Wedoany.com Report-Dec.25, Sanofi announced on Wednesday, December 24, 2025, that it has entered into an agreement to acquire U.S.-based Dynavax Technologies Corporation for approximately $2.2 billion in an all-cash deal.

Under the terms, Sanofi will commence a cash tender offer to purchase all outstanding shares of Dynavax at $15.50 per share. This price represents a 39% premium over Dynavax's closing share price on Tuesday, December 23, 2025.

The acquisition will add Dynavax's marketed adult hepatitis B vaccine, HEPLISAV-B, to Sanofi's portfolio. HEPLISAV-B is administered to individuals aged 18 and older in a two-dose regimen over one month, providing faster seroprotection compared to traditional three-dose vaccines given over six months.

The deal also includes Dynavax's shingles vaccine candidate, Z-1018, which is currently in phase 1/2 clinical development. Early data from a study in August showed Z-1018 generated a similar immune response to existing products while demonstrating a favorable safety profile in participants aged 50 to 69.

**Thomas Triomphe**, Executive Vice President of Vaccines at Sanofi, said: “Dynavax enhances Sanofi’s adult immunization presence by adding differentiated vaccines that complement Sanofi’s expertise.”

HEPLISAV-B generated $90 million in sales during the third quarter of 2025, with analysts projecting peak annual U.S. sales around $609 million.

This transaction supports Sanofi's efforts to expand its vaccine offerings, complementing existing products such as influenza, polio, and the antibody therapy Beyfortus for respiratory syncytial virus. It follows recent acquisitions, including Vicebio and Blueprint Medicines, as the company seeks additional growth drivers ahead of future patent expirations.

Sanofi plans to fund the acquisition with available cash resources. The deal is expected to close in the first quarter of 2026 and is not anticipated to affect the company's 2025 financial guidance.

Dynavax shares rose significantly following the announcement, reflecting market response to the premium offer.

In a separate development, Sanofi reported that the U.S. Food and Drug Administration issued a complete response letter for its experimental drug tolebrutinib, intended to slow disability progression in adults with non-relapsing secondary progressive multiple sclerosis.

**Houman Ashrafian**, Executive Vice President and Head of Research & Development at Sanofi, said: “Today’s FDA decision is a significant and meaningful change in direction from the feedback the agency previously provided to Sanofi. We are very disappointed by the FDA's action.”

Sanofi remains committed to collaborating with the FDA to explore potential next steps for tolebrutinib, which received provisional approval in the United Arab Emirates in July 2025.

The acquisition aligns with ongoing industry focus on strengthening adult immunization portfolios through targeted strategic partnerships and asset integration.