Merck has entered a definitive agreement to acquire Cidara Therapeutics, a biotechnology company developing drug-Fc conjugate (DFC) therapeutics, for $221.50 per share in cash, for a total transaction value of approximately $9.2 billion.

This acquisition expands and complements Merck’s respiratory portfolio and pipeline. 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 (NCT07159763) among adult and adolescent participants who are at higher risk of developing complications from influenza. Supported by results from the Phase 2b NAVIGATE study (NCT06609460), 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.

“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,” said Robert M. Davis, Chairman and CEO, Merck. “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.”

“This milestone represents a transformational moment for Cidara and for our mission to redefine influenza prevention,” said Jeffrey Stein, Ph.D., President and CEO of Cidara. “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.”

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 transaction is expected to close in the first quarter of 2026.

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