Phase III study of VLA 1553 completed and meets endpoints in chikungunya fever.- Valneva SE
Valneva SE announced the successful completion of the Phase III pivotal trial of its single-shot chikungunya vaccine candidate, VLA 1553. The positive final analysis included six-month follow-up data and confirmed the topline results reported in August 2021. Valneva now expects to commence the pre-submission process with the U.S. Food and Drug Administration (FDA) in the second quarter of 2022.
The VLA1553-301 trial, which enrolled 4,115 adults aged 18 years and above across 44 sites in the U.S., met all primary and secondary endpoints. The final analysis confirmed the very high level of seroprotection, with 98.9% of participants achieving protective levels of chikungunya virus (CHIKV) neutralizing antibodies one month after receiving a single vaccination (263 of 266 subjects from the per-protocol subgroup tested for immunogenicity, 95% CI: 96.7-99.8). The immunogenicity profile was maintained over time, with 96.3% of participants showing protective CHIKV neutralizing antibody titers six months after receiving a single vaccination (233 of 242 subjects from the per-protocol subgroup tested for immunogenicity, 95%CI: 93.1-98.3). The reported levels of seroprotection far exceeded the 70% threshold (for non-acceptance) based on a surrogate of protection agreed with the FDA under the accelerated approval pathway.
VLA1553 was also confirmed to be highly immunogenic in elderly study participants (65 years of age or older), who achieved equally high seroprotection rates and neutralizing antibody titers over time as younger adults. A dedicated antibody persistence trial (VLA1553-303) will monitor a subset of participants from study VLA1553-301 for a period of at least five years to confirm the anticipated long-term protection after a single vaccination. The six-month safety profile was also consistent with previous results across all age groups. VLA1553 was generally well tolerated among the 3,082 subjects evaluated for safety. An independent Data Safety Monitoring Board continuously monitored the study and identified no safety concerns. The majority of solicited adverse events were mild or moderate and resolved within three days. 2.0% 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.
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