France's Sanofi is acquiring all the outstanding shares of immuno-oncology company Synthorx Inc. in a deal with a total equity value of about $2.5 billion.

Under the agreement, Sanofi will initiate a cash tender offer for all the outstanding shares of Synthorx for $68 apiece, representing a 172% premium to Synthorx's closing price Dec. 6. Sanofi said the merger has a total enterprise value of about $2.35 billion.

La Jolla, Calif.-based Synthorx is developing therapies intended to treat cancer and autoimmune disorders through its proprietary technology. The company's lead asset, THOR-707, is being evaluated as a potential treatment of multiple solid tumor types as a standalone therapy and in combination with immune checkpoint inhibitors.

The tender offer is set to commence in December 2019, while the acquisition is expected to close in the first quarter of 2020.

Sanofi intends to finance the transaction with cash on hand.

Completion of the tender offer is subject to customary closing conditions, including at least a majority of Synthorx shares being tendered and expiration or termination of the waiting period under the Hart-Scott-Rodino Act.

The transaction, which has been unanimously approved by both companies' boards, is expected to boost French drugmaker Sanofi's oncology and immuno-oncology pipeline.

Morgan Stanley & Co. is acting as financial adviser to Sanofi, with Weil Gotshal & Manges LLP serving as legal counsel. Centerview Partners LLC is exclusive financial adviser to Synthorx, while Cooley LLP is acting as legal counsel.