At a Glance
- Companies: Sanofi, Dynavax
- Location: Paris, France; Emeryville, California, US
- Deal value: $15.50 per share in cash, total equity value about $2.2 billion
- Focus area: Adult vaccines: hepatitis B (HEPLISAV‑B) and phase 1/2 shingles candidate Z‑1018
- Next steps: Cash tender offer, regulatory clearances, targeted closing in Q1 2026
What happened?
Sanofi has signed a definitive agreement to acquire Dynavax Technologies, a vaccines-focused biopharmaceutical company, in an all‑cash deal valuing Dynavax at approximately $2.2 billion. Sanofi will launch a tender offer at $15.50 per share for all outstanding Dynavax stock, bringing into its portfolio the marketed adult hepatitis B vaccine HEPLISAV‑B and a differentiated shingles vaccine candidate currently in phase 1/2 trials.
Why does it matter?
The transaction significantly strengthens Sanofi’s adult immunisation franchise by adding a two‑dose, one‑month hepatitis B schedule that offers faster seroprotection than traditional three‑dose, six‑month regimens. It also provides Sanofi with an investigational shingles vaccine that could compete in a large and growing market, where one in three adults is expected to develop shingles over their lifetime.
Who’s behind it?
Sanofi is a large, R&D‑driven biopharmaceutical company with a global vaccines business anchored by its established influenza franchise. Dynavax is a commercial-stage vaccines company whose lead product HEPLISAV‑B is approved in the US, EU and UK for adults 18 years and older, and which is advancing Z‑1018 for shingles alongside other pipeline projects.
How was it achieved?
Under the merger agreement, Sanofi will fund the acquisition with existing cash resources and seek to complete a tender offer followed by a merger, subject to a majority of shares being tendered and customary regulatory approvals, including Hart‑Scott‑Rodino review. The scientific rationale centres on Dynavax’s CpG 1018 toll‑like receptor 9 agonist adjuvant platform, used in HEPLISAV‑B and in Z‑1018, which is designed to enhance immune responses in adults, including older populations with immunosenescence.
What’s next?
If conditions are met, Sanofi expects the transaction to close in the first quarter of 2026 and does not anticipate any change to its 2025 financial guidance. Post‑closing, Sanofi aims to integrate HEPLISAV‑B into its global commercial infrastructure and continue development of Z‑1018, including ongoing phase 1/2 work in adults aged 70 years and older with head‑to‑head evaluation against Shingrix.
What are people saying?
Sanofi’s vaccines head Thomas Triomphe said the deal “enhances Sanofi’s adult immunization presence” by adding differentiated vaccines that complement its existing expertise. Dynavax CEO Ryan Spencer highlighted that joining Sanofi will provide the global scale and development capabilities needed to maximise the impact of HEPLISAV‑B and the company’s innovative vaccine pipeline.