Merck & Co. is spending $9.2 billion for Cidara Therapeutics and its lead influenza antiviral that was dropped by Johnson & Johnson last year.
Merck is paying $221.50 cash per share of Cidara, a San Diego-based biotech that has been taking its antiviral, dubbed CD388, through a phase 3 study. Merck’s offer Friday morning is more than double the $105.99 share price Cidara’s stock closed at Thursday.
Merck CEO Robert Davis justified the deal by describing the pharma’s “confiden[ce] that CD388 has the potential to be another important driver of growth through the next decade, creating real value for shareholders.”
CD388 is being developed as a non-vaccine alternative for flu prevention. The prophylactic is a member of the drug-Fc conjugate class, comprised of multiple copies of a potent small molecule neuraminidase inhibitor conjugated to a bespoke Fc fragment of a human antibody.
Cidara read out a phase 2b trial in June that showed that the highest 450-mg dose of CD388 conferred 76% protection against seasonal influenza in unvaccinated adults versus placebo, while lower doses of 300 mg and 150 mg conferred 61% and 58% protection, respectively.
Since then, Cidara has taken the highest dose into phase 3, with the support of potentially up to $339 million in a funding deal from the Department of Health and Human Services' (HHS’) Biomedical Advanced Research and Development Authority (BARDA).
That funding deal included confirmed cash of $58 million over two years, which was earmarked to stand up domestic manufacturing for CD388 in the U.S. and help Cidara establish its “initial commercial supply chain,” the company explained last month.
The BARDA funding came in handy for Cidara, which had lost its Big Pharma partner Janssen in April 2024 following the Johnson & Johnson unit’s wind-down of all infectious disease and vaccine R&D. To recover its asset, Cidara handed Janssen $85 million upfront in a deal that also included the potential for development, regulatory and commercial milestone payments.
Janssen’s loss is Merck’s gain, at least according to Davis, who described CD388 this morning as “a potentially first-in-class, long-acting antiviral designed to prevent influenza in individuals at higher risk of complications.”
“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,” Cidara CEO Jeffrey Stein, Ph.D., said in this morning’s release.
“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,” Stein added.
Merck’s deal comes against a backdrop of a newfound skepticism of mRNA flu vaccines by Robert F. Kennedy Jr.'s HHS. However, Cidara has repeatedly stressed this year that drug-Fc conjugates are not vaccines or monoclonal antibodies. Rather, they are low molecular weight biologics meant to function as “long-acting small molecule inhibitors,” the biotech again pointed out in this morning’s release.