Vaxart Announces Positive Safety and Immunogenicity Results for Its Oral Norovirus Vaccine in a Phase 1b Clinical Study
- Category: Vaccines
- Published on Monday, 30 October 2017 18:42
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First Oral Tablet Norovirus Vaccine Progresses to Phase 2 Challenge Study
SOUTH SAN FRANCISCO, CA, USA I October 30, 2017 I Vaxart, Inc., a clinical-stage biotechnology company developing a range of oral recombinant vaccines that are administered by tablet rather than by injection, announced today that its norovirus tablet vaccine (VXA-G1.1-NN) generated broad systemic and intestinal immune responses, and was well-tolerated in a clinical phase 1b dose optimization study. Norovirus is the most common cause of acute gastroenteritis, an intestinal infection affecting 19 to 21 million people in the United States each year.
“Unlike vaccines delivered by injection, our oral tablet vaccine is delivered directly to the intestine, creating both a local response that serves as an effective first line of defense and a systemic response that offers an extra layer of protection,” said Sean Tucker, Ph.D., chief scientific officer of Vaxart. “This paired immune response is a fundamental feature of our oral vaccine that could provide an important advantage over injectable vaccines.”
In the study, Vaxart evaluated four different dosing regimens of the norovirus tablet vaccine in adults. Across all groups, 60 to 100 percent of adults had a positive immune response depending on the dosing schedule. In the high dose group, 100 percent of adults responded as measured by a significant increase in IgA and IgG antibody secreting cells. In the same group, there was at least a two-fold increase of norovirus blocking antibody titers (BT50) in serum in more than 90 percent of adults 28 days after dosing.
The norovirus tablet vaccine was generally well tolerated in all subjects. Adverse events (AEs) were mostly mild in severity with headache as the most frequent AE. No serious adverse events were reported. Based on these results, Vaxart is planning to initiate a Phase 2 norovirus challenge study in 2018.
“While norovirus causes frequent outbreaks, there are currently no norovirus vaccines approved for use in the United States,” said Wouter Latour, M.D., M.B.A., chief executive officer of Vaxart. “Our norovirus tablet vaccine candidate has the potential to protect vulnerable groups such as the elderly and the very young from norovirus infection, and could provide an important option for workers in the healthcare, food and travel industries. In addition, efficient distribution and administration of our convenient room temperature-stable tablet vaccine would greatly simplify vaccination campaigns in any setting.”
About the Study Design
The open label Phase 1b dose-ranging study assessed the safety and immunogenicity of VXA-G1.1-NN tablet vaccine in 60 healthy adult volunteers. Cohort 1 received two low doses delivered orally on days 1 and 8; cohort 2 received three low doses delivered on days 1, 3 and 5; cohort 3 received two low doses delivered on days 1 and 29, and cohort 4 received two high doses delivered on days 1 and 29. The primary endpoints were safety and immunogenicity as measured by blocking titer 50 (BT50), IgA and IgG antibody secreting cells, and IgA/IgG ELISA titers measured on days 28, 36 and 56.
Norovirus is recognized as the leading cause of acute gastroenteritis in the United States. It is a common intestinal infection that typically lasts three to five days and is marked by diarrhea, vomiting, abdominal cramps, nausea and sometimes fever. Symptoms can be more severe in older adults and young children and may lead to serious complications including death. Norovirus causes frequent and widespread outbreaks in the military, food industry, travel industry, child care facilities, elderly homes and healthcare facilities.
The U.S. Centers for Disease Control and Prevention (CDC) estimates that norovirus causes approximately 19 to 21 million illnesses in the United States each year, resulting in 56,000 to 71,000 hospitalizations and 570 to 800 deaths. In a recent Johns Hopkins University study, researchers estimated healthcare costs of norovirus at $4.2 billion and lost productivity costs at $56.2 billion globally.