Vaxart Announces Publication Demonstrating the Immunogenicity and Safety of its First-Generation Oral Pill Norovirus Vaccine Candidate in Elderly Adults
SOUTH SAN FRANCISCO, Calif., March 05, 2025 (GLOBE NEWSWIRE) -- Vaxart, Inc. (NASDAQ:VXRT) today announced that complete data from the Phase 1b trial of its first-generation oral pill norovirus vaccine candidate in elderly adults (55-80 years) (NCT04854746) have been published in Science Translational Medicine. The data, which show strong and durable antibody responses and induction of norovirus-specific antibody and T cell responses, support immunogenicity of the vaccine candidate in a patient population that often has age-related reductions in immune responses to injected vaccines.1,2 Norovirus is a highly contagious virus that causes acute gastroenteritis (AGE) and can lead to substantial morbidity in older adults.3
"A key finding of this study evaluating our first-generation oral pill norovirus vaccine candidate in elderly individuals was that the antibody and serum responses observed in these participants were robust and durable, and a cross-study analysis suggested that the observed antibody and cellular responses were independent of age. These findings are encouraging given that older adults have an increased risk of norovirus-related morbidity and may have less robust immune responses following vaccination compared with younger individuals," said James F. Cummings, MD, Chief Medical Officer at Vaxart. "Another key result was that an orally-administered vaccine can generate potent antibody responses in mucosal tissues outside the gastrointestinal tract, which could have important implications for use of our vaccine platform for norovirus and other indications as well."
The Phase 1b study evaluated the safety and immunogenicity of Vaxart's oral norovirus vaccine candidate in two groups of healthy older adults aged 55-65 and 66-80 years old. The vaccine was administered orally at three dose levels by prime and boost, 28 days apart. Participants were randomized to receive vaccine or placebo at a 2:1 ratio, and 63 volunteers completed the study, which included safety and immunogenicity assessments through day 390.
Key findings from the study include:
- The vaccine candidate generated robust and durable serum antibody responses, with all three dose cohorts demonstrating statistically significant increases in serum anti-VP1 IgA compared to the placebo cohort on day 29 and day 57. No statistically significant differences were found between the two age groups within each dosing cohort.
- Dose-dependent increases in vaccine-induced responses were also observed for serum anti-VP1 IgG in all vaccinated cohorts on day 29 and day 57 compared to pre-vaccination levels.
- The vaccine induced VP1-specific IgA mucosal-homing antibody-secreting B cells and this response was independent of age.
- The high-dose vaccine induced mucosal-homing T cells, which may contribute to protection against persistent infections.
- Oral administration of the vaccine stimulated strong and durable IgA responses in saliva and the nasal cavity.
- Overall, the vaccine was safe and well tolerated in older adults. All solicited events were mild to moderate, with no grade 3 events related to the vaccine. Headache (14%) and malaise/fatigue (16%) were the most common solicited symptoms reported in the week following vaccine administration; headache (14%) and malaise/fatigue (14%) were reported at similar rates in the placebo group.
"The results of this clinical trial suggest that our oral pill norovirus vaccine program may be uniquely positioned to protect elderly individuals from adverse norovirus infection outcomes," said Steven Lo, Chief Executive Officer at Vaxart. "These patients are at higher risk of severe AGE but also respond less effectively to injected vaccines. Additionally, most approved mucosal vaccines are not recommended for older individuals due to safety concerns. While early stage, the data reported today suggest that our candidate may prove to safely provide the benefits of a mucosal vaccine to patients at higher risk of adverse norovirus outcomes."
Vaxart previously reported that a Phase 2 challenge study of an oral pill norovirus vaccine candidate produced a statistically significant reduction in infection rate, a non-statistically significant reduction in norovirus AGE and a substantial reduction in viral shedding. A Phase 1 study in lactating mothers showed that the Company's vaccine candidate resulted in a 4-6-fold increase in norovirus antibodies in breast milk, which may help to protect infants through passive antibody transfer. In January 2025, Vaxart announced that the next step in its norovirus program will be a Phase 1, open label, dose ranging clinical trial evaluating its second-generation oral norovirus vaccine constructs head-to-head against its first-generation constructs. This trial is expected to initiate in the first half of 2025.
References
1. A. Ciabattini, C. Nardini, F. Santoro, P. Garagnani, C. Franceschi, D. Medaglini, Vaccination in the elderly: The challenge of immune changes with aging. Semin Immunol 40, 83-94 (2018).
2. A. Pera, C. Campos, N. López, F. Hassouneh, C. Alonso, R. Tarazona, R. Solana, Immunosenescence: Implications for response to infection and vaccination in older people. Maturitas 82, 50-55 (2015).
3. A. J. Hall, R. I. Glass, U. D. Parashar, New insights into the global burden of noroviruses and opportunities for prevention. Expert Rev Vaccines 15, 949-951 (2016).
About Vaxart
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 pills that can be stored and shipped without refrigeration and eliminate the risk of needle-stick injury. Vaxart believes that its proprietary pill 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 pill vaccines designed to protect against coronavirus, norovirus and influenza, 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.
Note Regarding Forward-Looking Statements
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Contact
Vaxart Media and Investor Relations:
Matt Steinberg
FINN Partners
[email protected]
(646) 871-8481
