On Nov. 14, 2025, Merck and Cidara Therapeutics, a biotechnology company developing drug-Fc conjugate (DFC) therapeutics, announced that the companies have entered into a definitive agreement under which Merck, through a subsidiary, will acquire Cidara for $221.50 per share in cash, for a total transaction value of approximately $9.2 billion.

Cidara’s lead candidate, CD388, consists of a small molecule neuraminidase inhibitor stably conjugated to a proprietary Fc fragment of a human antibody designed to prevent influenza A and B. CD388 is currently being evaluated in the Phase 3 ANCHOR study among adult and adolescent participants who are at higher risk of developing complications from influenza. Supported by results from the Phase 2b NAVIGATE study, the U.S. Food and Drug Administration (FDA) granted CD388 Breakthrough Therapy Designation. The NAVIGATE study met all primary and secondary endpoints associated with preventing symptomatic laboratory-confirmed influenza in healthy unvaccinated adults ages 18 to 64. CD388 was previously granted Fast Track Designation by the FDA.

The transaction has been approved by both Merck’s and Cidara’s Boards of Directors. Under the terms of the merger agreement, Merck, through a subsidiary, will acquire all of the outstanding shares of Cidara. The acquisition is subject to a majority of Cidara’s stockholders tendering their shares in a tender offer that will be initiated by a subsidiary of Merck. The closing of the proposed transaction will be subject to certain conditions, including the expiration of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act and other customary conditions. The transaction is expected to close in the first quarter of 2026 and is expected to be accounted for as an asset acquisition