A phase 3 trial of Valneva’s chikungunya vaccine candidate has induced protection in 98.5% of participants, exceeding the level needed for the FDA to accept an application for review and cementing the biotech’s lead over Merck in the race to develop a product to prevent the viral disease.
Valneva went into the clinical trial aiming to show a single dose of the vaccine, VLA1553, induced protection in at least 70% of participants, a threshold set with the FDA. Of the 268 subjects tested, 264 had protective neutralizing antibody titers against the virus 28 days after receiving the vaccine, resulting in a protection rate of 98.5%. The rates were similar in elderly and younger participants.
The safety analysis included 3,082 subjects. Valneva said 1.6% of subjects reported severe adverse events, typically fever. Around half of the participants experienced milder adverse events, with more than 20% of subjects suffering headache, fatigue and muscle pain.
Valneva is now on course to be the first company to win FDA approval for a chikungunya vaccine. Merck, which entered the race through the $366 million takeover of Themis, recently completed a phase 2 trial of its chikungunya vaccine candidate. The study was suspended “due to a clinical stock recovery action” from December 2020 to the completion date in June—never hitting its original enrollment goal.
RELATED: COVID player and Pfizer-partnered Valneva eyes $100M Nasdaq IPO
Emergent BioSolutions is also in the race. In May, Emergent shared two-year persistence data from a phase 2 clinical trial of its vaccine candidate. Emergent plans to start a phase 3 study this year, putting it on the heels of Valneva but likely too far back to beat VLA1553 to market.
The chikungunya race is about more than just first-mover advantage. The FDA is expected to grant a priority review voucher to the first company to win approval for a chikungunya vaccine under a push to incentivize tropical disease R&D. Priority review vouchers now sell for around $100 million.
Once on the market, Valneva sees reasons to think VLA1553 will fare well even if competition arrives from Merck and Emergent. In IPO paperwork filed earlier this year, Valneva said both rival vaccines “face limitations relative to VLA1553,” notably because they “are likely to require multiple shots to reach necessary effectiveness.”