French pharmaceutical giant Sanofi SA said Wednesday that it has agreed to acquire U.S. vaccine developer Dynavax Technologies Corp. for $2.2 billion in a recommended all cash transaction aimed at expanding its adult immunization portfolio.

Sanofi said it entered into an agreement to purchase Dynavax for $15.50 per share through a tender offer, valuing the company’s total equity at approximately $2.2 billion. The drugmaker said it plans to fund the acquisition using existing cash.

Dynavax is listed on the Nasdaq and develops vaccines for adult populations. Its approved hepatitis B vaccine is authorized for use in the United States, the European Union, and the United Kingdom and is administered in two doses over one month, compared with competing vaccines that require three doses over six months.

Sanofi said the deal also includes Dynavax’s shingles vaccine candidate, which is currently in clinical development.

Thomas Triomphe, Sanofi’s executive vice president of vaccines, said Dynavax’s products “bring new options to our portfolio.”

Ryan Spencer, Dynavax’s chief executive officer, said that “joining Sanofi will provide the global scale and expertise needed to maximize the impact of our vaccine portfolio.”

Dynavax’s board of directors has unanimously approved the transaction and will recommend it to shareholders. Completion of the tender offer requires at least 50 percent of Dynavax’s outstanding shares to be tendered.

Sanofi said it plans to merge Dynavax into one of its subsidiaries following the closing of the transaction.

The companies said the deal remains subject to clearance under the U.S. Hart Scott Rodino Antitrust Improvements Act and other customary regulatory approvals. They expect the transaction to close by March 2026.

Cooley LLP is serving as legal counsel to Dynavax. Counsel information for Sanofi, which is listed on Euronext Paris and the Nasdaq, was not immediately available.

Centerview Partners LLC and Goldman Sachs & Co. LLC are acting as financial advisers to Dynavax.