Merck announced a significant expansion of its infectious disease pipeline through a definitive agreement to acquire Cidara Therapeutics for approximately $9.2 billion in cash. The agreement will bring Cidara’s late-phase antiviral candidate CD388 into Merck’s portfolio as the company advances its strategy to broaden its development programs through science-driven transactions.
The all-cash deal values Cidara at $221.50 per share and has been approved by the boards of both companies. Through the transaction, Merck will gain full ownership of CD388, a long-acting antiviral candidate being evaluated in Phase 3 trials for the prevention of influenza in individuals who face an elevated risk of flu-related complications. The therapy uses a small molecule neuraminidase inhibitor conjugated to a proprietary Fc fragment, designed to address both influenza A and B. CD388 has received Breakthrough Therapy Designation and previously received Fast Track Designation from the U.S. Food and Drug Administration following positive results from the Phase 2b NAVIGATE study.
The ongoing Phase 3 ANCHOR trial is evaluating the therapy among adults and adolescents who are at a higher risk of experiencing severe outcomes from influenza. Data from NAVIGATE demonstrated strong performance in preventing symptomatic, laboratory-confirmed influenza in healthy unvaccinated adults ages 18 to 64, meeting all study endpoints. Merck noted that the acquisition supports the company’s long-term growth plans as CD388 advances toward potential commercialization.
Company leaders from both organizations highlighted the significance of the deal and emphasized the potential impact of CD388 on high-risk populations. They described the transaction as an essential step in expanding preventive options for individuals who face substantial burdens from seasonal influenza, including immunocompromised patients and those with chronic conditions.
The acquisition will proceed through a tender offer led by a subsidiary of Merck. Completion of the deal remains subject to a majority of Cidara shareholders tendering their shares and to regulatory approval, including clearance under the Hart-Scott-Rodino Act. The companies expect the transaction to close in the first quarter of 2026 and plan to account for it as an asset acquisition.
KEY QUOTES
“We continue to execute our science-led business development strategy, augmenting our pipeline with CD388, a potentially first-in-class, long-acting antiviral designed to prevent influenza in individuals at higher risk of complications. We intend to build on the Cidara team’s remarkable progress and are confident that CD388 has the potential to be another important driver of growth through the next decade, creating real value for shareholders.”
Robert M. Davis, Chairman And Chief Executive Officer, Merck
“This milestone represents a transformational moment for Cidara and for our mission to redefine influenza prevention. Thanks to the extraordinary dedication of our team, the Phase 2b NAVIGATE study delivered compelling results that demonstrate CD388’s potential to provide an additional option to vaccines and antivirals to help address unmet needs in influenza prevention. Merck’s global development, regulatory and commercial capabilities provide the expertise and resources needed to bring this important innovation to those individuals who need it most.”
Jeffrey Stein, Ph.D., President And Chief Executive Officer, Cidara Therapeutics
“This acquisition expands and complements our respiratory portfolio and pipeline. Influenza continues to pose a significant global health threat, causing widespread illness, morbidity and death each year especially in older adults and immunocompromised individuals, such as those with cancer and chronic diseases. CD388 is a novel late-phase candidate with important strain-agnostic properties being evaluated for the prevention of symptomatic influenza in high-risk individuals.”
Dr. Dean Y. Li, President, Merck Research Laboratories
