Speciality vaccine company Valneva has announced positive topline results from the Phase III pivotal trial of its single-shot chikungunya vaccine candidate, VLA1553.
The mosquito-borne viral disease caused by the chikungunya virus (CHIKV) is transmitted by Aedes mosquitoes. Valneva’s VLA1553 was recently awarded Breakthrough Designation status by the Food and Drug Administration (FDA).
The trial, involving 4,115 adults, aged 18 years and above, across 44 sites in the U.S., met its primary endpoint inducing protective CHIKV neutralizing antibody titers in 98.5% of participants 28 days after receiving a single shot. The seroprotection rate result of 98.5% exceeded the 70% threshold (for non-acceptance) agreed with the FDA. The seroprotective titer was agreed with the FDA to serve as a surrogate of protection that can be utilized in a potential FDA submission of VLA1553 under the accelerated approval pathway. The vaccine candidate was highly immunogenic with a GMT of approximately 3,270, confirming the immunogenicity profile seen in the Phase 1 trial.
Additionally, VLA1553 was also highly immunogenic in elderly study participants, who achieved equally high seroprotection rates and neutralizing antibody titers as younger adults, as well as an equally good safety profile.
VLA1553 was generally well tolerated among the 3,082 subjects evaluated for safety. The majority of solicited adverse events were mild or moderate and resolved within three days. 1.6% of study participants reported severe solicited adverse events, most commonly fever. Approximately 50% of study participants experienced solicited systemic adverse events, most commonly headache, fatigue and myalgia (seen in more than 20% of subjects). The local tolerability profile showed that approximately 15% of participants experienced solicited local adverse events.
Juan Carlos Jaramillo, M.D, Chief Medical Officer of Valneva commented said: “We are delighted with these Phase III results confirming the compelling profile of our vaccine candidate across all age groups. These first-ever Phase III trial results for a chikungunya vaccine mean that we are a step closer to addressing this major, growing and unmet public health threat. I would like to thank everyone who participated in the trial and who continued to advance the trial during the pandemic. We will continue to work with regulators to bring VLA1553 to market as soon as possible.”