Vir Biotechnology’s VIR-5500 gets FDA Fast Track
The Phase 1 program spans six dose-expansion cohorts, while pivotal Phase 3 trials are anticipated to begin in 2027.
Sentiment and the balance of points
Rhea-AI Sentiment reads the wording of the document, how positive or negative its language is on a 1 to 5 scale. The balance of points shown with the takes weighs what the document actually discloses, so the two can disagree, for example when a trial that missed its main goal is described in upbeat language.
Form Type
8-K
Rhea-AI Filing Summary
Vir Biotechnology, Inc. (VIR) said the FDA granted Fast Track designation to VIR-5500, a PSMA-targeted PRO-XTEN® dual-masked T-cell engager, for late-line metastatic castration-resistant prostate cancer (mCRPC). The candidate is being co-developed with Astellas Pharma Inc. through a global strategic collaboration. Fast Track is intended to facilitate and expedite development and review of drugs for serious conditions that fill an unmet need.
VIR-5500 is being evaluated in a Phase 1 study across six dose-expansion cohorts, including monotherapy and combination regimens. Vir said Phase 1 data reported earlier this year showed the candidate was generally well tolerated and exhibited promising anti-tumor activity in patients with mCRPC. Phase 3 trials are anticipated to begin in 2027.
8-K Event Classification
2 items: 8.01, 9.01
2 items
Item 8.01
Other Events
Other
Voluntary disclosure of events the company deems important to shareholders but not covered by other items.
Item 9.01
Financial Statements and Exhibits
Exhibits
Financial statements, pro forma financial information, or exhibit attachments filed with this report.
Key Figures
Dose-expansion cohorts: 6 cohorts
Anticipated Phase 3 start: 2027
Five-year survival rate: approximately 30%
3 metrics
Dose-expansion cohorts
6 cohorts
Phase 1 study of VIR-5500
Anticipated Phase 3 start
2027
Vir's stated expectation for VIR-5500 trials
Five-year survival rate
approximately 30%
Metastatic castration-resistant prostate cancer
Key Terms
Fast Track designation, PSMA-targeted, dual-masked T-cell engager (TCE), dose-expansion cohorts, +1 more
5 terms
Fast Track designation regulatory
"FDA granted Fast Track designation to VIR-5500"
Fast track designation is a status the U.S. Food and Drug Administration grants to drugs intended to treat serious conditions and address an unmet medical need. It gives the developer more frequent communication with the FDA and can allow parts of the application to be reviewed on a rolling basis, and it may pave the way to priority review or accelerated approval. It can shorten development timelines, though it does not guarantee approval.
PSMA-targeted medical
"a PSMA-targeted PRO-XTEN® dual-masked T-cell engager"
dual-masked T-cell engager (TCE) medical
"PRO-XTEN® dual-masked T-cell engager (TCE)"
dose-expansion cohorts medical
"Phase 1 study across six dose-expansion cohorts"
radioligand therapy medical
"radioligand therapy naïve mCRPC"
A treatment that uses a small molecule or antibody designed to seek out specific cells and deliver a tiny dose of radiation directly to them, like a guided missile carrying a limited explosive to a particular target rather than carpeting an area. Investors care because successful radioligand therapies can become high-value prescription products with clear market niches, regulatory hurdles, and reimbursement decisions that strongly affect a developer’s revenue and risk profile.
FAQ
AI-generated questions and answers. How Rhea-AI works. Not financial advice.
What cancer is VIR-5500 being developed to treat?
VIR-5500 received Fast Track designation for late-line metastatic castration-resistant prostate cancer (mCRPC). It is being evaluated in a Phase 1 study.
When are Phase 3 trials of VIR-5500 expected to begin?
Phase 3 trials are anticipated to begin in 2027. VIR-5500 is currently being evaluated in a Phase 1 study across six dose-expansion cohorts.
AI-generated analysis. How Rhea-AI works. Not financial advice.
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
________________________________________
FORM 8-K
________________________________________
CURRENT REPORT
Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934
Date of Report (Date of earliest event reported): October 8, 2026
________________________________________
(Exact name of Registrant as Specified in Its Charter)
________________________________________
| (State or Other Jurisdiction of Incorporation) | (Commission File Number) | (IRS Employer Identification No.) | ||||||
| (Address of Principal Executive Offices) | (Zip Code) | |||||||
Registrant’s Telephone Number, Including Area Code: (415 ) 906-4324
(Former Name or Former Address, if Changed Since Last Report)
________________________________________
Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:
| Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) | |||||
| Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) | |||||
| Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) | |||||
| Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) | |||||
Securities registered pursuant to Section 12(b) of the Act:
| Title of each class | Trading Symbol(s) | Name of each exchange on which registered | ||||||||||||
Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).
Emerging growth company o
If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. o
Item 8.01 Other Events.
On October 8, 2026, Vir Biotechnology, Inc. (the Company) issued a press release announcing that the U.S. Food and Drug Administration has granted Fast Track designation to VIR-5500, a PSMA-targeted PRO-XTEN® dual-masked T-cell engager (TCE), for the treatment of late-line metastatic castration-resistant prostate cancer. VIR-5500 is being co-developed by Astellas Pharma Inc. and the Company through a global strategic collaboration. A copy of the press release is filed herewith as Exhibit 99.1 and is incorporated herein by reference.
PRO-XTEN® is a trademark of Amunix Pharmaceuticals, Inc., a Sanofi company.
Item 9.01 Financial Statements and Exhibits.
(d) Exhibits
| Exhibit No. | Description | |||||||
| 99.1 | Press Release of the Company, dated October 8, 2026 | |||||||
| 104 | Cover Page Interactive Data File (embedded within the Inline XBRL document) | |||||||
SIGNATURES
Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.
| VIR BIOTECHNOLOGY, INC. | |||||||||||
| Date: | October 8, 2026 | By: | /s/ Marianne De Backer | ||||||||
| Marianne De Backer, M.Sc., Ph.D., MBA President and Chief Executive Officer | |||||||||||
Exhibit 99.1
Vir Biotechnology Announces PSMA-targeted PRO-XTEN® Dual-masked T-cell Engager VIR-5500 Received FDA Fast Track Designation for the Treatment of Prostate Cancer
SAN FRANCISCO, Calif. October 6, 2026 - Vir Biotechnology, Inc. (Nasdaq: VIR) today announced that the U.S. Food and Drug Administration (FDA) granted Fast Track designation to VIR-5500, a PSMA-targeted PRO-XTEN® dual-masked T-cell engager (TCE), for the treatment of late-line metastatic castration-resistant prostate cancer (mCRPC). VIR-5500 is being co-developed by Astellas Pharma Inc. and Vir Biotechnology through a global strategic collaboration.
“Receiving Fast Track designation reflects the potential of VIR-5500 to address an area of serious unmet need in late-line mCRPC and the strong momentum we have achieved with Astellas as we prepare to enter pivotal Phase 3 development in 2027,” said Marianne De Backer, President and Chief Executive Officer of Vir Biotechnology. “We look forward to working with the FDA to rapidly advance the development of VIR-5500 for people living with mCRPC.”
“People living with advanced prostate cancer need new treatment options that can offer meaningful and durable benefit,” said Moitreyee Chatterjee-Kishore, Executive Vice President and Head of Oncology Development, Astellas. “This Fast Track designation reinforces the importance of advancing VIR-5500 with urgency, and we are committed to exploring its potential to make a meaningful difference for patients and their families.”
FDA Fast Track designation is intended to facilitate and expedite the development and review of drugs to treat serious conditions and fill an unmet need.
VIR-5500 is being evaluated in a Phase 1 study across six dose-expansion cohorts. The monotherapy dose-expansion cohorts include patients with taxane naïve mCRPC, radioligand therapy naïve mCRPC and radioligand therapy exposed mCRPC. The combination regimen dose-expansion cohorts include VIR-5500 in combination with enzalutamide in early-line mCRPC, VIR-5500 in combination with docetaxel in early-line mCRPC and VIR-5500 in combination with darolutamide in metastatic hormone sensitive prostate cancer (mHSPC). Phase 1 data reported earlier this year showed VIR-5500 was generally well tolerated and exhibited promising anti-tumor activity in patients with mCRPC. Phase 3 trials are anticipated to begin in 2027.
About VIR-5500
T-cell engagers (TCEs) are powerful anti-tumor agents that can direct the immune system, specifically T-cells, to destroy cancer cells. VIR-5500 is an investigational PRO-XTEN® dual-masked TCE currently being evaluated in an open-label, non-randomized Phase 1 clinical trial (NCT05997615) designed to assess the safety, pharmacokinetics and preliminary efficacy in participants with metastatic castration-resistant prostate cancer (mCRPC).
VIR-5500 combines a bispecific PSMA and CD3 binding TCE with the PRO-XTEN® masking technology. 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 mask and activate the TCEs, enabling killing of cancer cells by T-cells. By confining the activity to the tumor microenvironment, we aim to circumvent the traditionally high toxicity associated with unmasked TCEs and increase their efficacy and tolerability. Additionally, the mask is designed to help drug candidates stay in the bloodstream longer in their inactive form, allowing them to better reach the site of action and potentially allowing for less frequent dosing regimens.
About PRO-XTEN® Dual-masked T-cell Engagers (TCEs)
T-cell engagers (TCEs) are powerful anti-tumor agents designed to direct the immune system, specifically T-cells, to destroy cancer cells. TCEs have become an important treatment option for blood cancers, but their usage in solid tumors has been limited due to toxicity. The universal PRO-XTEN® masking technology is designed to extend the half-life of the molecule and to keep TCEs inactive (or masked) until they reach the tumor microenvironment, where tumor-specific proteases cleave off the mask and activate the TCEs, leading to killing of cancer cells by T-cells. By extending the half-life and confining activity to the tumor microenvironment, the PRO-XTEN® technology could limit toxicity, widen the therapeutic index of TCEs, and potentially enable less frequent dosing regimens.
About Advanced Prostate Cancer
Prostate cancer remains a significant global health burden, representing the second leading cause of cancer-related mortality in men behind lung cancer.1 While diagnostic and therapeutic advances like androgen-directed therapy can improve outcomes in earlier settings, most patients ultimately relapse and develop metastatic hormone sensitive prostate cancer (mHSPC).2 mHSPC is characterized by its responsiveness to intensified hormonal interventions designed to reduce androgen levels or block their action. The majority of these patients eventually progress to metastatic castration-resistant prostate cancer (mCRPC).3 This stage is associated with poor clinical outcomes, including limited durability of existing therapies, with a 5-year survival rate of approximately 30%.4 There is a critical need for safer, more effective and precisely targeted therapies capable of improving long term disease control and quality of life across the prostate cancer continuum.
1 Kratzer TB, et. al. “Prostate cancer statistics, 2025.” CA Cancer J Clin. vol. 75 no. 6 (2025): 485-497. doi:10.3322/caac.70028.
2 Bernard-Terrier A & Beltran H. “Exploring the biology of metastatic hormone-sensitive prostate cancer: on the road to precision medicine.” J Clin Invest. vol. 136 no. 3 (2026):e200920. doi: 10.1172/JCI200920.
3 Leith A, et. al. “Real-World Treatment Patterns in Metastatic Castration-Resistant Prostate Cancer Across Europe (France, Germany, Italy, Spain, and the United Kingdom) and Japan.” Adv Ther. vol. 39 (2022): 2236-2255. doi: 10.1007/s12325-022-02073-w.
4 Huo, X et al. “Predicting Survival in Metastatic Castration-Resistant Prostate Cancer Patients: Development of a Prognostic Nomogram.” Studies in health technology and informatics vol. 323 (2025): 164-168. doi:10.3233/SHTI250070.
2 Bernard-Terrier A & Beltran H. “Exploring the biology of metastatic hormone-sensitive prostate cancer: on the road to precision medicine.” J Clin Invest. vol. 136 no. 3 (2026):e200920. doi: 10.1172/JCI200920.
3 Leith A, et. al. “Real-World Treatment Patterns in Metastatic Castration-Resistant Prostate Cancer Across Europe (France, Germany, Italy, Spain, and the United Kingdom) and Japan.” Adv Ther. vol. 39 (2022): 2236-2255. doi: 10.1007/s12325-022-02073-w.
4 Huo, X et al. “Predicting Survival in Metastatic Castration-Resistant Prostate Cancer Patients: Development of a Prognostic Nomogram.” Studies in health technology and informatics vol. 323 (2025): 164-168. doi:10.3233/SHTI250070.
About Vir Biotechnology, Inc.
Vir Biotechnology, Inc. 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. Its clinical-stage portfolio includes programs for chronic hepatitis delta and multiple PRO-XTEN® dual-masked T-cell engagers across validated targets in solid tumor indications. Vir Biotechnology also has a preclinical portfolio of programs across a range of oncologic malignancies. Vir Biotechnology routinely posts information that may be important to investors on its website.
Forward-looking Statements
This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as “should,” “could,” “may,” “might,” “will,” “plan,” “potential,” “aim,” “expect,” “anticipate,” “promising” and similar expressions (as well as other words or expressions referencing future events, conditions or circumstances) are intended to identify forward-looking statements. Forward-looking statements contained in this press release include, but are not limited to, statements regarding: the FDA Fast Track designation and potential expedited development for VIR-5500 to address an area of serious unmet need in late-line mCRPC; the therapeutic potential of VIR-5500, both as a monotherapy and as part of combination regimens, to be a treatment for advanced mCRPC (including in early-line) and mHSPC; Vir Biotechnology’s clinical development plans and expectations for VIR-5500, including protocols for and enrollment into ongoing and planned clinical trials (including pivotal Phase 3 trials in 2027), target endpoints and data readouts; Vir Biotechnology’s strategy and plans; and any assumptions underlying any of the foregoing. Many factors may cause differences between current expectations and actual results, including, without limitation: unexpected safety or efficacy data or results observed during clinical studies or in data readouts, including the occurrence of adverse safety events; risks of unexpected costs, delays or other unexpected hurdles; challenges in accessing manufacturing capacity; clinical site activation rates or clinical enrollment rates that are lower than expected; the timing and outcome of Vir Biotechnology’s planned interactions with regulatory authorities, as well as general difficulties in obtaining any necessary regulatory approvals; successful development and/or commercialization of alternative product candidates by Vir Biotechnology’s competitors, as well as changes in expected or existing competition; geopolitical changes or other external factors; and unexpected litigation or other disputes. In light of these risks and uncertainties, the events or circumstances referred to in the forward-looking statements may not occur. Drug development and commercialization involve a high degree of risk, and only a small number of research and development programs result in commercialization of a product. Results in early-stage clinical studies may not be indicative of full results or results from later stage or larger scale clinical studies and do not ensure regulatory approval. The actual results may vary from the anticipated results, and the variations may be material. You are cautioned not to place undue reliance on any scientific data presented or these forward-looking statements, which are based on Vir Biotechnology’s available information, expectations and assumptions as of the date of this press release. Other factors that may cause Vir Biotechnology’s actual results to differ from those expressed or implied in the forward-looking statements in this press release are discussed in Vir Biotechnology’s filings with the U.S. Securities and Exchange Commission, including the section titled “Risk Factors” contained therein. Except as required by law, Vir Biotechnology assumes no obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise.
Vir Biotechnology has exclusive rights to the universal PRO-XTEN® masking platform for oncology and infectious disease. PRO-XTEN® is a trademark of Amunix Pharmaceuticals, Inc., a Sanofi company.
Media Contact
Caren Scannell
Director, Communications
cscannell@vir.bio
Investor Contact
Kiki Patel, PharmD
Head of Investor Relations
kpatel@vir.bio
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