Astellas and Vir Biotechnology Announce Global Strategic Collaboration to Advance PSMA-targeting PRO-XTEN® Dual-masked T-Cell Engager VIR-5500 for the Treatment of Prostate Cancer

Rhea-AI Summary

Vir Biotechnology (Nasdaq: VIR) and Astellas (TSE: 4503) entered a global collaboration to co-develop and co-commercialize VIR-5500, a PSMA-targeting PRO-XTEN dual-masked T-cell engager for prostate cancer.

Vir will receive $335M upfront/near-term, share U.S. profits 50/50, and may receive up to $1.37B additional milestones; Astellas leads U.S. commercialization and holds ex-U.S. exclusive rights. Global development costs split 60/40 (Astellas/Vir). Closing is subject to customary conditions including HSR clearance.

Positive

• $335M upfront and near-term payments to Vir
• Potential $1.37B in additional development, regulatory, and sales milestones
• U.S. 50/50 profit/loss split between Vir and Astellas
• Astellas holds exclusive ex-U.S. commercialization rights

Negative

• Vir responsible for 40% of global development costs
• A portion of collaboration proceeds will be shared with Sanofi
• Closing contingent on HSR clearance and other customary conditions

Market Reaction – VIR

+71.60% $12.75 2.3x vol

15m delay 72 alerts

+71.60% Since News

+70.2% Peak in 1 hr 49 min

$12.75 Last Price

$7.26 $13.41 Day Range

+$431M Valuation Impact

$1.03B Market Cap

2.3x Rel. Volume

Following this news, VIR has gained 71.60%, reflecting a significant positive market reaction. Argus tracked a peak move of +70.2% during the session. Our momentum scanner has triggered 72 alerts so far, indicating high trading interest and price volatility. The stock is currently trading at $12.75. This price movement has added approximately $431M to the company's valuation. Trading volume is elevated at 2.3x the average, suggesting notable buying interest.

Data tracked by StockTitan Argus (15 min delayed). Upgrade to Silver for real-time data.

Key Figures

Upfront & near-term: $335M Cash component: $240M Equity investment: $75M +5 more

8 metrics

Upfront & near-term $335M Upfront and near-term milestone payments from Astellas

Cash component $240M Cash portion of upfront and near-term payments

Equity investment $75M Equity at a 50% premium as part of collaboration

Near-term milestone $20M Additional near-term milestone payment

Future milestones $1.37B Potential development, regulatory and sales milestones

Cost split 60% / 40% Global development costs: Astellas 60%, Vir 40%

U.S. profit share 50% / 50% Equal profit/loss sharing for VIR-5500 in the U.S.

mCRPC 5-year survival 30% Approximate 5-year survival rate in mCRPC

Market Reality Check

Price: $7.56 Vol: Volume 2,975,487 is 1.85x...

high vol

$7.56 Last Close

Volume Volume 2,975,487 is 1.85x the 20-day average of 1,609,926, indicating elevated trading interest into the collaboration news. high

Technical Price at $7.43 is trading above the 200-day moving average of $5.69, despite a -3.32% move over the last 24 hours.

Peers on Argus

VIR fell -3.32% while close biotech peers were mixed (e.g., PRME +2.14%, TNGX +2...

VIR fell -3.32% while close biotech peers were mixed (e.g., PRME +2.14%, TNGX +2.25%, KALV -1.64%). With no peers in the momentum scanner and no same-day peer headlines, the move appears stock-specific rather than sector-driven.

Historical Context

5 past events · Latest: Feb 09 (Neutral)

Pattern 5 events

Date	Event	Sentiment	Move	Catalyst
Feb 09	Earnings call notice	Neutral	+1.3%	Scheduled Q4 and full-year 2025 results call and corporate update.
Jan 12	Clinical update	Positive	+1.2%	Positive Phase 2 hepatitis delta data and VIR-5500 ASCO GU 2026 plans.
Jan 05	Conference appearance	Neutral	-2.5%	CEO presentation at J.P. Morgan Healthcare Conference with webcast access.
Dec 16	Licensing deal	Positive	-3.6%	Norgine license for hepatitis delta candidate with milestones and cost sharing.
Nov 19	Conference participation	Neutral	+2.2%	CEO fireside chat at Evercore Healthcare Conference with webcast.

Pattern Detected

Partnership and clinical updates have sometimes seen muted or even negative price reactions, as with the December 2025 licensing deal.

Recent Company History

Over the past six months, Vir has highlighted multiple strategic and clinical milestones. A December 2025-12-16 licensing deal with Norgine for hepatitis delta featured up to EUR 495M in milestones but saw a -3.57% next-day move. In January 2026, Vir reported positive Phase 2 SOLSTICE data and a cash position of about $781M, with modestly positive price reactions. Several investor conference appearances and an earnings call announcement produced only small moves. Today’s Astellas partnership continues the pattern of monetizing pipeline assets through co-development alliances.

Market Pulse Summary

The stock is surging +71.6% following this news. A strong positive reaction aligns with the sizable ...

Analysis

The stock is surging +71.6% following this news. A strong positive reaction aligns with the sizable collaboration economics, including $335M in upfront and near-term payments and eligibility for up to $1.37B in milestones. Past licensing and partnership news, such as the December 2025 Norgine deal, did not always yield sustained gains, so traders could monitor whether elevated volume and a short interest backdrop eventually cool. Execution on the ongoing Phase 1 VIR-5500 program would remain a key focus.

Key Terms

t-cell engager, psma, metastatic castration-resistant prostate cancer, mcrpc, +3 more

7 terms

t-cell engager medical

"investigational PRO-XTEN® dual-masked CD3 T-cell engager (TCE) targeting PSMA"

A T-cell engager is a type of medicine designed to help the body's immune system attack cancer cells more effectively. It works by acting like a bridge that brings immune cells (T-cells) close to cancer cells, prompting a targeted attack. For investors, T-cell engagers are significant because they represent innovative treatments that could lead to new growth opportunities in the healthcare and biotech sectors.

psma medical

"T-cell engager (TCE) targeting PSMA for the treatment of prostate cancer"

Prostate-specific membrane antigen (PSMA) is a protein on the surface of prostate cells that becomes much more common on many prostate cancer cells, acting like a biological “flag” that helps locate or attach to tumors. Investors care because diagnostic scans and drugs that detect or bind to PSMA can improve diagnosis and treatment; success or failure of those products often has a direct financial impact on the companies developing them.

metastatic castration-resistant prostate cancer medical

"prostate cancer, especially metastatic castration-resistant prostate cancer (mCRPC), remains"

An advanced form of prostate cancer that has spread beyond the prostate to other parts of the body (metastatic) and no longer responds to treatments that lower male hormones designed to starve the tumor (castration-resistant). It matters to investors because it defines a high unmet medical need with limited treatment options, so clinical trial results, new drug approvals, or safety setbacks can sharply change the valuation and prospects of companies working in this area; think of it as a weed that has spread and become resistant to the usual weedkiller.

mcrpc medical

"metastatic castration-resistant prostate cancer (mCRPC), remains an aggressive"

mCRPC stands for metastatic castration‑resistant prostate cancer, a form of prostate cancer that has spread beyond the prostate and keeps progressing despite treatments that lower male hormones. It matters to investors because this stage is harder to treat, drives demand for new therapies, and often involves large, expensive clinical trials and regulatory decisions that can strongly influence a drug maker’s future revenue and stock value—think of it as a stubborn problem that creates both medical need and commercial opportunity.

tumor microenvironment medical

"designed to keep the TCEs masked (or inactive) until they reach the tumor microenvironment"

The tumor microenvironment is the immediate area surrounding a cancer cell, made up of nearby cells, blood vessels, and support structures that influence how the cancer grows and spreads. It functions like a bustling neighborhood that can either help or hinder the tumor’s development. For investors, understanding changes in this environment can signal the effectiveness of treatments and potential shifts in a cancer-related market.

phase 1 medical

"currently in Phase 1 development for people with advanced, metastatic prostate cancer"

Phase 1 is the first stage of testing a new drug or medical treatment in people, focused primarily on safety, how the body handles the product, and finding a tolerated dose. Think of it as a short, tightly controlled experiment with a small group to check for dangerous side effects before wider testing; for investors it is an early milestone that reduces some uncertainty but still carries high risk and potential for both big value changes and setbacks.

cd3 medical

"dual-masked CD3 T-cell engager (TCE) targeting PSMA for the treatment"

CD3 is a group of proteins on the surface of T cells, the immune system’s front-line soldiers, that act like a control panel to turn those cells on and off. It matters to investors because many modern therapies work by engaging or blocking CD3 to direct T cells against cancer or dampen harmful immune reactions; success, safety and regulatory approval of CD3-targeting drugs can significantly affect a biotech company’s prospects.

AI-generated analysis. Not financial advice.

- Astellas and Vir Biotechnology to co-develop and co-commercialize VIR-5500 through a sharing of expenses and revenues -

- Astellas to lead commercialization of VIR-5500 in the U.S. with Vir Biotechnology retaining option to co-promote, and Astellas will obtain exclusive rights to commercialize VIR-5500 ex-U.S. -

- Vir Biotechnology will receive $335M in upfront and near-term milestone payments, will split U.S. profit/loss equally with Astellas (50/50), and is eligible to receive up to an additional $1.37B in development, regulatory and sales milestones, along with tiered, double-digit royalties on ex-U.S. net sales -

- Vir Biotechnology to host conference call today at 2:30 p.m. PT / 5:30 p.m. ET -

TOKYO and SAN FRANCISCO, Feb. 23, 2026 /PRNewswire/ -- Astellas Pharma Inc. (TSE: 4503, President and CEO: Naoki Okamura, "Astellas") and Vir Biotechnology, Inc. (Nasdaq: VIR) today announced they have entered into a global strategic collaboration to advance VIR-5500, an investigational PRO-XTEN^® dual-masked CD3 T-cell engager (TCE) targeting PSMA for the treatment of prostate cancer. The collaboration aims to accelerate the development of VIR-5500 and further strengthen Astellas' oncology pipeline and prostate cancer leadership.

Adam Pearson, Chief Strategy Officer, Astellas
"Astellas is proud to have helped 1.5 million patients with prostate cancer, and we are dedicated to expanding our impact as part of our R&D strategy. Our deep expertise in this disease area, combined with a growing immuno-oncology (IO) pipeline of biologics, including T-cell engagers, uniquely positions us to help advance VIR-5500, a potentially best-in-class T-cell engager for prostate cancer. This strategic collaboration allows Astellas and Vir Biotechnology to combine our expertise and reaffirms our commitment to improving the lives of people with prostate cancer."

Marianne De Backer, M.Sc., Ph.D., MBA, Chief Executive Officer, Vir Biotechnology
"Astellas is an ideal collaborator for the VIR-5500 program given the company's successful track record advancing therapies across the treatment continuum, building blockbuster franchises and delivering value to patients through strategic development alliances with other biotech partners. This collaboration will enable more rapid advancement of VIR-5500 to potentially benefit more people living with prostate cancer. We believe this collaboration reflects confidence in our PRO-XTEN^® platform, which has broad potential across multiple solid tumor indications."

Despite recent advances in treatment, prostate cancer, especially metastatic castration-resistant prostate cancer (mCRPC), remains an aggressive and difficult cancer to treat; mCRPC has a 5-year survival rate of approximately 30%.ⁱ Patients who progress to mCRPC develop therapeutic resistance and currently have limited treatment options.

VIR-5500 is a potential best-in-class dual-masked Prostate-Specific Membrane Antigen (PSMA)-targeting TCE and is currently in Phase 1 development for people with advanced, metastatic prostate cancer (NCT05997615). VIR-5500 combines a bispecific PSMA and CD3 binding TCE with the PRO-XTEN^® masking technology, which is designed to keep the TCEs masked (or inactive) until they reach the tumor microenvironment, reducing off-target effects and improving the therapeutic index.

Under the terms of the agreement, Vir Biotechnology will receive $335 million in upfront and near-term payments, including $240 million in cash, $75 million in equity investment at a 50% premium,ⁱⁱ and a near-term $20 million milestone. Global development costs for VIR-5500 will be shared, with Astellas responsible for 60% and Vir Biotechnology responsible for 40% of all costs. Vir Biotechnology will continue the ongoing Phase 1 trial, until responsibility is transitioned to Astellas, after which Astellas will be responsible for all development activities. In the U.S., Vir Biotechnology will have the option to co-promote VIR-5500 with Astellas, and profit/loss will be shared equally. Outside the U.S., Astellas will be exclusively responsible for commercialization of VIR-5500. In addition, Vir Biotechnology is eligible to receive up to $1.37 billion in development, regulatory and sales milestones, along with tiered, double-digit royalties on ex-U.S. net sales. Under the terms of Vir Biotechnology's licensing agreement with Sanofi, a portion of certain collaboration proceeds will be shared with Sanofi. 

Lazard acted as Vir Biotechnology's exclusive financial advisor. Closing of the transaction is contingent on customary closing conditions, including clearance under the Hart-Scott-Rodino (HSR) Act. 

Vir Biotechnology Conference Call
Vir Biotechnology will host its fourth quarter and full year 2025 financial results conference call at 2:30 p.m. PT / 5:30 p.m. ET today, when members of the executive team and Dr. de Bono will share the updated VIR-5500 Phase 1 data that is also being presented at the 2026 ASCO Genitourinary Cancers Symposium on February 26. A live webcast will be available at https://investors.vir.bio and will be archived for 30 days.

About Astellas
Astellas is a global life sciences company committed to turning innovative science into VALUE for patients. We provide transformative therapies in disease areas that include oncology, ophthalmology, urology, immunology and women's health. Through our research and development programs, we are pioneering new healthcare solutions for diseases with high unmet medical need. Learn more at www.astellas.com.

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 engagersⁱⁱⁱ across validated targets in solid tumor indications. Vir Biotechnology also has a preclinical portfolio of programs across a range of infectious diseases and oncologic malignancies. Vir Biotechnology routinely posts information that may be important to investors on its website. 

Footnotes:
ⁱHuo, Xingyue 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
ⁱⁱ50% premium to the 30 day volume weighted average share price as of February 19, 2026
ⁱⁱⁱVir Biotechnology retains exclusive rights to the PRO-XTEN^® masking platform for oncology and infectious disease. PRO-XTEN^® is a trademark of Amunix Pharmaceuticals, Inc., a Sanofi company.

Astellas Cautionary Notes
In this press release, statements made with respect to current plans, estimates, strategies and beliefs and other statements that are not historical facts are forward-looking statements about the future performance of Astellas. These statements are based on management's current assumptions and beliefs in light of the information currently available to it and involve known and unknown risks and uncertainties. A number of factors could cause actual results to differ materially from those discussed in the forward-looking statements. Such factors include, but are not limited to: (i) changes in general economic conditions and in laws and regulations, relating to pharmaceutical markets, (ii) currency exchange rate fluctuations, (iii) delays in new product launches, (iv) the inability of Astellas to market existing and new products effectively, (v) the inability of Astellas to continue to effectively research and develop products accepted by customers in highly competitive markets, and (vi) infringements of Astellas' intellectual property rights by third parties. Information about pharmaceutical products (including products currently in development) which is included in this press release is not intended to constitute an advertisement or medical advice.

Vir Biotechnology 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 therapeutic potential of the combination of VIR-5500 to treat prostate cancer (including mCRPC) and Vir Biotechnology's belief that it can be a best-in-class PSMA-targeting TCE; Vir Biotechnology's clinical development plans and expectations for VIR-5500, including protocols for and enrollment into ongoing and planned clinical studies, target endpoints and data readouts; Vir Biotechnology's immediate and potential future financial and other obligations under the agreement and collaboration with Astellas, as well as Vir Biotechnology's ability to realize the benefits; Vir Biotechnology's belief that Astellas is an ideal collaborator (given Astellas' successful track record advancing therapies across the treatment continuum, building blockbuster franchises and delivering value through strategic development alliances) and that the agreement will enable faster and broader advancement of VIR-5500 to potentially benefit more people living with prostate cancer; the timing of the anticipated closing of the transaction with Astellas, including receipt of any necessary regulatory clearances; 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; difficulties in collaborating with other companies, some of whom may be competitors of Vir Biotechnology or otherwise have divergent interests, and uncertainty as to whether the benefits of Vir Biotechnology's various collaborations can ultimately be achieved; 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.

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SOURCE Astellas Pharma Inc.

FAQ

What payments will Vir Biotechnology (VIR) receive from Astellas for VIR-5500?

Vir will receive $335 million in upfront and near-term payments. According to Vir Biotechnology, that includes $240 million cash, $75 million equity at a 50% premium, and a near-term $20 million milestone payment.

How are development costs for VIR-5500 allocated between Vir (VIR) and Astellas?

Astellas will cover 60% of global development costs and Vir will cover 40%. According to Vir Biotechnology, Vir will run the ongoing Phase 1 trial until responsibility transitions to Astellas.

Who will commercialize VIR-5500 in the U.S. and internationally (VIR)?

Astellas will lead U.S. commercialization with Vir retaining a co-promote option and 50/50 U.S. profit sharing. According to Vir Biotechnology, Astellas will have exclusive commercialization rights outside the U.S.

What total milestone and royalty upside can Vir (VIR) earn from the collaboration?

Vir is eligible for up to $1.37 billion in development, regulatory, and sales milestones plus tiered double-digit ex-U.S. royalties. According to Vir Biotechnology, royalties apply to ex-U.S. net sales.

What is VIR-5500 and what stage of development is it in (VIR)?

VIR-5500 is a PSMA-targeting PRO-XTEN dual-masked CD3 T-cell engager in Phase 1 development for advanced metastatic prostate cancer. According to Vir Biotechnology, the program aims to reduce off-target effects using tumor masking technology.

Are there closing conditions or third-party obligations affecting the VIR-5500 deal for Vir (VIR)?

Yes. Closing is contingent on customary conditions, including Hart-Scott-Rodino (HSR) clearance. According to Vir Biotechnology, a portion of certain collaboration proceeds will also be shared with Sanofi under an existing license agreement.