Vaxart Reports Positive Preliminary Data from Phase 1b Trial of its Oral Norovirus Vaccine Candidates in Elderly Adults

Results of the trial show a robust immune response across all doses, with a dose-dependent production of IgA antibody secreting cells (ASCs), consistent with previous studies conducted in younger populations. The results also demonstrate that the vaccine candidate was well tolerated with a favorable safety profile.

These data support the continued development of Vaxart’s oral norovirus vaccine candidate in adult populations, including elderly adults, and add to the growing body of evidence supporting its clinical utility. Vaxart is conducting a Phase 2 clinical challenge study of its norovirus vaccine candidate in adult volunteers.

Norovirus is the leading cause of acute gastroenteritis that produces vomiting and diarrhea among people of all ages. The World Health Organization’s (WHO) Product Development for Vaccines Advisory Committee has identified norovirus as a priority disease for vaccine development.

The virus causes up to 21 million cases, 109,000 hospitalizations and 900 deaths annually in the US. Adults over the age of 65 years are especially vulnerable to norovirus infection, with 7.5% of this population infected annually. Norovirus also has a negative health economic impact, which has been estimated to cost $10.6 billion annually in the US alone.

“Our norovirus vaccine candidate, the only investigational norovirus vaccine formulated for oral administration, is optimized for delivery to the gastrointestinal system, which is the site at which norovirus enters the body,” said James F. Cummings, MD, Chief Medical Officer at Vaxart. “The data reported today add to a growing body of preclinical and clinical evidence demonstrating the efficacy and safety of this approach in addressing the unmet and critical need for an approved norovirus vaccine.”

Key findings from the Phase 1b study in elderly patients include:

• Robust immune response across all doses, with a dose dependent IgA ASC response
• IgA ASC responses were consistent with previous studies in younger subjects
• All solicited adverse events were mild or moderate with generally similar rates of events between the vaccine groups and placebo

Vaxart is also reporting preliminary data from a Phase 1 boosting regimen of its norovirus vaccine candidate. These data show that the candidate was able to successfully boost antibody responses, with antibody responses trending better with administration spread out over 3 months versus a shorter interval. Vaxart has previously reported that booster administration at a year post first dose was able to return antibody titers to levels similar to what was observed after the first dose.

“The results reported today support the potential of our Norovirus vaccine candidate in key patient populations and in a variety of boosting schedules,” said Andrei Floroiu, Vaxart’s Chief Executive Officer. “We are making progress in our Phase 2 trial, which is designed to provide additional evidence validating the safety and efficacy of our norovirus vaccine candidate. The data we have generated across our clinical program increases our confidence that our norovirus vaccine candidate may demonstrate first- and best-in-class potential.”

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 immune-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.