SOUTH SAN FRANCISCO, Calif., July 29, 2021 /PRNewswire/ -- Vaxart, Inc. (Nasdaq: VXRT) today announced that it has shown for the first time in clinical trials that its oral tablet vaccine platform successfully boosted immune responses in subjects previously vaccinated with a Vaxart oral vaccine more than a year earlier.
Vaxart is a clinical-stage biotechnology company developing oral vaccines that are administered by tablet rather than by injection. Vaxart's programs are based on its proprietary oral vaccine platform called VAAST.
"These results are very important because they support our belief that our oral tablet vaccines have the potential to be used repeatedly for indications that may require an annual boost, such as flu, COVID-19, or norovirus," said Andrei Floroiu, Vaxart's Chief Executive Officer. "We are excited by these findings and by the implications for all of our vaccines."
"Using our oral norovirus vaccine candidate, we successfully boosted the immune responses of those previously vaccinated with our platform," said Dr. Sean Tucker, Vaxart's founder and Chief Scientific Officer. "We believe these results could have implications for the other vaccines we are developing, including our oral COVID-19 vaccine tablet, because they are all based on the same platform and use the same vector.
"Moreover," Dr. Tucker said, "this clinical evidence has the potential to differentiate our vaccines from injectable vector-based vaccines. Typically, when you inject viral vector-based vaccines, they generate immune responses against the against the viral vector as well as the intended antigens.
"Anti-vector antibodies from the injected vaccine immune response may prevent the viral vector from serving as a boosting agent. Our norovirus trial results suggest that Vaxart's vaccines may not be hampered by certain antibody response challenges that can occur with injectable viral vector-based vaccines."
The data came from Vaxart's 12-subject Phase 1b blinded study evaluating the ability of its norovirus vaccine to boost immunogenicity. Study participants were initially vaccinated with Vaxart's oral norovirus vaccine in late 2019 and were vaccinated again between February and April 2021.
All seven participants who had been previously immunized with the oral norovirus vaccine elicited a similar broad range of immune responses to norovirus as the five subjects that had not received a prior oral vaccine dose.
"We will continue to evaluate the capability of our norovirus and COVID-19 vaccine candidates to be used repeatedly as boosters to extend protection in those previously vaccinated with Vaxart candidate vaccines."
Key metrics identified in the boosting study were as follows:
- Serum antibody blocking titer 50, a surrogate neutralizing antibody measurement, increased in both previously vaccinated and unvaccinated subjects by similar amounts.
- Antibody secreting B cell (ASC) responses to norovirus VP1 measured seven days post-boost were no different than those in subjects receiving the vaccine for the first time.
- Serum IgG and IgA antibody responses were significantly elevated 29 days post-boost immunization, with no difference in titer between subjects that had received a prior oral norovirus vaccine and those who had not previously been vaccinated.
Vaxart is a clinical-stage biotechnology company developing a range of oral recombinant vaccines based on its proprietary delivery platform. Vaxart vaccines are designed to be administered using tablets that can be stored and shipped without refrigeration and eliminate the risk of needle-stick injury. Vaxart believes that its proprietary tablet vaccine delivery platform is suitable to deliver recombinant vaccines, positioning the company to develop oral versions of currently marketed vaccines and to design recombinant vaccines for new indications. Vaxart's development programs currently include tablet vaccines designed to protect against coronavirus, norovirus, seasonal influenza, and respiratory syncytial virus (RSV), as well as a therapeutic vaccine for human papillomavirus (HPV), Vaxart's first immuno-oncology indication. Vaxart has filed broad domestic and international patent applications covering its proprietary technology and creations for oral vaccination using adenovirus and TLR3 agonists.
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SOURCE Vaxart, Inc.