Merck & Co. Inc. has begun an official tender offer to acquire precision medicine specialist ArQule Inc., a $2.7 billion deal announced Dec. 9.

The deal amount values ArQule's shares at $20 each, and Merck said that the offer will expire Jan. 15. Merck plans to file the tender cash offer with the U.S. Securities and Exchange Commission on Dec. 17. ArQule is expected to tell the SEC that its board of directors recommended that shareholders accept the deal.

Merck reiterated that the acquisition is expected to close in the first quarter of 2020.

ArQule's lead pipeline product is ARQ 531, which is a BTK inhibitor for treating blood cancers like non-Hodgkin lymphomas and chronic lymphocytic leukemia. It is in a mid-stage clinical trial for patients with leukemia.