Vir Biotechnology says FDA grants Fast Track to VIR-5500 for prostate cancer

Vir Biotechnology's press release carries an October 6, 2026 dateline stating that the FDA granted Fast Track designation to VIR-5500, a PSMA-targeted PRO-XTEN dual-masked T-cell engager, for the treatment of late-line metastatic castration-resistant prostate cancer.¹ The company's 8-K filing, dated October 8, 2026, describes the release as having been issued on that later date, so the two documents give different dates for when the announcement went out.

VIR-5500 is being co-developed by Astellas Pharma Inc. and Vir Biotechnology through a global strategic collaboration.¹

Vir's CEO Marianne De Backer said the designation reflects momentum with Astellas as the companies prepare to enter pivotal Phase 3 development in 2027.¹ Astellas oncology development head Moitreyee Chatterjee-Kishore commented that patients with advanced prostate cancer need new options, and said the designation reinforces plans to advance the program, according to the release.

VIR-5500 is being evaluated in a Phase 1 study across six dose-expansion cohorts, including monotherapy cohorts in taxane naïve, radioligand therapy naïve and radioligand therapy exposed mCRPC, plus combination cohorts with enzalutamide, docetaxel, and darolutamide in earlier disease settings.¹ Phase 1 data reported earlier in 2026 showed VIR-5500 was generally well tolerated and exhibited promising anti-tumor activity in patients with mCRPC.¹ Phase 3 trials are anticipated to begin in 2027.¹

The ongoing Phase 1 trial is registered as NCT05997615. It is an open-label, non-randomized study designed to assess safety, pharmacokinetics and preliminary efficacy in participants with metastatic castration-resistant prostate cancer.¹

Vir holds exclusive rights to the PRO-XTEN masking platform for oncology and infectious disease, and PRO-XTEN is a trademark of Amunix Pharmaceuticals, Inc., a Sanofi company.¹