MSD has agreed to acquire Cidara Therapeutics in a $9.2bn deal, adding a new long-lasting infectious disease drug technology to its pipeline.
The big pharma company will pay $221.50 per share in cash to buy Cidara, a US biotech that has developed a platform of drug-Fc conjugates (DFCs). The technology has allowed Cidara to build molecules with prolonged half-life whose efficacy does not require an immune response. This means that unlike traditional vaccines, Cidara’s products do not rely on the immune system.
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The biotech’s lead asset is CD388, a small molecule neuraminidase inhibitor linked to an Fc fragment of a human antibody designed to prevent influenza A and B.
In an interview with Pharmaceutical Technology in October, Cidara’s CEO Jeff Stein said: “We turned a very potent enzyme inhibitor with poor drug properties into a great enzyme inhibitor with great drug properties. With those properties, it can be administered once per flu season.”
CD388 is currently being evaluated in the Phase III ANCHOR study (NCT07159763) in adult and adolescent participants who are at higher risk of developing complications from influenza. The antiviral demonstrated success in the Phase IIb NAVIGATE study (NCT06609460), which helped it gain breakthrough therapy designation from the US Food and Drug Administration (FDA).
MSD Research Laboratories president Dr Dean Li said: “This acquisition expands and complements our respiratory portfolio and pipeline.”
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By GlobalDataFor MSD, the acquisition of Cidara and CD388 looks set to add a strong growth avenue in the infectious disease sector. The buyout of a biotech developing antiviral drugs is even more significant given the modality’s distinction from vaccines, which have experienced volatility in the US under the Trump administration.
MSD CEO Robert Davis said: “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.”
The US Government has already seen the promise of Cidara’s technology, having awarded the biotech a hefty $339m funding award via the Biomedical Advanced Research and Development Authority (BARDA). The federal funding will be used to support domestic manufacturing of CD388 in the US and help establish an initial supply chain for commercialisation.
The long-lasting nature of CD388 confers several advantages over vaccines in national efforts to fight seasonal viruses such as influenza.
Stein added: “The most meaningful advantage is that we don’t have to change the manufacturing process from year to year, right in response to a changing influenza virus.
“CD388 should be immune to any of that. It’s a single manufacturing process that is going to be unchanged. From a sheer economic perspective, it’s going to be much more feasible to stockpile a drug like CD388.”
For MSD, the Cidara acquisition represents another billion-dollar deal in 2025. In July, the drugmaker agreed to acquire cardio-pulmonary specialist Verona Pharmaceuticals for $10bn. MSD is looking to shore up its pipeline as the loss of exclusivity for blockbuster cancer drug Keytruda (pembrolizumab) approaches. The company recently gained approval for a subcutaneous version oif the drug but analysts are uncertain about its chances on the market.
Reacting to the Cidara acquisition, Citi analysts said in a research note: “Building upon the Verona acquisition, we believe this deal makes strategic sense as Cidara would build upon the respiratory portfolio with the phase III lead asset, CD388, designed to prevent influenza A and B, but we note the flu/ vaccine landscape may be challenging given regulatory uncertainty.
“We note multiple deals may be necessary to offset loss of exclusivity exposure.”
