Merck completes $9.2B acquisition of Cidara Therapeutics securing CD388 a long-acting, strain-agnostic flu preventive for high-risk patients. Phase 3 data, financials & strategy revealed.
Written By: Pharmacally Medical News Desk
Merck has completed its tender offer for Cidara Therapeutics, bringing the biotechnology company fully under its umbrella and expanding Merck’s presence in respiratory infectious diseases. The deal centres on CD388, Cidara’s investigational, long-acting antiviral candidate that is being developed to help prevent symptomatic influenza in individuals at higher risk of complications.
Merck chairman and CEO Robert M. Davis said the acquisition aligns with the company’s focus on scientific innovation that delivers meaningful value to patients and health systems. He highlighted CD388 as a potentially first-in-class antiviral candidate with broad activity across influenza strains. Merck plans to build on Cidara’s work and continue evaluating the therapy for those at greatest risk of flu-related complications.
CD388: A New Approach to Flu Prevention
CD388 belongs to a class known as drug-Fc conjugates. It links a potent neuraminidase inhibitor to a proprietary antibody Fc fragment. This design allows the therapy to behave like a long-acting small molecule rather than a vaccine or monoclonal antibody.
The candidate is being developed for individuals at higher risk of complications from influenza, with the goal of offering protection across an entire flu season. In preclinical studies, CD388 demonstrated antiviral activity against both influenza A and B viruses, including strains with pandemic potential.
Unlike vaccines, CD388 does not rely on an immune response. This makes the approach appealing for people whose immune systems may be weakened or less responsive. Phase 2b NAVIGATE trial data (NCT06609460) showed up to 76% reduction in symptomatic influenza at the 450 mg dose over 24 weeks in healthy adults. The therapy is currently under evaluation in the Phase 3 ANCHOR study (NCT07159763) in adults and adolescents considered at increased risk of flu complications.
Influenza Burden Remains Significant
Seasonal influenza continues to place a heavy burden on global health. Each year, roughly one billion people are infected worldwide. An estimated three to five million cases become severe, with complications that can include pneumonia, sepsis, worsening of chronic conditions, and in some cases death. Global mortality tied to influenza ranges from about 290,000 to 650,000 deaths annually, with thousands of deaths reported each year in the United States.
Completion of the Tender Offer
Merck completed a cash tender offer for Cidara at 221.50 dollars per share, with more than 85 percent of outstanding shares tendered. The remaining shares were converted at the same price through a follow-on merger, making Cidara a wholly owned subsidiary. Its stock has now been delisted from the Nasdaq Global Market. The transaction, first announced in November 2025, closed in the first quarter of 2026 as planned.
With Cidara now set to join the Merck organization, CD388 becomes a key asset in Merck’s growing respiratory pipeline. The acquisition underscores the ongoing interest in preventive therapies for influenza, particularly for vulnerable populations. The coming results from the Phase 3 ANCHOR study will help determine the therapy’s place in future flu prevention strategies.
Reference
Merck to Complete Acquisition of Cidara Therapeutics, 07 January 2026, https://www.merck.com/news/merck-to-complete-acquisition-of-cidara-therapeutics/
Cidara Therapeutics Announces Positive Topline Results from its Phase 2b NAVIGATE Trial Evaluating CD388, a Non-Vaccine Preventative of Seasonal Influenza, June 23, 2025, https://www.cidara.com/news/cidara-therapeutics-announces-positive-topline-results-from-its-phase-2b-navigate-trial-evaluating-cd388-a-non-vaccine-preventative-of-seasonal-influenza/
Cidara Therapeutics Reaches Target Enrollment of Phase 3 ANCHOR Trial Evaluating CD388 for Prevention of Seasonal Influenza in High-Risk Populations, 24 November 2025, https://www.globenewswire.com/news-release/2025/11/24/3193451/0/en/Cidara-Therapeutics-Reaches-Target-Enrollment-of-Phase-3-ANCHOR-Trial-Evaluating-CD388-for-Prevention-of-Seasonal-Influenza-in-High-Risk-Populations.html