Cidara's stock doubles in value following universal flu vaccine results

Cidara Therapeutics’ stock soared after its experimental flu prevention drug, CD388, showed up to 76% efficacy in a Phase 2b trial, outperforming expectations and potentially rivaling vaccines.

Why it matters: If successful in later trials, CD388 could become a seasonal flu prevention alternative, especially for high-risk individuals and those who can't receive traditional vaccines. Analysts project up to $3B in peak annual sales if the drug is approved.

Backstory: Seasonal flu leads to serious illness annually, particularly among the elderly and immunocompromised. Vaccines vary in effectiveness and aren't suitable for everyone. Existing flu treatments, like Tamiflu, offer limited benefit.

Big picture: CD388 could transform flu prevention by offering broad, long-lasting protection from a single dose, combining a known antiviral (zanamivir) with a protein fragment for sustained impact. This innovation could reduce flu-related hospitalizations and healthcare strain.

Behind the result: The Phase 2b trial included 18–64-year-olds receiving 150–450 mg doses or placebo. CD388 met both primary and secondary trial endpoints over a 24-week period. No unexpected safety issues were observed.

Next steps: Cidara plans to present full results at an upcoming medical conference and will meet with the FDA to discuss a Phase 3 clinical trial.

Yes, but: Cidara announced a proposed $250.0 million public offering a few hours after disclosing the trial results, which brought the stock down by 4%.