Single-dose, non-vaccine antiviral shows significant seasonal prophylactic efficacy and favorable safety profile in over 5,000 healthy adults.
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Cidara Therapeutics has announced positive topline results from its phase 2b NAVIGATE trial evaluating CD388, a novel, long-acting antiviral being developed as a once-per-season preventive treatment for influenza. The study met its primary and all secondary efficacy endpoints, with single doses of CD388 demonstrating up to 76% protection against symptomatic, laboratory-confirmed influenza in healthy, unvaccinated adults.
The trial included over 5,000 participants aged 18 to 64, randomized to receive one of three CD388 doses (150 mg, 300 mg, 450 mg) or placebo at the beginning of the flu season. Prevention efficacy (PE) was observed across all dose groups over a 24-week period. Statistical significance was also confirmed for combined higher-dose groups (300 mg + 450 mg), showing a PE of 68.6% (p < .0001).
CD388 met secondary endpoints evaluating prevention at fever thresholds ≥37.8°C and ≥37.2°C, with durable protection extending up to 28 weeks post-dose. The agent was well tolerated, with no drug-related serious adverse events and a safety profile similar to placebo, including injection site reactions.
CD388 demonstrated up to 76% efficacy in preventing laboratory-confirmed influenza following a single seasonal dose in healthy adults.
The investigational drug was well tolerated with no serious adverse events or dose-limiting toxicities observed across all dose levels.
Cidara has initiated regulatory engagement with the FDA and plans to advance CD388 into Phase 3 development.
CD388 is a drug-Fc conjugate (DFC), not a vaccine, and works independently of host immune response, a potential advantage for individuals who are immunocompromised or have suboptimal vaccine responses. Designed to neutralize all known strains of influenza A and B, CD388 is administered via a single intramuscular or subcutaneous injection each flu season.
“These results are unprecedented and affirm our belief in CD388’s potential to transform flu prevention,” said Jeffrey Stein, PhD, CEO of Cidara. “This approach could offer a once-per-season option that works across immune profiles.” Nicole Davarpanah, MD, JD, chief medical officer, added, “These Phase 2b results are both statistically and clinically meaningful, and support further evaluation in high-risk populations.”
Cidara has submitted an End-of-phase 2 meeting request to the US FDA and is preparing for a phase 3 trial. Additional NAVIGATE data are expected to be presented at upcoming scientific meetings in 2025.
CD388 is an investigational DFC composed of a potent neuraminidase inhibitor conjugated to a proprietary human Fc fragment. It is designed to provide broad, long-acting protection against seasonal and pandemic influenza strains, with efficacy independent of patient immune status.
The NAVIGATE trial (NCT06609460) is a randomized, double-blind, placebo-controlled Phase 2b study conducted at sites across the US and UK, enrolling healthy adults not at high risk for influenza complications. Participants were monitored throughout the flu season for laboratory-confirmed ILI and fever-based endpoints.
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