Vir Biotechnology today announced that the exclusive worldwide license agreement with Sanofi announced on August 1, 2024, has closed following expiration of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976.

The agreement provides Vir with an exclusive worldwide license to three clinical-stage masked T-cell engagers (TCEs) with potential applications in a range of cancers and exclusive use of the proprietary PRO-XTEN masking platform for oncology and infectious disease. Key employees from Sanofi with extensive scientific and development expertise in TCEs, and in-depth experience using the PRO-XTEN platform, will join Vir. Further information about the TCEs and their respective development plans will be provided at Vir’s upcoming R&D Day in November.

“The closing of this strategic agreement with Sanofi is a pivotal moment for Vir and a significant opportunity to help address patient unmet needs. We are excited to further advance the masked T-cell engagers in clinical development, bolstering our clinical pipeline and adding near-term value creation opportunities,” said Marianne De Backer, M.Sc., Ph.D., MBA, Vir’s Chief Executive Officer. “Our proven expertise in antibody engineering and clinical development combined with the innovative PRO-XTEN masking platform offers a unique opportunity to discover and develop therapies in oncology and infectious disease.”

The clinical-stage assets Vir is licensing under the agreement are:

  • SAR446309 is a dual-masked HER2-targeted TCE in phase 1 clinical study including participants with metastatic treatment resistant HER2+ tumors such as breast and colorectal cancers.
  • SAR446329 is a dual-masked PSMA-targeted TCE in phase 1 clinical study including participants with metastatic castration-resistant prostate cancer.
  • SAR446368 is a dual-masked EGFR targeted TCE with an active IND. A phase 1 clinical study, which is expected to begin enrollment in the first quarter of 2025, will include participants with EGFR-expressing tumors of various types.

About the PRO-XTEN Masking Platform

The PRO-XTEN proprietary masking platform can be applied to TCEs, cytokines, and other molecules potentially broadening the therapeutic index (TI) for patients. This technology exploits the high protease activity of the tumor microenvironment (TME) to specifically activate (unmask) drug candidates in tumor tissues. The selective cleavage results in the active molecule being released preferentially in the TME, potentially increasing the TI by minimizing off-target activity and toxicity associated with the systemic immune activation seen with traditional TCEs. Vir has exclusively licensed the PRO-XTEN proprietary masking platform from Sanofi in the fields of oncology and infectious diseases.