A new influenza drug that lasts for an entire flu season may outperform flu vaccines, according to the results of a large phase 2b trial released by Cidara Therapeutics of San Diego, USA.
CIDRAP reports that single doses of 150mg, 300mg, and 450mg provided 58%, 61%, and 76% protection from symptomatic flu, respectively, for about six months after injection, according to the data, which have been submitted to the US Food and Drug Administration (FDA).
The trial involved 5 071 healthy, unvaccinated adults 18 to 64 assessed at 57 American sites and one British site. They received a single shot of the experimental small-molecule neuraminidase inhibitor, called CD388, at the beginning of the flu season – from September to December 2024 – and were evaluated for clinically confirmed and lab-confirmed influenza for 24 weeks.
The results have not yet been published in a peer-reviewed journal.
The researchers found that 2.8% of the placebo group contracted influenza within the study timeframe. But those receiving the drug had lower rates.
Highest dose provided 76% protection
The drug’s prevention efficacy (PE) was 76.1% in the 450-mg group, 61.3% in the 300mg group, and 57.7% in the 150-mg group. All results for the 4 726 participants assessed for the primary end point were statistically significant.
According to the US Centres for Disease Control and Prevention data, the effectiveness of flu vaccines in the past 15 flu seasons has ranged from 19% to 60%.
CD388 also met all secondary end points, including efficacy at body temperatures of 37.8°C and 37.2°C thresholds, as well as statistically significant maintenance of PE for up to 28 weeks.
Safety data were similar across all three dose groups and the placebo group, with no serious adverse events noted.
Cidara plans to present additional results from this NAVIGATE trial at scientific conferences this year. It is assessing the data to determine what dose or doses to assess in the next step, a phase 3 clinical trial set to begin next spring.
“We are blessed by the fact that any of the three doses are likely to be well suited for the phase 3 study,” said Jeffrey Stein, PhD, President and CEO of Cidara.
“Traditionally, in clinical trials you tend to the go with the highest dose so long as there is no safety limitation or tolerability issues. And certainly that’s the case that we have here.
“But the final dose selection will be dependent on our final analysis of the pharmacokinetics and virology data.” He said more detailed results will be available by September, and that CD388 was designed to provide once per season protection against all strains of influenza in all people, irrespective of immune status.
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