On December 24, 2025 Sanofi reported that it has entered into an agreement to acquire Dynavax Technologies Corporation (Nasdaq: DVAX), a publicly traded vaccines company with a marketed adult hepatitis B vaccine (HEPLISAV-B) and a differentiated shingles vaccine candidate. The acquisition augments Sanofi’s presence in adult immunization by bringing together Dynavax’s vaccines with Sanofi’s global scale, development capabilities and commercial reach.

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Dynavax’s adult hepatitis B vaccine HEPLISAV-B is currently marketed in the US and is differentiated by its two-dose regimen over one month, which enables high levels of seroprotection faster than other hepatitis B vaccines, which are given in three doses over six months.

The acquisition also includes Dynavax’s shingles vaccine candidate (Z-1018), which is currently in phase 1/2 clinical development, and additional vaccine pipeline projects.

"Dynavax enhances Sanofi’s adult immunization presence by adding differentiated vaccines that complement Sanofi’s expertise," said Thomas Triomphe, Executive Vice President, Vaccines, Sanofi. "Its marketed adult hepatitis B vaccine and shingles candidate bring new options to our portfolio and underscore our commitment to providing vaccine protection across the lifespan."

"Joining Sanofi will provide the global scale and expertise needed to maximize the impact of our vaccine portfolio," said Ryan Spencer, Chief Executive Officer, Dynavax. "We believe Sanofi’s commercial reach, development capabilities and commitment to evidence-based immunization will amplify the opportunity for HEPLISAV-B and our innovative pipeline to address important public health needs, further advancing our mission to help protect the world against infectious disease. We are confident that this transaction – and the compelling value it provides – is in the best interests of the Company and its stockholders."

Dynavax believes hepatitis B and shingles represent a significant public unmet health need and adult vaccination opportunities. In the US alone, nearly 100 million adults born before 1991 remain unvaccinated, with many potentially at risk for infection. Chronic infection with the hepatitis B virus can cause liver damage and lead to cirrhosis and liver cancer. Shingles, which is caused by the varicella zoster virus, affects one in three adults over their lifetime, according to the World Health Organization. In most people shingles causes a painful, itchy rash, but in some cases it can lead to long-term nerve pain, serious eye infections that can damage the vision and, rarely, dangerous inflammation of the brain.

Financial considerations
Under the terms of the merger agreement, Sanofi will commence a cash tender offer to acquire all outstanding shares of Dynavax for $15.50 per share in cash, reflecting a total equity value of approximately $2.2 billion.

The offer price represents a premium of approximately 39% over the closing price of Dynavax on December 23, 2025 and a premium of approximately 46% over the 3-month volume-weighted average price (VWAP) of Dynavax as of December 23, 2025.

The transaction has been unanimously approved by the Dynavax board of directors. The consummation of the tender offer is subject to customary closing conditions, including the tender of a number of shares of Dynavax common stock that represent at least a majority of the outstanding shares of Dynavax common stock, the expiration or termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, certain foreign regulatory filings and clearances and other customary conditions.

If the tender offer is successfully completed, then following the successful completion of the tender offer, a wholly owned subsidiary of Sanofi will merge with and into Dynavax, and all of the outstanding Dynavax common stock that are not tendered in the tender offer will be converted into the right to receive the same $15.50 per share in cash offered to Dynavax shareholders in the tender offer.

Sanofi plans to fund the acquisition with available cash resources. Subject to the satisfaction or waiver of customary closing conditions, the transaction is expected to close in the first quarter of 2026.

Centerview Partners LLC and Goldman Sachs & Co. LLC are acting as financial advisors to Dynavax, and Cooley LLP is acting as its legal counsel.

About HEPLISAV-B
HEPLISAV-B is an adult hepatitis B vaccine that combines hepatitis B surface antigen with Dynavax’s vaccine adjuvant, a toll-like receptor (TLR) 9 agonist, to enhance the immune response.

HEPLISAV-B is a shot given to adults 18 years of age and older to help prevent infection caused by the hepatitis B virus. HEPLISAV-B is usually given in the arm muscle. HEPLISAV-B is given in two doses, one month apart, by a healthcare provider.

IMPORTANT SAFETY INFORMATION
Do not administer HEPLISAV-B to individuals with a history of severe allergic reaction (e.g., anaphylaxis) after a previous dose of any hepatitis B vaccine or to any component of HEPLISAV-B, including yeast.

Appropriate medical treatment and supervision must be available to manage possible anaphylactic reactions following administration of HEPLISAV-B.

Immunocompromised persons, including individuals receiving immunosuppressant therapy, may have a diminished immune response to HEPLISAV-B.

Hepatitis B has a long incubation period. HEPLISAV-B may not prevent hepatitis B infection in individuals who have an unrecognized hepatitis B infection at the time of vaccine administration.

The most common patient-reported adverse reactions reported within 7 days of vaccination were injection site pain (23%-39%), fatigue (11%-17%), and headache (8%-17%).

There are no adequate and well-controlled studies of HEPLISAV-B in pregnant individuals. Available data, primarily in individuals who received one dose of HEPLISAV-B in the 28 days prior to or during pregnancy, do not suggest an increased risk of major birth defects and miscarriage.

It is not known whether HEPLISAV-B is excreted in human milk.

Data are not available to assess the effects of HEPLISAV-B on the breastfed infant or on milk production/excretion.

Vaccination with HEPLISAV-B may not result in protection of all vaccine recipients.

(Press release, Sanofi, DEC 24, 2025, View Source [SID1234661622])