New Drug Shows Promise in Flu Prevention

An experimental influenza drug, CD388, may provide longer-lasting protection compared to traditional flu vaccines, according to recent trial findings. The drug, developed by **Cidara Therapeutics**, could offer a new approach to seasonal flu prevention.

Efficacy Over Six Months

Data indicates that single doses of the drug provided significant protection against symptomatic flu for approximately six months. Specifically, 150 mg, 300 mg, and 450 mg doses yielded protection rates of 58%, 61%, and 76%, respectively, according to the company’s announcement. This information has been submitted to the FDA for review.

Study Highlights

The phase 2b trial, named NAVIGATE, involved over 5,000 healthy adults aged 18 to 64 across 57 US sites and one UK site. Participants were monitored for 24 weeks after receiving a single dose of CD388 between September and December 2024. Researchers evaluated the participants for both clinically confirmed and lab-confirmed influenza cases.

Significant Results

In the placebo group, 2.8% of participants contracted influenza. The group receiving the highest dose (450 mg) demonstrated a prevention efficacy (PE) of 76.1%. The 300-mg group showed 61.3% PE, while the 150-mg group had a 57.7% PE. These results, derived from 4,726 participants, were statistically significant.

For context, the Centers for Disease Control and Prevention reports that flu vaccine effectiveness over the past 15 flu seasons has ranged from 19% to 60% (CDC Data). CD388 also achieved all secondary goals, including sustained efficacy for up to 28 weeks at specific body temperature thresholds.

Safety Profile and Next Steps

Safety data remained consistent across all dose groups, including the placebo group, with no serious adverse events reported. **Cidara** plans to share more data at upcoming scientific conferences and is deciding on dosages for a phase 3 clinical trial, set to commence next spring.

“We are blessed by the fact that any of the three doses would likely be well suited for the phase 3 study.”

—Jeffrey Stein, PhD, president and CEO of Cidara

**Stein** indicated that the final dose selection will hinge on the analysis of pharmacokinetics and virology data, with more detailed results expected by September.

Company Perspective

**Nicole Davarpanah**, MD, JD, **Cidara’s** chief medical officer, described the results as “mark[ing] a potential breakthrough for patients and the future of influenza prevention.” She emphasized CD388’s potential as a highly effective prophylactic for high-risk individuals.

“CD388 was designed to provide once per season protection against all strains of influenza in all people, irrespective of immune status.”

—Jeffrey Stein, CEO of Cidara

During a press conference, **Stein** mentioned that **Cidara** has contacted the Biomedical Advanced Research and Development Authority (BARDA) to explore potential support for the drug’s development.