primary endpoint was the cumulative number of new gadolinium-enhancing (“Gd+”) T1 brain lesions at Week 12 (based on new Gd+ T1 lesions at Weeks 4, 8, and 12) compared to placebo. The results of the Phase 2 trial demonstrated that treatment with orelabrutinib resulted in a rapid and deep reduction in new Gd+ T1 lesions across all evaluated doses. In the trial, 158 eligible RMS patients were randomized in a 1:1:1:1 ratio to one of four treatment groups: placebo, orelabrutinib 50 mg once daily (“QD”), orelabrutinib 80 mg QD, and orelabrutinib 50 mg twice daily (“BID”). Subjects in the placebo group were switched to orelabrutinib 50 mg QD at Week 13.

Figure 9: Phase 2 Study of Orelabrutinib in RMS Schema

​

At Week 12, all three treatment groups showed statistically significant reductions in the cumulative number of new Gd+ T1 lesions and new/enlarging T2 lesions compared to the placebo group (p 0.05). At week 24, the 80 mg QD and 50 mg BID groups showed statistically significant reductions compared to the placebo/50 mg QD group (p 0.05). The 80 mg QD group demonstrated the highest reductions in new Gd+ T1 lesions of 90.4% at Week 12 compared to placebo and 92.3% at Week 24 compared to the placebo/50 mg QD group. New lesion control in each orelabrutinib group occurred at the earliest assessment timepoint of Week 4 and was sustained through Week 24.

Safety Summary

Orelabrutinib was generally well tolerated in the Phase 2 study of patients with RMS. The known potential risks of orelabrutinib, as observed in clinical trials in patients with B-cell malignancies and autoimmune disease, include those associated with BTK inhibitor treatment such as hepatotoxicity, hemorrhage, cytopenia, infection, malignancy, hypertension, and arrhythmia.

29

Table of Contents

In the Phase 2 RMS trial, 151 patients received at least one dose of orelabrutinib. TEAEs leading to drug discontinuation occurred in 2.6% of patients. The majority of TEAEs were Grades 1 or 2. Observed Grade 3 or higher events primarily included hematologic toxicities and infections, which are mechanism-related and commonly reported with BTK inhibitor treatment.

Elevation of liver enzyme levels classified as hepatotoxicity were observed in the Phase 2 RMS trial (ICP-CL-00112), as well as in Phase 1/2 trials in patients with SLE (ICP-CL-00109 and ICP-CL-00124) and Phase 2/3 trials in patients with Immune Thrombocytopenia (ICP-CL-00116 and ICP-CL-00126). Two cases of elevated liver enzymes and bilirubin met Hy’s Law criteria, one in the Phase 2 RMS trial and the other in the SLE trial. Both affected patients were asymptomatic and their liver markers normalized after treatment was discontinued. FDA issued a partial clinical hold for the conduct of the ongoing RMS trial. Three other BTK inhibitors, including those currently in development for progressive MS, were also placed on a partial clinical hold while under development in the U.S. for RMS. No development restrictions were placed by the EMA. In the Phase 3 progressive MS trials, for which no partial clinical hold is imposed, weekly liver function monitoring will be conducted during the first 12 weeks of treatment, which will be implemented through an established hepatotoxicity management scheme. In addition, the safety of the study, including hepatotoxicity, will be monitored by an Independent Data Monitoring Committee (“IDMC”) and a Hepatoxicity Assessment Committee (“HAC”) through periodic or ad hoc reviews of study safety observations.

Orelabrutinib has been approved for commercial use for chronic lymphocytic leukemia and small lymphocytic lymphoma in China since December 2020.

PriMroSe Trial – Our Global Phase 3 Trial in Primary Progressive Multiple Sclerosis (PPMS)

In September 2024, InnoCare and the FDA reached an agreement to initiate a Phase 3 trial of orelabrutinib in patients with PPMS. The FDA also encouraged InnoCare to initiate a second Phase 3 clinical trial of orelabrutinib in Progressive Multiple Sclerosis (“PMS”) within the SPMS population. In February 2025, InnoCare reached alignment with the FDA on the Phase 3 clinical trial protocol for SPMS.

In September 2025, the Phase 3, PriMroSe Trial of orelabrutinib in patients with PPMS was initiated. The PriMroSe Trial is a global, multicenter, randomized, double-blind, placebo-controlled clinical trial evaluating the safety and efficacy of orelabrutinib dosed 80 mg once daily QD compared to placebo in patients with PPMS, with a primary endpoint of time to onset of 12-week composite confirmed disability progression (“cCDP”), with a goal to report topline results in 2030. We expect to enroll approximately 705 patients and to conduct the trial at over 300 sites worldwide.

Figure 10: PriMroSe Trial Schema

Monarch Trial – Our Global Phase 3 Trial in non-active Secondary Progressive Multiple Sclerosis

In the first quarter of 2026, we plan to initiate a second global, Phase 3, multicenter, randomized, double-blind, placebo-controlled clinical trial evaluating orelabrutinib dosed 80 mg QD compared to placebo in patients with non-active SPMS, with a primary endpoint of time to onset of 24-week CDP, and with a goal to report topline results in 2030. We expect to enroll approximately 990 patients and to conduct the trial at over 300 sites worldwide.

​

30

Table of Contents

Figure 11: Monarch Trial Schema

Early-Development Product Candidates: ZB021 and ZB022

We also in-licensed from InnoCare certain exclusive rights to two early-development product candidates: ZB021, an oral IL-17AA/AF inhibitor designed to block both IL-17AA homodimer and IL-17AF heterodimer signaling, and ZB022, an oral, brain-penetrant TYK2-JH2 inhibitor.

ZB021, is an oral IL-17AA/AF inhibitor. As demonstrated in Figure 12 below, IL-17 is a pro-inflammatory cytokine secreted by immune cells in response to IL-23-dependent and -independent signals. Normally Il-17 predominately acts at mucosal and epithelial surfaces to provide defense against bacterial and fungal infections. Il-17 is implicated in multiple immune-mediated diseases by driving chronic inflammation in dermatological and rheumatological indications leading to manifestation such as skin thickening and joint inflammation. Substantial clinical efficacy and the approval of several biologics targeting Il-17 or its receptor (Cosentyx®, Taltz®, Siliq®, and Bimzelx®), establishes IL-17 as a well-validated target for immune-mediated diseases.

Figure 12:

Preclinical studies for ZB021 have shown favorable PK and ADME properties. ZB021 achieved comparable activity in vivo to a reference anti-IL-17 biologic in a rat CIA model, as demonstrated in Figure 13 below. We expect Phase 1 clinical study initiation in 2026, with the potential for initial clinical data in patients in 2027.

31

Table of Contents

Figure 13: ZB021 Activity in Rat CIA Model

​

We believe ZB021 provides an opportunity for Zenas to expand its pipeline within rheumatology and into other therapeutic areas including dermatology. Anti-IL-17 biologics are a drug class focused on the treatment of rheumatic and dermatologic diseases that we estimate currently represents an approximately $10 billion commercial opportunity, with an average of approximately 50% annual growth since the first approval of a product was obtained.

ZB022 is an oral, brain-penetrant TYK2-JH2 inhibitor currently in IND-enabling studies. Subject to the results of IND-enabling studies, Zenas expects to submit an IND application for ZB022, and if cleared, initiate a Phase 1 clinical study in 2026, with the potential for initial clinical data in 2027.

TYK2 is an enzyme expressed inside immune cells and a member of the JAK-STAT family of kinases critical for cytokine signaling. Normally TYK2-mediated signaling orchestrates adaptive and innate immune responses, including responses by helper T cell subsets and myeloid cells, involved in host defense against infectious agents. In inflammatory conditions, dysregulated signaling through TYK2 drives pathological processes downstream of type 1 interferons and the IL-12/IL-23 cytokine axis. TYK2 inhibition allows for a more targeted approach to cytokine inhibition, with approval of the first Tyk2 inhibitor (Sotyktu), establishing TYK2 as a viable target for immune-mediated diseases. More recently, TYK2 has been implicated in driving neuroinflammation by resident immune cells and neuronal cells in multiple sclerosis and neurodegenerative diseases, indicating that a brain-penetrant TYK2 inhibitor has the potential to modulate pathogenic processes in the central nervous system, as demonstrated in Figure 14 below.

32

Table of Contents

Figure 14: ZB022

Other Programs

We have two other programs for the potential treatment of other I&I indications that we may continue to advance and ultimately commercialize with partners. These consist of ZB002 (an anti-TNFα monoclonal antibody) and ZB004 (a CTLA-4-Ig fusion). We retain global rights for both assets.

ZB002 Program (anti-tumor necrosis alpha monoclonal antibody)

ZB002 is a monoclonal antibody inhibitor of TNFα designed to have an extended half-life as compared to existing anti-TNFα therapies. ZB002 is identical to adalimumab in the TNFα-binding region of the fragment variable domain, but the Fc domain contains modifications to extend ZB002’s half-life in vivo (Xencor’s Xtend technology). Our Phase 1 SAD study demonstrated a half-life of approximately 55 days for ZB002, which we believe may allow for dosing once every four to eight weeks. In the second quarter of 2024, we initiated a Phase 1b MAD study of ZB002 in patients with rheumatoid arthritis. If the results of our ongoing Phase 1b MAD study of ZB002 are favorable, we may seek to identify a partner to advance ZB002 in subsequent trials for potential use as a treatment for certain I&I diseases that can benefit from TNFα inhibition.

ZB004 Program (CTLA-4-IG fusion)

ZB004 is a CTLA-4-Ig fusion protein designed to have an extended half-life versus existing CTLA-4-Ig fusion protein therapies. Based on the results from our ongoing Phase 1 study, we plan to evaluate the path forward for the development of ZB004 in the treatment of I&I indications.

ZB004 is comprised of two CTLA-4 extracellular domain substitutions and an IgG Fc region containing substitutions (Xencor’s Xtend technology). This design allows for increased binding affinity to human CD80 and CD86 and FcRn. Its mechanism of action is selective inhibition of T cell co-stimulation by binding to CD80 and CD86 receptors, which blocks their interaction with CD28 on T cells.

We conducted a Phase 1 SAD study designed to evaluate the safety, tolerability, PK immunogenicity and PD profiles of ZB004 in healthy volunteers. Our Phase 1 SAD study demonstrated a half-life of approximately 17.4 days at the highest dose level of 200 mg, where CD86 receptor occupancy reached a maximum peak value of 81%, overcoming the effect of target mediated drug disposition. There were no SAEs reported.

33

Table of Contents

Partnered Regional Programs

We license ZB001, an anti-IGF-1R monoclonal antibody, and related programs, from Viridian. For these assets we hold the development and commercialization rights in greater China and recently sublicensed these rights to Zai.

ZB001 is a monoclonal antibody that binds to, and is designed to act as a full antagonist of, IGF-1 receptor. This mechanism of action has been clinically and commercially validated by the only FDA product approved for the treatment of thyroid eye disease (“TED”), Tepezza (teprotumumab). For more information on our agreement with Viridian, see the section titled “Certain Relationships and Related Party Transactions—Director Affiliations—Agreements with Viridian Therapeutics Inc.”

In January 2025, we entered into the Zai License Agreement with Zai, under which we granted Zai an exclusive sublicense to develop and commercialize ZB001 and related programs in greater China.  As partial consideration for the Zai License Agreement, we received an upfront fee of $10.0 million from Zai. In addition, we are eligible to receive up to $96.0 million upon the achievement of certain future development and commercial milestones and royalty percentage rates from the low to mid-single digits, net of pass-through obligations due to Viridian.

In addition, in October 2024, we entered into the Tenacia Agreement, under which we transferred to Tenacia our rights and obligations under our agreements with Dianthus for ZB005. As partial consideration for the Tenacia Agreement, we received an upfront fee of $5.0 million from Tenacia. In addition, we are eligible to receive up to $86.0 million upon the achievement of certain future regulatory and commercial milestones.

License Agreements

License Agreements with Xencor

2020 Xencor Agreement

In September 2020, we entered into a license agreement (the “2020 Xencor Agreement”) with Xencor, to obtain (i) an exclusive, royalty-bearing, sublicensable worldwide license under certain patent rights controlled by Xencor and (ii) a non-exclusive payment bearing license under certain know-how controlled by Xencor to research, develop, manufacture, market and sell three antibody product candidates (the “2020 Licensed Assets”), including ZB002 and ZB004. We subsequently relinquished rights to the third product candidate back to Xencor and that asset is no longer a 2020 Licensed Asset. Xencor obtained the rights to some of the intellectual property licensed to us pursuant to license agreements between Xencor and a third party (each such agreement, an “Upstream License Agreement” and collectively, the “Upstream License Agreements”). As such, the 2020 Xencor Agreement provides that the parties agree that some of the licenses granted by Xencor to us constitute sublicenses under the Upstream License Agreements and are subject, and subordinate, to the terms and conditions of the Upstream License Agreements. As consideration for the 2020 Xencor Agreement, we issued Xencor a 15% equity interest in Zenas. The 2020 Xencor Agreement became effective in November 2020, upon Zenas’ issuance of 5,041,542 shares of its Series A Preferred Stock with a fair value of $16.1 million to Xencor as initial consideration.

Under the 2020 Xencor Agreement, we are obligated to use commercially reasonable efforts to conduct all future preclinical, clinical and regulatory activities necessary to develop and obtain the regulatory approval of the 2020 Licensed Assets worldwide. We are further required to use commercially reasonable efforts to commercialize the 2020 Licensed Assets having regulatory approvals in certain specified countries (U.S., UK, France, Germany, Italy, and Spain). We are not required to pay any development, regulatory or sales milestone payments under the 2020 Xencor Agreement. We are required to pay Xencor tiered royalties on annual net sales of successfully commercialized products utilizing the 2020 Licensed Assets. The royalty percentage rates vary by geographic areas and range from the mid-single digits to the mid-teens. On a region-by region basis and product-by-product basis, the term during which the royalties are payable by us to Xencor is until the latest of (a) last-to-expire licensed patent covering the product in the applicable region, (b) the expiration of regulatory exclusivity for the product in the applicable region, or (c) the twelfth anniversary of the first commercial sale of the product in the applicable region. The last-to-expire patent under the 2020 Xencor Agreement will have an expiration date of December 22, 2028 for ZB002 and February 22, 2031 for ZB004, provided the latest application in each of these countries is allowed. The expected termination of the royalty obligations will depend on factors such as the filing of additional patents covering the products during the term of the 2020 Xencor Agreement, the availability and application

34

Table of Contents

of patent term extensions and/or expiration of regulatory exclusivity for the products in the applicable region. We are obligated to reimburse Xencor for certain third-party costs as further specified under the 2020 Xencor Agreement. During the years ended December 31, 2025 and 2024, no costs were reimbursed, respectively.

Under the 2020 Xencor Agreement, (i) Xencor owns all know-how and patent rights invented solely by Xencor, (ii) we own all know-how and patent rights invented solely by us; and (iii) Xencor and we jointly own all joint intellectual property. Subject to the license grants under the 2020 Xencor Agreement, both parties may practice the joint intellectual property for all purposes on a worldwide basis without consent of and without a duty of accounting to the other party.

Under the 2020 Xencor Agreement, during the term of the agreement and for two years thereafter, we agree we will not develop, manufacture, or commercialize a competing product for any 2020 Licensed Asset (i.e., any product that binds to the same target as such 2020 Licensed Asset). The 2020 Xencor Agreement will remain in effect, on a region-by region basis and product-by-product basis, until the expiration of all royalty payment obligations. The 2020 Xencor Agreement may be terminated by either party for the other party’s uncured material breach or insolvency. Xencor may terminate the 2020 Xencor Agreement if we challenge a licensed patent. We may terminate for convenience on a country-by-country basis with advance notice to Xencor, with the notice period differing based on whether such termination right is exercised prior to or following the first commercial sale. Upon termination, all licenses granted by Xencor to us automatically terminate. We are obligated to assign to Xencor all regulatory filings or approvals specifically related to the terminated assets or products. At Xencor’s sole discretion, we are obligated to transfer (a) our rights under agreements between us and third parties that solely relate to the development, manufacture or commercialization of terminated assets or products, (b) all materials developed by us for use for commercialization of terminated assets or products and (c) any product mark for terminated assets or products. Upon termination, if Xencor elects to continue development and commercialization of terminated assets or products, we are obligated to grant to Xencor (a) an exclusive license under certain of our patent rights and (b) a nonexclusive license under certain of our know-how, where such licenses are irrevocable, perpetual, royalty-bearing and sublicensable solely to develop, manufacture, and commercialize the terminated assets or products. In consideration for these licenses, Xencor is obligated to pay us (a) mid-single digits royalty on net sales of the terminated assets or products if Xencor commercializes such terminated assets or products and (b) low double digits percentage of all payments receives from sublicensees if Xencor sublicenses the licenses granted by us. Xencor’s obligation to make payments for these licenses is, on a product-by-product basis and region-by-region basis, until last-to-expire licensed patent covering the product in the applicable region.

2021 Xencor Agreement

In May 2021, we entered into a license agreement (the “2021 Xencor Agreement”) with Xencor to obtain (i) an exclusive, royalty-bearing, sublicensable worldwide license under certain patent rights controlled by Xencor and (ii) a non-exclusive payment bearing license under certain know-how controlled by Xencor to research, develop, manufacture, market and sell obexelimab, an antibody product candidate based on Xencor’s (and its licensors’) proprietary technology. In addition, Xencor granted us a non-exclusive, royalty-free, sublicensable worldwide license under the same patent and know-how rights to develop, manufacture and commercialize companion diagnostics for obexelimab. Xencor obtained the rights to some of the intellectual property licensed to us pursuant to the Upstream Agreements. As such, the 2021 Xencor Agreement provides that the parties agree that some of the licenses granted by Xencor to us constitute sublicenses under the Upstream Agreements and are subject and subordinate to the terms and conditions of the Upstream Agreements. The 2021 Xencor Agreement became effective in November 2021, upon the execution of an amendment to the 2021 Xencor Agreement and Zenas’ concurrent issuance to Xencor of a warrant with a fair value of $20.7 million to Xencor as initial consideration providing Xencor the right to acquire additional equity, such that its total equity in Zenas would be 15% of its fully diluted capitalization at the completion of our Series B financing.

Under the 2021 Xencor Agreement, we are obligated to use commercially reasonable efforts to conduct all future preclinical, clinical, regulatory and other activities necessary to develop and obtain the regulatory approval of obexelimab worldwide. We are further required to use commercially reasonable efforts to commercialize obexelimab following regulatory approvals in certain specified countries (U.S., UK, France, Germany, Italy, and Spain). We were obligated to make development milestone payments of up to $10.0 million, at Xencor’s option either in cash or fully-paid newly issued shares, which milestone payment was paid in Series B Preferred Shares in June 2023.

35

Table of Contents

We are obligated to make regulatory milestone payments up to $75.0 million. We are also obligated to make one-time sales milestone payments up to $385.0 million upon achieving milestone events of net sales in a given calendar year in the territory equal to certain threshold amounts. In addition, we are required to pay Xencor tiered royalties on annual net sales of successfully commercialized products utilizing obexelimab, with the royalty rates varying based on regions and ranging from the mid-single digits to the mid-teens. On a region-by region basis and product-by-product basis, the term during which the royalties are payable by us to Xencor is until the latest of (i) the last-to-expire licensed patent covering the product in the applicable region, (ii) the expiration of regulatory exclusivity for the product in the applicable region, or (c) the twelfth anniversary of the first commercial sale of the product in the applicable region. The last-to-expire patent under the 2021 Xencor Agreement will have an expiration date of October 6, 2041, provided the latest application in each of these countries is allowed. The expected termination of the royalty obligations will depend on factors such as the filing of additional patents covering product during the term of the 2021 Xencor Agreement, the availability and application of patent term extensions and/or expiration of regulatory exclusivity for the product in the applicable region.

Under the 2021 Xencor Agreement, we agree we will not research or develop obexelimab in a way that would produce a molecule that would be classified as obexelimab or an obexelimab product. In addition, during the term and for two years thereafter, we agree not to develop, manufacture, or commercialize a competing product to obexelimab (i.e., any product that binds to CD19 and incorporates FcγRIIb Technology). During the term, Xencor is obligated to refrain from developing, manufacturing, or commercializing a competing product to obexelimab as well. The non-competes do not apply to any pre-existing activity for a competing product of an acquirer, subject to customary restrictions on such activity following such acquisition.

The 2021 Xencor Agreement will remain in effect, on a region-by region basis and product-by-product basis, until the expiration of all royalty payment obligations. The 2021 Xencor Agreement may be terminated by either party for the other party’s uncured material breach or insolvency. We may terminate for convenience on a country-by-country basis with advance notice to Xencor, with the notice period differing based on whether such termination right is exercised prior to or following the first commercial sale. Upon termination, all licenses granted by Xencor to us automatically terminate. We are obligated to assign to Xencor all regulatory filings or approvals specifically related to the terminated assets or products. At Xencor’s sole discretion, we are obligated to transfer (a) our rights under agreements between us and third parties that solely relate to the development, manufacture or commercialization of terminated assets or products, (b) all materials developed by us for use for commercialization of terminated assets or products; and (c) any product mark in relation to the Compound or the Products. Upon termination, if Xencor elects to continue development and commercialization of terminated assets or products, we are obligated to grant to Xencor (a) an exclusive license under certain of our patent rights, and (ii) a nonexclusive license under certain of our know-how, where such licenses are irrevocable, perpetual, royalty-bearing and sublicensable solely to develop, manufacture, and commercialize the terminated assets or products. In consideration for these licenses, Xencor is obligated to pay us (a) mid-single digits royalty on net sales of the terminated assets or products if Xencor commercializes such terminated assets or products and (b) low double digits percentage of all payments receives from sublicensees if Xencor sublicenses the licenses granted by us. Xencor’s obligation to make payments for these licenses is, on a product-by-product basis and region-by-region basis, until the last-to-expire licensed patent covering the product in the applicable region.

License Agreement with Bristol-Myers Squibb

In August 2023 (the “BMS Effective Date”), we entered into a strategic license and collaboration agreement (the “BMS Agreement”) with Bristol-Myers Squibb (“BMS”)  under which we provided (a) an exclusive (even as to us) license under certain of our patents and joint patents to be developed under the BMS Agreement, and (b) a non-exclusive license under certain of our know-how. The license grants are for BMS to (a) develop, manufacture (subject to our rights to be the exclusive manufacturer for BMS for a certain period of time), commercialize or otherwise exploit our proprietary CD19 and FcγRIIb antibody, obexelimab (the “Compound”) and any biological product (irrespective of presentations, formulations or dosages) containing the Compound but not any of our other proprietary active ingredient (the “Product”) for treatment of any disease in human or animal in Japan, South Korea, Taiwan, Singapore, Hong Kong and Australia (the “BMS Territory”) and (b) conduct development and manufacture of the Compound and Products outside the BMS Territory provided that the Compound and Product are solely used in the BMS Territory. We also provided BMS a non-exclusive and royalty-free license under the same patent and know-how rights for BMS to develop, manufacture, commercialize, or otherwise exploit companion diagnostics for the Compound and Products in the BMS Territory. We retain all rights to commercialize obexelimab outside of the BMS Territory.

36

Table of Contents

Under the BMS Agreement, during the term of the BMS Agreement and for a certain period thereafter, BMS has agreed not to develop, manufacture, or commercialize in the BMS Territory a competing product to obexelimab. We have similarly agreed, during the term of the BMS Agreement and for a certain period thereafter, not to develop, manufacture of commercialize in the BMS Territory a product that competes with obexelimab. The non-competes do not apply to any pre-existing activity for a competing product of an acquirer, subject to customary restrictions on such activity following such acquisition.

Under the BMS Agreement, we own all intellectual property in (a) improvements and modification to our pre-existing intellectual property, irrespective of which party develops such improvements and modification, (b) any item relating solely to the Compound and Products derived from use of our pre-existing intellectual property and confidential information, irrespective of which party develops such item and (c) any item generated solely by us in relation to the BMS Agreement. With the exclusion of intellectual property allocated as our intellectual property pursuant to (a) or (b) in the foregoing, (a) BMS shall own intellectual property generated solely by BMS under this Agreement and (b) parties will jointly own all other jointly developed intellectual property.

As part of the BMS Agreement, BMS is solely responsible for conducting all development activities required to obtain regulatory approval for the Compound or Products in the BMS Territory and BMS is obligated to use commercially reasonable efforts to develop at least one Product and seek and maintain regulatory approvals for such Product in Japan and certain other jurisdictions in the BMS Territory.

The parties agreed that we will manufacture and supply and BMS will exclusively purchase all of BMS’s requirements of (a) Products (and placebo) for development in the BMS Territory, subject to the terms of a separate clinical supply agreement and clinical supply quality agreement, to be executed after the BMS Effective Date and (b) finished Products for commercialization in the BMS Territory, subject to the terms of a separate commercial supply agreement and commercial supply quality agreement, to be executed within a certain number of months prior to the first regulatory approval in the BMS Territory. However, BMS may elect to manufacture the Product itself or via a third party (a) at any time after a certain period following the BMS Effective Date or (b) during such period following the BMS Effective Date if we fail to supply above a certain threshold quantity of the Product ordered in any given calendar quarter. BMS has exclusive rights to commercialize the Product in the BMS Territory and is obligated to use commercially reasonable efforts to commercialize Products in Japan and certain other jurisdictions in the BMS Territory after obtaining the applicable regulatory approvals.

Under the terms of the BMS Agreement, we have received a one-time upfront payment of $50.0 million. We are entitled to receive further separate development and regulatory milestone payments up to $79.5 million and sales milestone payments up to $70.0 million upon BMS achieving certain net sales milestones in a given calendar year in the BMS Territory.

In addition, if BMS successfully develops and commercializes the Product in the BMS Territory, BMS will pay us tiered royalties ranging from (a) the mid-teens to very-low twenties for net sales of Product in Japan and (b) high single digit to low-teens for net sales of Product in all other countries in the BMS Territory, subject to specified reductions. On a country-by-country basis, the term during which the royalties are payable to us is until the latest of (a) the last-to-expire licensed patent covering the Product, (b) the expiration of regulatory exclusivity for the Product or (c) the twelfth anniversary of the first commercial sale of the Product. As of the date of this Annual Report, the last-to-expire patent under the BMS Agreement will have an expiration date of October 2, 2044, provided the latest application in each of these countries is allowed. The expected termination of the royalty obligations will depend on factors such as the filing of additional patents covering the Product during the term of the BMS Agreement, the availability and application of patent term extensions and/or expiration of regulatory exclusivity for the Product in the BMS Territory. Finally, BMS will be required to pay a portion of the costs associated with our ongoing INDIGO Trial, in which BMS is participating, as well as any other global study in which BMS elects to participate. During the years ended December 31, 2025 and 2024, we recorded $5.5 million and $6.0 million, respectively, as a reduction to research and development expense for costs associated with our INDIGO Trial, including the OLE, that have been reimbursed by BMS. During the fiscal years ended December 31, 2025 and 2024, we did not recognize revenue pursuant to the BMS Agreement.

The BMS Agreement will remain in effect, on a country-by-country basis, until the expiration of all royalty payment obligations, and may be earlier terminated by either party for the other party’s uncured material breach or insolvency.

37

Table of Contents

BMS may terminate for convenience on a country-by-country basis with advance notice to us, with the notice period differing based on whether such termination right is exercised prior to or following the first commercial sale. In addition to customary events of termination, we also have a right to terminate the agreement (a) automatically upon written notice if the 2020 Xencor Agreement terminates and (b) with written notice if BMS challenges the licensed patents.

Upon termination of the BMS Agreement, all licenses granted by us to BMS will automatically terminate and BMS is obligated to cease developing, manufacturing (subject to any transition assistance) and commercializing the Compound and Products in the BMS Territory. Additionally, BMS is obligated to transfer to us all regulatory filings and regulatory approvals related to the Compound or the Products in the Field in the BMS Territory. BMS is further obligated, at our sole discretion, to assign to us (to the extent permissible) (a) BMS’s rights under agreements between BMS and third parties that solely relate to the development, commercialization or manufacture of the Compound or the Products, (b) documentation relating to the commercialization of the Compound or the Products in the BMS Territory; and (c) any BMS owned marks for the Compound or the Products. BMS is obligated to provide reasonable transition supply assistance with respect to any agreement for manufacturing Compound or Products transferred to us, including manufacturing the Compound or Products for up to 18 months following termination.

License Agreement with InnoCare Pharma Inc.

In October 2025, we entered into a License Agreement (the “InnoCare License Agreement”) with InnoCare to obtain exclusive rights to develop, manufacture, and commercialize: i) orelabrutinib, in the MS field worldwide, and in all non-oncology indications outside greater China and Brunei, Burma, Cambodia, Timor-Leste, Indonesia, Laos, Malaysia, Philippines, Singapore, Thailand and Vietnam (“Southeast Asia”), ii) ZB021 (an IL-17AA/AF inhibitor) in all fields of use worldwide, excluding greater China and Southeast Asia and iii) ZB022 (a TYK2 inhibitor) in all fields of use worldwide. We also obtained certain non-exclusive rights to perform development and manufacturing activities in greater China and Southeast Asia to support each program in its respective licensed territories.

Pursuant to the InnoCare License Agreement, made a one-time non-refundable upfront cash payment of $35.0 million, which was recorded in the consolidated statement of operations and comprehensive loss as acquired in-process research and development expenses for the year ended December 31, 2025. We issued 5,000,000 shares of common stock to InnoCare in a private placement as partial consideration for these rights.

We are also required to make an additional one-time non-refundable cash payment of $25.0 million and issue an additional 2,000,000 shares of common stock through a private placement upon the occurrence of our initiation of a Phase 3 clinical trial for orelabrutinib in any indication other than PPMS, or by March 31, 2026, upon the occurrence of certain specified events, whichever comes first (together with the 5,000,000 shares issued to InnoCare upfront, the “InnoCare Shares”). During the year ended December 31, 2025, we recorded $136.7 million of expense based on fair value of the 5,000,000 shares issued and the 2,000,000 shares to be issued to InnoCare on the date the InnoCare License Agreement was executed, in the consolidated statement of operations and comprehensive loss as acquired in-process research and development expense.

In addition, we have agreed to make one-time, potential near-term milestone payments of $20.0 million each, upon the achievement of certain regulatory milestones for ZB021 and ZB022 (the “Regulatory Milestones”).

We are further obligated to pay future regulatory and commercial milestones of up to $723.0 million related to orelabrutinib, and future development, regulatory, and commercial milestones of up to $656.0 million, inclusive of the two $20.0 million Regulatory Milestones specified above, for each preclinical compound if certain milestones are successfully achieved. In addition, we may be obligated to pay royalties on net sales at rates ranging from high-single digits to high-teens for orelabrutinib, and mid-single digits to mid-teens for the preclinical compounds.

We simultaneously entered into a Subscription Agreement and a Registration Rights Agreement with InnoCare related to the shares of common stock issued and to be issued in the private placements. The Subscription Agreement provides for transfer restrictions on the InnoCare Shares and contains other customary representations, warranties and covenants that were made solely for the benefit of the parties to the Subscription Agreement. The Registration Rights Agreement requires us to among other things, prepare and file a registration statement to register the InnoCare Shares.

38

Table of Contents

Intellectual Property

We own or license patents in the U.S. and foreign countries that protect our products, their methods of use and manufacture, as well as other innovations important to our business, and in order to help bring new therapies to patients. We consider the overall protection of our patents, trademarks, licenses and other intellectual property rights to be of material value. We also rely on trade secrets to protect aspects of our business that are not amenable to, or that we do not consider appropriate for, patent protection. Our success will, in part, depend on our ability to obtain and maintain patent and other proprietary protection for commercially important technology, inventions and know-how related to our business, defend and enforce our patents, preserve the confidentiality of our trade secrets and operate without infringing the valid and enforceable patents and other proprietary rights of third parties. We also rely on regulatory protection, particularly biological data exclusivity, know-how, continuing technological innovation and in-licensing opportunities to develop, strengthen and maintain the proprietary position of our products and development programs.

In the biopharmaceutical industry, a substantial portion of an innovative product’s commercial value is usually realized during the period in which the product has exclusivity. A product’s exclusivity is generally determined by two forms of intellectual property: patent rights held by the innovator company and any regulatory forms of exclusivity to which the innovative drug is entitled.

Patents are a key determinant of exclusivity for most pharmaceuticals. Patents provide the innovator with the right to exclude others from practicing an invention related to the medicine. Patents may cover, among other things, the active ingredient(s), various uses of a drug product, discovery tools, pharmaceutical formulations, biomarkers, drug delivery mechanisms and processes for (or intermediates useful in) the manufacture of products. The protection afforded by a patent extends for a 20-year term from its filing date, without taking into account any potential patent term adjustment or extension. The protection provided by a patent depends on the scope of its coverage and the availability of meaningful legal remedies to enforce patent claims in the country or countries where it has issued.

Market exclusivity can also be influenced by regulatory data protection (“RDP”). Many developed countries provide certain non-patent incentives for the development of medicines. For example, in the U.S., EU member states, UK, Japan, and certain other countries, RDP intellectual property rights are offered to: (i) provide a time period of data protection during which a generic company is not allowed to rely on the innovator’s data in seeking approval; (ii) restore patent term lost during drug development and approval; and (iii) provide incentives for research on medicines for rare diseases, or orphan drugs, and on medicines useful in treating pediatric patients. These incentives may extend a product’s market exclusivity period beyond the patent term.

Patent Portfolio

As of February 1, 2026, we own or exclusively in-license 28 patent families that specifically cover our product candidates obexelimab (our CD19 and FcγRIIb antibody), orelabrutinib (our BTK inhibitor), ZB002 (our anti-TNFα antibody), ZB004 (our CTLA-4-Ig fusion protein), ZB021 (our IL-17AA/AF inhibitor) and ZB022 (our TKY2 inhibitor). These families include 25 issued U.S. patents, 13 pending U.S. applications, 198 issued foreign patents, seven pending patent cooperation treaty (“PCT”) applications and 88 pending foreign patent applications in Australia, Brazil, Canada, China, Colombia, Eurasia, Europe, Hong Kong, India, Israel, Japan, Malaysia, Mexico, New Zealand, Saudi Arabia, Singapore, South Africa, South Korea, Taiwan and the United Arab Emirates. In addition, we own or exclusively in-license seven U.S. provisional patent applications, which belong to five different patent families, within the priority year. Any U.S. or foreign patents issued from national stage filings of our owned, or exclusively in-licensed PCT patent applications, any U.S. patents issued from our exclusively in-licensed non-provisional applications, and any U.S. patents or foreign patents issued from non-provisional applications we may file in connection with our provisional patent applications would be scheduled to expire on various dates from 2027 through 2047.

All expected expiration dates provided herein are based on a 20-year term, without taking into account any possible patent term adjustment (“PTA”) or patent term extension (“PTE”) and assuming payment of all appropriate maintenance, renewal, annuity or other governmental fees.

39

Table of Contents

Obexelimab

Obexelimab is a bifunctional, non-cytolytic, humanized monoclonal antibody that binds CD19 and FcγRIIb to inhibit B-lineage cell activity. As of February 1, 2026, we own or exclusively in-license from Xencor 14 patent families that specifically cover the composition of matter, mechanism of action, formulation, manufacturing, biomarkers, and clinical uses of obexelimab for treating IgG4-RD, SLE, MS and wAIHA.

A first patent family specifically covers the composition of matter of obexelimab and includes seven issued patents and one pending applications in the U.S., and 21 issued foreign patents in Australia, Hong Kong, India, Israel and various European countries including Belgium, Denmark, France, Germany, Ireland, Italy, Latvia, Lithuania, Luxembourg, Monaco, Netherlands, Spain, Sweden, Switzerland, and UK. The 20-year statutory term for the patents issued in this family expires in May 2028, excluding any extension of patent term that may be available.

A second patent family is directed to obexelimab’s mechanism of action and formulation, which includes two issued patents and one pending application in the U.S., five pending applications in Canada, Europe, Hong Kong and Japan, and 20 issued patents in Japan and European countries including Austria, Belgium, Denmark, France, Finland, Germany, Hungary, Ireland, Italy, Netherlands, Norway, Poland, Portugal, Spain, Switzerland, Sweden, Turkey and UK. The 20-year statutory term for any patents issued in this family expires in June 2037, excluding any extension of patent term that may be available.

A third patent family is directed to the use of biomarkers for treating autoimmune diseases (e.g., SLE) and includes one pending U.S. application, and 12 pending applications in Australia, Brazil, Canada, China, Europe, Hong Kong, Israel, Japan, South Korea, Mexico, South Africa and Taiwan and one issued patent in Eurasia. The 20-year statutory term for any patents issued in this family would expire in October 2041, excluding any extension of patent term that may be available.

A fourth patent family is directed to the clinical use of obexelimab for treating IgG4-RD, currently including one pending U.S. Application, and 20 pending applications in Australia, Brazil, Canada, China, Eurasia, Europe, Hong Kong, Israel, Japan, Malaysia, Mexico, New Zealand, Saudi Arabia, Singapore, South Africa, South Korea, Taiwan and the United Arab Emirates. The 20-year statutory term for any patents issued in this family would expire in June 2043, excluding any extension of patent term that may be available.

A fifth patent family is directed to the clinical use of obexelimab for treating AIHA, including wAIHA, currently including one pending U.S. application and six pending applications in Australia, Europe, Japan, South Korea, Singapore, and Taiwan. The 20-year statutory term for any patents issued in this family would expire in April 2044, excluding any extension of patent term that may be available.

A sixth patent family is directed to the clinical use and dosing regimen of obexelimab for treating forms of MS, including RMS, and currently including a pending PCT application, a pending U.S. application, and a pending Taiwanese application. The 20-year statutory term for any patents issued in this family would expire in October 2044, excluding any extension of patent term that may be available.

A seventh patent family is directed to the clinical use and dosing regimen of obexelimab for treating forms of MS, including RMS, and currently including a pending PCT application, a pending U.S. application, and a pending Taiwanese application. The 20-year statutory term for any patents issued in this family would expire in January 2045, excluding any extension of patent term that may be available.

An eighth patent family is directed to the SC administration of obexelimab for treating SLE currently including a pending PCT application, a pending U.S. application, and a pending Taiwanese application. The 20-year statutory term for any patents issued in this family would expire in January 2045, excluding any extension of patent term that may be available.

A ninth patent family is directed to the manufacturing processes for obexelimab currently including a pending PCT application, a pending U.S. application, and a pending Taiwanese application. The 20-year statutory term for any patents issued in this family would expire in June 2045, excluding any extension of patent term that may be available.

40

Table of Contents

A tenth patent family is related to the clinical use of obexelimab for treating wAIHA and includes a pending PCT application, and a Taiwanese application.  The 20-year statutory term for any patents issued in this family would expire in October 2045, excluding any extension of patent term that may be available.

An eleventh patent family is directed to methods of determining potency of obexelimab currently including two provisional applications filed within the priority year. Assuming the provisional application is converted to a non-provisional application at the 12-month from priority deadline, the 20-year statutory term for any patents issued in this family would expire in May 2046, excluding any extension of patent term that may be available.

A twelfth patent family is directed to methods of vaccination during treatment course with obexelimab currently including one provisional application filed within the priority year. Assuming the provisional application is converted to a non-provisional application at the 12-month from priority deadline, the 20-year statutory term for any patents issued in this family would expire in June 2046, excluding any extension of patent term that may be available.

A thirteenth patent family is directed to the clinical use and dosing regimen of obexelimab for treating forms of MS, including RMS and SPMS, currently including two provisional applications filed within the priority year. Assuming the provisional application is converted to a non-provisional application at the 12-month from priority deadline, the 20-year statutory term for any patents issued in this family would expire in October 2046, excluding any extension of patent term that may be available.

A fourteenth patent family is based on the Phase 3 clinical data of obexelimab for treating IgG4-RD currently including one provisional application filed within the priority year. Assuming the provisional application is converted to a non-provisional application at the 12-month from priority deadline, the 20-year statutory term for any patents issued in this family would expire in January 2047, excluding any extension of patent term that may be available.  A PTE of up to five years may be available and can be applied in one of these families as appropriate.

Orelabrutinib

Orelabrutinib is a highly selective CNS-penetrant, oral small molecule BTK inhibitor. As of February 1, 2026, we exclusively in-licensed seven patent families from InnoCare that specifically cover the composition of matter, polymorphs, amorphous solid dispersion form, synthetic processes, and the uses of orelabrutinib for treating multiple sclerosis and Alzheimer’s disease.

A first patent family covers the composition of matter of orelabrutinib and includes five issued patents and one pending patent application in the U.S., and 45 issued patents in Australia, Canada, India, Japan, South Korea, Mexico, New Zealand, Russia and various European countries including Albania, Austria, Belgium, Bulgaria, Croatia, Cyprus, Czechia, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Monaco, the Netherlands, North Macedonia, Norway, Poland, Portugal, Romania, San Marino, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey, and UK. The 20-year statutory term for the patents issued in this family expires in September 2034, excluding any extension of patent term that may be available.

A second family covers the polymorphs of orelabrutinib and currently includes one issued patent in the U.S., four pending patent applications in Canada, India, Japan, and South Korea, and 10 issued patents in Australia, Mexico, New Zealand and various European countries including France, Germany, Italy, the Netherlands, Spain, Switzerland, and UK. The 20-year statutory term for the patents issued in this family expires in September 2039, excluding any extensions of patent term that may be available.

A third family covers the amorphous solid dispersion form of orelabrutinib and currently includes one issued patent in the U.S., one pending patent application in Canada, and 13 issued patents in Australia, Japan, South Korea, Mexico, New Zealand and various European countries including Belgium, France, Germany, Italy, the Netherlands, Spain, Switzerland, and UK. The 20-year statutory term for the patents issued in this family expires in October 2039, excluding any extensions of patent term that may be available.

A fourth family covers processes for synthesizing orelabrutinib and currently includes one issued patent in the U.S., four pending applications in Brazil, Canada, Europe, and South Korea, and six issued patents in Australia, India, Japan, Mexico,

41

Table of Contents

New Zealand, and Russia. The 20-year statutory term for the patents issued in this family expires in February 2040, excluding any extensions of patent term that may be available.

A fifth family covers improved processes for synthesizing orelabrutinib and currently includes one pending U.S. application and 16 pending applications in Australia, Brazil, Canada, Colombia, Eurasia, Europe, Israel, India, Japan, Mexico, New Zealand, Saudi Arabia, South Africa, South Korea, and the United Arab Emirates. The 20-year statutory term for any patents issued in this family would expire in July 2044, excluding any extensions of patent term that may be available.

A sixth family covers the use of orelabrutinib for treating multiple sclerosis and currently includes one pending U.S. patent application and 10 pending patent applications in Australia, Canada, China, Europe, Hong Kong, Japan, South Korea, Mexico, New Zealand, and Singapore. The 20-year statutory term for any patents issued in this family would expire in November 2043, excluding any extensions of patent term that may be available.

A seventh family covers the use of orelabrutinib for treating Alzheimer’s disease and currently includes a pending PCT application. The 20-year statutory term for any patents issued in this family would expire in January 2045, excluding any extensions of patent term that may be available.

A PTE of up to five years may be available and can be applied in one of these families as appropriate.

ZB002

ZB002 is an anti-TNFα monoclonal antibody with the Xtend technology modified to have an extended half-life as compared to existing anti- TNFα therapies. As of February 1, 2026, we exclusively own or in-licensed three patent families covering ZB002.

A first patent family specifically covers the full-length amino acid sequences of ZB002, including four issued patents in the U.S., Brazil, Japan and Russia, and two pending applications in Europe and Hong Kong. The 20-year statutory term for U.S. patents in this family expires in October 2027 and any foreign patents that are in this family are expected to expire in December 2028, excluding any extension of patent term that may be available.

A second patent family is directed to the formulation and dosing of ZB002 in treating autoimmune diseases including one pending U.S. application, one pending PCT application and one pending application in Taiwan. The 20-year statutory term for any patents issued in this family would expire in March 2045.

A third patent family is directed to the manufacturing processes for ZB002 including one provisional application. Assuming the provisional application is converted to a non-provisional application at the 12-month from priority deadline, the 20-year statutory term for any patents issued in this family would expire in September 2046, excluding any extension of patent term that may be available. Assuming the provisional application is converted to a non-provisional application at the 12-month from priority deadline, the 20-year statutory term for any patents issued in this family would expire in September 2046, excluding any extension of patent term that may be available.

A PTE of up to five years may be available and can be applied in one of these families as appropriate.

ZB004

ZB004 is a CTLA-4-Ig fusion protein with the Xtend technology modified to have an extended half-life versus existing CTLA-4-Ig fusion protein therapies. As of February 1, 2026, we own or exclusively in-licensed two patent families relating to the composition of matter of ZB004 and related methods of use.

A first patent family specifically covers the composition of matter and related methods of use ZB004 including seven issued patents and 81 issued foreign patents in Australia, Canada, China, Hong Kong, India, Japan, South Korea and European countries including Albania, Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lichtenstein, Lithuania, Luxembourg, Macedonia, Malta, Monaco, Netherlands, Norway, Poland, Portugal, Romania, San Marino, Serbia, Slovakia, Slovenia,

42

Table of Contents

Spain, Sweden, Switzerland, Turkey, and UK. The 20-year statutory term for the patents issued in this family expires in February 2031, excluding any extension of patent term that may be available.

A second patent family is related to the formulation and dosing regimen of ZB004 in treating autoimmune diseases currently including one pending PCT application. The 20-year statutory term for any patents issued in this family would expire in September 2045.

A PTE of up to five years may be available and can be applied in one of these families as appropriate.

ZB021

ZB021 is a small molecule IL-17AA/AF inhibitor that blocks IL-17AA homodimer and IL-17AF heterodimer signaling for minimizing inflammatory responses. As of February 1, 2026, we exclusively in-license from InnoCare one patent family that specifically covers the composition of matter. This family includes one pending PCT application, and one pending U.S. patent application. The 20-year statutory term for the patents issued in this family expires in March 2045, excluding any extensions of patent term that may be available.

ZB022

ZB022 is a small molecule brain-penetrant TYK2-JH2 inhibitor that blocks the TYK2-mediated receptor-stimulated pathways. As of February 1, 2026, we exclusively in-license from InnoCare one patent family that specifically covers the composition of matter. This family currently includes one pending PCT application. The 20-year statutory term for the patents issued in this family expires in July 2045, excluding any extensions of patent term that may be available.

Trademark Portfolio

The Company owns trademark applications and registrations for “Zenas BioPharma” and the Zenas BioPharma logo, and the “lightning bold” design in the U.S. and other foreign jurisdictions. The Company also owns trademark applications and registrations related to potential drug name candidate trademarks in the U.S. and other foreign jurisdictions.

​

Manufacturing

We do not own or operate, and currently have no plans to establish, any manufacturing facilities. We have engaged, and currently rely on, single source third-party CMO, WuXi Biologics, for the supply of obexelimab drug product, and our collaboration partner, InnoCare, for the supply of orelabrutinib, ZB021 and ZB022, for use in our preclinical and clinical trials. In addition, we have selected new CMOs in the U.S., which are not affiliated with Wuxi Biologics, to establish additional sources of supply for obexelimab drug substance and drug product for both commercial and clinical use. However, should our CMO, WuXi Biologics, or our collaboration partner, InnoCare, become unavailable to us for any reason, we believe that we would incur delay and cost in order to complete the manufacturing validation and qualification process for such replacements.

We maintain a master services agreement with Wuxi Biologics pursuant to which it provides biologics development and manufacturing services on a per-project basis. We may terminate the master services agreement at any time for convenience in accordance with the terms of the agreement. We may also terminate the master services agreement in the event that Wuxi Biologics does not obtain or maintain any material governmental license or approval in accordance with the terms of the agreement. The agreement includes confidentiality and intellectual property provisions to protect our proprietary rights related to our product candidates. While any reduction or halt in supply from the CMO could limit our ability to develop our product candidates until a replacement CMO is found and qualified, we believe that we have sufficient supply to support our current clinical trial programs. See “Risk Factors” for additional information.

We have a long-term commercial supply agreement with WuXi Biologics to fulfill and secure obexelimab drug substance and drug product for an anticipated commercial launch, if approved. In addition, we have selected new CMOs in the U.S., which are not affiliated with WuXi Biologics, to establish additional sources of supply for obexelimab drug substance and drug product for both commercial and clinical use. For the medical device component of our product (i.e., prefilled syringe

43

Table of Contents

or autoinjector), we plan to utilize device assembly facilities in the U.S. or EU for the global supply. While the drug substances used in our product candidates are manufactured by more than one supplier, we rely on a single third-party manufacturer to manufacture and supply the drug substances, drug products, raw materials, samples, components and other materials for our product candidates. In the event it is necessary or advisable to acquire supplies from alternative sources, we might not be able to obtain them at reasonable prices, or at all. It could also require significant time and expense to transfer our manufacturing processes to another company. If we need to change manufacturers for any reason, we will be required to verify that the new manufacturer maintains facilities and procedures that comply with applicable quality standards, regulations and guidelines, and we may be required to conduct additional studies.

Additionally, to adequately meet our projected manufacturing needs for commercializing obexelimab and our other product candidates, our CMOs will need to scale-up production or we will need to secure additional suppliers. Processes for producing obexelimab drug substance and drug product for commercial supply have been developed and defined. We believe the drug substance and drug product processes for obexelimab and our other product candidates are amenable to scale-up.

Sales, Marketing and Commercialization

We hold global development and commercialization rights to obexelimab, excluding Japan, Taiwan, South Korea, Singapore, Hong Kong and Australia, which we have licensed to BMS. We also hold the global development and commercialization rights to ZB002 and ZB004.  We also in-licensed from InnoCare certain exclusive rights to orelabrutinib and two early-development product candidates: ZB021 and ZB022.

If our product candidates receive FDA or EMA approval, we intend to build our own commercialization infrastructure in the U.S. and Europe, to market and sell our products. For Asia and other geographies, we plan to conduct the initial clinical development work and then seek to enter into an agreement with a third party to complete the clinical development work, obtain regulatory approval, and ultimately commercialize in these territories. However, we intend to continually evaluate the economics of potentially commercializing our product candidates ourselves, if approved, versus other strategic commercialization arrangements.

We currently have limited sales, marketing and commercialization capabilities as we are early in the process of building a commercial organization to support the potential launch of obexelimab in the U.S. and Europe. We intend to continue to build the necessary capabilities and infrastructure over time We believe that clinical data, the size of the market opportunity and the size of the required commercial infrastructure will influence our commercialization plans and decision making.

Competition

The biotechnology and pharmaceutical industries are characterized by rapidly advancing technologies, intense competition and a strong emphasis on proprietary drugs. While we believe that our knowledge, experience and scientific resources provide us with competitive advantages, we face potential competition from many different sources, including large and specialty pharmaceutical and biotechnology companies, academic research institutions and governmental agencies, as well as public and private research institutions. Any product candidates that we successfully develop and commercialize, if approved, will compete with existing therapies and new therapies that may become available in the future.

The key competitive factors affecting the success of all of our product candidates, if approved, are likely to be their safety, efficacy, convenience, price, the level of generic competition, the existence of therapeutic alternatives and the availability of coverage and reimbursement from government and other third-party payors.

Many of the companies against which we are competing, or against which we may compete in the future, have significantly greater financial resources and expertise in research and development, manufacturing, preclinical testing, conducting clinical trials, obtaining regulatory approvals and marketing approved drugs than we do. Mergers and acquisitions in the pharmaceutical and biotechnology industries may result in even more resources being concentrated among a smaller number of our competitors. Smaller or early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies. These competitors also compete with us in recruiting and retaining qualified scientific and management personnel and establishing clinical trial sites and patient registration for clinical trials, as well as in acquiring technologies complementary to, or necessary for, our programs.

44

Table of Contents

We are currently developing obexelimab for IgG4-RD, MS, and SLE. In April 2025, FDA approved Uplizna® (inebilizumab-cdon), an anti-CD19 antibody, which is the first and only FDA-approved therapy for adults with IgG4-RD. There are also two products approved for SLE, and a number of products approved for MS. Moreover, there are a number of product candidates in clinical development by other companies for IgG4-RD, MS, and SLE that may become available in the future.

We are also currently developing orelabrutinib for PPMS and non-active SPMS. For PPMS, there is currently one FDA-approved therapy, Ocrevus® (ocrelizumab), a humanized anti-CD20 monoclonal antibody marketed by F. Hoffmann-La Roche Ltd. For non-active SPMS, there are currently no FDA-approved therapies. Additional product candidates in clinical development by other companies may become available for PPMS and non-active SPMS in the future.

Potentially competitive therapies by indication fall primarily into the following groups of treatment:

IgG4-RD:

RMS:

45

Table of Contents

PPMS:

SPMS:

SLE:

46

Table of Contents

We are also developing ZB021, an oral IL-17 AA/AF inhibitor. There are four FDA-approved IL-17 programs for various indications, all of which are in intravenous or subcutaneous formulations, including Cosentyx® (secukinumab) marketed by Novartis AG, Taltz® (ixekizumab) marketed by Eli Lilly and Company, Bimzelx® (bimekizumab-bkzx) marketed by UCB SA, and Siliq® (brodalumab) marketed by Bausch Health Companies Inc. There are currently no FDA-approved IL-17 biosimilars. There are several IL-17 programs in clinical development in the US, including oral small molecule and oral peptide programs such as simepdekinra by Eli Lilly and Company in Phase 2 development, PN-881 by Protagonist Therapeutics Inc. in Phase 1 development, and ASC-50 by Ascletic Pharma Inc. in Phase 1 development. Additional oral IL-17 programs are in preclinical development.

We are also developing ZB022, a brain-penetrant TYK2 inhibitor. There is one FDA-approved TYK2 inhibitor, Sotyktu® (deucravacitinib) marketed by Bristol-Myers Squibb Company, indicated for adults with moderate-to-severe plaque psoriasis. Sotyktu is a peripheral acting TYK2 inhibitor. There are currently no FDA-approved TYK2 inhibitor biosimilars. There are several TYK2 inhibitor programs in clinical development in the US, including the following Phase 3 programs: zasocitinib, a peripheral acting TYK2 inhibitor being developed by Takeda Pharmaceutical Company Limited, envudeucitinib, a brain-penetrant TYK2 inhibitor being developed by Alumis Inc., and BHV-8000, a brain-penetrant TYK2/JAK1 inhibitor being developed by Biohaven Therapeutics Ltd. Additional Phase 1 and Phase 2 clinical TYK2 programs, as well as preclinical TYK2 programs, are in development across numerous indications.

47

Table of Contents

Government Regulation

Government authorities at the federal, state and local level in the U.S. and in other countries and jurisdictions, including the EU, extensively regulate, among other things, the research, development, testing, manufacture, pricing, reimbursement, sales, quality control, approval, packaging, storage, recordkeeping, labeling, advertising, promotion, distribution, marketing, post-approval monitoring and reporting and import and export of biological products such as those we are developing.

We, along with our CMOs, contract research organizations (“CROs”) and third-party vendors, will be required to satisfy these requirements in each of the countries in which we wish to conduct studies or seek approval or licensure of our product candidates. The processes for obtaining marketing approvals in the U.S. and in foreign countries and jurisdictions, along with subsequent compliance with applicable statutes, regulations, and other regulatory requirements, require the expenditure of substantial time and financial resources.

In the U.S., where we are initially focusing our product development, the FDA regulates biologics and small molecule drugs under the Federal Food Drug and Cosmetic Act (“FDCA”) and Public Health Service Act (“PHSA”), and their implementing regulations. Both biologics and small molecule drugs are also subject to other federal, state and local statutes and regulations. Our product candidates have not been approved for marketing in the U.S.

An applicant seeking approval to market and distribute a new biologic or small molecule drug in the U.S. must satisfactorily complete each of the following steps:

48

Table of Contents

Failure to comply with the applicable requirements at any time during the product development process, including preclinical testing, clinical testing, the approval process, or post-approval process, may subject an applicant to delays in the conduct of the study or regulatory review and approval, as well as administrative or judicial sanctions or other consequences. These sanctions or consequences may include, but are not limited to, the FDA’s refusal to allow an applicant to proceed with clinical testing, issuance of clinical holds for planned or ongoing studies, refusal to approve pending applications, suspension or revocation of existing product licenses or approvals, issuance of warning or untitled letters, adverse publicity, product recalls, marketing restrictions, product seizures, import detentions and refusals, total or partial suspension of manufacturing or distribution, injunctions, fines and civil or criminal investigations and penalties brought by the FDA or the Department of Justice (“DOJ”), and other governmental entities, including state agencies.

Preclinical Studies and Investigational New Drug Application

Once a therapeutic product candidate is identified for development, it must undergo preclinical studies (also known as preclinical testing) before any testing may be conducted in humans. Preclinical tests include laboratory evaluations of product chemistry, formulation and stability, as well as studies to evaluate the potential for efficacy and toxicity in animals. The conduct of preclinical tests and formulation of the compounds for testing must comply with federal regulations and requirements, including GLPs. The results of the preclinical tests, together with manufacturing information, analytical data, and plans for the proposed clinical studies, are submitted to the FDA as part of an IND. Some preclinical testing may continue after an IND is submitted.

An IND is a request for FDA authorization to administer an investigational new drug product to humans. The IND automatically becomes effective 30 days after receipt by the FDA, unless before that time the FDA raises concerns or questions about the product or the conduct of the proposed clinical trial, including concerns that human research subjects will be exposed to unreasonable health risks. In that case, the IND sponsor and the FDA must resolve any outstanding FDA concerns before the clinical trials can begin. As a result, submission of an IND may or may not result in FDA authorization to begin a clinical trial, or to begin a clinical trial on the terms originally specified by the sponsor in the IND.

At any time during the initial 30-day IND review period or while clinical trials are ongoing under the IND, the FDA may impose a partial or complete clinical hold. Clinical holds may be imposed by the FDA when there is concern for patient safety, and may be a result of new data, findings, or developments in clinical, preclinical, and/or chemistry, manufacturing and controls (“CMC”) or where there is non-compliance with regulatory requirements. This order would delay either a proposed clinical trial or cause suspension of an ongoing trial, until all outstanding concerns have been adequately addressed and the FDA has notified the company that investigations may proceed. A separate submission to an existing IND must also be made for each successive clinical trial conducted, and the FDA must grant authorization, either explicitly or implicitly, by not objecting before each clinical trial can begin.

Human Clinical Trials

Clinical trials involve the administration of an investigational drug product to healthy volunteers or patients with the disease or condition to be treated under the supervision of qualified investigators. Clinical trials must be conducted in accordance with cGCPs, which establish ethical and data integrity standards for clinical testing, as well as the requirements for informed consent.

Clinical trials are conducted under protocols detailing, among other things, the objectives of the trial, dosing procedures, inclusion and exclusion criteria, the parameters to be used in monitoring safety, and the effectiveness criteria to be evaluated. A protocol for each clinical trial and any subsequent protocol amendments must be submitted to the FDA as part of the IND.

49

Table of Contents

For clinical trials conducted in the U.S., an IND is required, and each clinical trial must be reviewed and approved by an IRB either centrally or individually at each institution at which the clinical trial will be conducted. The IRB will consider, among other things, clinical trial design, patient informed consent, ethical factors, the safety of human subjects and the possible liability of the institution. An IRB must operate in compliance with FDA regulations.

The FDA, Institutional Review Board (“IRB”) or the trial sponsor may suspend a clinical trial at any time on various grounds, including a finding that the trial is not being conducted in accordance with cGCPs or IRB requirements or that research subjects or patients are being exposed to an unacceptable health risk. In addition, some clinical trials are overseen by an independent group of qualified experts organized by the sponsor, known as a data safety monitoring board or data monitoring committee. Depending on its charter, this group may recommend continuation of the trial as planned, changes in trial conduct, or cessation of the trial at designated check points based on certain available data from the trial.

A sponsor who wishes to conduct a clinical trial outside the U.S. may, but need not, obtain FDA authorization to conduct the clinical trial under an IND. When a foreign clinical trial is conducted under an IND, all FDA IND requirements must be met unless waived. When a foreign clinical trial is not conducted under an IND, FDA may accept the results of the study in support of a BLA or NDA if the study was well-designed and conducted in accordance with cGCPs, and the FDA is able to validate the data through an onsite inspection if deemed necessary.

Clinical trials typically are conducted in three sequential phases, but the phases may overlap or be combined. Additional studies may be required after approval.

In some cases, the FDA may approve a BLA or NDA for a product but require the sponsor to conduct additional clinical trials to further assess the product’s safety and effectiveness after approval. Such post-approval trials are typically referred to as confirmatory studies, or Phase 4 clinical trials. These studies are used to gain additional experience from the treatment of patients in the intended therapeutic indication and verify clinical benefit for products approved under accelerated approval regulations. Failure to exercise due diligence with regard to conducting required confirmatory studies could result in withdrawal of approval for products.

While the IND is active and before approval, progress reports detailing the results of the clinical trials and preclinical studies performed since the last progress report must be submitted at least annually to the FDA and written IND safety reports must be submitted to the FDA and the investigators for serious and unexpected suspected adverse events, findings from other studies or animal or in vitro testing that suggest a significant risk for human subjects and any clinically important increase in the rate of a serious suspected adverse reaction over that listed in the protocol or investigator brochure. The sponsor must submit an IND safety report within 15 calendar days after the sponsor determines that the information qualifies for reporting. The sponsor also must notify the FDA of any unexpected fatal or life-threatening suspected adverse reaction within seven calendar days after the sponsor’s initial receipt of the information.

50

Table of Contents

There are also requirements governing the reporting of ongoing clinical trials and clinical trial results to public registries. Sponsors of certain clinical trials of FDA-regulated products are required to register and disclose information about ongoing clinical trials, including information related to the drug, patient population, phase of investigation, trial sites and investigators. Sponsors are also obligated to disclose the results of completed clinical trials, other than Phase 1 clinical trials, within specific timeframes. Information about applicable clinical trials is published on www.ClinicalTrials.gov, a clinical trials database maintained by the National Institutes of Health.

During the development of a new biologic, sponsors are given opportunities to meet with the FDA at certain points. These points may be prior to submission of an IND, at the end of Phase 2, and before a BLA or NDA is submitted. Meetings at other times may be requested. These meetings can provide an opportunity for the sponsor to share information about the data gathered to date, for the FDA to provide advice, and for the sponsor and the FDA to reach agreement on the next phase of development.

Compliance with cGMPs

Concurrent with clinical trials, companies must finalize a process for manufacturing the product in commercial quantities in accordance with cGMPs. The manufacturing process must be capable of consistently producing quality batches of the product and, among other things, companies must develop methods for testing the identity, strength, quality and purity of the final product. Additionally, appropriate packaging must be selected and tested and stability studies must be conducted to demonstrate that the products do not undergo unacceptable deterioration over their shelf life. Before approving a BLA or NDA, the FDA will typically inspect the facility or facilities where the product is manufactured. The FDA will not approve an application unless it determines that the manufacturing processes and facilities are in compliance with cGMPs and adequate to assure consistent production of the product within required specifications. The PHSA emphasizes the importance of manufacturing controls for products like biologics whose attributes cannot be precisely defined. Material changes in manufacturing equipment, location, or process post-approval, may result in additional regulatory review and approval.

Review and Approval of a BLA/NDA

The results of clinical trials and preclinical studies, together with detailed information regarding the manufacturing processes, chemistry and composition of the product, the proposed labeling and other relevant information, are submitted to the FDA as part of a BLA or NDA requesting approval to market the product for one or more specified indications. Clinical and preclinical data may come from company-sponsored trials or from a number of alternative sources, including studies initiated by investigators, and the BLA or NDA must include any negative and ambiguous results, as well as positive findings. To support marketing approval, the data submitted must be sufficient in quality and quantity to establish the safety, purity, and potency of the investigational product to the satisfaction of the FDA. For most BLAs or NDAs, the sponsor is required to pay a substantial application user fee at the time of submission and the sponsor of an approved BLA or NDA is subject to an annual program fee. Certain exceptions and waivers are available for some of these fees, such as an exception from the application fee for products with orphan designation and a waiver for certain small businesses.

The FDA has 60 days after submission of the application to conduct an initial review to determine whether to accept it for filing based on the agency’s threshold determination that it is sufficiently complete to permit substantive review. If the submission has been accepted for filing, the FDA begins an in-depth review of the application. Under the goals and policies agreed to by the FDA under PDUFA, the FDA has ten months from the acceptance date in which to complete its initial review of a standard application and respond to the applicant, and six months for a priority review of the application. The FDA does not always meet its PDUFA goal dates for standard and priority BLAs or NDAs and the review process may be significantly extended by FDA requests for additional information or clarification. For example, the review process and the PDUFA goal date may be extended by three months if the FDA requests or if the applicant otherwise provides additional data, analysis or information that FDA deems a major amendment.

During its review of a BLA/NDA, the FDA may refer applications for novel drug or biological products, or drug or biological products that present difficult questions of safety or efficacy to an advisory committee. Typically, an advisory committee is a panel of independent experts, including clinicians and other scientific experts, that reviews, evaluates and provides a recommendation as to whether the application should be approved and under what conditions, if any. The FDA

51

Table of Contents

is not bound by the recommendations of an advisory committee, but it considers such recommendations carefully when making decisions.

On the basis of the FDA’s evaluation of the application and accompanying information, including the results of the inspection of the manufacturing facilities and any FDA audits of preclinical and clinical trial sites to assure compliance with GLPs or GCPs, the FDA may approve the BLA/NDA or issue a complete response letter. Under the PHSA, the FDA may approve a BLA if it determines the product is safe, pure, and potent, and that the facility in which the product will be manufactured, processed, packaged or held meets standards designed to assure the product’s continued safety, purity and potency. Similarly, under the FDCA, the FDA may approve an NDA if it determines the product is safe and effective and that the facility in which the product will be manufactured, processed, packaged or held meets standards designed to assure the product’s continued safety and efficacy. If FDA determines the product meets these standards, it may issue an approval letter authorizing the commercial marketing of the product with specific prescribing information for specific indications. If the application is not approved, the FDA will issue a complete response letter, which will contain the conditions that must be met in order to secure final approval of the application, and when possible, will outline recommended actions the sponsor might take to obtain approval of the application. A complete response letter may require additional clinical data and/or other significant and time-consuming requirements related to clinical trials, preclinical studies or manufacturing. Sponsors that receive a complete response letter have one year to submit information that represents a complete response to the deficiencies identified by the FDA. The FDA will then re-review the application, taking into consideration the response, and determine whether the application meets the criteria for approval. Failure to respond to a complete response letter will serve as a withdrawal of an application. The FDA will not approve an application until issues identified in any complete response letters have been addressed.

If the FDA approves a new product, it may limit the approved indication(s) for use of the product. It may also require that contraindications, warnings, or precautions be included in the product labeling. In addition, the FDA may require post-approval studies, including Phase 4 clinical trials, to further assess the product’s efficacy and/or safety after approval. The agency may also require testing and surveillance programs to monitor the product after commercialization, or impose other conditions, including distribution restrictions or other risk management mechanisms, including REMS, to help ensure that the benefits of the product outweigh the potential risks. REMS can include medication guides, communication plans for healthcare professionals and elements to assure safe use (“ETASU”). ETASU can include, but are not limited to, special training or certification for prescribing or dispensing, dispensing only under certain circumstances, special monitoring and the use of patent registries. The FDA may prevent or limit further marketing of a product based on the results of post-market studies or surveillance programs.

After approval, if there are any modifications to the approved product, including changes in the indications, dosage forms, labeling, or manufacturing processes or facilities, the sponsor may be required to submit and obtain FDA approval of a new BLA/NDA or BLA/NDA supplement, which may require the generation of additional data or the conduct of additional preclinical studies and clinical trials.

Post-Approval Regulation

Upon FDA approval of a BLA or NDA, the sponsor will be required to comply with all post-approval regulatory requirements for biologics, as well as any specific post-approval requirements that the FDA has imposed as part of the product or indication’s approval process. The sponsor will be required to report certain adverse reactions and production problems to the FDA, provide updated safety and efficacy information, obtain FDA approval for certain manufacturing and labeling changes, and comply with requirements concerning advertising and promotional labeling, record-keeping, and drug supply chain security. Manufacturers and certain of their subcontractors are required to register their establishments with the FDA and certain state agencies and are subject to periodic unannounced inspections for compliance with ongoing regulatory requirements, including cGMPs. Accordingly, the sponsor and its third-party manufacturers must continue to expend time, money and effort in the areas of production and quality control, as well as pharmacovigilance activities, to maintain compliance with cGMPs and other regulatory requirements.

A biological product may also be subject to official lot release, meaning that the manufacturer is required to perform certain tests on each lot of the product before it is released for distribution. If the product is subject to official lot release, the manufacturer must submit samples of each lot, together with a release protocol showing a summary of the history of manufacture of the lot and the results of all of the manufacturer’s tests performed on the lot, to the FDA. The FDA may

52

Table of Contents

perform certain confirmatory tests on lots of some products before releasing the lots for distribution. In addition, the FDA strictly regulates the marketing, labeling, advertising and promotion of prescription drug products, including biological products. These regulations include, among other things, standards and regulations for direct-to-consumer advertising, communications regarding unapproved uses, industry-sponsored scientific and educational activities and promotional activities involving the internet and social media. Promotional claims about a drug’s safety or effectiveness are prohibited before the BLA/NDA is approved. Once a BLA/NDA is approved, the sponsor can make only those claims relating to safety, efficacy, purity and potency that are in accordance with the provisions of the approved label. In the U.S., healthcare professionals are generally permitted to prescribe legally available drugs for uses that are not described in the product’s labeling and that differ from those approved by the FDA. Such off-label uses are common across medical specialties. The FDA does not regulate the practice of medicine or healthcare providers’ choice of treatments. However, FDA regulations do impose rigorous restrictions on manufacturers’ communications of off-label uses. Additionally, promotional materials for prescription drug products must be submitted to the FDA in conjunction with their first use.

If a company, including any agent of the company or anyone speaking on behalf of the company, is found to have promoted off-label uses, the company may become subject to adverse public relations and administrative and judicial enforcement by the FDA, the DOJ, or the Office of the Inspector General of the Department of Health and Human Services (“HHS”), as well as state authorities. This could subject a company to a range of penalties that could have a significant commercial impact, including civil and criminal fines and agreements that materially restrict the manner in which a company promotes or distributes drug products. The federal government has levied large civil and criminal fines against companies for alleged improper promotion and has also requested that companies enter into consent decrees or permanent injunctions under which specified promotional conduct is changed or curtailed.

The FDA may require testing and surveillance programs to monitor the effect of approved products that have been commercialized, and the FDA has the power to prevent or limit further marketing of a product based on the results of these post-marketing programs.

The FDA may withdraw product approval if compliance with regulatory requirements and standards is not maintained or if issues occur after the product reaches the market. Later discovery of previously unknown issues with a product, including adverse events of unanticipated severity or frequency, or with manufacturing processes, or failure to comply with regulatory requirements, may result in revisions to the approved labeling to add new safety information; imposition of post-market studies or clinical trials to assess new safety risks; or imposition of distribution or other restrictions under a REMS program. Other potential consequences include:

53

Table of Contents

FDA Regulation of Combination Products

Certain therapeutic products are comprised of multiple FDA-regulated components, such as drugs and medical devices, that are physically combined and produced as a single entity, packaged together in a single package, or packaged separately but intended to be labeled for use together. These products are known as combination products. We expect that obexelimab and our other product candidates packaged in a prefilled syringe or autoinjector would be subject to regulation as a combination product if consisting of a therapeutic biologic or small molecule and a delivery device.

The constituent elements of such combination products would normally be subject to different FDA regulatory frameworks and regulated by different Centers at the FDA. Depending on the type of combination product, its approval, clearance or licensure may usually be obtained through the submission of a single marketing application; however, FDA could require separate marketing applications for individual constituent parts of the combination product which may require additional time, effort and information. Even when a single marketing application is required for a combination product, such as a BLA for a combination biologic and device product, both FDA’s Center for Biologics Evaluation and Research and FDA’s Center for Devices and Radiological Health may participate in the review. If a product candidate is considered a combination product, the sponsor will also need to comply with post-marketing regulatory requirements, including adverse event reporting and applicable portions of the FDA’s Quality Management System regulation, applicable to combination products.

Fast Track, Breakthrough Therapy and Priority Review Designations

The FDA has several programs intended to facilitate and expedite development and review of new products that are intended to address an unmet medical need in the treatment of a serious or life-threatening disease or condition. These programs are referred to as fast track designation, breakthrough therapy designation and priority review designation. These designations are not mutually exclusive, and a product candidate may qualify for one or more of these programs. While these programs are intended to expedite product development and approval, they do not alter the standards for FDA approval.

The FDA may designate a product for fast track designation if it is intended for the treatment of a serious or life-threatening disease or condition, and preclinical or clinical data demonstrate the potential to address unmet medical needs for such a disease or condition. For products with fast track designation, sponsors may have more frequent interactions with the FDA, the product is potentially eligible for accelerated approval and priority review, if relevant criteria are met, and the BLA/NDA may be eligible for “rolling review,” under which the FDA may consider sections of the BLA for review on a rolling basis before the complete application is submitted. This rolling review may be available if the FDA determines, after preliminary evaluation of clinical data submitted by the sponsor, that a product with fast track designation may be effective. The sponsor must also provide, and the FDA must approve, a schedule for the submission of the remaining sections of the BLA/NDA, and the sponsor must pay any required user fees upon submission of the first section of the BLA/NDA. The FDA’s time goal for reviewing a fast track application does not begin until the last section of the application is submitted.

A product may be designated as a breakthrough therapy if it is intended to treat a serious or life-threatening disease or condition and preliminary clinical evidence indicates that the product may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints. The designation includes all of the fast track program features, including eligibility for rolling review. Additionally, the FDA may take certain actions to expedite the development and review of breakthrough therapies, including holding meetings with the sponsor throughout the development process; providing timely advice to the product sponsor regarding development and approval; involving more senior staff managers in the review process; assigning a cross-disciplinary lead for the review team; and taking other steps to design the clinical trials in an efficient manner.

The FDA may designate a product for priority review if it is a product that treats a serious condition and, if approved, would provide a significant improvement in safety or effectiveness when compared with other available therapies. A priority review designation is intended to direct the FDA’s attention and resources to the evaluation of such applications, and to shorten the FDA’s goal for taking action on an original BLA/NDA from ten months to six months from the acceptance date.

54

Table of Contents

Fast track designation, breakthrough therapy designation, and priority review do not change the standards for approval but may expedite the development or approval process. Even if a drug qualifies for one or more of these programs, the FDA may later withdraw or rescind the designation if it decides that the drug no longer meets the conditions for qualification or decides that the time period for FDA review or approval will not be shortened.

Accelerated Approval Pathway

The FDA may grant accelerated approval to a product candidate designed to treat a serious or life-threatening condition that provides a meaningful therapeutic advantage to patients over existing treatments based upon a determination that the product has an effect on a surrogate endpoint that is reasonably likely to predict clinical benefit. For the purposes of accelerated approval, a surrogate endpoint is a marker, such as a laboratory measurement, radiographic image, physical sign, or other measure that is thought to predict clinical benefit but is not itself a measure of clinical benefit. The FDA may also grant accelerated approval for such a condition when the product has an effect on an intermediate clinical endpoint that can be measured earlier than an effect on irreversible morbidity or mortality (“IMM”), and that is reasonably likely to predict an effect on IMM or other clinical benefit, taking into account the severity, rarity or prevalence of the condition and the availability or lack of alternative treatments.

The accelerated approval pathway is most often used in settings in which the course of a disease is long, and an extended period of time is required to measure the intended clinical benefit of a product, even if the effect on the surrogate or intermediate clinical endpoint occurs rapidly. Products granted accelerated approval must meet the same statutory standards for safety and effectiveness as those granted traditional approval.

The FDA’s approval of a candidate product under the accelerated approval pathway is usually contingent on a sponsor’s agreement to conduct post-approval confirmatory studies to verify and describe the product’s clinical benefit, and the FDA may require such studies to be underway prior to approval. Failure to conduct required post-approval studies, confirm a clinical benefit during post-marketing studies may result in the FDA’s withdrawal of the product from the market on an expedited basis. All promotional materials for therapeutic candidates approved under accelerated regulations are subject to prior review by the FDA.

Orphan Drug Designation and Exclusivity

Orphan drug designation in the U.S. is designed to encourage sponsors to develop products intended for treatment of rare diseases or conditions. In the U.S., a rare disease or condition is statutorily defined as a condition that affects fewer than 200,000 individuals in the U.S. or that affects 200,000 or more individuals in the U.S. and for which there is no reasonable expectation that the cost of developing and making available the drug or biologic for the disease or condition will be recovered from sales of the product in the U.S.

Orphan drug designation qualifies a company for tax credits and market exclusivity for seven years following the date of the product’s marketing approval if granted by the FDA. An application for designation as an orphan product can be made any time prior to the filing of an application for approval to market the product. If orphan drug designation is granted by the FDA, the generic identity of the therapeutic agent and its potential orphan use are disclosed publicly by the FDA. After FDA grants orphan designation, the product must then go through the review and approval process like any other product.

A sponsor may request orphan drug designation of a previously unapproved product or new orphan indication for an already marketed product. In addition, a sponsor of a product that is otherwise the same product as an already approved orphan drug may seek and obtain orphan drug designation for the subsequent product for the same rare disease or condition if it can present a plausible hypothesis that its product may be clinically superior to the first drug. More than one sponsor may receive orphan drug designation for the same product for the same rare disease or condition, but each sponsor seeking orphan drug designation must file a complete request for designation.

If a product with orphan designation receives the first FDA approval for the disease or condition for which it has such designation or for a select indication or use within the rare disease or condition for which it was designated, the product generally will receive orphan drug exclusivity. Orphan drug exclusivity means that the FDA may not approve another sponsor’s marketing application for the same product for the same indication for seven years, except in certain limited circumstances. If a product designated as an orphan drug ultimately receives marketing approval for an indication broader

55

Table of Contents

than what was designated in its orphan drug application, it may not be entitled to exclusivity. Orphan drug exclusivity does not prevent the FDA from approving a different drug for the same disease or condition, or the same drug for a different disease or condition.

The period of exclusivity begins on the date that the marketing application is approved by the FDA and applies only to the indication for which the product has been designated. The FDA may approve a second application for the same product for a different use or a second application for a clinically superior version of the product for the same use. The FDA cannot, however, approve the same product made by another manufacturer for the same indication during the market exclusivity period unless it has the consent of the sponsor, or the sponsor is unable to provide sufficient quantities.

The FDA has historically taken the position that the scope of orphan exclusivity aligns with the approved indication or use of a product, rather than the disease or condition for which the product received orphan designation. However, in Catalyst Pharms., Inc. v. Becerra, 14 F.4th 1299 (11th Cir. 2021), the court disagreed with this position, holding that orphan-drug exclusivity blocked the FDA’s approval of the same drug for all uses or indications within the same orphan-designated disease. On January 24, 2023, the FDA published a notice in the Federal Register to clarify that the FDA intends to continue to apply its longstanding interpretation of the regulations to all matters outside of the scope of the Catalyst order and will continue tying the scope of orphan-drug exclusivity to the uses or indications for which a drug is approved. It is unclear how future litigation, legislation, agency decisions, and administrative actions will impact the scope of the orphan drug exclusivity.

Development in Pediatric Patients

Under the Pediatric Research Equity Act of 2003, a BLA, NDA or BLA supplement thereto must contain data that are adequate to assess the safety and effectiveness of the product for the claimed indications in all relevant pediatric subpopulations and to support dosing and administration for each pediatric subpopulation for which the product is safe and effective. A sponsor who is planning to submit a marketing application for a product that includes a new active ingredient, new indication, new dosage form, new dosing regimen or new route of administration must submit a Pediatric Study Plan (“PSP”) that contains an outline of the proposed pediatric study or studies the applicant plans to conduct, including study objectives and design, any deferral or waiver requests and other information required by regulation. The sponsor and the FDA must reach agreement on the PSP. The FDA or the applicant may request an amendment to the plan at any time.

The FDA may, on its own initiative or at the request of the applicant, grant deferrals for submission of some or all pediatric data until after approval of the product for use in adults, or full or partial waivers from the pediatric data requirements. The FDA must send a non-compliance letter to any sponsor that fails to submit the required assessment, keep a deferral current or fails to submit a request for approval of a pediatric formulation. Unless otherwise required by regulation, the pediatric data requirements do not apply to products with orphan designation.

Pediatric Exclusivity

Pediatric exclusivity is a type of non-patent marketing exclusivity in the U.S. and, if granted, provides for the attachment of an additional six months of marketing protection to the term of any existing regulatory exclusivity, including orphan exclusivity. This six-month exclusivity may be granted if a BLA or NDA sponsor submits pediatric data that fairly respond to a written request from the FDA for such data. The data do not need to show the product to be effective in the pediatric population studied; rather, if the clinical trial is deemed to fairly respond to the FDA’s request, the additional protection is granted.

Biosimilars and Exclusivity

The Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act of 2010 (collectively the “ACA”), which was signed into law in March 2010, included the Biologics Price Competition and Innovation Act of 2009 (“BPCIA”). The BPCIA established a regulatory scheme authorizing the FDA to approve biosimilars and interchangeable biosimilars. A biosimilar is a biological product that is highly similar to an existing FDA-licensed “reference product.” Under the BPCIA, a manufacturer may submit an application for licensure of a biologic product that is “biosimilar to” or “interchangeable with” a previously approved biological product or “reference product.”

56

Table of Contents

In order for the FDA to approve a biosimilar product, it must find that there are no clinically meaningful differences between the reference product and proposed biosimilar product in terms of safety, purity and potency. For the FDA to approve a biosimilar product as interchangeable with a reference product, the agency must find that the biosimilar product can be expected to produce the same clinical results as the reference product in any given patient, and (for products administered multiple times to an individual) that the biologic and the reference biologic may be switched after one has been previously administered without increasing safety risks or risks of diminished efficacy relative to exclusive use of the reference biologic. A product shown to be biosimilar or interchangeable with an FDA-approved reference biological product may rely in part on the FDA’s previous determination of safety and effectiveness for the reference product for approval, which can potentially reduce the cost and time required to obtain approval to market the product.

Under the BPCIA, an application for a biosimilar product may not be submitted to the FDA until four years following the date of approval of the reference product. The FDA may not approve a biosimilar product until 12 years from the date on which the reference product was approved. Even if a product is considered to be a reference product eligible for exclusivity, another company could market a competing version of that product if the FDA approves a full BLA for such product containing the sponsor’s own preclinical data and data from adequate and well-controlled clinical trials to demonstrate the safety, purity and potency of their product. The BPCIA also created certain exclusivity periods for biosimilars approved as interchangeable products. The law also includes an extensive process for the innovator biologic and biosimilar manufacturer to litigate patent infringement, validity and enforceability prior to the approval of the biosimilar. Since the passage of the BPCIA, many states have passed laws or amendments to laws, including laws governing pharmacy practices, which are state regulated, to regulate the use of biosimilars.

Small Molecule Marketing Exclusivity

The FDCA provides a five-year period of non-patent marketing exclusivity within the United States to the first applicant to gain approval of an NDA for a new chemical entity. A drug is a new chemical entity if the FDA has not previously approved any other new drug containing the same active moiety, which is the molecule or ion responsible for the action of the drug substance. During the exclusivity period, the FDA may not accept for review an abbreviated new drug application ("ANDA") or a 505(b)(2) NDA submitted by another company for another version of such drug where the applicant does not own or have a legal right of reference to all the data required for approval. However, an application may be submitted after four years if it contains a certification of patent invalidity or non-infringement. The FDCA also provides three years of marketing exclusivity for an NDA, 505(b)(2) NDA, or supplement to an existing NDA if new clinical investigations, other than bioavailability studies, that were conducted or sponsored by the applicant are deemed by the FDA to be essential to the approval of the application. Examples of applications that may require new clinical investigations essential to approval and receive three-year exclusivity include applications for new indications, dosages or strengths of an existing drug. This three-year exclusivity covers only the conditions of use associated with the new clinical investigations and does not prohibit the FDA from approving ANDAs or 505(b)(2) NDAs for drugs containing the original active agent. Five-year and three-year exclusivity will not delay the submission or approval of a full NDA. However, an

applicant submitting a full NDA would be required to conduct or obtain a right of reference to all of the preclinical studies and adequate and well-controlled clinical trials necessary to demonstrate safety and effectiveness.

​

U.S. Patent Term Restoration and Extension

In the U.S., a patent claiming a new biologic product, its method of use or its method of manufacture may be eligible for a limited patent term extension under the Hatch-Waxman Amendments, which permits a patent extension of up to five years for patent term lost during product development and FDA regulatory review. Assuming grant of the patent for which the extension is sought, the restoration period for a patent covering a product is typically one-half the time between the effective date of the IND and the submission date of the BLA/NDA, plus the time between the submission date of the BLA/NDA and the ultimate approval date, except that the review period is reduced by any time during which the applicant failed to exercise due diligence. Patent term restoration cannot be used to extend the remaining term of a patent past a total of 14 years from the product’s approval date in the U.S. Only one patent applicable to an approved product is eligible for the extension, and the application for the extension must be submitted prior to the expiration of the patent for which extension is sought. A patent that covers multiple products for which approval is sought can only be extended in connection with one of the approvals. The United States Patent and Trademark Office (“USPTO”) reviews and approves the application for any patent term extension in consultation with the FDA.

57

Table of Contents

Federal and State Data Privacy and Security Laws

Under the Federal Health Insurance Portability and Accountability Act of 1996 (“HIPAA”), HHS has issued regulations to protect the privacy and security of protected health information, used or disclosed by covered entities including certain healthcare providers, health plans and healthcare clearinghouses. HIPAA also regulates standardization of data content, codes and formats used in healthcare transactions and standardization of identifiers for health plans and providers. HIPAA, as amended by the Health Information Technology for Economic and Clinical Health Act of 2009 (“HITECH”), and their regulations, including the final omnibus rule published on January 25, 2013, also imposes certain obligations on the business associates of covered entities and their covered subcontractors that obtain protected health information in providing services to or on behalf of covered entities or business associates. In addition to federal privacy regulations, there are a number of state laws governing confidentiality and security of health information that are applicable to our business. In addition to possible federal, administrative, civil and criminal penalties for HIPAA violations, state attorneys general are authorized to file civil actions for damages or injunctions in federal courts to enforce HIPAA and seek attorney’s fees and costs associated with pursuing federal civil actions. Accordingly, state attorneys general have brought civil actions seeking injunctions and damages resulting from alleged violations of HIPAA’s privacy and security rules. New laws and regulations governing privacy and security may be adopted in the future as well.

Additionally, states, such as California, Virginia and Colorado have recently enacted the consumer privacy laws that grant rights to data subjects and place increased privacy and security obligations on entities handling personal data of consumers or households. While we are not currently subject to laws such as the California Consumer Privacy Act (“CCPA”), some observers note that the CCPA and similar legislation could mark the beginning of a trend toward more stringent privacy legislation in the U.S., which could increase our potential liability and adversely affect our business.

Because of the breadth of these laws and the narrowness of the statutory exceptions under such laws, it is possible that some of our current or future business activities, including certain clinical research, sales and marketing practices and the provision of certain items and services to our customers, could be subject to challenge under one or more of such privacy and data security laws. The heightening compliance environment and the need to build and maintain robust and secure systems to comply with different privacy compliance and/or reporting requirements in multiple jurisdictions could increase the possibility that we may fail to comply fully with one or more of these requirements. If our operations are found to be in violation of any applicable privacy or data security laws or regulations, we may be subject to penalties, including potentially significant criminal, civil and administrative penalties, damages, fines, imprisonment, contractual damages, reputational harm, diminished profits and future earnings, additional reporting requirements and/or oversight if we become subject to a consent decree or similar agreement to resolve allegations of non-compliance with these laws, and the curtailment or restructuring of our operations, any of which could adversely affect our ability to operate our business and our results of operations. To the extent that we collect or otherwise process personal information, we may be subject to privacy or data protection laws that are in effect in such third countries.

Regulation and Procedures Governing Approval of Medicinal Products in Europe

In order to market any medicinal product outside of the U.S., a company must also comply with numerous and varying regulatory requirements to generate relevant data for the purpose of establishing its quality, safety and efficacy. There are specific rules governing, among other things, clinical trials, marketing authorization, commercial sales and distribution of products. Regardless of the product approval status in the U.S., an applicant will need to obtain the necessary approvals granted by the comparable foreign regulatory authorities before it can commence clinical trials or marketing of a medicinal product in those countries or jurisdictions.

The processes governing approval of medicinal products in the EU and UK generally adopt a similar approach to that applied in the U.S. They entail satisfactory completion of preclinical studies and adequate and well-controlled clinical trials to establish the safety and efficacy of the product for each proposed indication. Data should be generated to demonstrate that a drug substance and a drug product can be manufactured and controlled according to the pre-specified quality standards. The data relating to quality, preclinical testing and clinical trials should be submitted to the relevant competent authorities in an MAA for regulatory review in order to determine whether a marketing authorization can be granted. Even if a marketing authorization has been granted, there is a need to obtain a pricing and reimbursement decision before a new medicinal product can be marketed and sold in the EU and/or the UK (as applicable).

58

Table of Contents

Clinical Trial Approval

Pursuant to the currently applicable Regulation (EU) No 536/2014 (CTR) and Directive 2005/28/EC on GCP, an applicant must obtain approval from the national competent authority of an EU member state in which the clinical trial is to be conducted, or in multiple member states if the clinical trial is to be conducted in a number of member states. Furthermore, the applicant can only start a clinical trial at a specific site after a research ethics committee has issued a favorable opinion. The clinical trial application must be accompanied by an investigational medicinal product dossier with supporting information prescribed by the CTR and corresponding national laws of the member states. All suspected unexpected serious adverse reactions to the investigational medicinal product that occur during the clinical trial have to be reported to the national competent authorities and research ethics committees of the member state where they occurred.

Pursuant to the CTR, a sponsor must submit a single application for a new clinical trial authorization through a centralized EU clinical trials portal called the Clinical Trials Information System (“CTIS”). One national competent authority (from the reporting EU member state selected by the applicant) takes the lead in validating and evaluating the application, as well as consulting and coordinating with the other concerned member states in which the clinical trial is to be conducted. If an application is rejected, it may be amended and resubmitted through CTIS. A concerned member state may in limited circumstances declare an “opt-out” from an approval and prevent the clinical trial from being conducted in that member state. By January 31, 2025, all ongoing trials approved under the CTD must comply with the CTR and information relating to such clinical trials must be recorded in CTIS. The CTR aims to streamline and simplify the rules on safety reporting, and introduces enhanced transparency requirements such as mandatory submission of a summary of the clinical trial results to the CTIS.

The UK formally left the EU on January 31, 2020, under the terms of the Agreement on the withdrawal of the UK of Great Britain and Northern Ireland from the EU and the European Atomic Energy Community (the EU-UK Withdrawal Agreement). Despite this, EU law continued to apply in the UK until the expiry of the transition period on 31 December 2020. Following the UK’s departure from the EU, the UK and the EU entered into a trade and cooperation agreement (“TCA”), which includes specific provisions concerning pharmaceuticals (such as the mutual recognition of cGMP inspections of manufacturing facilities for medicinal products and cGMP documents issued), but which does not provide for wholesale mutual recognition of UK and EU pharmaceutical regulations. At the point that the transition period expired, the Northern Ireland Protocol, which is contained in the EU-UK Withdrawal Agreement, took effect. The Northern Ireland Protocol makes certain provisions of EU law, including several concerning medicinal products, applicable in Northern Ireland. This position has recently been revised via the Windsor Framework. Under the Windsor Framework, from January 1, 2025, all new medicinal products for the UK market will be authorized by the UK’s Medicines and Healthcare products Regulatory Agency (“MHRA”) (see further below).

In the UK, clinical trials of medicinal products are primarily governed by the Medicines for Human Use (Clinical Trials) Regulations 2004, as amended (the UK Regulations). The UK Regulations sought to implement the CTD while the UK was a member state of the EU. Since the CTR was not in force in the EU at the time when the UK exited the EU, it was not retained in UK law on exit day under the terms of the European Union (Withdrawal) Act 2018. Following a public consultation which was conducted in early 2022, the UK authorities are in the process of developing legislation which seeks to improve and strengthen the clinical trials regulatory regime in the UK. The extent to which the regulation of clinical trials in the UK will mirror the CTR is unknown at present.

Accelerated Assessment Pathways

The EU’s Priority Medicines (“PRIME”) scheme is intended to encourage drug development in areas of unmet medical need and facilitates accelerated assessment of medicinal products representing substantial innovation reviewed under the centralized procedure. Eligible products must target conditions for which there is an unmet medical need (there is no satisfactory method of diagnosis, prevention or treatment in the European Economic Area (“EEA”) or, if there is, the new medicine will bring a major therapeutic advantage) and they must demonstrate the potential to address the unmet medical need by, for example, introducing new methods of therapy or improving existing ones. Products from small- and medium-sized enterprises may qualify for earlier entry into the PRIME scheme. Many benefits accrue to sponsors of therapeutic candidates with PRIME designation, including but not limited to, early and proactive regulatory dialogue with the EMA, frequent discussions on clinical trial designs and other development program elements, and accelerated MAA assessment once a dossier has been submitted. Importantly, an EMA contact and rapporteur from the Committee for Human Medicinal

59

Table of Contents

Products (“CHMP”), or Committee for Advanced Therapies are appointed early in the PRIME scheme facilitating increased understanding of the product at the EMA’s Committee level. A kick-off meeting initiates these relationships and includes a team of multidisciplinary experts at the EMA to provide guidance on the overall development and regulatory strategies. Where, during the course of development, a medicine no longer meets the eligibility criteria, support under the PRIME scheme may be withdrawn.

The UK’s Innovative Licensing and Access Pathway (“ILAP”) aims to accelerate the time to market of innovative medicinal products. It is open to both commercial and non-commercial applicants, who are based in the UK or global, and who are developing medicinal products which include products containing new chemical entities, biological medicinal products, new indications and repurposed medicinal products. It comprises of an Innovation Passport designation and a Target Development Profile, and provides applicants with access to a toolkit to support all stages of the design, development and approvals process. The major benefit of the ILAP scheme is that it provides applicants with opportunities for enhanced regulatory and stakeholder input during the development of their medicinal products.

Marketing Authorization

To obtain a marketing authorization for a medicinal product under the EU regulatory system, an applicant must submit an MAA, either under a centralized procedure administered by the EMA or one of the procedures administered by competent authorities in EU member states (decentralized procedure, national procedure, or mutual recognition procedure). A marketing authorization may be granted only to an applicant established in the EU.

Regulation (EC) No 1901/2006 provides that prior to obtaining a marketing authorization in the EU, an applicant must demonstrate compliance with all measures included in an EMA-approved Pediatric Investigation Plan (“PIP”), covering all subsets of the pediatric population, unless the EMA has granted a product-specific waiver, class waiver or a deferral for one or more of the measures included in the PIP. The Paediatric Committee of the EMA (“PDCO”), may grant deferrals for some medicines, allowing a company to delay development of the medicine for children until there is enough information to demonstrate its effectiveness and safety in adults. The PDCO may also grant waivers when development of a medicine for children is not needed or is not appropriate, such as for diseases that only affect the elderly population. An application for marketing authorization or a variation or a variation or a line-extension which is accompanied by the pediatric clinical trials conducted in accordance with the PIP (even where such results are negative) are eligible for a six months extension of their supplementary protection certificate. In the case of orphan medicinal products, a two-year extension of the orphan market exclusivity may be available. This pediatric reward is not automatically available and is subject to the EMA or the relevant national competent authorities confirming compliance with the agreed PIP that may require an opinion to be given by the EMA’s Pediatric Committee.

The centralized procedure provides for the grant of a single marketing authorization by the European Commission that is valid for all EU member states, as well as the additional member states of the EEA (Norway, Iceland and Liechtenstein). Pursuant to Regulation (EC) No 726/2004, the centralized procedure is compulsory for specific products, including for medicines developed by means of certain biotechnological processes (including, recombinant DNA technology, controlled expression of genes coding for biologically active proteins in prokaryotes and eukaryotes including transformed mammalian cells, and hybridoma and monoclonal antibody methods), products designated as orphan medicinal products, advanced therapy medicinal products (gene-therapy, somatic cell-therapy or tissue-engineered medicines) and products containing a new active substance indicated for the treatment of certain diseases, including products for the treatment of cancer, HIV / AIDS, neurodegenerative disorders, diabetes, auto-immune diseases and other immune dysfunctions, and viral diseases. The centralized procedure is optional for products containing a new active substance which was not authorized in the EU on May 20, 2004, or for products that constitute a significant therapeutic, scientific or technical innovation or which are in the interest of public health in the EU. An applicant for the centralized MA must demonstrate the quality, safety and efficacy of their products to the EMA for an opinion to be adopted regarding the approvability of the MAA. The European Commission grants or refuses marketing authorization in light of the opinion delivered by the EMA.

Under the centralized procedure, the CHMP established within the EMA is responsible for conducting an initial assessment of a medicinal product. The maximum timeframe for the evaluation of an MAA is 210 days, excluding clock stops when additional information or written or oral explanation is to be provided by the applicant in response to questions of the CHMP. Clock stops may extend the timeframe of evaluation of an MAA considerably beyond 210 days. Where the CHMP

60

Table of Contents

gives a positive opinion, the EMA provides the opinion together with supporting documentation to the European Commission, who make the final decision to grant a marketing authorization, which is issued ordinarily within 67 days of receipt of the EMA’s recommendation. Accelerated evaluation may be granted by the CHMP in exceptional cases, when a medicinal product is of major interest from the point of view of public health and, in particular, from the viewpoint of therapeutic innovation. If the CHMP accepts such a request, the time limit of 210 days will be reduced to 150 days (excluding clock stops), but it is possible that the CHMP may revert to the standard time limit for the centralized procedure if it determines that it is no longer appropriate to conduct an accelerated assessment.

National marketing authorizations, which are issued by the national competent authorities of the member states of the EEA and only cover their respective territory, are available for products not falling within the mandatory scope of the centralized procedure. Where a medicinal product has already been authorized for marketing in a member state of the EEA, this national authorization can be recognized in other member states through the mutual recognition procedure. If the product has not received a national authorization in any member state at the time of application, it can be approved simultaneously in two or more member states through the decentralized procedure.

For the time being, under the Northern Ireland Protocol, centralized marketing authorizations continue to provide a valid basis for commercializing medicinal products in Northern Ireland. However, centralized marketing authorizations no longer provide a valid basis for the commercialization of medicinal products in Great Britain. Pursuant to the Windsor Framework, from January 1, 2025, all new medicinal products for the UK market will be authorized by the Medicines and Healthcare Regulatory Agency (“MHRA”). In this regard, the MHRA will grant a single UK-wide marketing authorization for all medicinal products intended for sale in the UK, enabling medicinal products to be sold in a single pack and under a single authorization throughout the UK.

Following its departure from the EU, the UK has introduced changes to its national licensing procedures, including procedures to prioritize access to new medicines that will benefit patients, ILAP (described above) and new routes of evaluation for novel products and biotechnological products. Notwithstanding that there is no wholesale recognition of EU pharmaceutical legislation under the Trade and Cooperation Agreement (“TCA”), and that EU marketing authorizations do not automatically provide a valid basis for the commercialization of medicinal products in Great Britain from January 1, 2024, applicants will be able to request the MHRA to recognize marketing authorizations granted in foreign jurisdictions (including the EU) under a new International Recognition Procedure.

Regulatory Data Protection in Europe

In the EU and the UK, new chemical entities (including both small molecules and biological medicinal products) and new biological substances approved on the basis of a complete independent data package consisting of quality, preclinical testing results and clinical trial data qualify for eight years of Regulatory Data Protection (“RDP”) upon grant of a marketing authorization and two years of marketing protection. Data protection prevents generic or biosimilar applicants from referencing the innovator’s preclinical and clinical trial data contained in the MAA dossier of the reference medicinal product when applying for a generic or biosimilar marketing authorization, for a period of eight years from the date on which the reference product was first authorized in the EU. During the two-year period of marketing protection, a generic or biosimilar MAA can be submitted, and the innovator’s data may be referenced. Even if a generic or biosimilar medicinal product is approved, it cannot be marketed until the expiration of the marketing protection. The ten-year protection period can be extended to a maximum of eleven years if, during the first eight years of those ten years, the marketing authorization holder obtains an authorization for one or more new therapeutic indications which, during the scientific evaluation prior to authorization, is held to bring a significant clinical benefit in comparison with existing therapies. Even if a compound is considered to be a new chemical or a new biological entity so that the innovator gains the prescribed period of data protection, another company may market another version of the medicinal product if such company obtained marketing authorization based on an MAA with a complete and independent data package consisting of pharmaceutical and preclinical testing results and clinical trial data.

Patent Term Extensions in the EU and Other Jurisdictions

The EU also provides for patent term extension through Supplementary Protection Certificate (“SPCs”) which aim to offset the loss of patent protection for pharmaceutical products arising from the lengthy testing and clinical trials required to obtain an MA. The rules and requirements for obtaining a SPC are similar to those in the U.S. An SPC may extend the

61

Table of Contents

term of a basic patent for up to five years after its originally scheduled expiration date in order to provide up to a maximum of fifteen years of exclusivity from the time the medicinal product in question first obtains an MA for it to be placed on the market. As mentioned above, in certain circumstances, these periods may be extended for six additional months if pediatric exclusivity is obtained; and in the case of orphan medicinal products, a two-year extension of the orphan market exclusivity may be available. Although SPCs are available throughout the EU, holders must apply the patent term extension on a country-by-country basis. Similar patent term extension rights exist in certain other foreign jurisdictions outside the EU.

Orphan Drug Designation and Exclusivity

Regulation (EC) No 141/2000 and Regulation (EC) No. 847/2000 provide that a medicinal product can be designated as an orphan medicinal product by the European Commission, upon satisfactory scientific assessment by the EMA’s Committee for Orphan Medicinal Products (“COMP”), if the sponsor can establish: (1) that the product is intended for the diagnosis, prevention or treatment of a life-threatening or chronically debilitating condition, where either (i) such condition affects not more than five in ten thousand persons in the EU when the application is made, or (ii) without incentives it is unlikely that the marketing of the drug in the EU would generate sufficient return to justify the necessary investment in its development, and (2) that there exists no satisfactory method of diagnosis, prevention or treatment of the condition in question that has been authorized in the EU or, if such method exists, the drug will be of significant benefit to those affected by that condition. In the UK, the MHRA conducts an equivalent assessment, against criteria which have been tailored for the UK population.

The COMP is required to re-assess the granted orphan designation at the time of marketing authorization grant to ensure that it continues to meet the criteria for the designation to be maintained. Otherwise, the orphan designation can be revoked. In relation to the UK, the MHRA does not grant orphan designations during the development of the medicinal product. Instead, the MHRA will decide whether the criteria are satisfied at the point of marketing authorization grant. An orphan drug designation provides a number of benefits, including fee reductions, fee waivers, protocol assistance (as a type of scientific advice specific for orphan medicinal products) and the possibility to apply for a centralized EU marketing authorization. Marketing authorization for an orphan medicinal product benefits from a ten-year period of market exclusivity. During this period of market exclusivity, the European Commission, national competent authorities of the EU member states may only grant marketing authorization to a “similar medicinal product” for the same therapeutic indication if: (i) a second applicant can establish that its medicinal product, although similar to the authorized product, is safer, more effective or otherwise clinically superior; (ii) the marketing authorization holder for the authorized product consents to a second orphan medicinal product application; or (iii) the marketing authorization holder for the authorized product cannot supply enough orphan medicinal product. A “similar medicinal product” is defined as a medicinal product containing a similar active substance or substances as contained in an authorized orphan medicinal product, and which is intended for the same therapeutic indication. The period of marketing protection for the authorized therapeutic indication may, however, be reduced to six years if, at the end of the fifth year, it is established that the product no longer meets the criteria for orphan drug designation because, for example, the product is sufficiently profitable not to justify market exclusivity. Orphan medicinal product designation does not convey any advantage in, or shorten the duration of, the regulatory review and approval process. Following the UK’s exit from the EU, the MHRA continues to apply the same orphan market exclusivity framework as the EU.

Periods of Authorization and Renewals

A marketing authorization is valid for five years, in principle, and it may be renewed indefinitely after five years on the basis of a reevaluation of the risk-benefit balance by the EMA, the competent authority of the authorizing member state, or the MHRA. To that end, the marketing authorization holder must provide the EMA, the relevant national competent authority, or the MHRA with a consolidated version of the file in respect of quality, safety and efficacy, including all variations introduced since the marketing authorization was granted, at least six months before the marketing authorization expiry date. Once renewed, the marketing authorization is valid for an unlimited period, unless the European Commission, the relevant national competent authority, or the MHRA decides, on justified grounds relating to pharmacovigilance, to proceed with one additional five-year renewal period. Any marketing authorization ceases to be valid if it is not followed by the placement of the medicinal product on the EU market (in the case of the centralized procedure), on the market of the authorizing member state (in the case of a national procedure), or the UK market (as applicable), within three years after grant of such an authorization.

62

Table of Contents

Regulatory Requirements After Marketing Authorization

Following approval, the holder of the marketing authorization is required to comply with a range of requirements applicable to the manufacturing, marketing, promotion and sale of the medicinal product, and must adhere in strict compliance with the applicable EU laws, regulations and guidance. These include compliance with stringent pharmacovigilance rules, pursuant to which post-authorization studies and additional monitoring obligations can be imposed. In addition, manufacture and control must also be conducted in strict compliance with cGMP requirements and comparable requirements of other regulatory bodies in the EU and UK. cGMP requirements apply to the methods, facilities and controls used in manufacturing, processing and packing of drugs against the quality standards appropriate to the intended use of a medicinal product and as required by the marketing authorization, clinical trial authorization or product specification.

Much like the federal healthcare program anti-kickback law in the U.S., the provision of benefits or advantages to physicians to induce or encourage the prescription, recommendation, endorsement, purchase, supply, order or use of medicinal products is also prohibited in the EU and the UK. The provision of benefits or advantages to induce or reward improper performance generally is governed by the national anti-bribery laws of EU member states and the Bribery Act 2010 in the UK. Infringement of these laws could result in substantial fines and imprisonment. Applicable law in Europe further provides that, where medicinal products are being promoted to persons qualified to prescribe or supply them, no gifts, pecuniary advantages or benefits in kind may be supplied, offered or promised to such persons unless they are inexpensive and relevant to the practice of medicine or pharmacy.

Pursuant to national laws, industry codes or professional codes of conduct payments made to physicians in certain EU member states and the UK must be publicly disclosed. Moreover, agreements with physicians often must be the subject of prior notification and approval by the physician’s employer, his or her competent professional organization and/or the regulatory authorities of the individual EU member states, or the UK (as applicable). Failure to comply with these requirements could result in reputational risk, public reprimands, administrative penalties, fines or imprisonment.

The advertising and promotion of medicinal products is also subject to laws concerning promotion of medicinal products, interactions with physicians, misleading and comparative advertising and unfair commercial practices. All advertising and promotional activities for the product must be consistent with the approved summary of product characteristics, and therefore all off-label promotion is prohibited. Direct-to-consumer advertising of prescription medicines is also prohibited in the EU and the UK. Although general requirements for advertising and promotion of medicinal products are established under Directive 2001/83/EC, which was transposed into national law in the UK via the Human Medicines Regulations 2012, the details are governed by regulations in each European jurisdiction and can differ from one country to another.

General Data Protection Regulation

The processing of personal data regarding individuals in the EU, including personal health data, is regulated by Regulation (EU) 2016/679, which took effect on May 25, 2018. The General Data Protection Regulation (“GDPR”) is wide-ranging in scope and imposes numerous requirements on companies that process personal data, including requirements relating to processing health and other sensitive data, obtaining consent of the individuals to whom the personal data relates, providing information to individuals regarding data processing activities, implementing safeguards to protect the security and confidentiality of personal data, providing notification of data breaches and taking certain measures when engaging third-party processors. The GDPR also imposes strict rules on the transfer of personal data to countries outside the EU, including the U.S., and permits data protection authorities to impose large penalties for violations of the GDPR, including potential fines of up to €20 million or 4% of annual global revenues, whichever is greater. The GDPR also confers a private right of action on data subjects and consumer associations to lodge complaints with supervisory authorities, seek judicial remedies and obtain compensation for damages resulting from violations of the GDPR. Compliance with the GDPR will be a rigorous and time-intensive process that may increase the cost of doing business or require us to change our business practices to ensure full compliance.

As of January 1, 2021, the UK’s European Union (Withdrawal) Act 2018 incorporated the GDPR (as it existed on December 31, 2020 but subject to certain UK specific amendments) into UK law, referred to as the UK GDPR. The UK GDPR and the UK Data Protection Act 2018 set out the UK’s data protection regime, which is independent from but

63

Table of Contents

aligned to the EU’s data protection regime. Non-compliance with the UK GDPR may result in monetary penalties of up to £17.5 million or 4% of worldwide revenue, whichever is higher.

Coverage and Reimbursement

Significant uncertainty exists as to the coverage and reimbursement status of any product candidates for which we may seek regulatory approval by the FDA or other government authorities. In the U.S. and markets in other countries, patients generally rely on third-party payors to reimburse all or part of the costs associated with their treatment. Adequate coverage and reimbursement from governmental healthcare programs, such as Medicare and Medicaid, and commercial payors is critical to new product acceptance. Our ability to successfully commercialize our product candidates will depend in part on the extent to which coverage and adequate reimbursement for these products and related treatments will be available from government health authorities or programs, private health insurers and other organizations. Even if coverage is provided, the approved reimbursement amount may not be high enough to allow us to establish or maintain pricing sufficient to realize a sufficient return on our investment.

Government authorities and other third-party payors, such as private health insurers and health maintenance organizations, decide which medications they will pay for and establish reimbursement levels. Additionally, coverage and reimbursement for drug products can differ significantly from payor to payor. One third-party payor’s decision to cover a particular drug product or service does not ensure that other payors will also provide coverage for the drug product, or will provide coverage at an adequate reimbursement rate. Coverage policies and third-party reimbursement rates may change at any time. Even if favorable coverage and reimbursement status is attained for one or more product candidates for which we receive regulatory approval from one or more third party payors, less favorable coverage policies and reimbursement rates may be implemented in the future. Additionally, if a companion diagnostic test is developed for use with a drug product, any coverage and reimbursement for that test would be separate and apart from the coverage and reimbursement sought for such product. A lack of coverage or adequate reimbursement for such a test could adversely affect access to a drug product.

Within the U.S., third-party payors are increasingly seeking to control drug costs by examining the cost-effectiveness of new products and services in addition to their safety and efficacy; managing drug utilization and challenging the price of drugs. To obtain or maintain coverage and reimbursement for any future product, we may need to conduct expensive pharmacoeconomic studies to demonstrate the medical necessity and cost-effectiveness of our product. These studies will be in addition to the studies required to obtain regulatory approvals. Third-party payors may limit coverage of product by, for example, only covering specific products on an approved list, or formulary, which might not include all of the FDA-approved products for a particular indication. Some third-party payors may manage utilization of a particular product by requiring pre-approval (known as “prior authorization”) for coverage of particular prescriptions (to allow the payor to assess medical necessity) or otherwise restricting coverage of a product even if used consistent with its approved indication. Manufacturers of marketed drugs may be required to provide discounts or rebates under government healthcare programs or to certain government and private purchasers in order to obtain coverage under federal healthcare programs such as Medicaid. More generally, price concessions may need to be offered to third party payors to obtain favorable coverage or to purchasers to achieve sales. Hospitals and health systems are increasingly using bidding procedures to determine what pharmaceutical products and which suppliers will be included in their prescription drug and other healthcare programs. Arrangements with third party payors or purchasers may include value-based arrangements under which the amount paid for products depends on the performance of the product. Net prices for drugs may be further reduced by any future relaxation of laws that presently restrict imports of drugs from countries where they may be sold at lower prices than in the U.S.

In addition, in some foreign countries, the proposed pricing for a drug must be approved before it may be lawfully marketed. The requirements governing drug pricing vary widely from country to country. For example, the EU provides options for its member states to restrict the range of medicinal products for which their national health insurance systems provide reimbursement and to control the prices of medicinal products for human use. To obtain reimbursement or pricing approval, some of these countries may require the completion of clinical trials that compare the cost effectiveness of a particular medicinal product candidate to currently available therapies. A member state may approve a specific price for the medicinal product or it may instead adopt a system of direct or indirect controls on the profitability of the company placing the medicinal product on the market. There can be no assurance that any country that has price controls or reimbursement limitations for pharmaceutical products will allow favorable reimbursement and pricing arrangements for

64

Table of Contents

any of our product candidates. Historically, products launched in the EU do not follow price structures of the U.S. and generally prices tend to be significantly lower.

Healthcare Reform

Payors, whether domestic or foreign, or governmental or private, are developing increasingly sophisticated methods of controlling healthcare costs and those methods are not always specifically adapted for therapies addressing rare diseases such as those we are developing. In both the U.S. and certain foreign jurisdictions, there have been a number of reforms to the healthcare system that could impact our ability to sell our product candidates profitably if and when approved for marketing. For example, in 2010, the ACA was enacted, which, among other things, subjected biologic products to potential competition by lower-cost biosimilars; addressed a new methodology by which rebates owed by manufacturers under the Medicaid Drug Rebate Program are calculated for drugs that are inhaled, infused, instilled, implanted or injected; increased the minimum Medicaid rebates owed by most manufacturers under the Medicaid Drug Rebate Program; extended the Medicaid Drug Rebate program to utilization of prescriptions of individuals enrolled in Medicaid managed care organizations; subjected manufacturers to new annual fees and taxes for certain branded prescription drugs; created a new Medicare Part D coverage gap discount program, in which manufacturers must agree to offer point-of-sale discounts off negotiated prices of applicable brand drugs to eligible beneficiaries during their coverage gap period, as a condition for the manufacturer’s outpatient drugs to be covered under Medicare Part D.

Beyond the ACA, there have been ongoing healthcare reform efforts, including efforts focused on drug pricing and payment. For example, the Inflation Reduction Act (“IRA”), includes a number of changes intended to address rising prescription drug prices in Medicare Parts B and D. These changes include caps on Medicare Part D out-of-pocket costs, Medicare Part B and Part D drug price inflation rebates, a new Medicare Part D manufacturer discount drug program (replacing the ACA Medicare Part D coverage gap discount program) and a drug price negotiation program for certain high spend Medicare Part B and D drugs (with negotiated prices for the first set of drugs taking effect in 2026). The IRA has had and will likely continue to have a significant impact on the pharmaceutical industry. Additionally, changes to Medicaid effective in 2024 eliminated the Medicaid rebate cap and changes to certain Medicare price reporting requirements for drugs beginning in 2026 will likely increase the administrative and compliance burden for manufacturers.

Recently, drug pricing and payment has been subject to a number of reform initiatives. For example, the current presidential administration issued an Executive Order in April 2025 with multiple directives aimed at lowering drug prices, including refining the Medicare drug price negotiation program established by the IRA; accelerating competition for high-cost prescription drugs by accelerating approval of generics and biosimilars and facilitating the process for re-classifying prescription drugs as over-the-counter drugs; and increasing drug importation. In May 2025, the current presidential administration issued another Executive Order that directed government agencies and officials to identify most-favored nation pricing targets for prescription drugs (and looked to pharmaceutical manufacturers to make significant progress towards delivering target prices to patients); prevent foreign countries from disproportionately shifting the cost of global pharmaceutical research and development to the United States; and facilitate direct-to-consumer purchasing programs for pharmaceutical manufacturers to sell their products to patients at the most-favored-nation price. In the wake of the Executive Orders and related executive initiatives, a number of pharmaceutical manufacturers have announced direct-to-consumer offerings with discounted prices and/or reached agreement with the federal government regarding pricing for drugs, including prices for Medicaid drugs and newly launched products. A website sponsored by the federal government offering pharmaceutical direct-to-consumer channels has also been launched. Federal agencies are developing new drug pricing pilot programs, such as a voluntary Medicaid initiative which would authorize the federal government to negotiate Medicaid supplemental rebates with participating manufacturers on behalf of state Medicaid programs, in exchange for standardized coverage criteria for participating manufacturer drugs, and proposed Medicare Part B and Part D pilot models that, if finalized as proposed, would replace existing inflation-based Medicare rebates with rebates determined on the basis of international prices, for drugs and patients subject to the model. Many of these reform initiatives would require additional legal and/or administrative action to implement and may be subject to legal challenge.

Other federal healthcare reform efforts or actions may affect access to healthcare coverage or the funding of health care benefits, although the full impact of such efforts or actions cannot be predicted. For example, the Congressional Budget Office has estimated that Medicaid provisions in the 2025 budget reconciliation legislation, including restrictions in eligibility and funding for Medicaid, as well as changes to the healthcare marketplace such as the elimination of certain subsidies, will increase the number of uninsured.

65

Table of Contents

There have also been efforts by federal and state government officials or legislators to implement measures to regulate prices or payment for pharmaceutical products, including legislation on drug importation. For example, on January 5, 2024, the FDA approved Florida’s Section 804 Importation Program (“SIP”) proposal to import certain drugs from Canada for specific state healthcare programs. It is unclear how this program will be implemented, including which drugs will be chosen, and whether it will be subject to legal challenges in the U.S. or Canada. Other states have also submitted SIP proposals that are pending review by the FDA. Any such approved importation plans, when implemented, may result in lower drug prices for products covered by those programs. Recently, there has been considerable public and government scrutiny of pharmaceutical pricing and proposals to address the perceived high cost of pharmaceuticals.

At the state level, individual states are increasingly implementing initiatives designed to control pharmaceutical and biological product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and measures to encourage importation from other countries and bulk purchasing. For example, certain states have formed Prescription Drug Affordability Boards that assert authority to set reimbursement rates and/or drug pricing in the state. States are also increasingly expanding or changing Medicaid supplemental rebate programs to secure additional rebates from manufacturers in exchange for drug coverage and to limit coverage of certain drugs for certain Medicaid patients or to all Medicaid patients. These and other future state-level reform activities could negatively affect Medicaid coverage and reimbursement for our products.

Healthcare reform efforts have been and may continue to be subject to scrutiny, legal challenge and subsequent amendment, creating further uncertainty.

Other recent government actions may also affect prices or payments for prescription drugs. For example, the Trump Administration’s recently announced tariff on branded or patented drugs may increase the cost of drug products that are imported from abroad or manufactured using products or materials imported from abroad. The timeline for implementation of this tariff has not yet been finalized. As another example, the Budget Control Act, as amended (the “Budget Control Act”), resulted in the imposition of reductions in Medicare (but not Medicaid) payments to providers in 2013 that remain in effect through 2032 unless additional Congressional action is taken. Any significant spending reductions affecting Medicare, Medicaid or other publicly funded or subsidized health programs that may be implemented and/or any significant taxes or fees that may be imposed on us could have an adverse impact on our results of operations.

Future healthcare or related reforms could affect demand for, or pricing of, any future products if approved for sale. We cannot, however, predict the ultimate content, timing or effect of any reform efforts. There is no assurance that such reform will not adversely affect our future business and financial results.

Other Healthcare Laws

Pharmaceutical companies are subject to additional healthcare regulation and enforcement by the federal government and by authorities in the states and foreign jurisdictions in which they conduct their business that may constrain how we conduct our business, including the financial arrangements and relationships through which we research, as well as sell, market and distribute any products for which we obtain marketing authorization. Restrictions under applicable federal and state healthcare laws and regulations, some of which will apply only if and when we receive marketing approval for a product candidate, include the following:

66

Table of Contents

Some state laws require pharmaceutical companies to comply with specific compliance standards, restrict financial interactions between pharmaceutical companies and healthcare providers or require pharmaceutical companies to report information related to payments to healthcare providers or marketing expenditures. Other state laws may require pharmaceutical companies to file reports relating to pricing and marketing information, and state and local laws may require registration of pharmaceutical sales representatives.

Efforts to ensure that our business arrangements with third parties comply with applicable healthcare laws and regulations will involve substantial costs. Given the breadth of the laws and regulations, limited guidance for certain laws and regulations and evolving government interpretations of the laws and regulations, governmental authorities may possibly conclude that our business practices may not comply with healthcare laws and regulations. If our operations are found to be in violation of any of the laws described above or any other government regulations that apply to us, we may be subject to penalties, including significant civil and criminal penalties, damages, fines, exclusion from participation in government healthcare programs, such as Medicare and Medicaid, imprisonment, and the curtailment or restructuring of our operations, any of which could adversely affect our business, financial condition, results of operations, and prospects.

Employees and Human Capital Resources

As of February 28, 2026, we had 167 full-time employees, consisting of clinical, scientific, development, medical affairs, technical operations, regulatory, finance, legal and operational personnel. None of our employees is represented by labor unions or subject to a collective bargaining agreement. Our personnel outside of the U.S. are subject to employment contracts which contain customary notice periods. We consider our relationship with our employees to be good.

Of our 167 full-time employees as of February 28, 2026, 16 were located in China and consisted of clinical, technical operations, regulatory, finance and human resources personnel. Our China-based employees support clinical operations and regulatory matters related to obexelimab in the Asia-Pacific region and technical operations, with all functions in China reporting to management in the U.S. We also have 4 dedicated medical and commercial personnel located in Europe to advance our obexelimab strategy in that region. We recognize that our continued ability to attract, retain, and motivate exceptional employees is vital to ensuring our long-term competitive advantage. Our employees are critical to our long-term success and are essential to helping us meet our goals. Among other things, we support and incentivize our employees in the following ways:

67

Table of Contents

Corporate and Other Information

We incorporated in November 2019 as Zenas BioPharma (Cayman) Limited, an exempted company incorporated in the Cayman Islands with limited liability, and commenced operations in 2020. On August 2, 2023, the Company (then known as Zenas BioPharma (Cayman) Limited) de-registered from the Cayman Islands and registered by way of continuation in the State of Delaware. Our common stock currently trades on the Nasdaq Global Select Market under the ticker symbol “ZBIO”. Our principal executive offices are located at 852 Winter Street, Suite 250, Waltham MA 02451, and our telephone number at that address is (857) 271-2954.

Available Information

Our Internet address is www.zenasbio.com. Our website and the information contained on, or that can be accessed through, the website will not be deemed to be incorporated by reference in, and are not considered part of, this Annual Report on Form 10-K. We have included our website in this Annual Report solely as an inactive textual reference. Our Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K, including exhibits, proxy and information statements and amendments to those reports filed or furnished pursuant to Sections 13(a), 14, and 15(d) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) are available through the “Investor & Media Relations” portion of our website free of charge as soon as reasonably practicable after we electronically file such material with, or furnish it to, the SEC. In addition, our filings with the SEC may be accessed through the SEC’s Electronic Data Gathering, Analysis and Retrieval system at http://www.sec.gov. All statements made in any of our securities filings, including all forward-looking statements or information, are made as of the date of the document in which the statement is included, and we do not assume or undertake any obligation to update any of those statements or documents unless we are required to do so by law.