Merck to Acquire Cidara Therapeutics for $9.2 Billion to Expand Influenza Prevention Portfolio with Breakthrough Therapy CD388

On November 14, MSD announced the acquisition of Cidara Therapeutics for $9.2 billion to obtain its flu prevention drug CD388. According to the agreement, MSD will acquire Cidara through its subsidiary in an all-cash deal at $221.50 per share, with a total transaction value of approximately $9.2 billion.

MSD Chairman and CEO Robert M. Davis stated, "We will continue to execute our science-driven business development strategy by expanding the CD388 pipeline, a potential first-in-class long-acting antiviral designed to prevent influenza in individuals at higher risk of complications. We aim to build on the significant progress made by the Cidara team and believe that CD388 has the potential to become another key growth driver in the next decade, creating real value for shareholders."

Cidara's lead candidate, CD388, consists of a small-molecule neuraminidase inhibitor, zanamivir, which is stably conjugated to a proprietary Fc fragment of a human antibody designed to prevent both influenza A and B. CD388 is currently being evaluated in the ANCHOR Phase 3 study (NCT07159763), targeting adult and adolescent participants at high risk for influenza complications. Supported by the results of the Phase 2b NAVIGATE study (NCT06609460), the U.S. FDA has granted CD388 Breakthrough Therapy designation. The NAVIGATE study met all primary and secondary endpoints related to the prevention of laboratory-confirmed symptomatic influenza in healthy, unvaccinated adults aged 18 to 64. CD388 had previously received Fast Track designation from the U.S. FDA.

Dr. Jeffrey Stein, President and CEO of Cidara Therapeutics, stated: "This milestone marks a transformative moment for Cidara and our mission to redefine influenza prevention. Thanks to the extraordinary dedication of our team, the Phase 2b NAVIGATE study has yielded compelling results, demonstrating the potential of CD388 to provide an additional option to vaccines and antivirals to help address unmet needs in flu prevention. MSD’s global development, regulatory, and commercial capabilities bring the expertise and resources needed to deliver this important innovation to those who need it most."

Dr. Dean Y.Li, President of Merck Research Laboratories, stated: "This acquisition expands and complements our respiratory portfolio and pipeline. Influenza continues to pose a significant threat to global health, causing widespread illness, morbidity, and mortality each year, particularly among the elderly and immunocompromised populations such as cancer patients and those with chronic conditions. CD388 is a novel late-stage candidate with important strain-agnostic properties, currently being evaluated for its efficacy in preventing symptomatic influenza in high-risk populations."

The transaction has been approved by the boards of directors of both Merck and Cidara. According to the terms of the merger agreement, Merck will acquire all outstanding shares of Cidara through a subsidiary. The completion of this acquisition is contingent upon the tender of their shares by a majority of Cidara's shareholders in the offer initiated by Merck’s subsidiary. The closing of the proposed transaction is 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 be completed in the first quarter of 2026 and is anticipated to be accounted for as an asset acquisition.