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Vaxart Announces Positive Preliminary Data from Phase 1 Clinical Trial Evaluating Its Oral COVID-19 Tablet Vaccine Candidate

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February 3, 2021 at 8:30 AM ESTPDF Version

  • Study reached primary and secondary endpoints of safety and immunogenicity, respectively
  • VXA-CoV2-1 induced potent CD8T-cell responses
  • VXA-CoV2-1 potentially protective against new and emerging COVID-19 strains
  • Data to be presented today at the New York Academy of Sciences Symposium “The Quest for a COVID-19 Vaccine”

SOUTH SAN FRANCISCO, Calif., Feb. 03, 2021 (GLOBE NEWSWIRE) — Vaxart, Inc., (NASDAQ: VXRT), a clinical-stage biotechnology company developing oral vaccines administered by tablet, today announced preliminary data from its Phase 1 study of VXA-CoV2-1 showing that its oral COVID-19 tablet vaccine candidate was generally well-tolerated, and immunogenic as measured by multiple markers of immune response to SARS-CoV-2 antigens.

“Our Phase I results highlight the importance of our differentiated vaccine design, as they suggest VXA-CoV2-1 could have broad activity against existing and future coronavirus strains. These results are timely, as we are seeing the emergence of new variants less responsive to first generation vaccines, thus making potential cross-reactivity another important advantage of next-generation vaccines,” said Andrei Floroiu, Vaxart’s Chief Executive Officer.

Vaxart’s scientists recognized early the risk of variants of SARS-CoV-2 emerging and they designed a vaccine with the potential to be protective not only against the prevalent strain, but also against emerging mutations of the Spike (S) protein, by including both the S and N proteins. Virtually all other COVID-19 vaccines include just the S protein.

“These results, together with recent data from our peers, further raise our confidence in the success of VXA-CoV2-1 and the broad potential of our platform,” continued Floroiu.

“We previously showed that our oral tablet vaccine technology worked to protect against flu – another airborne virus – as well as the leading injectable, but through a different mechanism, in a Phase II trial sponsored by BARDA. With COVID-19, we have now seen that many vaccine approaches— mRNA, protein, and viral vector, including three adenovirus vaccines – are protective, and that all available positive COVID-19 hamster challenge studies such as ours have translated into protection against COVID-19 in human trials,” Floroiu said.

“These clinical data further differentiate our COVID-19 vaccine and enable us to meaningfully advance discussions with healthcare officials in the U.S. and around the world about how Vaxart may be able to help them fight back against COVID-19 with a transformative solution – a room-temperature stable oral vaccine that is not only easier to distribute and administer, but may also be more broadly protective,” Floroiu added.

Sean Tucker, Ph.D., Vaxart’s Chief Scientific Officer, will present the Phase 1 data as part of a clinical trial update at the New York Academy of Sciences Symposium “The Quest for a COVID-19 Vaccine” today at 1:15 p.m. ET. Register here to attend the symposium.

Preliminary Phase 1 trial results from a pooled analysis of all cohorts include:

VXA-CoV2-1 was generally well-tolerated:

  • No severe adverse events were reported
  • Adverse events were generally mild and primarily gastrointestinal in nature
  • Including this study, a total of 495 subjects have now been dosed with our platform, with no serious adverse events reported

VXA-CoV2-1 triggered multiple immune responses against SARS-CoV-2 antigens, including:

  • CD8+ cytotoxic T-cell response to the viral Spike (S) protein, necessary for long-lasting cross-reactive immunity, higher than we have seen in any previous Vaxart clinical trial
  • An increase in plasmablast cell number and an upregulation of the mucosal homing receptor, indicating activation of B cells that will home to the mucosa
  • An increase in proinflammatory Th1 cytokines, responsible for orchestrating the immune response to viral infection
  • IgA responses in serum and/or nasal swab samples in 100% of 2 dose subjects; neutralizing antibodies were not detected in serum and IgG responses were not detected in most subjects

“Viral variants with altered S proteins are becoming established in the population before the majority of people can be vaccinated. To end the pandemic, the world needs a vaccine that can provide long-lasting protection from emerging strains,” Dr. Tucker said.

“T-cells can provide long-lasting cross-reactive protection against current and emerging strains of the virus. Our vaccine induced a high percentage of responding CD8+ T cells against both Spike (S) and Nucleoprotein (N) proteins, which may provide protection against variants with alterations in the faster-changing S protein. We expect that our vaccine will be less impacted by new variants than injectable vaccines,” Dr. Tucker added.

Vaxart expects to broaden its COVID-19 vaccine development plans, with efforts that could include:

  • VXA-CoV2-1 in COVID-19 naïve subjects: Phase II studies to evaluate optimal dosing schedule, and to then assess efficacy against COVID-19
  • VXA-CoV2-1 in previously vaccinated or exposed subjects: investigating single dose boosting protocol to broaden and strengthen immune responses

Clinical Trial design

The Phase I study (NCT04563702) was designed to evaluate the safety and immunogenicity of VXA-CoV2-1 vaccine with multiple dosing schedules. Subjects were divided into three cohorts. The first cohort (5 subjects) received two low doses of vaccine 29 days apart. The remaining cohorts (15 subjects each) received a single low or high dose of the vaccine. Safety and tolerability were monitored following vaccination as well as signs of immunogenicity, including general and SARs-CoV-2 specific immune responses.

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