Vaxart to present new data from Phase 2 Challenge Study of H1 influenza oral tablet vaccine

Reviewed by Alina Shrourou, B.Sc. (Editor)Oct 4 2018

Vaxart, Inc., a clinical-stage biotechnology company developing oral recombinant vaccines that are administered by tablet rather than by injection, announced it will present new data from the Phase 2 Challenge Study of its H1 influenza oral tablet vaccine at IDWeek 2018 in San Francisco on Saturday, October 6, 2018.

"These latest results show that our vaccine elicited a significant expansion of mucosal homing receptor α4β7⁺ (β7⁺) plasmablasts to approximately 60% of all activated B cells, while Fluzone only maintained baseline levels of 20%. We believe these β7⁺ plasmablasts are a key indicator of a protective mucosal immune response and a unique feature of our oral recombinant vaccines," said Sean Tucker Ph.D., chief scientific officer of Vaxart. "Further analysis of the data also confirm that, while our vaccine also generated protective hemagglutinin inhibition (HAI) antibodies in serum like conventional injectable flu vaccines, it primarily protected through the mucosal mechanism, providing a robust 39% reduction in illness versus placebo overall. In contrast, Fluzone, the market-leading injectable quadrivalent influenza vaccine, only provided a 27% reduction in illness versus placebo, while protecting primarily through HAI antibodies."

Vaxart previously reported only 37% of study participants receiving the Vaxart vaccine developed influenza infection after challenge, compared to 44% of those receiving Fluzone and 71% of those receiving placebo. The new Phase 2 data to be presented at IDWeek 2018 showed that the Vaxart vaccine generated a strong increase in mucosal homing antibody secreting cells, or β7⁺ plasmablasts. In protected study participants, the percentage of β7⁺ plasmablasts in recipients of the Vaxart vaccine nearly doubled, whereas the percentage of β7⁺ plasmablasts in Fluzone recipients remained unchanged.

"In all our studies to date, we have seen both systemic and mucosal immune responses, and this latest data provides solid evidence that our vaccines indeed protect through mucosal immunity, the first line of defense against mucosal infections," said Wouter Latour, M.D., chief executive officer of Vaxart. "We believe this clearly differentiates our oral vaccines from conventional injectable vaccines, and strongly suggests that vaccines based on Vaxart's proprietary vector adjuvant system could be optimal to protect against mucosal pathogens, including some of the major public health threats such as flu, norovirus, RSV and many others."

The Phase 2 study was completed with support from Biomedical Advanced Research and Development Authority (BARDA). Vaxart received a $13.9 million contract from BARDA in September 2015 to support the advanced development of more effective influenza vaccines to ultimately improve seasonal and pandemic influenza preparedness. The contract was increased to $15.7 million in 2017.

The project has been funded in whole or in part with federal funds from the Department of Health and Human Services' Office of the Assistant Secretary for Preparedness and Response; Biomedical Advanced Research and Development Authority under Contract No. HHSO100201500034C.