Sanofi has signed an agreement to acquire UK-based biotechnology company Vicebio’s share capital for $1.15bn upfront, to expand its vaccine development capabilities.

The deal also includes additional milestone payments up to $450m contingent on development and regulatory successes.

Sanofi’s acquisition adds an early-stage combination vaccine for respiratory syncytial virus (RSV) and human metapneumovirus (hMPV), as well as the Molecular Clamp technology.

The technology stabilises viral proteins in their native shape, which may lead to more effective immune responses.

This method facilitates the development of fully liquid combination vaccine candidates which can be stored at standard refrigeration temperatures (between 2°C and 8°C), removing the need for freezing or freeze-drying and streamlining both manufacturing and distribution processes.

These fully liquid vaccines can be provided in prefilled syringes, improving safety, ease of use and operational efficiency in healthcare settings.

The deal will be finalised in the fourth quarter (Q4) of 2025, pending regulatory approvals.

Sanofi research and development vaccines global head Jean-François Toussaint stated: "Vicebio's Molecular Clamp technology introduces a purposefully simple but thoughtful approach to further improve vaccine designs at a time when respiratory viral infections continue to impact millions globally.

“This acquisition furthers Sanofi's dedication to vaccine innovation with the potential to develop next-generation combination vaccines that could protect older adults against multiple respiratory viruses with a single immunisation."

Vicebio's product pipeline features VXB-241, a bivalent vaccine that targets RSV and hMPV, currently investigated in exploratory Phase I studies in older adults.

The company’s VXB-251 is a trivalent preclinical vaccine targeting RSV, hMPV and parainfluenza virus Type 3 (PIV3).

Vicebio CEO Emmanuel Hanon stated: “As part of the Sanofi team, we look forward to advancing our platform and pipeline to deliver meaningful benefits for patients and public health.”

The latest development comes after Sanofi completed its acquisition of Blueprint Medicines, enhancing its portfolio with a commercialised therapy and the expertise of a company focused on systemic mastocytosis and other KIT-driven diseases [a group of diseases in which mutations in proto-oncogene tyrosine-protein kinase lead to uncontrolled cell growth and proliferation].