Vir Biotechnology, Inc. (VIR) Business

Item 1. Business.

Overview and Strategy

Powering the Immune System to Transform Lives.

Vir Biotechnology, Inc. (including its subsidiaries, referred to as “Vir Bio,” “the Company,” “we,” “our” or “us”) is a clinical-stage biopharmaceutical company focused on powering the immune system to transform lives by discovering and developing medicines for serious infectious diseases and cancer.

These diseases represent formidable challenges to human health. Under normal conditions, our immune system is naturally equipped to protect us by identifying and eradicating both cancer cells and viruses. However, these threats have evolved sophisticated mechanisms to evade our immune defenses. When cancer cells or viruses successfully bypass our immune system, they have the potential to cause diseases that may be life-threatening. We are focused on developing therapies that enhance the immune system’s ability to overcome these evasion tactics, effectively powering the immune system to combat viruses and fight cancer.

We believe our unified approach of leveraging our deep understanding of immunology to address seemingly disparate threats distinguishes us in the field. Our mission is to develop innovative therapies that can transform patients' lives by addressing areas of high unmet medical need.

Our clinical development pipeline consists of investigational therapies targeting hepatitis delta virus (HDV) and multiple solid tumors. In hepatitis delta, we have initiated our registrational ECLIPSE clinical program evaluating the tobevibart and elebsiran combination in people living with chronic hepatitis delta (CHD). The three randomized, controlled trials (ECLIPSE 1, 2, and 3) are ongoing, with ECLIPSE 1 and 3 completing enrollment ahead of the Company’s expectations. Topline results from ECLIPSE 1 are expected in the fourth quarter of 2026 with topline results from ECLIPSE 2 and 3 expected in the first quarter of 2027. Should the ECLIPSE program yield positive results that support regulatory approval and subsequent commercial launch, we believe the combination has the potential to be a new standard of care for CHD patients, for whom approved treatment options are either limited or unavailable. In oncology, we are advancing three Phase 1 clinical studies of dual-masked T-cell engagers (TCEs): VIR-5500 in patients with Prostate-Specific Membrane Antigen (PSMA)-expressing metastatic castration-resistant prostate cancer (mCRPC); VIR-5818 in patients with HER2-expressing tumors; and VIR-5525 in patients with EGFR-expressing tumors.

We are developing therapeutic candidates in HIV cure and multiple solid tumors. Our HIV broadly neutralizing antibodies (bnAbs) are being developed as a potential long-acting treatment or cure in combination with existing or investigational regimens. We have also made available for external partnerships our next-generation preclinical influenza A and B antibodies and antibody drug conjugates (ADCs), along with our next generation coronavirus (COVID) monoclonal antibodies.

We are advancing multiple undisclosed PRO-XTEN® dual-masked TCEs targeting clinically validated targets with potential applications across a variety of solid tumors. These preclinical candidates leverage the PRO-XTEN® masking technology with novel TCE fragments discovered and engineered using our antibody discovery platform.

These research and development efforts are driven by Vir Bio’s discovery engine, comprised of our exceptional protein engineering and antibody discovery expertise and our two core technology platforms — our proprietary dAIsY™ (data, AI structure and antibodY) platform utilizing artificial intelligence and machine learning (collectively referred to as AI) for antibody optimization, and the exclusive PRO-XTEN® (a trademark of Amunix Pharmaceuticals, Inc., a Sanofi company) masking platform, which we in-licensed from Sanofi for worldwide rights in oncology and infectious diseases. The PRO-XTEN® platform allows for the development of potentially best-in-class TCEs with improved safety and efficacy profiles across multiple therapeutic areas. The dAIsY™ and PRO-XTEN® platforms, individually and in combination, enable us to modulate the immune system in innovative ways, harnessing its power to combat viruses and fight cancer.

We have an industry-leading management team and board of directors with significant immunology, infectious diseases and oncology experience, including a proven track record of progressing product candidates from early-stage research through clinical development, and worldwide regulatory approval and commercialization experience. Given the global impact of infectious diseases and cancer, we are committed to developing transformative therapies that can make a meaningful difference in the lives of people living with these serious diseases.

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Our Research and Development Pipeline

At Vir Bio, we are advancing our mission of powering the immune system with innovative medicines to transform lives, with the goal of driving better outcomes for patients in areas of high unmet medical need, such as infectious diseases and cancer. We use our world-class capabilities in antibody discovery and engineering, coupled with our proprietary AI engine dAIsY™ system, and the PRO-XTEN® masking platform, to quickly and effectively discover and optimize potential new medicines.

We have built a strong foundation based on cutting-edge core scientific capabilities and a world-class team of experts who bring deep knowledge and experience to our R&D efforts. This has enabled us to make significant strides in developing treatments for infectious diseases and to strategically expand our approach to address critical oncology indications with limited treatment options. Our pipeline includes multiple candidates in clinical development for diseases with significant unmet medical need, which is categorized by disease area in the chart below.

1: Masked TCEs licensed from Sanofi

2 In collaboration with the Gates Foundation

ARPIs: androgen receptor pathway inhibitors; EGFR: epidermal growth factor receptor; HER2: human epidermal growth factor receptor 2; HIV: human immunodeficiency virus; PSMA: prostate-specific membrane antigen; siRNA: small interfering RNA; TCE: T-cell engager

Tobevibart incorporates Xencor’s XtendTM and other Fc technologies.

Norgine holds exclusive license for the commercial rights to the combination of tobevibart and elebsiran in Europe, Australia and New Zealand

Brii Bioscience retains rights to the combination of tobevibart and elebsiran in the Greater China Territory (People’s Republic of China, Hong Kong, Taiwan and Macau)

Infectious Diseases

Tobevibart

Molecular Characteristics and Preclinical Data. Tobevibart is an investigational neutralizing monoclonal antibody (mAb) that has been engineered for immune engagement and targets a conserved region on the hepatitis B surface antigen (HBsAg), a protein which is required for the HDV viral life cycle. Tobevibart specifically targets the antigenic loop (AGL) on HBsAg. The AGL helps HBV bind to hepatocytes and subsequently infect these cells. By binding to the AGL, tobevibart is designed to prevent viral entry, which prevents the spread of HDV to uninfected hepatocytes. It has been engineered to neutralize strains from all 10 HBV genotypes. Tobevibart, through a process called opsonization, also helps remove HBV virions and sub-viral particles (SVPs) from the blood.

Tobevibart was identified using our proprietary antibody discovery platform. Tobevibart’s proprietary fragment crystallizable (Fc) engineering enhances its ability to engage immune cells, promoting the removal of antibody-virion complexes. Tobevibart also incorporates Xencor’s Xtend™ neonatal Fc receptor technology, which extends its half-life.

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Tobevibart has the potential to activate the immune system to fight the virus via three different processes. First, due to specialized mutations in the Fc domain, tobevibart has the potential to act as a T-cell vaccine, inducing the production of protective T-cells and promoting immunity. This is based on a mechanism by which tobevibart could capture virions and SVPs, deliver them to dendritic cells and instruct these cells to mature and stimulate T-cells that can then eliminate HBV- infected hepatocytes. Second, tobevibart has the potential to act via antibody-dependent cell cytotoxicity (ADCC). In this process, by binding to HBsAg at the cell surface, tobevibart recruits natural killer cells to eliminate infected hepatocytes. The Fc domain of tobevibart has been engineered to promote ADCC. Third, when large quantities of HBV proteins are released into the blood, especially HBsAg, they can be immunosuppressive. Tobevibart has the potential to activate the immune system by reducing the amount of HBsAg in the blood, decreasing the ability of HBV to suppress the immune system and further enabling the natural immune response to the virus.

Elebsiran

Molecular Characteristics and Preclinical Data. Elebsiran is an investigational HBV-targeted small interfering RNA (siRNA) that reduces HBsAg. Elebsiran targets a conserved sequence of HBV that allows for predicted activity against 99.7% of the strains of HBV, including all 10 HBV genotypes. Because this conserved sequence falls within a specific region of the X gene of HBV that exists within all four HBV RNA transcripts, elebsiran is designed to degrade each transcript, and consequently decrease the expression of all proteins produced by the virus: X, polymerase, S, and core.

Once inside the infected cell, DNA from the HBV virus can become integrated into human DNA as integrated DNA (intDNA). Because elebsiran targets a region of HBV that is conserved in the large majority of HBV intDNA, this single siRNA is predicted to be able to prevent the production of HBV proteins derived from intDNA, as well as the production of all other HBV proteins from covalently closed circular DNA (cccDNA).

There are at least two potential mechanisms by which the large amount of HBV protein that is transcribed in liver cells can suppress the immune system. The first mechanism is T-cell tolerance and exhaustion by the presentation of intracellular HBV antigens on hepatocytes. The second is the large quantities of HBV proteins that are released into the blood, especially HBsAg, which may also be immunosuppressive. By directly reducing the amount of HBV proteins made, elebsiran has the potential to decrease the ability of HBV to suppress the immune system and enable the natural immune response to the virus. In mice models, siRNAs that are able to reduce HBsAg expression can transform an otherwise ineffective therapeutic HBV vaccine into one that can functionally cure the mice of HBV, suggesting that HBsAg suppression has the ability to enhance the immune response against HBV.

We believe that elebsiran is the only HBV-targeting siRNA currently in development that includes enhanced stabilization chemistry (ESC+) technology and preclinical modeling. Initial clinical data suggest this technology may be able to enhance the safety profile of elebsiran.

Simplified mechanism of action representation of tobevibart and elebsiran.

cccDNA: covalently closed circular DNA, HBsAg: hepatitis B virus surface antigen, HBV: hepatitis B virus, HDV: hepatitis D virus, Int: integrated, NRTI: nucleoside/nucleotide reverse transcriptase inhibitor, RNP: ribonucleoprotein, SVP: subviral particle

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CHD

CHD is a progressive liver disease caused by HDV, which requires HBV for its replication. This means that HDV infection cannot occur in the absence of HBV. HDV-HBV coinfection is the most severe form of chronic viral hepatitis. HDV, recently classified as carcinogenic by the International Agency for Research on Cancer, increases the risk of liver cancer and accelerates progression to cirrhosis and liver failure, which often occurs within five years of infection. There is no approved CHD treatment in the U.S., and options are limited in the European Union and globally.

Vir Bio is working to develop a chronic suppressive therapy to help address this significant unmet medical need, based on a combination of our investigational antibody, tobevibart, and a siRNA, elebsiran.

Tobevibart + elebsiran for CHD

SOLSTICE is a Phase 2 study to evaluate the safety, tolerability, and efficacy of tobevibart, alone or in combination with elebsiran, in people with CHD. This Phase 2 study is a multi-center, open-label, randomized study. Primary endpoints include proportion of participants with protocol defined virologic endpoint (defined as HDV RNA equal or greater than 2 log10 decrease from baseline or below limit of detection) up to Week 24, alanine aminotransferase (ALT) normalization (defined as ALT below upper limit of normal) up to Week 24, and treatment-emergent adverse events (TEAEs) and serious adverse events (SAEs) up to 118 weeks. Secondary endpoints include proportion of participants with undetectable HDV RNA at different timepoints up to 192 weeks. Clinical trial participants have been randomized to receive tobevibart 300 mg monotherapy every two weeks (n=33) or a combination of tobevibart 300 mg and elebsiran 200 mg every four weeks (combination de novo arm, n=32). In addition, the participants from previous tobevibart or elebsiran monotherapy cohorts could rollover to receive the combination of tobevibart 300 mg and elebsiran 200 mg every four weeks (combination rollover, n=13). 48-week data from the ongoing clinical trial was presented in an oral session at the American Association for the Study of Liver Diseases (AASLD) The Liver Meeting®, in Washington, D.C., in November 2025 and simultaneously published in the New England Journal of Medicine.

Additional data was later presented at the 44ᵗʰ Annual J.P. Morgan Healthcare Conference in January 2026. These data demonstrate that undetectable hepatitis delta virus RNA (HDV RNA Target Not Detected, TND) was achieved and maintained by 77% (24/31) of participants receiving the combination of tobevibart and elebsiran at Week 72, and this rate increased to 88% (21/24) in the subset of participants evaluated through Week 96. By contrast, HDV RNA TND was achieved by 53% (17/32) of participants receiving tobevibart antibody monotherapy at Week 72 and 46% (11/24) in the subset of participants evaluated through Week 96. Additionally, approximately 90% of participants receiving the combination therapy achieved reduction in HBsAg to values 10 IU/mL by Week 24 and kept that response through Week 72 and (for the subset of patients evaluable) Week 96, compared to approximately 20% of participants receiving antibody monotherapy at every time point. HBsAg reduction indicates suppression of the fundamental biologic mechanisms that HDV requires for viral replication. ALT was normalized in approximately half of participants by Week 72 and (for the subset of patients evaluable) Week 96. There were no grade 3 or higher treatment-related adverse events in the combination arm, and treatment emergent adverse events were generally mild to moderate and transient.

Vir Bio initiated its registrational clinical program, ECLIPSE, evaluating the tobevibart and elebsiran combination in people living with CHD, in March of 2025. The program includes three randomized, controlled trials (ECLIPSE 1, 2, and 3) designed to evaluate the combination therapy in comparison to deferred treatment or bulevirtide. All three trials are ongoing, with ECLIPSE 1 and 3 completing enrollment ahead of the Company’s expectations. Topline results from ECLIPSE 1 are expected in the fourth quarter of 2026, and topline results from ECLIPSE 2 and ECLIPSE 3 are expected in the first quarter of 2027.

The combination of tobevibart and elebsiran has now been recognized by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for their potential to address the critical unmet need in CHD. The investigational combination therapy has been granted Breakthrough Therapy and Fast Track designations by the U.S. Food and Drug Administration (FDA), and Priority Medicines (PRIME) and orphan drug designations by the EMA.

On December 15, 2025, we and Norgine Pharma UK Limited (together with its affiliates in the Norgine group of companies, Norgine) entered into a License Agreement (the Norgine Agreement) with respect to certain commercial and certain development rights to the combination of tobevibart and elebsiran for the treatment of people living with CHD as described in further detail below under “—Our Collaboration, License and Grant Agreements,” Under the terms of the Norgine Agreement, Vir Bio granted Norgine an exclusive license for the commercial rights and certain development rights to the combination for the treatment of CHD in Europe, Australia, and New Zealand (collectively, the Norgine Territory), while Vir Bio will retain commercial rights for the combination in the United States and all other international markets outside of the People’s Republic of China and Taiwan.

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Chronic Hepatitis B (CHB)

CHB is a long-lasting, inflammatory liver disease caused by the HBV. The World Health Organization estimates that 254 million people live with CHB, and an estimated 1.1 million yearly deaths are associated with the disease. Complications from CHB may include liver cirrhosis, liver failure and liver cancer.

The rate of functional cure (lifelong control of the virus after a finite duration of treatment) with current approved treatments is 3%-7%. Alternatively, suppressive therapy with daily nucleotide/nucleoside reverse transcriptase inhibitors (NRTIs) is commonly used, and CHB patients often require a lifetime of therapy, and NRTIs reduce but do not eliminate the risk of further progression and developing end-stage liver disease complications such as cirrhosis or cancer.

In July 2021 we initiated the MARCH two-part study to evaluate the combination of tobevibart and elebsiran in virally suppressed HBV patients. The latest results from the MARCH Part B Phase 2 trial evaluating the combination of tobevibart and elebsiran without or with pegylated interferon alpha (PEG-IFNα) were presented in an oral session at the European Association for the Study of the Liver (EASL) congress in Amsterdam (The Netherlands) in May 2025. The 24-week post-end of treatment data revealed that the study-defined primary endpoint, proportion of participants with undetectable HBsAg at 24 weeks post-end of treatment, was achieved by 17% (3/18) and 21% (3/14) of participants with baseline HBsAg1,000 IU/mL receiving tobevibart and elebsiran without or with PEG-IFNα, respectively. These proportions were 8% (4/51) and 16% (5/32) for tobevibart and elebsiran without or with PEG-IFNα, respectively, in all participants. The safety and tolerability profile of tobevibart and elebsiran was consistent with prior studies, with no new safety concerns and generally only mild or moderate treatment emergent adverse events being reported throughout the study. Vir Bio decided not to pursue Phase 3 development of combinations of tobevibart, and elebsiran in CHB. We have streamlined the final stages of the MARCH Phase 2 program to ensure continued participant benefit and safety.

Elebsiran is also being evaluated in additional Phase 2 clinical trials with collaborators. Brii Biosciences Offshore Limited (Brii Bio) is the sponsor for the Phase 2 trial of elebsiran in combination with BRII-179, an investigational therapeutic vaccine, for the treatment of chronic HBV infection. As described in further detail below under “—Our Collaboration, License and Grant Agreements,” we granted Brii Bio an option to obtain exclusive rights to develop and commercialize elebsiran and tobevibart in the Greater China Territory (People’s Republic of China, Hong Kong, Taiwan and Macau), for the treatment, palliation, diagnosis, prevention or cure of acute and chronic diseases of infectious pathogen origin or hosted by pathogen infection, or the Field of Use.

HIV treatment and functional cure

Despite major advances in HIV treatment, most people living with HIV must take daily antiretroviral medications for viral control. HIV broadly neutralizing antibodies (bnAbs) are a novel modality that has shown promise for controlling the virus without daily antiretroviral medications. Furthermore, HIV bnAb treatment can induce a state of viral control off therapy, effectively a functional cure. While these outcomes are currently only found in rare individuals and for limited time periods, it suggests that HIV bnAbs could be an important part of a functional cure regimen.

With the support of the Gates Foundation, we are developing a unique and innovative HIV bnAb therapeutic. We have in-licensed HIV bnAbs from Togontech GmbH, including the 04-A06 bnAb published in Nature Immunology, that shows what we believe to be favorable preclinical properties, including neutralization breadth and potency to combat the diversity of HIV strains worldwide and resistance to the ability of the virus to escape from therapeutic intervention. We are further engineering HIV bnAbs with our Fc engineering technology to enhance their half-life, effector functions, and engagement with the patient’s immune system. We believe the resulting therapeutic can make an important impact on the lives of people living with HIV.

Oncology

One in five people worldwide develop cancer during their lifetime, and although tremendous strides have been made in cancer prevention and treatment, cancer still remains the second-leading cause of death globally and remains the leading or second-leading cause of premature death (before age 70 years) in 112 countries.

While major advances have been made in immunotherapies for hematologic malignancies, a large unmet need remains for novel and tolerable therapeutics for patients with solid tumors. TCEs are potent anti-tumor agents that direct the immune system, specifically T-cells, to attack cancer cells. Vir Bio’s bi-specific TCE is comprised of two antibody fragments: a tumor-associated antigen (TAA) binding domain and a CD3 binding domain. They are designed to simultaneously recruit T-cells and TAA-expressing cancer cells, directing the cytotoxic activity of T-cells against the tumor. However, if the antigen is also expressed on healthy cells, bi-specific TCEs can similarly bind to TAAs present in non-cancerous cells or healthy tissue, driving on-target, off-tumor toxicity, including cytokine release syndrome (CRS), thus limiting the potential therapeutic index of TCEs.

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Masking of TCEs is a strategy designed to circumvent these limitations. This technology specifically leverages overactivity of proteases in the tumor microenvironment (whereas proteases are tightly regulated by protease inhibitors elsewhere in the body). By attaching masks joined by protease cleavable linkers to the TCE, Vir Bio’s TCEs are designed to remain inactive until they reach the tumor microenvironment. Once in the tumor microenvironment, tumor-specific proteases can cleave off the mask and release the unmasked TCE, which can bind to both T-cell and tumor cells expressing the TAA, and lead to killing of cancer cells. By limiting the unmasking of the TCEs to the tumor microenvironment, we aim to limit the toxicity of these agents in the periphery and potentially increase their safety and efficacy.

We are currently advancing three clinical-stage dual-masked TCEs: VIR-5500 (Phase 1); VIR-5818 (Phase 1); and VIR-5525 (Phase 1). These molecules leverage the PRO-XTEN® masking technology with TCEs targeting CD3 on T-cells and HER2, PSMA and EGFR, respectively, on tumor cells.

VIR-5500 for the treatment of metastatic castration-resistant prostate cancer

Molecular Characteristics and Preclinical Data. VIR-5500 is a protease-activated, bispecific dual-masked TCE, designed to exploit the dysregulated protease activity in tumors relative to healthy tissues, thus expanding the safety margin and therapeutic index. The VIR-5500 core consists of a VHH (single-variable domain on a heavy chain) domain targeting PSMA and an scFv-targeting CD3. The core is flanked by two unstructured polypeptide masks (XTEN™ masks) that sterically reduce target engagement in healthy tissue and extend the half-life of the protein. Protease cleavage sites at the base of the XTEN™ masks enable proteolytic activation of unmasked protein in the tumor microenvironment, unleashing a small, highly potent unmasked TCE, designed to redirect cytotoxic T-cells to kill PSMA-expressing tumor cells. In healthy tissues, in which protease activity is minimal due to tight regulation, VIR-5500 should remain predominantly inactive.

Phase 1 Trial of VIR-5500. VIR-5500 is being evaluated in a Phase 1 clinical trial designed to assess its safety, pharmacokinetics, and preliminary efficacy as a monotherapy in late-line mCRPC and standard-of-care combinations in earlier-line settings. Positive updated monotherapy dose-escalation data from the ongoing Phase 1 trial will be presented at the 2026 American Society of Clinical Oncology (ASCO) Genitourinary Cancers Symposium in February 2026. These data support VIR-5500’s favorable safety and tolerability profile and show that treatment with VIR-5500 provided dose-dependent anti-tumor activity as measured by both PSA declines and radiographic responses.

Data across all patients receiving VIR-5500 monotherapy in the Phase 1 trial (n=58) show that VIR‑5500 was generally well tolerated with no dose‑limiting toxicities observed to date. Grade ≥3 treatment‑related adverse events occurred in 12% (7/58) of patients and were manageable. Limited CRS was observed in 50% (29/58) of patients, with events generally limited to Grade 1 (fever only). Prophylactic steroids were not required and were only explored in a small cohort of three patients. Enrolled patients were heavily pretreated (median of four prior lines) and a substantial proportion presented with high tumor burden, including 45% (25/58) with visceral metastases.

Dose‑dependent activity was observed across the entire treatment group as measured by both prostate-specific antigen (PSA) declines and radiographic responses. Efficacy data were reported in the highest dose cohorts (≥3,000 µg/kg Q3W; n=22/58) as of the January 9, 2026 data cut-off. In these cohorts, among those patients who were PSA-evaluable (i.e., received a full cycle of treatment and had completed both pre- and post-treatment PSA assessments in accordance with applicable prostate cancer clinical trial guidance) (n=17), PSA501 declines occurred in 82% (14/17) and PSA902 declines occurred in 53% (9/17) of patients. Among RECIST (Response Evaluation Criteria in Solid Tumors)‑evaluable patients, objective responses were seen in 45% (5/11). Of the five responders, four achieved confirmed responses with one patient pending confirmation. Reductions on PSMA‑PET (positron emission tomography) affirm PSA declines and radiographic responses, with tumor shrinkage observed across multiple lesions, including visceral metastases. These findings support proof‑of‑concept and further evaluation in expansion cohorts.

We have concluded QW and Q3W monotherapy dose-escalation in late-line mCRPC and has defined a preliminary go-forward dose and regimen recommendation for expansion. In parallel, dose-escalation of VIR-5500 in combination with enzalutamide continues in early-line mCRPC patients. We anticipate initiating monotherapy dose-expansion cohorts in late-line mCRPC and combination dose-expansion cohorts in both early-line mCRPC and metastatic hormone-sensitive prostate cancer (mHSPC) in the second quarter of 2026 followed by pivotal Phase 3 trials in 2027.

1 PSA decline of 50%-100% from baseline.

2 PSA decline of 90%-100% from baseline.

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VIR-5818 ± pembrolizumab for the treatment of HER2-positive solid tumors

Molecular Characteristics and Preclinical Data. While the role of HER2 in breast and gastric cancer has been well established for many years, only recently has there been a recognition of the importance of HER2 in other disease types, in particular as a resistance biomarker to other signaling pathways such as EGFR. With more patients undergoing biopsies after progression from prior therapies, and the advance of more routine molecular genotyping, numerous aberrations in HER2 have been discovered. Collectively, HER2+ tumors (IHC 3+ or in situ hybridization [ISH]+) and solid tumors with activating HER2 mutations represent a large unmet need. VIR-5818, with its novel mode of action and potential for large safety margins due to masking, may be an important treatment option that can extend survival and provide cancer immunity to these tumors.

VIR-5818 is a HER2-targeted, conditionally activated masked TCE designed to exploit dysregulated protease activity in tumors while sparing healthy tissues in which there is minimal protease activity, thus broadening the safety margin and therapeutic index. The core consists of two, tandem, single-chain variable fragments (scFvs) targeting CD3 and HER2 that are flanked by two unstructured polypeptide masks (XTEN™) that sterically reduce target engagement in normal tissues and extend half-life. Protease cleavage sites at the base of the XTEN™ masks enable proteolytic activation of fully masked TCE in the tumor microenvironment, unleashing a small, highly potent, unmasked TCE, which is able to redirect cytotoxic T-cells to kill target-expressing tumor cells. The potent, unmasked form (uTCE) of VIR-5818, also has a much shorter half-life to potentially increase the therapeutic index if the activated form should leak back into circulation. In healthy tissues, in which protease activity is tightly regulated, VIR-5818 should remain predominantly masked and as an intact prodrug. Additional information is available below under “— Our Technology Platforms.”

GLP NHP toxicology studies have demonstrated minimal toxicities with a NOAEL at the top dose evaluated of 6mg/kg. Unmasked VIR-5818 had single digit pM potent cytotoxicity to HER-2 expressing tumor cells, but significantly less cytotoxic to HER-2 expressing cardiomyocytes, requiring 1uM, thus demonstrating the potential wide therapeutic index compared to normal tissue and showing the need for dysregulated proteases (only found in tumor cells) for unmasking and eventual cell killing.

Phase 1 Trial of VIR-5818 ± pembrolizumab. VIR-5818 is being evaluated in a Phase 1 clinical trial designed to study its safety and pharmacokinetics alone, and in combination with pembrolizumab, in participants with a variety of HER2-expressing cancers, including breast and colorectal cancer (CRC). Early safety and efficacy data from the monotherapy cohort was presented at an investor event on January 8, 2025.

Early efficacy data showed that 50% (10/20) of participants receiving VIR-5818 doses ≥400 µg/kg experienced dose-dependent tumor shrinkage across multiple HER2-positive tumor types at either QW or Q3W dosing schedule after an initial step-up dosing in Cycle 1. This includes participants who had received up to nine prior lines of therapy. Strong anti-tumor activity was observed in a subset of participants with HER2-positive CRC who have exhausted standard of care. In this subset, confirmed partial responses (cPRs) were seen in 33% (2/6) of participants at early doses, and one patient continued in cPR for more than 18 months as of the data cut-off in November 2024. All the HER2-positive CRC tumors were also MSS (Microsatellite Stable) which traditionally are unresponsive to immunotherapies.

Preliminary safety data demonstrated that VIR-5818 was generally well-tolerated, with minimal grade 1 or 2 CRS (20% and 10%, respectively) and no grade 3 or greater CRS observed in any of the 79 participants across doses up to 1 mg/kg. Most TEAEs were low grade, reversible and manageable. The maximum tolerated dose (MTD) has not yet been reached. Preliminary pharmacokinetics and safety data indicate low systemic unmasking of the TCE, suggesting tumor-specific activation. Dual masking results in a half-life of approximately six days, which may enable a less frequent dosing regimen, such as Q3W. VIR-5818 continues to advance through dose escalation as a monotherapy, and in combination with pembrolizumab, in multiple tumor types, including metastatic breast cancer and metastatic colorectal cancer.

VIR-5525

Molecular Characteristics and Preclinical Data. VIR-5525 is an investigational dual-masked TCE that combines a bispecific EGFR and CD3 binding TCE with the PRO-XTEN® masking technology. Similarly to VIR-5818 and VIR-5500, VIR-5525 is also conditionally activated and designed to exploit dysregulated protease activity in tumors while sparing healthy tissues in which there is minimal protease activity, thus broadening the safety margin and therapeutic index. The core consists of two, tandem, single-chain variable fragments (scFvs) targeting CD3 and EGFR, that are flanked by two unstructured polypeptide masks (XTEN™) that sterically reduce target engagement in normal tissues and extend half-life. Protease cleavage sites at the base of the XTEN™ masks enable proteolytic activation of fully masked TCE in the tumor microenvironment, unleashing a small, highly potent, unmasked TCE, which is able to redirect cytotoxic T-cells to kill target-expressing tumor cells. The potent, unmasked form (uTCE) of VIR-5525, also has a much shorter half-life to potentially increase the therapeutic index if the activated form should leak back into circulation. In healthy tissues, in which protease activity is tightly regulated, VIR-5525 should remain predominantly masked and as an intact prodrug.

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Phase 1 Trial of VIR-5525. VIR-5525 is being evaluated in a Phase 1 clinical trial designed to assess its safety, pharmacokinetics, and preliminary efficacy as a monotherapy and in combination with pembrolizumab in a variety of EGFR-expressing solid tumors, such as non-small cell lung cancer (NSCLC), CRC, head and neck squamous cell carcinoma (HNSCC), and cutaneous squamous cell carcinoma (cSCC). We announced in July 2025 that the first patient in the trial had been dosed. VIR-5525 continues to advance through Phase 1 dose escalation as a monotherapy.

Undisclosed PRO-XTEN® TCE Targets

We are advancing multiple undisclosed PRO-XTEN® dual-masked TCEs targeting clinically validated targets with potential applications across a variety of solid tumors. These preclinical candidates leverage the PRO-XTEN® masking technology with novel TCE fragments discovered and engineered using our antibody discovery platform.

Our Technology Platforms

Vir Bio has built a strong foundation based on cutting-edge core scientific capabilities and a team of experts who bring deep knowledge and experience to our R&D efforts. This has enabled us to make significant strides in infectious disease, and strategically expand our focus to address critical unmet needs in oncology.

Platforms for the Creation of Transformative Medicines

Millions of people suffer from infectious diseases and cancer, both of which result in disease by evading the immune system. We have purposefully assembled a portfolio of technology platforms that we believe will, individually or in combination, allow us to modulate the immune system in innovative ways, harnessing its power to combat viruses and fight cancer.

Vir Bio’s Discovery Engine is propelled by our exceptional protein engineering and antibody discovery expertise and our two core technology platforms:

1.Antibody and TCE Discovery and Engineering Platform: We continue to leverage our expertise in antibody discovery and development, enhanced by machine learning and artificial intelligence. Using strategies such as our dAIsY™ system, we can engineer our candidates to optimize key biological and biophysical properties, such as half-life and developability. This discovery platform is utilized to generate antibodies that can be further developed into therapeutic molecules, including the generation of dual-masked TCEs against novel tumor targets.

2.PRO-XTEN® Masking Technology Platform: This innovative technology aims to prevent potential toxicity of highly active drugs outside of their intended site of action. In oncology, this means anti-cancer agents, such as TCEs, become active selectively when entering the tumor microenvironment. This enhances tumor specificity while minimizing off-target effects, potentially improving both efficacy and safety. Masking also increases half-life in circulation, potentially resulting in more convenient dosing regimens for patients and clinicians. Importantly, the PRO-XTEN® masking technology is a universal platform – meaning that it can be used with different molecules without the need to tailor it every single time.

This discovery engine is complemented by our internal capabilities in process development, analytical development, manufacturing, and quality control. We also maintain strategic partnerships with contract development and manufacturing organizations (CDMOs) to support our clinical programs. This combination of cutting-edge technologies, artificial intelligence-driven optimization, and deep immunological expertise positions us to create potentially transformative medicines for some of the more challenging diseases facing humanity today.

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mAb: monoclonal antibody platform; prot. eng: protein engineering capabilities; AI: artificial intelligence

Antibody and TCE Discovery and Engineering Platform

Overview

We have developed cutting-edge platforms to identify and enhance rare, potent mAbs using AI-enabled protein engineering for the treatment of infectious diseases and cancer. Our platforms leverage the efficient interrogation of memory B cells from two primary sources: convalescent human patients and transgenic mice expressing human- immunoglobulin G (IgG) following immunization. This approach enables the selection of highly potent antibodies with unique characteristics that can be further developed into therapeutic molecules, including PRO-XTEN® dual-masked TCEs targeting novel TAAs.

Our platform has been successfully applied to identify mAbs for multiple pathogens including SARS-CoV-2, HBV, HDV, Ebola virus, and HIV. Noteworthy achievements include:

•Sotrovimab (Xevudy®): Anti-SARS-CoV-2 mAb, granted Emergency Use Authorization (EUA) or marketing authorization in multiple regions.

•Ansuvimab (Ebanga™): Anti-Ebola virus mAb developed in collaboration with the NIH and marketed by Ridgeback Biotherapeutics LP.

Our Approach

mAbs function through various mechanisms including pathogen neutralization, target cell lysis (infected or tumor cells), and immunomodulation. Our approach combines rapid, high-throughput isolation of rare and highly potent fully human mAbs from cell culture-based libraries of clonal B lymphocytes. Our deep expertise in antibody discovery and engineering provides a strong foundation for developing next-generation TCEs as well as antibody-based therapeutics for multiple therapeutic areas, including cancer.

Our proprietary antibody screening technology enables the screening of antibodies from hundreds of millions of B cells derived from either convalescent individuals or human-Ig immunized mice. This screening identifies rare and potent mAbs capable of binding highly conserved antigens, neutralizing multiple pathogens, or selectively targeting host proteins, including tumor antigens or antigens involved in the modulation of anti-tumor immune responses.

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These fully human antibodies can be refined using our proprietary AI-driven protein engineering technology, dAIsY™, enhancing their potency, resistance, pharmacokinetics, as well as their manufacturability. This involves optimizing the antigen-binding fragment (Fab) regions to improve efficacy, potency, and manufacturability, as well as the Fc region to fine-tune the antibody's half-life and to enhance its ability to engage effector functions of the immune system. In this context, we have developed a set of novel and proprietary Fc mutations that have the potential to enhance the anti-tumor efficacy of antibodies.

PRO-XTEN® Masking Technology Platform

Overview

The PRO-XTEN® masking technology exploits the high protease activity of the tumor microenvironment to specifically release the active form of a drug via release of the mask selectively in tumor tissues. It can be applied to a variety of molecules such as TCEs or cytokines to broaden the therapeutic index for patients. The preferential release of the drug in the tumor microenvironment is designed to minimize on-target, off-tumor toxicity. The PRO-XTEN® mask is designed to extend the half-life resulting in more convenient dosing regimens for patients and clinicians. This masking approach could be key to pursuing validated oncology targets typically associated with therapies of high toxicity, ultimately offering an opportunity to potentially increase the therapeutic index of drug candidates and deliver more efficacious and safer options for patients.

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Our Approach

We are currently investigating the PRO-XTEN® technology in conjunction with TCEs. These are powerful anti-tumor agents that direct the immune system, specifically T-cells, to destroy cancer cells. The PRO-XTEN® masking technology is designed to keep the TCEs inactive (or masked) until they reach the tumor microenvironment, where tumor-specific proteases cleave off the masks and activate the TCEs leading to killing of cancer cells. By driving the activity selectively to the tumor microenvironment, we aim to circumvent the traditionally high toxicity associated with TCEs and increase their efficacy and tolerability.

TCE: T-Cell Engager

Our dual-masked TCEs are single protein polypeptides with three key functions, a bi-specific TCE at their core, two universal PRO-XTEN® masks, which are connected to the TCE component by protease-cleavable linkers. The bi-specific TCE is comprised of two antibody fragments: a TAA binding domain and a CD3 binding domain. Upon unmasking, they are designed to simultaneously recruit T-cells to cells expressing the target TAA, preferentially cancer cells, directing the cytotoxic activity of T-cells against the tumor. Our discovery and antibody engineering capabilities are extendable to optimizing TAA and T-cell engagement components and identifying novel TCE fragments for additional targets. The protease-activated linkers that are part of PRO-XTEN® were discovered by applying a combination of in vitro and in vivo experiments together with a genetic algorithm for sequence optimization.

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TME: tumor microenvironment; TCE: T-Cell Engager; CD3: cluster of differentiation 3; TAA: tumor associated antigen; CRS: cytokine release syndrome; Q3W: once every 3 weeks

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Our Collaboration, License and Grant Agreements

Collaboration and License Agreement with Astellas

On February 19, 2026, we and Astellas US LLC (together with its subsidiaries and affiliates (including its indirect parent, Astellas Pharma Inc.), Astellas) entered into a Collaboration and License Agreement (the Astellas Agreement). Upon closing of the transaction contemplated by the Astellas Agreement, we and Astellas will enter into a global strategic collaboration to co-develop and co-commercialize VIR-5500, an investigational PRO-XTEN® dual-masked CD3 TCE targeting PSMA for the treatment of prostate cancer that is currently in Phase 1 development, through a sharing of expenses and revenues. We have agreed to grant to Astellas, subject to certain intellectual property rights of Sanofi, an exclusive license to develop, manufacture, commercialize and otherwise exploit VIR-5500 and certain related derivative compounds throughout the world for therapeutic, prophylactic, palliative and diagnostic uses.

Under the terms of the Astellas Agreement, in the U.S., we will share profits and losses from future sales of VIR-5500 equally with Astellas, should VIR-5500 receive regulatory approval, and we will have the option to co-promote VIR-5500. Outside of the U.S., Astellas will obtain exclusive rights to commercialize VIR-5500 and be responsible for all commercialization costs. We will jointly develop VIR-5500, with global clinical development costs shared 40% by us and 60% by Astellas, while costs of U.S.-specific studies will be shared equally, and Astellas will be solely responsible for costs of ex-U.S.-specific studies. In addition, we have the option to opt out of development cost sharing responsibilities and U.S. profit sharing, and in such case, Astellas will pay us royalties on net sales made in the U.S., as described below.

We will receive $335 million in upfront and near-term milestone payments, including $240 million in cash, a $75 million equity investment pursuant to a separate Stock Purchase Agreement (the Astellas SPA, described further below), and a near-term $20 million milestone payment upon completion of manufacturing technology transfer, anticipated in the second quarter or third quarter of 2027. We will also be eligible to receive up to $1.37 billion in future development, regulatory and ex-U.S. sales milestones, along with tiered, double-digit royalties on ex-U.S. net sales, which royalties are subject to reduction under certain specified circumstances. If we elect to opt out of development cost sharing responsibilities and U.S. profit sharing, we would be eligible to receive up to $1.37 billion (or $1.60 billion if we have met a pre-defined limited funding threshold at the time of the opt-out) in future development, regulatory and global sales milestones, along with tiered, double-digit royalties on global net sales, which royalties are subject to reduction under certain specified circumstances. Further, certain opt-out milestones, if met, will include reimbursement of a portion of our previously expensed development and commercialization spend. The closing of the transaction is subject to the expiration or termination of the applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended.

Under the terms of the Sanofi Agreement, we will share with Sanofi 20% of certain future collaboration proceeds, including the upfront payment, equity premium and the portion of milestones, profit-share and royalties that exceed amounts already owed to Sanofi.

Either party may terminate the Astellas Agreement in cases of uncured, material breaches or insolvency. Astellas may terminate the Astellas Agreement for convenience in its entirety (upon 90 days’ notice to us if there has not been any commercial sale for any licensed product in any covered territory or else upon 180 days’ written notice) or with respect to a licensed product and a given country (upon 90 days’ written notice if there has been no commercial sale in the relevant country or else upon 180 days’ written notice). Astellas may also terminate the agreement in its entirety or with respect to one or more products upon 30 days’ written notice if Astellas determines in good faith that the risks to patients from continuing the development or commercialization of the relevant product or products are greater than the potential benefits of such development and commercialization. Subject to certain conditions, we have the right to terminate the agreement upon certain patent challenges by Astellas or if Astellas does not conduct any material development or commercialization activities or otherwise ceases or abandons all such activities for 12 consecutive months.

Concurrently with the execution of the Astellas Agreement, we have also entered into the Astellas SPA, pursuant to which Astellas has agreed to purchase 7,239,382 shares of our common stock for an aggregate purchase price of approximately $75 million, subject to customary closing conditions and the closing of the Astellas Agreement. The purchase price per share of our common stock of $10.36 is equal to a 50% premium of the 30-day volume weighted average price of a share of our common stock as of February 17, 2026. The Astellas SPA includes standstill, voting and lockup provisions, with customary exceptions, that expire one year after the date of the anticipated closing of the Astellas SPA. One year after the anticipated closing of the Astellas SPA, Astellas will have, under certain circumstances, a customary right to require us to register the resale of the shares purchased pursuant to the Astellas SPA.

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License Agreement with Norgine

On December 15, 2025, we and Norgine Pharma UK Limited (together with its affiliates in the Norgine group of companies, Norgine) entered into a License Agreement (the Norgine Agreement) under which we granted Norgine an exclusive license for the commercial rights to the combination of tobevibart and elebsiran for the treatment of CHD in Europe, Australia, and New Zealand (collectively, the Norgine Territory), while we will retain commercial rights for the combination in the United States and all other international markets outside of the Greater China Territory. In exchange, we received an initial reimbursement of development costs from Norgine in the amount of €55 million in December 2025 and are eligible to receive up to an additional €495 million in clinical, regulatory and sales milestones, along with tiered, mid-teen to high-twenties percent royalties on net sales in the Norgine Territory. In addition, clinical development costs for the ongoing trials in our ECLIPSE registrational program (ECLIPSE 1, 2 and 3) will be shared, with Norgine contributing approximately 25% of go-forward external costs.

The Norgine Agreement will remain in force, on a licensed product-by-licensed product and country-by-country basis, until the latest of (a) the 12th anniversary of the first commercial sale; (b) the date of expiration of the last-to-expire valid claim of any licensed patent; and (c) the expiration of regulatory exclusivity. Either party may terminate the Norgine Agreement in cases of material breaches or insolvency. Norgine may terminate the Norgine Agreement with 180 days’ prior written notice prior to the first commercial sale of any licensed product and with 12 months’ prior written notice on or after the first commercial sale of any licensed product.

License Agreement with Sanofi

On September 9, 2024, we closed a license agreement with Amunix Pharmaceuticals Inc. (Amunix), a Sanofi company, previously announced on August 1, 2024 (the Sanofi Agreement), pursuant to which we obtained an exclusive (as to Sanofi and its affiliates), worldwide, royalty-bearing, sublicensable (through multiple tiers), transferable license to research, develop, manufacture, commercialize and otherwise exploit: (i) three clinical-stage masked TCEs of Sanofi, for all therapeutic, prophylactic, palliative, and diagnostic uses, and (ii) the PRO-XTEN® universal masking technology for oncology and infectious disease, excluding the ophthalmological field. As part of the closing of the Sanofi Agreement, we made an upfront payment to Sanofi in the amount of $100.0 million and transferred $75.0 million to an escrow account that was due to former shareholders of Amunix upon VIR-5525 achieving “first in human dosing” by 2026. In July 2025, the first patient was dosed in a phase 1 study evaluating VIR-5525 and as a result, we paid the $75.0 million milestone during the third quarter of 2025. Sanofi will also be eligible to receive up to an additional $323.0 million in future development and regulatory milestone payments, up to an additional $1.49 billion in commercial net sales-based milestone payments, and low single-digit to low double-digit tiered royalties on worldwide net sales. In addition, if, within a two-year period from the execution of the Sanofi Agreement, we execute a transaction that gives rise to Vir Bio receiving certain sublicense income related to the licenses obtained from the Sanofi Agreement, Sanofi may be eligible to receive a portion of such income.

The Sanofi Agreement will remain in force, on a product-by-product and country-by-country basis, until the expiration of all royalty payment obligations. We may terminate the Sanofi Agreement in its entirety, or on a product-by-product basis, for convenience upon 120 days’ written notice if there have been no commercial sales of such target or upon 12 months written notice after the first commercial sale of such target as long as such termination is after December 31, 2026.

Collaboration Agreements with GSK

2020 Collaboration Agreement with GSK

In June 2020, we entered into a definitive collaboration agreement with GSK (the 2020 GSK Agreement), pursuant to which we agreed to collaborate to research, develop and commercialize products for the prevention, treatment and prophylaxis of diseases caused by SARS-CoV-2, the virus that causes COVID-19, and potentially other coronaviruses. The collaboration was originally structured around three categories of product candidates; however, only sotrovimab, VIR-7832, and certain related antibody variants remain active programs under the 2020 GSK Agreement. In connection with the 2020 GSK Agreement, we also entered into a stock purchase agreement in April 2020, pursuant to which we issued 6,626,027 shares of our common stock to Glaxo Group Limited, an affiliate of GSK, at a price per share of $37.73 and an aggregate purchase price of approximately $250.0 million.

We retained the sole right to progress the development and commercialization of the terminated antibody products independently (including with or for third parties), subject to the payment of tiered royalties to GSK on net sales of such terminated antibody products at percentages ranging from the very low single digits to the mid-single digits, depending on the nature of the antibody product being commercialized.

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Regarding sotrovimab, the parties share all development costs, manufacturing costs, and costs and expenses for the commercialization of the collaboration products, with us bearing 72.5% of such costs for sotrovimab, except that GSK has the sole right to develop (including to seek, obtain or maintain regulatory approvals), manufacture and commercialize sotrovimab in and for the Greater China Territory at GSK’s sole cost and expense. As the lead party for all manufacturing and commercialization activities, GSK incurs all of the manufacturing, sales and marketing expenses and is the principal on sales transactions with third parties.

The 2020 GSK Agreement will remain in effect with respect to sotrovimab for as long as it is being commercialized by the lead party. Either party has the right to terminate the 2020 GSK Agreement in the case of the insolvency of the other party, an uncured material breach of the other party with respect to a collaboration program or collaboration product, or as mutually agreed by the parties.

In May 2021, the FDA granted an EUA in the U.S. for sotrovimab, for the early treatment of mild to moderate COVID-19 in adults and pediatric patients (12 years of age and older weighing at least 40 kg) with positive results of direct SARS-CoV-2 viral testing, and at high risk for progression to severe COVID-19, including hospitalization or death. In December 2021, the EC granted marketing authorization to Xevudy® (sotrovimab) in the EU for the treatment of adults and adolescents at increased risk of progressing to severe COVID-19. In April 2022, the FDA excluded the use of sotrovimab in all U.S. regions due to the continued proportion of COVID-19 cases caused by certain variants, and in December 2024, the FDA revoked EUA granted to sotrovimab. Going forward, we expect a nominal amount of license and collaboration revenue, if any, from our 2020 GSK Agreement, and we may incur negative license and collaboration revenue related to costs for ongoing required support efforts that our partner GSK leads.

2021 Expanded GSK Collaboration

In 2021, we entered into the 2021 GSK Agreement under which the parties agreed to expand the 2020 GSK Agreement and to collaborate on three separate programs, all of which had been subsequently terminated except for an RSV program selected in 2022.

We opted-out of the RSV program during the fourth quarter of 2024. As a result of our opt-out, GSK may continue to pursue the development and commercialization of the RSV program unilaterally. If the RSV program reaches commercialization, GSK will pay us a royalty on net sales in the low single digits.

In connection with the 2021 GSK Agreement, we entered into a stock purchase agreement with GGL pursuant to which we issued 1,924,927 shares of our common stock to GGL for an aggregate purchase price of approximately $120.0 million.

Collaboration and License Agreement with Alnylam

In October 2017, we and Alnylam Pharmaceuticals, Inc. (Alnylam) entered into a collaboration and license agreement (the Alnylam Agreement). Under the Alnylam Agreement, we obtained a worldwide, exclusive license to develop, manufacture and commercialize siRNA product candidates directed to HBV, including elebsiran, for all uses and purposes including the treatment of HBV and HDV indications. Under the Alnylam Agreement, we also held options to obtain similar licenses to siRNA product candidates for up to four other infectious disease targets selected by Vir Bio, but following an amendment and restatement of the Alnylam Agreement in March 2025 (the Restated Alnylam Agreement), those options (and all rights and obligations related to those infectious disease targets) were terminated. At the same time Alnylam elected to not opt-in to the profit-sharing arrangement with respect to any licensed siRNA product candidates, including elebsiran, directed to HBV or HDV. We remain solely responsible, at our expense, for conducting all development, manufacture and commercialization activities for elebsiran in HBV and HDV indications, and we are required to use commercially reasonable efforts to develop and commercialize elebsiran for the treatment of HBV or HDV indications in the United States and specified major markets.

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In connection with the Restated Alnylam Agreement and Alnylam’s election to not opt-in to the profit-sharing arrangement, we paid Alnylam $30.0 million in April 2025, and we will be required to pay Alnylam up to $145.0 million for remaining development and regulatory milestones for elebsiran. Such development and regulatory milestones for elebsiran will be payable to Alnylam only once, irrespective of dosage, formulation forms, route of administration or indication. Following commercialization, we will be required to pay Alnylam up to $250.0 million in the aggregate for the first achievement of specified levels of net sales by elebsiran products directed to HBV, whether for the treatment of HBV or HDV indications. We will also be required to pay Alnylam tiered royalties at percentages ranging from the low double-digits to mid-teens on annual net sales of siRNA products directed to HBV, such as elebsiran, whether for the treatment of HBV or HDV indications, subject to specified reductions and offsets. The royalties are payable on a product-by-product and country-by-country basis until the later of the expiration of all valid claims of specified patents covering such product in such country and 10 years after the first commercial sale of such product in such country. Alnylam is entitled to receive a portion of consideration we receive as a result of granting a sublicense under the licenses granted to Vir Bio by Alnylam under the Alnylam Agreement.

The term of the Restated Alnylam Agreement will continue, on a product-by-product and country-by-country basis, until expiration of all royalty payment obligations under the Restated Alnylam Agreement. We may terminate the Alnylam Agreement on a program-by-program basis or in its entirety for any reason on 90 days’ written notice. Either party may terminate the agreement for cause for the other party’s uncured material breach on 60 days’ written notice (or 30 days’ notice for payment breach), or if the other party challenges the validity or enforceability of any patent licensed to it under the Restated Alnylam Agreement on 30 days’ notice.

Exclusive License Agreement with the Institute for Research in Biomedicine

Prior to our acquisition of Humabs BioMed SA (referred to herein as Humabs) in August 2017, it entered into an exclusive license agreement in December 2011 with the Institute for Research in Biomedicine (IRB, and the agreement, the IRB Agreement). The IRB Agreement amended and restated an original 2004 exclusive license agreement between the parties in connection with IRB’s proprietary technologies relating to human monoclonal antibodies and the discovery of unique epitopes recognized by such antibodies performed at the IRB. In May 2008, Humabs entered into an exclusive license agreement with IRB (the Humabs IRB Agreement, and together with the IRB Agreement, the Current IRB License Agreements). Pursuant to the Humabs IRB Agreement, IRB granted to Humabs an exclusive license under certain intellectual property rights for the development of certain monoclonal antibodies with certain proprietary technologies of the IRB. In February 2012, Humabs and IRB entered into a research agreement (the IRB Research Agreement) to provide for a continuing research collaboration between Humabs and IRB, and to coordinate the exploitation of intellectual property rights arising from the IRB Research Agreement with the rights granted under the Current IRB License Agreements. Under the terms of the IRB Research Agreement, IRB performs certain research activities for Humabs, and all intellectual property rights arising under the IRB Research Agreement are either owned by Humabs, or included in and licensed to Humabs pursuant to the terms of the Current IRB License Agreements.

We use technology licensed under the Current IRB License Agreements in our product candidate tobevibart.

Pursuant to the Current IRB License Agreements, IRB granted to Humabs an exclusive, worldwide, royalty-bearing, sublicensable license under patent and know-how rights covering or associated with certain IRB’s proprietary technology platforms relating to antibody discovery, as well as rights in certain antibodies, including as a result of activities under the IRB Research Agreement, in each case for all purposes, including to practice the licensed technology platform, and to develop, manufacture and commercialize any drug, vaccine or diagnostic product containing such licensed antibodies.

Humabs is required to use commercially reasonable efforts to develop and commercialize licensed products, as well as maintain an active program to commercialize licensed products. Humabs is required to pay to IRB a flat royalty on net sales of licensed products approved for non-diagnostic use in the low single-digits, and a flat royalty on licensed products for diagnostic use at 50% of the non-diagnostic product rate, in each case subject to standard reductions and offsets. Humabs is also required to pay to IRB a specified percentage in the sub-teen double-digits of consideration received in connection with the grant of a sublicense to a non-affiliate third party, subject to a specified maximum dollar amount for the first up front or milestone payment received under such sublicense for each licensed product, and a lower specified maximum dollar amount for subsequent up front or milestone payments for such licensed product.

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Each of the Current IRB License Agreements remains in force until the expiration of all valid claims of the licensed patent rights and trade secrets included in the licensed IRB know-how. In addition, no royalties shall be payable under IRB know-how for any licensed product in any country after ten years from the date of first commercialization of such licensed product in that country. Humabs may terminate the IRB Agreement at will on 90 days’ written notice to IRB, and either party may terminate either of the Current IRB License Agreements on 60 days’ written notice for the uncured material breach of the other party.

Exclusive License Agreement with The Rockefeller University

In July 2018, we entered into an exclusive license agreement with The Rockefeller University, or Rockefeller, which was amended in May 2019, in September 2020, and in March 2021, or the Rockefeller Agreement. Pursuant to the Rockefeller Agreement, Rockefeller granted us a worldwide exclusive license under certain patent rights, and a worldwide non-exclusive license under certain materials and know-how covering certain antibody variants relating to a specified mutation leading to enhanced antibody function and utility, to develop, manufacture and commercialize infectious disease products covered by the licensed patents, or that involve the use or incorporation of the licensed materials and know-how, in each case for all uses and purposes for infectious diseases. The licenses granted to us are freely sublicensable to third parties. Rockefeller retains the right to use the licensed patents outside the field of use, and within the field of use solely in connection with educational, research and non-commercial purposes, as well as for certain research being conducted in collaboration with us. We are obligated to grant sublicenses to third parties with respect to products that are not being pursued and are not of interest to us following a specified anniversary of the May 2019 amendment date. Pursuant to the Rockefeller Agreement, we are required to use commercially reasonable efforts to develop and commercialize infectious disease products as soon as reasonably practicable, including by achieving certain specified development milestone events within specified time periods for products arising from our HBV and influenza programs.

We use technology licensed under the Rockefeller Agreement in our antibody platform and in our product candidate tobevibart.

Under the agreement we are required to pay license maintenance fees of $1.0 million annually, which will be creditable against royalties following commercialization. In addition, for the future achievement of specified development, regulatory and commercial success milestone events, we will be required to pay up to $80.3 million, in the aggregate, for up to six infectious disease products. Any follow-on products beyond six products may result in additional milestone event payments. We will also be required to pay Rockefeller a tiered royalty at a low single-digit percentage rate on net sales of licensed products, subject to certain adjustments. Our obligation to pay royalties to Rockefeller will terminate, on a product-by-product and jurisdiction-by-jurisdiction basis, upon the latest of the expiration of the last valid claim of a licensed patent in such jurisdiction, the expiration of all regulatory exclusivity in such jurisdiction or 12 years following the first commercial sale of the applicable licensed product in such jurisdiction. If we grant a sublicense to a non-affiliate third party under the Rockefeller technology, we will be required to pay Rockefeller a specified percentage of the consideration received from such sublicensee for the grant of the sublicense, depending on the date of receipt of the applicable sublicense income from such sublicensee.

The Rockefeller Agreement will remain in force, absent earlier termination, until the expiration of all of our obligations to pay royalties to Rockefeller in all jurisdictions. We have the right to terminate the Rockefeller Agreement in its entirety, or in part, for any reason on 60 days’ written notice to Rockefeller. Rockefeller may terminate the Rockefeller Agreement on 90 days’ written notice for our uncured material breach, or if we challenge the validity or enforceability of any of the licensed patents, or immediately in the event of our insolvency. Rockefeller may also terminate the Rockefeller Agreement if we cease to carry on business with respect to the rights granted to us under the agreement.

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Collaboration, Option and License Agreement with Brii Bio

In May 2018, we entered into a collaboration, option and license agreement with Brii Biosciences Limited (Brii Bio Parent) (formerly known as BiiG Therapeutics Limited), and Brii Bio (and such agreement, the Brii Agreement), pursuant to which we granted to Brii Bio, with respect to up to four of our programs, an exclusive option to obtain exclusive rights to develop and commercialize compounds and products arising from such programs in the Greater China Territory, for the treatment, palliation, diagnosis, prevention or cure of acute and chronic diseases of infectious pathogen origin or hosted by pathogen infection, or the Field of Use. In partial consideration for the options granted by us to Brii Bio, Brii Bio Parent and Brii Bio in turn granted us, with respect to up to four of Brii Bio Parent’s or Brii Bio’s programs, an exclusive option to be granted exclusive rights to develop and commercialize compounds and products arising from such Brii Bio programs in the United States for the Field of Use. The number of options that we may exercise for a Brii Bio program is limited to the corresponding number of options that Brii Bio exercises for a Vir Bio program. All options granted to Brii Bio under the Brii Agreement that are not exercised expired in May 2025. All options granted to us under the Brii Agreement that are not exercised will expire no later than two years following the expiration of all options granted to Brii Bio.

We are responsible, at our expense and discretion, for the conduct of all development activities under our programs prior to the exercise of Brii Bio’s options, and Brii Bio is responsible, at its expense and discretion, for all activities under its programs prior to the exercise of our options. Following the exercise of an option for a specified program by either us or Brii Bio, the exercising party is granted an exclusive, royalty-bearing license to develop, manufacture and commercialize products arising from the applicable program in the United States (where we are exercising the option) or the Greater China Territory (where Brii Bio is exercising the option), and such party is thereafter responsible for all development and commercialization activities, at its expense, in the optioned territory. If Brii Bio exercises its option with respect to our development program being conducted under the Amended Alnylam Agreement, Brii Bio’s rights will be subject to the terms of such amended agreement.

Under the terms of the Brii Agreement, following our option exercise, we are obligated to use commercially reasonable efforts to develop at least one licensed product arising from each optioned Brii Bio program, and to commercialize each such product in the United States following regulatory approval, and following Brii Bio’s option exercise, Brii Bio is obligated to use commercially reasonable efforts to develop at least one licensed product arising from each optioned Vir Bio program and to commercialize each such product in the Greater China Territory following regulatory approval.

On June 12, 2020, Brii Bio notified us of the exercise of its option to obtain exclusive rights to develop and commercialize compounds and products arising from elebsiran in the Greater China Territory. Brii Bio paid us a $20.0 million option exercise fee in connection with the option exercise. As mentioned above, our elebsiran program is being developed under the Amended Alnylam Agreement and as a result, we separately paid $10.0 million, half of the option proceeds, to Alnylam. In July 2022, Brii Bio notified us of the exercise of its option to obtain exclusive rights to develop and commercialize compounds and products arising from tobevibart in the Greater China Territory. Brii Bio paid us a $20.0 million option exercise fee in connection with the option exercise.

With respect to elebsiran and tobevibart for which Brii Bio exercised its options, Brii Bio will be required to pay regulatory milestone payments on a licensed product-by-licensed product basis ranging from the mid-single-digit millions up to $30.0 million, also determined based on the commercial potential of such program. Following commercialization, Brii Bio will be required to make sales milestone payments based on certain specified levels of aggregate annual net sales of products arising from each licensed program in the Greater China Territory, up to an aggregate of $175.0 million per licensed program. Brii Bio also will pay us royalties that range from the mid-teens to the high-twenties.

As partial consideration for our entry into the Brii Agreement, upon closing of Brii Bio Parent’s Series A preferred stock financing, we received Class A ordinary shares equal to 9.9% of the outstanding shares in Brii Bio Parent. As a result of Brii Bio’s right to exercise one of its options for elebsiran, under the terms of the Amended Alnylam Agreement, in February 2020 we transferred to Alnylam a specified percentage of such equity consideration allocable to such program. In July 2021, Brii Bio Parent completed its initial public offering, or the Brii Bio Parent IPO, on the Stock Exchange of Hong Kong Limited. Upon completion of the Brii Bio Parent IPO, our Class A ordinary shares held at Brii Bio Parent converted into the same single class of ordinary shares issued in the Brii Bio Parent IPO.

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In the event that we exercise an option for a Brii Bio program, we will be required to pay to Brii Bio an option exercise fee ranging from the low tens of millions to up to $50.0 million, determined based on the commercial potential of the licensed program. We will be required to make regulatory milestone payments to Brii Bio on a licensed product-by-licensed product basis ranging from the low tens of millions up to $100.0 million, also determined based on the commercial potential of such program. We will also be required to make sales milestone payments based on certain specified levels of aggregate annual net sales of products in the United States arising from each licensed program, up to an aggregate of $175.0 million per licensed program.

In addition, we are obligated under the Brii Agreement to pay Brii Bio tiered royalties based on net sales of products arising from the programs licensed to Vir Bio in the United States, and Brii Bio is obligated to pay us tiered royalties based on net sales of products arising from the programs licensed to Brii Bio in the Greater China Territory. The rates of royalties payable by us to Brii Bio, and by Brii Bio to us on net sales range from mid-teens to high-twenties. Each party’s obligations to pay royalties expires, on a product-by-product and territory-by-territory basis, on the latest of 10 years after the first commercial sale of such licensed product in the United States or Greater China Territory, as applicable; the expiration or abandonment of licensed patent rights that cover such product in the United States or Greater China Territory, as applicable; and the expiration of regulatory exclusivity in the United States or the Greater China Territory, as applicable. Royalty rates are subject to specified reductions and offsets.

The Brii Agreement will remain in force until the expiration of all options or, if any option is exercised, expiration of all royalty payment obligations for all licensed products within such licensed program, unless terminated in its entirety or on a program-by-program basis by either party. Each party may terminate for convenience all rights and obligations with respect to any program for which it has an option, with 30 days’ written notice (if the terminating party has not exercised an option for such program) or 180 days’ notice (following the exercise of an option for such program). The Brii Agreement may also be terminated by either party for insolvency of the other party, and either party may terminate the Brii Agreement in its entirety or on a program-by-program basis for the other party’s uncured material breach on 60 days’ written notice (or 30 days’ notice following failure to make payment).

Patent License Agreements with Xencor

In August 2019, we entered into a patent license agreement, which was amended in February 2021, or the 2019 Xencor Agreement, with Xencor, pursuant to which we obtained a non-exclusive, sublicensable (only to our affiliates and subcontractors) license to incorporate Xencor’s licensed technologies into, and to evaluate, antibodies that target influenza A and HBV, and a worldwide, non-exclusive, sublicensable license to develop and commercialize products containing such antibodies incorporating such technologies for all uses, including the treatment, palliation, diagnosis and prevention of human or animal diseases, disorders or conditions. We are obligated to use commercially reasonable efforts to develop and commercialize an antibody product that incorporates Xencor’s licensed technologies, for each of the influenza A and HBV research programs. These technologies are used in tobevibart, incorporating Xencor’s Xtend.

In consideration for the grant of the license, we paid Xencor an upfront fee. For each of the influenza A and HBV research programs, we will be required to pay Xencor development and regulatory milestone payments of up to $17.8 million in the aggregate and commercial sales milestone payments of up to $60.0 million in the aggregate, for a total of up to $77.8 million in aggregate milestones for each program and $155.5 million in aggregate milestones for both programs. On a product-by-product basis, we will also be obligated to pay tiered royalties based on net sales of licensed products ranging from low- to mid-single-digits. The royalties are payable, on a product-by-product and country-by-country basis, until the expiration of the last to expire valid claim in the licensed patents covering such product in such country.

The 2019 Xencor Agreement will remain in force, on a product-by-product and country-by-country basis, until the expiration of all royalty payment obligations. We may terminate the agreement in its entirety, or on a target-by-target basis, for convenience upon 60 days’ written notice. Either party may terminate the agreement for the other party’s uncured material breach upon 60 days’ written notice (or 30 days in the case of non-payment) or in the event of bankruptcy of the other party immediately upon written notice. Xencor may terminate the agreement immediately upon written notice if we challenge, or upon 30 days’ written notice if any of our sublicensees challenge the validity or enforceability of any patent licensed to us under each respective agreement.

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Amended and Restated Letter Agreement with the Gates Foundation

In January 2022, we entered into an amended and restated letter agreement with the Gates Foundation (formerly known as the Bill & Melinda Gates Foundation, and the agreement, the Gates Agreement), which amended and restated the original letter agreement with the Gates Foundation that we entered into in December 2016. In connection with the Gates Agreement, the Gates Foundation purchased $10.0 million of shares of our Series A-1 convertible preferred stock in December 2016, $10.0 million of shares of our Series B convertible preferred stock in January 2019 and $40.0 million of shares of our common stock in January 2022. We are obligated to use the proceeds of the Gates Foundation’s January 2022 investment in furtherance of its charitable purposes to develop our vaccinal antibody program, in each case for use in specified developing countries. We agreed to use reasonable efforts to achieve specified research and development milestones with respect to our vaccinal antibody program, and, if requested by the Gates Foundation and agreed by us, on further development of such programs beyond stated milestones. Additionally, we are bound by specified global access commitments including a commitment to provide any products developed using the proceeds of the Gates Foundation’s investment at an affordable price to the people most in need within the specified low- and middle-income countries, not to exceed a specified percentage over our fully burdened manufacturing and sales costs. As of December 31, 2025, the Company had stock purchase premium liability of $9.3 million, which will be recognized as we advance the development of our vaccinal antibody program with the Gates Foundation.

If we fail to comply with (i) our obligations to use the proceeds of the Gates Foundation’s investment for the purposes described in the paragraph above and to not use such proceeds for specified prohibited uses, (ii) specified reporting requirements or (iii) specified applicable laws, or if we materially breach our specified global access commitments (any such failure or material breach, a Specified Default), we will be obligated to redeem or arrange for a third party to purchase all of our stock purchased by the Gates Foundation under the Gates Agreement at the Gates Foundation’s request, at a price equal to the greater of (a) the original purchase price or (b) the fair market value, such redemption or sale, a Gates Foundation Redemption. Following a Gates Foundation Redemption, if a sale of the company or all of our material assets relating to the Gates Agreement occurs prior to the six month anniversary of the first redemption or sale of any stock in such Gates Foundation Redemption, then the Gates Foundation will receive compensation equal to the excess of what it would have received in such transaction if it still held the stock redeemed or sold at the time of such sale transaction over what it actually received in the Gates Foundation Redemption. Additionally, if a specified default occurs, if we are unable or unwilling to continue the vaccinal antibody program or, if applicable, any mutually agreed additional program (except for scientific or technical reasons), or if we institute bankruptcy or insolvency proceedings, then the Gates Foundation will have the right to exercise a non-exclusive, fully-paid license (with the right to sublicense) under our intellectual property to the extent necessary to use, make and sell products arising from such programs, in each case solely to the extent necessary to benefit people in specified low- and middle-income countries (as defined in the Gates Agreement) in furtherance of the Gates Foundation’s charitable purpose.

In the event that we sell, exclusively license, or transfer to a third party all or substantially all of our assets, the technology platform, or products arising from programs that are funded using the proceeds of the Gates Foundation’s investment, such third party is required to assume our specified global access commitments on terms that are reasonably acceptable to the Gates Foundation. Additionally, we will not grant any third party any rights or enter into any agreement with any third party that would restrict the Gates Foundation’s rights with respect to our specified global access commitments unless such third party expressly assumes such commitments to the reasonable satisfaction of the Gates Foundation. The global access commitments will continue for as long as the Gates Foundation continues to be a charitable entity.

In relation to the agreements discussed above, we have entered into various grant agreements with the Gates Foundation, to support our HIV vaccine program, TB vaccine program, HIV vaccinal antibody program and malaria vaccinal antibody program. During the year, all of the grant agreements expired except for the HIV vaccine program, for which the term expires in June 2027. The remaining grant agreement may be terminated early by the Gates Foundation for our breach, failure to progress the applicable funded projects, in the event of our change of control, change in our tax status, or significant changes in our leadership that the Gates Foundation reasonably believes may threaten the success of the applicable project.

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Sales and Marketing

Given our stage of development, we have not yet established a meaningful commercial (sales or marketing) organization, nor distribution capabilities. We intend to build a commercial infrastructure to support the sales and marketing of our product candidates, if approved, including tobevibart and elebsiran for the treatment of CHD. We expect to manage sales, marketing and distribution through internal resources and third-party relationships, including with Norgine with respect to commercialization of the combination of tobevibart and elebsiran for the treatment of CHD patients in the Norgine Territory. While we may commit significant financial and management resources to commercial activities for tobevibart and elebsiran and our broader portfolio, we will also consider collaborating with one or more biopharmaceutical companies to enhance our commercial capabilities going forward, as we have with the exclusive license granted to Norgine.

Manufacturing

We manufacture product candidates for three therapeutic modalities: mAbs, masked TCEs and siRNA. We have established our own internal process, analytical and pharmaceutical development, manufacturing, supply chain and quality organizations that work with our selected CDMOs, to develop, manufacture, test and supply our early- and late-stage product candidates developed with our proprietary and external technology platforms. Contract development and manufacturing of our antibody, TCE and siRNA product candidates is supported at our San Francisco, California, corporate headquarters for process, analytical and formulation development, small-scale non-current Good Manufacturing Practice (cGMP) manufacturing for preclinical studies. Our headquarters also conducts cell line development for our antibody and TCE product candidates.

We have established relationships with multiple CDMOs and have produced material to support preclinical studies and Phase 1, Phase 2 and Phase 3 clinical trials. Material for any Phase 3 clinical trials and commercial supply will generally require large-volume, low-cost-of-goods production. However, there are no assurances that our manufacturing and supply chain infrastructure will remain uninterrupted and reliable, or that the third parties we rely on to manufacture our products will be able to satisfy demand in a timely manner or not have supply chain disruptions, stock-outs due to raw material shortages, extended lead times, and/or greater than anticipated demand or quality issues.

Manufacturing Technology Platforms

Antibody

We currently leverage the antibody process platforms and manufacturing facilities of our CDMOs and strategic collaborators for development, manufacturing and supply of our preclinical, clinical and future commercial mAb product candidates. These manufacturing platforms are based on mAb technology and industrial processes that have been optimized, standardized and well-established across the biopharmaceutical industry over the last 30 years to enable process portability between biomanufacturing facilities and manufacturing with high success rates at most biologic CDMOs, as well as the partnered use of excess capacity with other biopharmaceutical companies. We established in-house capabilities in our San Francisco headquarters for mAb cell line development, Phase 1/2 process development, and small-scale drug substance and drug product manufacturing to produce non-cGMP material for preclinical studies. Our new process development laboratory was successfully brought online in 2024.

T-Cell Engager - PRO-XTEN®

We have also established process, analytical and formulation development capabilities for our E. coli -derived TCEs in our San Francisco facility. The manufacturing processes for TCE drug substances (DS) and drug products (DP) have been developed by our scientists based on standard E. coli manufacturing and pharmaceutical processes that have been well-established across the biopharmaceutical industry for other biologics. Similar to our antibody programs, we leverage the E.coli process platforms and manufacturing facilities of our CDMOs and strategic collaborators for further development and optimization, manufacturing and supply of our preclinical, clinical and future E.coli TCE product candidates.

siRNA

Vir Bio licensed and conducted a technology transfer of the siRNA DS and DP process for elebsiran. Similarly, we rely on the siRNA process platforms and manufacturing facilities of our CDMOs and strategic collaborators for further development, optimization, manufacturing and supply of our siRNA product candidate.

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Manufacturing Agreements

In 2024, we and a large CDMO entered into various scopes of work and continue to do so with the respect to process performance qualification (PPQ) for tobevibart DS (the Tobevibart Agreements). Under the terms of these agreements, the CDMO has reserved these manufacturing slots and will manufacture the agreed upon number of batches in accordance with an agreed upon manufacturing schedule to successfully complete PPQ. Future commercial supply will be subject to finalizing a commercial supply agreement and relevant terms by the end of 2026.

In 2024, we entered into binding commitments with a large CDMO for process characterization and manufacture through completion of PPQ of elebsiran DS (the Elebsiran Agreements). Under the terms of these agreements, the CDMO has reserved these manufacturing slots and will manufacture the agreed upon number of batches in accordance with the agreed upon manufacturing schedule to successfully complete PPQ. Future commercial supply will be subject to finalizing a commercial supply agreement and relevant terms in 2026. As of December 31, 2025, we had unaccrued unpaid commitments of approximately $24 million under the Tobevibart Agreements and Elebsiran Agreements.

For TCEs, we have agreements with CDMOs to manufacture our DS and DP for clinical trials on a yearly basis with commitments through 2028. In 2025, we entered into binding commitments with a CDMO for manufacture of our TCE products. As of December 31, 2025, we had unaccrued unpaid commitments of approximately $20 million for various TCE programs.

Competition

The pharmaceutical industry is characterized by rapidly advancing technologies, intense competition and a strong emphasis on proprietary products. While we believe that our technology, the expertise of our executive and scientific team, research, clinical capabilities, development experience and scientific knowledge provide us with competitive advantages, we face increasing competition from many different sources, including pharmaceutical and biotechnology companies, academic institutions, governmental agencies and public and private research institutions. Product candidates that we successfully develop and commercialize may compete with existing therapies and new therapies that may become available in the future.

Many of our competitors, either alone or with their collaborators, have significantly greater financial resources, established presence in the market, expertise in research and development, manufacturing, preclinical and clinical testing, obtaining regulatory approvals and reimbursement and marketing approved products than we do. These competitors also compete with us in recruiting and retaining qualified scientific, sales, marketing and management personnel, establishing clinical trial sites and patient registration for clinical trials, as well as in acquiring technologies complementary to, or potentially necessary for, our programs. Smaller or early-stage companies may also prove to be significant competitors, particularly through collaborative arrangements with large and established companies. Additional mergers and acquisitions may result in even more resources being concentrated in our competitors.

Our commercial potential could be reduced or eliminated if our competitors develop and commercialize products that are safer, more effective, have fewer or less severe side effects, are more convenient or are less expensive than products that we may develop. Our competitors also may obtain FDA or other regulatory approval for their products more rapidly than we may obtain approval for ours, which could result in our competitors establishing a strong market position before we are able to enter the market or make our development more complicated. The key competitive factors affecting the success of all of our programs are likely to be efficacy, safety, convenience, and cost/access.

HDV

There are currently no FDA-approved treatments for CHD. Gilead’s bulevirtide is approved for use by the EMA. Gilead has refiled for bulevirtide with the FDA and has announced that they expect a U.S. launch in the first half of 2026 should bulevirtide be approved by the FDA. Bulevirtide has led to limited HDV clearance and requires daily injections to maintain viral suppression. Mirum recently acquired Bluejay Therapeutics and their pipeline asset, brelovitug, which is currently in pivotal trials. Additionally, there are two known small pharmaceutical companies developing programs with various mechanisms of action, including Huahui Health and Assembly Biosciences (in partnership with Gilead).

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Prostate Cancer

Novartis’ lutetium Lu 177 vipivotide tetraxetan is the only currently approved PSMA-targeted therapy for prostate cancer. There are a number of PSMA therapies in development for prostate cancer including TCEs (e.g., Janux’s JANX007), ADC’s (e.g., Johnson & Johnson’s JNJ-8177) and other mechanisms of action from various companies, including Regeneron, GSK, and Bayer, among others. Beyond PSMA-targeted therapies, there are other clinical development programs focused on other prostate cancer targets (STEAP1, KLK2, B7-H3, etc.) utilizing various mechanisms of action that are sponsored by various companies, including J&J, Amgen, Novartis, Merck (MSD), Pfizer, and AstraZeneca, among others.

HER2-Expressing Solid Tumors

There are several HER2 therapies currently approved and in development for HER2-expressing solid tumors. For HER2 positive breast cancer, there are a number of approved drugs including ADCs (e.g. AstraZeneca’s and Daiichi Sankyo’s trastuzumab deruxtecan, Roche’s trastuzumab emtansine); monoclonal antibodies (e.g. Roche’s trastuzumab & pertuzumab); and inhibitors (e.g. Pfizer's tucatinib). Outside of HER2 positive breast cancer, there are other companies evaluating HER2 therapies in HER2-expressing solid tumors with various mechanisms of action including AstraZeneca, Daiichi Sankyo, Pfizer, Remegen, Jazz, BioNTech, Duality Bio, Hengrui Pharma, Adagene among others. Beyond HER2 therapies, companies are also developing programs targeting other tumor targets (non-HER2) that could also compete in HER2-expressing solid tumors.

EGFR-Expressing Solid Tumors

There are several EGFR therapies currently approved and in development for EGFR-expressing solid tumors. For colorectal cancer, EGFR-targeting mAbs including Lilly’s cetuximab and Amgen’s cetuximab are currently approved globally. Outside of colorectal cancer, there are also other companies evaluating EGFR therapies in EGFR-expressing solid tumors with various mechanisms of action including Janux, Regeneron, J&J, Genmab, Bicara, BMS, SystImmune, Affimed, AstraZeneca and others. Beyond EGFR therapies, companies are also developing programs targeting other tumor targets (non-EGFR) that could also compete in EGFR-expressing solid tumors.

Intellectual Property

Our intellectual property is critical to our business and we strive to protect it, including by obtaining and maintaining patent protection in the United States and internationally for our product candidates, new therapeutic approaches and potential indications, and other inventions that are important to our business. Our policy is to seek to protect our proprietary and intellectual property position by, among other methods, filing U.S. and foreign patent applications related to our proprietary technology, inventions and improvements that are important for the development and implementation of our business. We also rely on the skills, knowledge, and experience of our scientific and technical personnel, as well as that of our advisors, consultants, and other contractors. To help protect our proprietary know-how that is not patentable, we rely on confidentiality agreements to protect our interests. We require our employees, consultants and advisors to enter into confidentiality agreements prohibiting the disclosure of confidential information and requiring disclosure and assignment to us of the ideas, developments, discoveries and inventions important to our business.

Our patent portfolio includes patents and patent applications that are licensed from several collaborators and other third parties, including Sanofi, Alnylam, IRB, Rockefeller and Xencor, and patents and patent applications that are owned by us. Our patent portfolio includes patents and patent applications that cover our product candidates elebsiran, tobevibart, VIR-5500, VIR-5818, and VIR-5525, and the use of these candidates for therapeutic purposes. Our proprietary technology has been developed primarily through in-licenses, acquisitions, relationships with academic research centers, and contract research organizations (CROs).

For our product candidates, we will, in general, initially pursue patent protection covering compositions of matter and methods of use. Throughout the development of our product candidates, we seek to identify additional means of obtaining patent protection that would potentially enhance commercial success, including through additional methods of use, process of making, formulation and dosing regimen-related claims.

In total, our patent portfolio, including patents licensed from our collaborators and other third parties, comprises over 90 different patent families as of December 31, 2025, filed in various jurisdictions worldwide. Our patent portfolio includes over 1,500 active cases with over 690 issued patents in the United States and abroad. Our patent portfolio for our product candidates and technology platforms is outlined below.

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Patents and Proprietary Rights

U.S. and European Patent Expiration

We have a number of U.S. and foreign patents, patent applications and rights to patents related to our molecules, products and technology, but we cannot be certain that issued patents will be enforceable or provide adequate protection or that pending patent applications will result in issued patents.

The following table shows the estimated expiration dates (including patent term extensions, supplementary protection certificates and/or pediatric exclusivity where granted) in the United States and the European Union for the primary patents for our key product candidates as described above. Dates in parentheses reflect the estimated expiration date of patents which may issue from currently pending applications. The estimated expiration dates do not include any potential additional exclusivity (e.g., patent term extension, supplementary protection certificates or pediatric exclusivity) that have not yet been granted.

Platform Patent Portfolio by Technology Platform

Antibody Platform

Licensed Patents

We have exclusively licensed a patent family from Rockefeller. The 20-year term of any patents issuing from the application in this family is presently estimated to expire in 2038, absent any available patent term adjustments or extensions.

We have exclusively licensed from IRB two patent families that relate to our antibody platform technology. The 20-year term of the first of these families expired in 2024. The US patent in this family is, however, still in force as its term was extended until 2027 due to patent office delay. The 20-year term of the issued patents and any patent issuing from the pending patent applications in the second patent family is estimated to expire in 2038, absent any available patent term adjustments or extensions.

In addition, we have non-exclusively licensed a group of patents and applications from Xencor. The 20-year term of these patents and applications if granted is presently estimated to expire between 2024 and 2028, absent any available patent term adjustments or extensions.

Patents Owned by Us

We also own, with our subsidiary Humabs, one patent family that includes, as of December 31, 2025, 33 pending applications in both the US and abroad. These applications include composition of matter claims, pharmaceutical composition claims, method of treatment claims, and composition for use in treatment claims. The 20-year term of any patents issuing from patent applications in this family is presently estimated to expire in 2042, absent any available patent term adjustments or extensions.

PRO-XTEN® Platform

Licensed Patents

We have exclusively licensed from Sanofi 13 different patent families related to our PRO-XTEN® portfolio.

The 20-year term of the issued patents in these families is presently estimated to expire between 2036 and 2041, absent any available patent term adjustments or extensions.

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Patent Term and Term Extensions

Individual patents have terms for varying periods depending on the date of filing of the patent application or the date of patent issuance and the legal term of patents in the countries in which they are obtained. Generally, utility patents issued for applications filed in the United States are granted a term of 20 years from the earliest effective filing date of a non-provisional patent application. In addition, in certain instances, the term of a U.S. patent can be extended to recapture a portion of the delay from the U.S. Patent and Trademark Office (USPTO) in issuing the patent, as well as a portion of the term effectively lost as a result of the FDA regulatory review period. However, as to the FDA component, the restoration period cannot be longer than five years, and the restoration period cannot extend the patent term beyond 14 years from FDA approval. In addition, only one patent applicable to an approved drug is eligible for the extension, and only those claims covering the approved drug, a method for using it, or a method of manufacturing may be extended. The duration of foreign patents varies in accordance with provisions of applicable local law, but typically is also 20 years from the earliest effective filing date. All taxes, annuities or maintenance fees for a patent, as required by the USPTO and various foreign jurisdictions, must be timely paid in order for the patent to remain in force during this period of time.

The actual protection afforded by a patent may vary on a product by product basis, from country to country, and can depend upon many factors, including the type of patent, the scope of its coverage, the availability of regulatory-related extensions and the availability of legal remedies in a particular country and the validity and enforceability of the patent.

Patent Protection and Certain Challenges

Patents and other proprietary rights are very important to our business. If we have a properly drafted and enforceable patent, it can be more difficult for our competitors to use our technology to create competitive products and more difficult for our competitors to obtain a patent that prevents us from using technology we create. As part of our business strategy, we actively seek patent protection both in the United States and internationally and file additional patent applications, when appropriate, to cover improvements in our molecules, products and technology.

Patents covering certain of our products are held by third parties. We acquired exclusive rights to these patents in the agreements we have with these parties.

We may obtain patents for certain products many years before marketing approval is obtained. Because patents have a limited life that may begin to run prior to the commercial sale of the related product, the commercial value of the patent may be limited. However, we may be able to apply for patent term extensions or supplementary protection certificates in some countries. For example, extensions for the patents or supplementary protection certificates on many of our products have been granted in the United States and in several European countries, compensating in part for delays in obtaining marketing approval. Similar patent term extensions may be available for other products we are developing, but we cannot be certain we will obtain them in some countries.

It is also important that we do not infringe the valid patents of third parties. If we infringe the valid patents of third parties, our reputation may be harmed and we may be required to pay significant monetary damages, we may be prevented from commercializing products, or we may be required to obtain licenses from these third parties. We may not be able to obtain alternative technologies or any required license on reasonable terms or at all. If we fail to obtain these licenses or alternative technologies, we may be unable to develop or commercialize some or all of our products.

Because patent applications are confidential for a period of time until a patent is issued, we may not know if our competitors have filed patent applications for technology covered by our pending applications or if we were the first to invent or first to file an application directed toward the technology that is the subject of our patent applications. Competitors may have filed patent applications or received patents and proprietary rights that block or compete with our products. In addition, if competitors file patent applications covering our technology, we may have to participate in litigation, post-grant proceedings before the USPTO or other proceedings to determine the right to a patent or validity of any patent granted.

Future litigation or other proceedings regarding the enforcement or validity of our existing patents, or any future patents could result in the invalidation of our patents or substantially reduce their protection.

Our pending patent applications and patent applications filed by our collaborative partners may not result in the issuance of any patents or may result in patents that do not provide adequate protection. As a result, we may not be able to prevent third parties from developing compounds or products that are closely related to those which we have developed or are developing. In addition, certain countries do not provide effective enforcement of our patents, and third-party manufacturers may be able to sell generic versions of our products in those countries. For more information, see the section titled “Risk Factors—Risks Related to Our Intellectual Property.”

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Trademarks and Know-How

In connection with the ongoing development and advancement of our products and services in the United States and various international jurisdictions, we seek to create protection for our marks and enhance their value by pursuing trademarks and service marks where available and when appropriate. In addition to patent and trademark protection, we rely upon know-how and continuing technological innovation to develop and maintain our competitive position. We seek to protect our proprietary information, in part, by using confidentiality agreements with our commercial partners, collaborators, employees and consultants, and invention assignment agreements with our employees and consultants. These agreements are designed to protect our proprietary information and, in the case of the invention assignment agreements, to grant us ownership of technologies that are developed by our employees and through relationships with third parties. For more information, see “Item 1A. Risk Factors—Risks Related to Our Intellectual Property.”

Government Regulation and Product Approval

The FDA and other regulatory authorities at federal, state and local levels, as well as in foreign countries, extensively regulate, among other things, the research, development, manufacture, quality control, import, export, safety, effectiveness, labeling, packaging, storage, distribution, approval, advertising, promotion, marketing, post-approval monitoring and post-approval reporting of drugs and biologics such as those we are developing.

In the United States, the FDA approves and regulates drugs under the Federal Food, Drug, and Cosmetic Act (FDCA). Biological products, or biologics, are licensed for marketing under the Public Health Service Act (PHSA) and regulated under the FDCA. A company, institution or organization which takes responsibility for the initiation and management of a clinical development program for such products is typically referred to as a sponsor. We, as a sponsor, along with third-party contractors, will be required to navigate the various preclinical, clinical and commercial approval requirements of the governing regulatory agencies of the countries in which we wish to conduct studies or trials, seek approval or licensure or commercialize our product candidates.

U.S. Biopharmaceuticals Regulation

The process required by the FDA before drug and biologic product candidates may be marketed in the United States generally involves the following:

•completion of extensive preclinical laboratory tests and animal trials performed in accordance with applicable regulations, including the FDA’s current Good Laboratory Practice (cGLP), regulations;

•design of a clinical protocol and submission to the FDA of an application(s) which must become effective before clinical trials may begin;

•approval by an independent institutional review board or ethics committee at each clinical site before the trial is commenced;

•performance of adequate and well-controlled human clinical trials in accordance with FDA’s current Good Clinical Practice (cGCP) regulations to establish the safety and efficacy of a drug candidate, and compliance with cGMP to establish safety, purity and potency of a proposed product candidate for its intended purpose;

•preparation of and submission to the FDA of a new drug application (NDA) or biologics licensing application (BLA), as applicable, after completion of all pivotal clinical trials;

•satisfactory completion of an FDA Advisory Committee review, if applicable;

•a determination by the FDA within 60 days of its receipt of an NDA or BLA whether the application is accepted for filing;

•satisfactory completion of an FDA pre-approval inspection of the manufacturing facility or facilities at which the proposed product is produced to assess compliance with cGMP and of selected clinical investigation sites to assess compliance with cGCP;

•FDA review and approval of an NDA or BLA to permit commercial marketing of the product for particular indications for use in the United States; and

•completion of any post-approval requirements, including the potential requirement to implement a risk evaluation and mitigation strategy, or REMS, and any post-approval studies required by the FDA to maintain the marketed status in the US of an approved drug.

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Preclinical and Clinical Development

Prior to beginning the first clinical trial with a product candidate, we must submit an IND to the FDA. An IND is a request for authorization from the FDA to administer an investigational new drug product to humans. The central focus of an IND submission is on the general investigational plan and the protocol or protocols for preclinical studies and clinical trials. An IND must become effective before human clinical trials may begin. The IND automatically becomes effective 30 days after receipt by the FDA, unless the FDA, within the 30-day period, raises safety concerns or questions about the proposed clinical trial.

Clinical trials involve the administration of the investigational product to human subjects under the supervision of qualified investigators in accordance with cGCP, which include the requirement that all research subjects provide their informed consent for their participation in any clinical study. Clinical trials are conducted under protocols detailing, among other things, the objectives of the study, the parameters to be used in monitoring safety and the effectiveness criteria to be evaluated. Furthermore, an independent institutional review board for each site proposing to conduct the clinical trial must review and approve the plan for any clinical trial and its informed consent form before the clinical trial begins at that site, and must monitor the trial until completed.

Regulatory authorities, the institutional review board or the sponsor may suspend a clinical trial at any time on various grounds, including a finding that the subjects are being exposed to an unacceptable health risk or that the trial is unlikely to meet its stated objectives. Some trials also include oversight by an independent group of qualified experts organized by the clinical trial sponsor, known as a data safety monitoring board, which provides authorization for whether or not a trial may move forward at designated check points based on access to certain data from the trial.

For purposes of biopharmaceutical development, human clinical trials are typically conducted in three sequential phases that may overlap or be combined:

•Phase 1. The investigational product is initially introduced into patients with the target disease or condition or healthy volunteers. These trials are designed to test the safety, dosage tolerance, absorption, metabolism and distribution of the investigational product in humans, the side effects associated with increasing doses, and, if possible, to gain early evidence on effectiveness.

•Phase 2. The investigational product is administered to a limited patient population to evaluate the preliminary efficacy, optimal dosages and dosing schedule and to identify possible adverse side effects and safety risks.

•Phase 3. The investigational product is administered to an expanded patient population to further evaluate dosage, to provide statistically significant evidence of clinical efficacy and to further test for safety, generally at multiple geographically dispersed clinical trial sites. These clinical trials are intended to establish the overall benefit-risk ratio of the investigational product and to provide an adequate basis for product approval.

In some cases, the FDA may require, or companies may voluntarily pursue, additional clinical trials after a product is approved or as a condition to full approval to gain more information about the safety and efficacy of the product. Concurrent with clinical trials, companies must finalize a process for manufacturing the product in commercial quantities in accordance with cGMP requirements.

Under the PHSA, sponsors of clinical trials are required to register and disclose certain clinical trial information on a public registry (clinicaltrials.gov) maintained by the NIH. In particular, information related to the product, patient population, phase of investigation, study sites and investigators and other aspects of the clinical trial is made public as part of the registration of the clinical trial.

NDA/BLA Submission and Review

Assuming successful completion of all required testing in accordance with all applicable regulatory requirements, the results of product development, nonclinical trials and clinical trials are submitted to the FDA as part of an NDA or BLA, as applicable, requesting approval to market the product for one or more indications.

Once an NDA or BLA has been accepted for filing, the FDA’s goal is to review standard applications within 10 months after it accepts the application for filing, or, if the application qualifies for priority review, six months after the FDA accepts the application for filing. In both standard and priority reviews, the review process can be extended by FDA requests for additional information or clarification. The FDA reviews an NDA to determine whether a drug is safe and effective for its intended use and a BLA to determine whether a biologic is safe, pure and potent. The FDA also reviews and conducts inspections to determine whether the facility in which the product is manufactured, processed, packed or held meets standards designed to assure and preserve the product’s identity, safety, strength, quality, potency and purity. The FDA may convene an advisory committee to provide clinical insight on application review questions.

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The FDA will not approve an application unless it determines that the manufacturing processes and facilities are in compliance with cGMP requirements and adequate to assure consistent production of the product within required specifications.

After the FDA evaluates an application and conducts inspections of manufacturing facilities where the investigational product and/or its drug substance will be manufactured, the FDA may issue an approval letter or a CRL (Complete Response Letter). An approval letter authorizes commercial marketing of the product with specific prescribing information for specific indications. A CRL will describe all of the deficiencies that the FDA has identified in the application, except that where the FDA determines that the data supporting the application are inadequate to support approval, the FDA may issue the CRL without first conducting required inspections, testing submitted product lots and/or reviewing proposed labeling.

If regulatory approval of a product is granted, such approval will be granted for particular indications and may entail limitations on the indicated uses for which such product may be marketed. For example, the FDA may approve the application with a risk evaluation and management strategy, or REMS, to ensure the benefits of the product outweigh its risks. A REMS could include medication guides, physician communication plans, or other elements to assure safe use, such as restricted distribution methods, patient registries and other risk minimization tools. Once approved, the FDA may withdraw the product approval if compliance with pre- and post-marketing requirements is not maintained or if problems occur after the product reaches the marketplace. The FDA may require one or more Phase 4 post-market trials and surveillance to further assess and monitor the product’s safety and effectiveness after commercialization, and may limit further marketing of the product based on the results of these post-marketing trials.

Expedited Development and Review Programs

The FDA offers a number of expedited development and review programs for qualifying product candidates. The Fast Track program is intended to expedite or facilitate the process for reviewing new products that meet certain criteria. Specifically, new products are eligible for Fast Track designation if they are intended to treat a serious or life-threatening disease or condition and demonstrate the potential to address unmet medical needs for the disease or condition. Fast Track designation applies to the combination of the product and the specific indication for which it is being studied. The sponsor of a Fast Track product has opportunities for frequent interactions with the review team during product development and, once an NDA or BLA is submitted, the product may be eligible for priority review. A Fast Track product may also be eligible for rolling review, where the FDA may consider for review sections of the NDA or BLA on a rolling basis before the complete application is submitted, if the sponsor provides a schedule for the submission of the sections of the application, the FDA agrees to accept sections of the application and determines that the schedule is acceptable, and the sponsor pays any required user fees upon submission of the first section of the application.

A product intended to treat a serious or life-threatening disease or condition may also be eligible for Breakthrough Therapy designation to expedite its development and review. A product can receive Breakthrough Therapy designation if preliminary clinical evidence indicates that the product, alone or in combination with one or more other drugs or biologics, may demonstrate substantial improvement over existing therapies on one or more clinically significant endpoints, such as substantial treatment effects observed early in clinical development. The designation includes all of the Fast Track program features, as well as more intensive FDA interaction and guidance beginning as early as Phase 1 and an organizational commitment to expedite the development and review of the product, including involvement of senior managers.

Any marketing application for a drug or biologic submitted to the FDA for approval, including a product with a Fast Track designation and/or Breakthrough Therapy designation, may be eligible for other types of FDA programs intended to expedite the FDA review and approval process, such as Priority Review and Accelerated Approval. A product is eligible for Priority Review if it has the potential to provide a significant improvement in the treatment, diagnosis or prevention of a serious disease or condition. Priority Review designation means the FDA’s goal is to take action on the marketing application within six months of the 60-day filing date.

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 product qualifies for one or more of these programs, the FDA may later decide that the product no longer meets the conditions for qualification or decide that the time period for FDA review or approval will not be shortened.

In 2025, the FDA announced a new pilot program called National Priority Voucher (CNPV). This program is designed to further accelerate drug review time for companies supporting US national interests. The review time may be reduced from 10-12 months to just 1-2 months under this pilot program.

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Orphan Drug Designation

Under the Orphan Drug Act, the FDA may grant orphan designation to a drug or biologic intended to treat a rare disease or condition, which is a disease or condition that affects fewer than 200,000 individuals in the United States, or more than 200,000 individuals in the United States for which there is no reasonable expectation that the cost of developing and making available in the United States a drug or biologic for this type of disease or condition will be recovered from sales in the United States for that drug or biologic.

If a product that has orphan drug designation subsequently receives the first FDA approval for the disease for which it has such designation, the product is entitled to orphan drug exclusive approval (or exclusivity), which means that the FDA may not approve any other applications, including a full NDA or BLA, to market the same drug or biologic for the same indication for seven years, except in limited circumstances, such as a showing of clinical superiority to the product with orphan drug exclusivity or if the FDA finds that the holder of the orphan drug exclusivity has not shown that it can assure the availability of sufficient quantities of the orphan drug to meet the needs of patients with the disease or condition for which the drug was designated. Orphan drug exclusivity does not prevent the FDA from approving a different drug or biologic for the same disease or condition, or the same drug or biologic for a different disease or condition.

Post-Approval Requirements

Any products manufactured or distributed by us pursuant to FDA approvals are subject to pervasive and continuing regulation by the FDA, including, among other things, requirements relating to record-keeping, reporting of adverse experiences, periodic reporting, product sampling and distribution, manufacturing and advertising and promotion of the product. After approval, most changes to the approved product, such as adding new indications, manufacturing methods or amended labeling claims, are subject to prior FDA review and approval.

The FDA may withdraw approval if compliance with regulatory requirements and standards is not maintained or if problems occur after the product reaches the market. Later discovery of previously unknown problems 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 trials or clinical trials to assess new safety risks; or imposition of distribution restrictions or other restrictions under a REMS program. Other potential consequences include, among other things:

•restrictions on the marketing or manufacturing of a product, complete withdrawal of the product from the market or product recalls;

•fines, warning or untitled letters or holds on post-approval clinical trials;

•refusal of the FDA to approve pending applications or supplements to approved applications, or suspension or revocation of existing product approvals;

•product seizure or detention, or refusal of the FDA to permit the import or export of products;

•consent decrees, corporate integrity agreements, debarment or exclusion from federal healthcare programs;

•mandated modification of promotional materials and labeling and the issuance of corrective information;

•the issuance of safety alerts, Dear Healthcare Provider letters, press releases and other communications containing warnings or other safety information about the product; or

•injunctions or the imposition of civil or criminal penalties.

The FDA closely regulates the marketing, labeling, advertising and promotion of biopharmaceutical products. A company can make only those claims relating to safety and efficacy, purity and potency that are approved by the FDA and in accordance with the provisions of the approved label. However, companies may share truthful and not misleading information that is otherwise consistent with a product’s FDA approved labeling.

The FDA and other agencies actively enforce the laws and regulations prohibiting the promotion of off-label uses. Failure to comply with these requirements can result in, among other things, adverse publicity, warning letters, corrective advertising and potential civil and criminal penalties. Physicians may prescribe legally available products for uses that are not described in the product’s labeling and that differ from those tested by us and approved by the FDA. Such off-label uses are common across medical specialties. Physicians may believe that such off-label uses are the best treatment for their patients in varied circumstances. The FDA does not regulate the behavior of physicians in their choice of treatments. The FDA does, however, restrict manufacturer’s communications on the subject of off-label use of their products.

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Biosimilars and Regulatory Exclusivity

The Patient Protection and Affordable Care Act, as amended by the Health Care and Education Reconciliation Act (collectively, the ACA), signed into law in 2010, includes a subtitle called the Biologics Price Competition and Innovation Act of 2009 (BPCIA), which created an abbreviated approval pathway for biological products that are biosimilar to or interchangeable with an FDA-licensed reference biological product. The FDA has since approved a number of biosimilars products.

Biosimilarity, which requires that there be no clinically meaningful differences between the biological product and the reference product in terms of safety, purity and potency, can be shown through analytical testing, animal trials and clinical trials. Interchangeability requires that a product is biosimilar to the reference product and the product must demonstrate that it can be expected to produce the same clinical results as the reference product in any given patient and, for products that are administered multiple times to an individual, the biologic and the reference biologic may be alternated or switched after one has been previously administered without increasing safety risks or risks of diminished efficacy relative to exclusive use of the reference biologic.

Under the BPCIA, an application for a biosimilar product may not be submitted to the FDA until four years following the date that the reference product was first licensed by the FDA. In addition, the approval of a biosimilar product may not be made effective by the FDA until 12 years from the date on which the reference product was first licensed. During this 12-year period of exclusivity, another company may still market a competing version of the reference product if the FDA approves a full BLA for the competing product containing that applicant’s own preclinical data and data from adequate and well-controlled clinical trials to demonstrate the safety, purity and potency of its product.

Generic Drugs and Regulatory Exclusivity

Section 505 of the FDCA provides a pathway for generic manufacturers to rely, in part, on the FDA’s prior findings of safety and efficacy for an existing product, or published literature, in support of its application. Section 505(j) establishes an abbreviated approval process for a generic version of approved drug products through the submission of an Abbreviated New Drug Application (ANDA). An ANDA provides for marketing of a generic drug product that has the same active ingredients, dosage form, strength, route of administration, labeling, performance characteristics and intended use, among other things, to a previously approved product. The generic version must deliver the same amount of active ingredient(s) in the same amount of time as the innovator drug and can often be substituted by pharmacists under prescriptions written for the reference listed drug.

Upon submission of an ANDA, an applicant must certify to the FDA that: (1) no patent information on the drug product that is the subject of the application has been submitted to the FDA; (2) such patent has expired; (3) the date on which such patent expires; or (4) such patent is invalid or will not be infringed upon by the manufacture, use or sale of the drug product for which the application is submitted. Generally, the ANDA cannot be approved until all listed patents have expired, except where the ANDA applicant challenges a listed patent through the last type of certification, also known as a paragraph IV certification.

The filing of a patent infringement lawsuit within 45 days after the receipt of a Paragraph IV certification automatically prevents the FDA from approving the ANDA until the earliest of 30 months after the receipt of the Paragraph IV notice, expiration of the patent and a decision in the infringement case that is favorable to the ANDA applicant. If the applicant does not challenge the listed patents, or indicates that it is not seeking approval of a patented method of use, the ANDA will not be approved until all of the listed patents claiming the referenced product have expired.

The FDA also cannot approve an ANDA until all applicable non-patent exclusivities listed in the Orange Book for the branded reference drug have expired. For example, a pharmaceutical manufacturer may obtain five years of non-patent exclusivity upon NDA approval.

Pediatric Exclusivity

Pediatric exclusivity is a type of non‑patent marketing exclusivity in the United States that provides for an additional six months of exclusivity under certain conditions. The conditions for pediatric exclusivity include the FDA’s determination that the use of a new product in the pediatric population may produce health benefits in that population, the FDA making a written request for pediatric clinical trials, and the sponsor agreeing to perform, and reporting on, the requested clinical trials within the statutory timeframe. 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, additional protection is granted.

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Patent Term Restoration and Extension

In the United States, a patent claiming a new product, its method of use or its method of manufacture may be eligible for a limited patent term extension under the Hatch‑Waxman Act, which permits a patent extension of up to five years for patent term lost during product development and FDA regulatory review. The restoration period for a patent covering a product is typically one‑half the time between the effective date of the IND involving human beings and the submission date of the NDA or BLA, plus the time between the submission date of the application and the ultimate approval date. 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 United States. Only one patent applicable to an approved product is eligible for the extension.

Federal and State Fraud and Abuse, and Transparency Laws and Regulations

In addition to strict FDA regulation of marketing of biopharmaceutical products, federal and state healthcare laws strictly regulate business practices in the biopharmaceutical industry. These laws may impact, among other things, our current and future business operations, including our clinical research activities, and proposed sales, marketing and education programs and constrain the business or financial arrangements and relationships with healthcare providers and other parties through which we market, sell and distribute our products for which we obtain marketing approval. These laws include anti-kickback and false claims laws and regulations, and transparency laws and regulations, including, without limitation, those laws described below.

The U.S. federal Anti-Kickback Statute prohibits any person or entity from, among other things, knowingly and willfully offering, paying, soliciting or receiving remuneration to induce or in return for purchasing, leasing, ordering or arranging for or recommending the purchase, lease or order of any item or service reimbursable under Medicare, Medicaid or other federal healthcare programs. The term “remuneration” has been broadly interpreted to include anything of value. The U.S. federal Anti-Kickback Statute has been interpreted to apply to, among others, arrangements between biopharmaceutical manufacturers on the one hand and prescribers, purchasers and formulary managers on the other. Although there are a number of statutory exceptions and regulatory safe harbors protecting some common arrangements and other activities from prosecution, the exceptions and safe harbors are drawn narrowly. Courts have interpreted the statute’s intent requirement to mean that if any one purpose of an arrangement involving remuneration is to induce referrals of federal healthcare covered business, the statute has been violated.

Federal civil and criminal false claims laws, including the federal civil False Claims Act, which can be enforced by individuals through civil whistleblower and qui tam actions, and civil monetary penalties laws, prohibit any person or entity from, among other things, knowingly presenting, or causing to be presented, a false claim for payment to the federal government or knowingly making, using or causing to be made or used a false record or statement material to a false or fraudulent claim to the federal government. A claim includes “any request or demand” for money or property presented to the U.S. government. A number of biopharmaceutical and other healthcare companies have been prosecuted under these laws for allegedly providing payments or other items of value to customers with the expectation that the providers, payers, and other third parties would bill federal programs for their products or services. Other companies have been prosecuted for causing false claims to be submitted because of the companies’ marketing of products for unapproved uses.

The federal Health Insurance Portability and Accountability Act of 1996, as amended (HIPAA), created additional federal healthcare fraud criminal statutes that prohibit, among other things, knowingly and willfully executing a scheme to defraud any healthcare benefit program, including private third-party payors and knowingly and willfully falsifying, concealing or covering up a material fact or making any materially false, fictitious or fraudulent statement in connection with the delivery of or payment for healthcare benefits, items or services. Also, many states have similar fraud and abuse statutes or regulations that apply to items and services reimbursed under Medicaid and other state programs, or, in several states, apply regardless of the payor.

The federal Physician Payments Sunshine Act requires certain manufacturers of drugs, devices, biologics and medical supplies for which payment is available under Medicare, Medicaid or the Children’s Health Insurance Program, with specific exceptions, to report annually to the Centers for Medicare & Medicaid Services (CMS) information related to payments or other transfers of value made to physicians (defined to include doctors, dentists, optometrists, podiatrists and chiropractors), and teaching hospitals, and applicable manufacturers and applicable group purchasing organizations to report annually to CMS ownership and investment interests held by physicians and their immediate family members. As of January 2022, applicable manufacturers are also required to report such information regarding its payments and other transfers of value to physician assistants, nurse practitioners, clinical nurse specialists, anesthesiologist assistants, certified registered nurse anesthetists and certified nurse midwives during the previous year. We may also be subject to similar state laws.

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Because of the breadth of these laws and the narrowness of available statutory exceptions and regulatory safe harbors, it is possible that some of our business activities could be subject to challenge under one or more of such laws. If our operations are found to be in violation of any of the federal and state laws described above or any other governmental regulations that apply to us, we may be subject to significant criminal, civil and administrative penalties including damages, fines, imprisonment, disgorgement, additional reporting requirements and oversight if we become subject to a corporate integrity agreement or similar agreement to resolve allegations of non-compliance with these laws, contractual damages, reputational harm, diminished profits and future earnings, exclusion from participation in government healthcare programs 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 any of our products are sold in a foreign country, we may be subject to similar foreign laws and regulations.

Coverage and Reimbursement

The future commercial success of our product candidates, if approved, will depend in part on the extent to which third-party payors, such as governmental payor programs at the federal and state levels, including Medicare and Medicaid, private health insurers and other third-party payors, provide coverage of and establish adequate reimbursement levels for our product candidates. Third-party payors decide which therapies they will pay for and establish reimbursement levels. In particular, in the United States, no uniform policy for coverage and reimbursement exists. Private health insurers and other third-party payors often provide coverage and reimbursement for products based on the level at which the government, through the Medicare program, provides coverage and reimbursement for such products, but also on their own methods and approval process apart from Medicare determinations. Therefore, coverage and reimbursement can differ significantly from payor to payor.

In the United States, the EU and other potentially significant markets for our product candidates, government authorities and third-party payors are increasingly attempting to limit or regulate the price of products, particularly for new and innovative products, which often has resulted in average selling prices lower than they would otherwise be. Further, the increased emphasis on managed healthcare in the United States and on country and regional pricing and reimbursement controls in the EU will put additional pressure on product pricing, reimbursement and usage. These pressures can arise from rules and practices of managed care groups, judicial decisions and laws and regulations related to Medicare, Medicaid and healthcare reform, biopharmaceutical coverage and reimbursement policies and pricing in general.

Third-party payors may limit coverage to specific products on an approved list, or formulary, which might not include all of the FDA-approved products for a particular indication. Similarly, because certain of our product candidates are intended to be physician-administered, separate reimbursement for the product itself may or may not be available. Instead, the administering physician may only be reimbursed for providing the treatment or procedure in which our product is used. Third-party payors are increasingly challenging the price and examining the medical necessity and cost-effectiveness of products, in addition to their safety and efficacy. We may need to conduct expensive pharmacoeconomic trials in order to demonstrate the medical necessity and cost-effectiveness of our product candidates. Adequate third-party payor reimbursement may not be available to enable us to realize an appropriate return on our investment in product development.

Healthcare Reform

The United States and some foreign jurisdictions are considering enacting or have enacted a number of additional legislative and regulatory proposals to change the healthcare system in ways that could affect our ability to sell our product candidates profitably, if approved. Among policy makers and payors in the United States and elsewhere, there is significant interest in promoting changes in healthcare systems with the stated goals of containing healthcare costs, improving quality and expanding access. In the United States, the biopharmaceutical industry has been a particular focus of these efforts, which include major legislative initiatives to reduce the cost of care through changes in the healthcare system, including limits on the pricing, coverage, and reimbursement of biopharmaceutical products, especially under government-funded healthcare programs, and increased governmental control of drug pricing. It is unclear whether the new Trump Administration will reverse or modify any existing regulatory requirements, pursue new reform initiatives or otherwise influence the overall healthcare regulatory environment, and even if proposed, whether such changes or modifications would be implemented or withstand potential litigation.

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Pharmaceutical Prices

In August 2022, the Inflation Reduction Act of 2022 (IRA) was signed into law. The new legislation has implications for Medicare Part D, which is a program available to individuals who are entitled to Medicare Part A or enrolled in Medicare Part B to give them the option of paying a monthly premium for outpatient prescription drug coverage. Among other things, the IRA: requires manufacturers of certain drugs to engage in price negotiations with Medicare (to go into effect in 2026), with prices that can be negotiated subject to a cap; imposes rebates under Medicare Part B and Medicare Part D to penalize price increases that outpace inflation (first due in 2023); and replaces the prior Part D coverage gap discount program with the new Manufacturer Discount Program (effective in January 2025). The IRA permits the Secretary of HHS to implement many of these provisions through guidance, as opposed to regulation, for the initial years.

These provisions of the IRA may also further heighten the risk that we would not be able to achieve the expected return on our drug products or full value of our patents protecting our products if prices are set after such products have been on the market for nine years.

The legislation also requires manufacturers to pay rebates for drugs in Medicare Part D whose price increases exceed inflation. The new law also caps Medicare out-of-pocket drug costs at an estimated $4,000 a year in 2024 and, thereafter, beginning in 2025, at $2,000 a year. Among other things, the IRA contains many provisions aimed at reducing this financial burden on individuals by reducing the co-insurance and co-payment costs, expanding eligibility for lower income subsidy plans, and price caps on annual out-of-pocket expenses, each of which could have potential pricing and reporting implications.

While it is currently unclear whether certain new measures, including the drug pricing provisions of the IRA, will ultimately be effectuated, we cannot predict with certainty what impact any federal or state health reforms will have on us, but such changes could impose new or more stringent regulatory requirements on our activities or result in reduced reimbursement for our products, any of which could adversely affect our business, results of operations and financial condition.

At the state level, legislatures have increasingly passed legislation and implemented regulations designed to control biopharmaceutical and biological product pricing, including price or patient reimbursement constraints, discounts, restrictions on certain product access and marketing cost disclosure and transparency measures, and, in some cases, designed to encourage importation from other countries and bulk purchasing. In addition, regional healthcare authorities and individual hospitals are increasingly using bidding procedures to determine which drugs and suppliers will be included in their healthcare programs. A number of states, for example, require drug manufacturers and other entities in the drug supply chain, including health carriers, pharmacy benefit managers, and wholesale distributors, to disclose information about pricing of pharmaceuticals. Furthermore, there has been increased interest by third party payors and governmental authorities in reference pricing systems and publication of discounts and list prices. These measures could reduce future demand for our products or put pressure on our pricing.

Foreign Regulation

In order to market any product outside of the United States, we would need to comply with numerous and varying regulatory requirements of other countries regarding safety and efficacy and governing, among other things, clinical trials, marketing authorization, commercial sales and distribution of our product candidates. For example, in the EU, we must obtain authorization of a clinical trial application in each member state in which we intend to conduct a clinical trial. The approval process varies from country to country and can involve additional product testing and additional administrative review periods. The time required to obtain approval in other countries might differ from and be longer than that required to obtain FDA approval. Regulatory approval in one country does not ensure regulatory approval in another, but a failure or delay in obtaining regulatory approval in one country may negatively impact the regulatory process in others. Similar to the United States, other countries offer pathways for expedited review, such as the EMA’s PRIME designation, which is granted to investigational medicines that target conditions with unmet medical needs for which no treatment option exists, or where they can offer a major therapeutic advantage over existing treatments. Orphan drug designation is also available in the EU for medicines intended to treat rare, life-threatening or chronically debilitating conditions where no other satisfactory treatment option is available, or where the medicine can be of significant benefit to those affected by a specific condition, and the benefits include access to specific scientific advice, fee reductions and 10 years of market exclusivity once the medicine is approved.

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In addition, in most foreign countries, the proposed pricing for a drug must be approved before it may be lawfully marketed. The requirements governing drug pricing and reimbursement vary widely from country to country. 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. 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 any of our products. Historically, products launched in the EU do not follow price structures of the United States and generally prices tend to be significantly lower.

Privacy Laws

We, and our service providers, receive, process, store and use personal information and other data about our clinical trial participants, employees, collaborators and others. Thus we are subject to local, state, federal and international privacy and data protection laws and regulations, which among other things, impose certain requirements related to the privacy, security and transmission of personal information, including comprehensive regulatory systems in the United States, EU and the U.K. The legislative and regulatory landscape for privacy and data protection continues to evolve in jurisdictions worldwide, subject to differing applications and interpretations, and in some cases inconsistencies or conflicts with other rules.

At the federal level, HIPAA, imposes specific requirements on certain types of individuals and entities relating to the privacy, security and transmission of individually identifiable health information and although we are not considered to be a covered entity or business associate under HIPAA, certain third parties with whom we collaborate in administering our clinical studies (or may collaborate with in the future for any clinical, regulatory or commercial activities) are within the scope of HIPAA. Penalties for failure to comply with these requirements vary significantly, and include significant civil monetary penalties and, in certain circumstances, criminal penalties and/or imprisonment. Congress has also considered passing a federal privacy law.

Numerous U.S. states, such as California, Colorado, Oregon, Texas, Utah and Virginia, among others, have adopted comprehensive privacy laws, including laws and regulations similar to HIPAA, that impose restrictive requirements regulating the processing of “sensitive” data (which includes health data in some cases). Where state laws are more protective, we have to comply with the stricter provisions. In addition to fines and penalties imposed upon violators, some of these state laws also afford private rights of action to individuals who believe their personal information has been misused.

Regulation of privacy, data protection and data security has also become more stringent in foreign jurisdictions. For example, the EU General Data Protection Regulation 2016/679 (GDPR) imposes onerous and comprehensive privacy, data protection, and data security obligations onto data controllers and processors, including, as applicable, contractual privacy, data protection and data security commitments, expanded disclosures to data subjects about how their personal information is used, honoring individuals’ data protection rights, limitations on retention of personal information, additional requirements pertaining to sensitive information (such as health data) and pseudonymized (i.e., key-coded) data, data breach notification requirements, and higher standards for obtaining consent from data subjects. Penalties for non-compliance with the GDPR can be significant. Furthermore, European privacy, data protection, and data security laws, including the GDPR and the EU’s Standard Contractual Clauses adopted in 2021, generally restrict the transfer of personal information to other countries unless the parties to the transfer have implemented specific safeguards to protect the transferred personal information. Approximately 50 countries worldwide have modeled their data privacy regulations after the GDPR or adopted similar laws, and other countries outside of Europe have enacted or are considering enacting cross-border data transfer restrictions and laws requiring local data residency. There is uncertainty as to how to implement such safeguards and how to conduct such transfers in compliance with the GDPR or similar laws, and certain safeguards may not be available or applicable with respect to some or all the personal information processing activities necessary to research, develop and market our products and services. Assisting parties with whom we exchange personal data in complying with these laws and regulations, or complying with these laws and regulations ourselves, may cause us to incur substantial operational costs or require us to change our business practices.

We may rely on others, such as health care providers, to obtain valid and appropriate consents from data subjects whose data we process. The failure of third parties to obtain consents that are valid under applicable law could result in our own non-compliance with privacy laws. Such failure would expose us to risk of enforcement actions from data protection authorities in the United States, EU and elsewhere, with the potential for significant civil or criminal penalties and/or orders requiring us to change our practices if we are found to be non-compliant, as well as private lawsuits or adverse publicity, all of which could negatively affect our operating results and business.

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Human Capital Management

Employees

Our inclusive, patient-centric culture is critical to delivering on our mission to transform patients’ lives. Our human capital programs are aimed at fostering engagement, innovation and community.

As of December 31, 2025, we had 367 employees, 282 of whom were primarily engaged in research and development activities. Our employees who work full-time in the office are predominantly located in San Francisco, California and Bellinzona, Switzerland, and employees not within commuting distance of our office locations work remotely. None of our employees are represented by a labor union and we consider our employee relations to be good.

The principal purpose of our annual incentive plan is to attract, retain, and motivate our employees through cash bonuses based on the achievement of the most significant drivers of our near-term goals. The principal purpose of our equity incentive plan is to encourage long-term, sustainable performance and ongoing retention of our employees, non-employee directors, and consultants with stock-based compensation as well as to align their interests with those of our stockholders.

In addition to highly competitive base compensation, cash bonuses granted pursuant to our annual incentive plan and stock-based awards granted pursuant to our equity incentive plan, we offer numerous benefits to employees on a country-by-country basis, including a 401(k) plan with matching, health (medical, dental and vision) insurance, life insurance, paid time off, paid parental leave and short-term and long-term disability. To drive further engagement and individual ownership of the Company, we also maintain an employee stock purchase plan, which provides eligible employees an opportunity to purchase Company stock at a discounted price.

Equity, Inclusion and Development

We take a proactive approach to promoting equity and inclusion. We support formalized employee resource groups and initiatives such as heritage and inclusivity focused events, open forum discussions, ongoing mentoring, and networking for our employees. To ensure pay equity at all levels, we use a leading independent third party pay equity firm to perform an independent audit of our pay practices periodically.

We offer ongoing, targeted inclusive developmental training for employees and leaders. We cultivate an environment where all employees can develop personally and professionally. Within this, we focus on individual opportunities for growth, developing people managers’ skills and cultivating our leaders’ capabilities to align the organization in service of our mission.

Our Corporate Information

We were incorporated under the laws of the State of Delaware on April 7, 2016. Our principal executive offices are located at 1800 Owens Street, Suite 900, San Francisco, California 94158, and our telephone number is (415) 906-4324. Our corporate website address is www.vir.bio. Information contained on, or accessible through, our website shall not be deemed incorporated into and is not a part of this Annual Report on Form 10-K, and the inclusion of our website address in this report is an inactive textual reference only. We make available free of charge through our website our Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, Current Reports on Form 8-K and amendments to those reports filed or furnished pursuant to Sections 13(a) and 15(d) of the Securities Exchange Act of 1934, as amended, or the Exchange Act. We make these reports available through our website as soon as reasonably practicable after we electronically file such reports with, or furnish such reports to, the SEC. We may use our website as a means of disclosing material non-public information and for complying with our disclosure obligations under Regulation Fair Disclosure promulgated by the SEC. These disclosures will be included on our website under the “Investors” section.