Vaxart Announces Topline Data from the Phase 2 Challenge Study of its Monovalent Norovirus Vaccine Candidate
Study met 5 of 6 primary endpoints
Vaccine was safe and well tolerated with no vaccine-related serious adverse events (SAEs)
Vaccination led to a statistically significant reduction in infection rate, a non-statistically significant reduction in norovirus acute gastroenteritis (AGE), and a substantial reduction in viral shedding
Conference call today at
The Phase 2 challenge study enrolled 165 healthy adults, who were randomized 1:1 to receive Vaxart’s monovalent oral tablet vaccine targeting the norovirus GI.1 genotype or placebo. Four weeks after vaccination, subjects were challenged with GI.1 norovirus. The study achieved its primary endpoints of a statistically significant 29% reduction in the rate of norovirus infection between the vaccinated and placebo arms through Day 8 post challenge, a strong induction of norovirus-specific immunoglobulin A (IgA) and immunoglobulin G (IgG) antibodies, and other immune response endpoints. Vaccination also led to a reduction in norovirus AGE in the vaccine arm compared to placebo, but this was not statistically significant. In a prespecified analysis, the study also showed an 85% decrease in viral shedding in the vaccine arm compared with placebo.
“Challenge studies use higher quantities of virus than an individual may encounter during a naturally occurring infection, yet our vaccine candidate demonstrated a significant effect on infection and viral shedding, even though it did not achieve a statistically significant reduction in norovirus AGE,” said Dr.
Key Study Findings:
- Primary Endpoints:
- 29% reduction in the rate of infection in the vaccinated cohort compared with placebo (82% vs. 58%) (p=0.003)
- 21% reduction in the rate of norovirus AGE in the vaccinated cohort compared with placebo (45% vs. 57%) that was not statistically significant (p=0.149)
- Significant increase in the induction of norovirus-specific IgA antibody-secreting cells (ASC) in the vaccinated cohort, with a 79% response rate in the vaccinated cohort, compared with 2.5% in the placebo cohort (p<0.001) on Day 8 post-vaccination; mean response was 375 ASC per million cells for the vaccinated cohort, compared with 26 ASC per million cells for placebo
- Significant increase in the induction of HBGA blocking anti-bodies in the vaccinated cohort (GMFR 3.23) compared with the placebo cohort (GMFR 1.0) on Day 29 post-vaccination (p<0.001)
- Significant increases in norovirus-specific serum IgA (GMFR 7.14) and IgG (GMFR 4.64) in the vaccinated cohort compared with placebo from baseline to Day 29 post-vaccination (p<0.001)
- No vaccine-related SAEs or dose-limiting toxicities were reported, consistent with the safety profile observed in all of Vaxart’s norovirus trials
- Pre-specified Analysis:
- 85% decrease in viral shedding in the vaccinated cohort compared with placebo
- No statistically significant difference in disease severity in the vaccinated cohort compared with placebo
“The results of this study highlight the potentially distinctive profile of mucosal vaccination and the potential that our oral pill vaccines may have in protecting against infection and blocking transmission – potential benefits that have also been seen with our influenza vaccine. We are excited to further our understanding of these data and determine the optimal path forward for our norovirus program,” added
Norovirus is the leading cause of acute viral gastroenteritis in all age groups in the
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Conference ID: 13740946
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Source: Vaxart, Inc.