Vaxart Announces Positive Preliminary Topline Data from Dose-Ranging Phase 2 Study of its Bivalent Norovirus Vaccine Candidate

Met all primary endpoints: Vaccine was well-tolerated with robust immunogenicity

Continue to expect topline data from Phase 2 GI.1 challenge study in Q3 2023

SOUTH SAN FRANCISCO, Calif., July 06, 2023 (GLOBE NEWSWIRE) -- Vaxart, Inc. (Nasdaq: VXRT) today announced positive topline data from the dose-ranging Phase 2 clinical trial of its oral pill bivalent norovirus vaccine candidate.

Preliminary results of the trial (NCT05626803) showed robust serum immune responses across all doses at Day 29 relative to Day 1. Both doses showed a similar increase in serum antibody responses with no statistical difference between the medium and high dose arms. At Day 29, increases in serum IgA, IgG, and BT50, for both the GII.4 and GI.1 strains in the vaccine arms, were similar to those seen in previous norovirus studies conducted by Vaxart. Mucosal and cell-based assay data will be available at a later date.

Mean Fold Rise Summary (Day 1 to Day 29) Preliminary Data

	G1.1			GII.4
Serum antibodies	IgA	IgG	BT50	IgA	IgG	BT50
Medium Dose (n=50)	5.9	4.8	3.0	9.3	6.1	4.3
High Dose (n=59)	6.4	4.2	2.3	8.6	5.1	7.8
Placebo (n=25)	1.0	1.0	1.1	1.1*	1.0	1.0*
*excluding subject with confirmed gastroenteritis.

Results from this Phase 2 dose-ranging study also demonstrated that the bivalent norovirus vaccine candidate was well tolerated, with a favorable safety profile that included no vaccine-related serious adverse events (SAEs) and no dose limiting toxicity. Adverse event rates for both doses were similar to placebo.

“Topline data reported today further validate the potential of our norovirus vaccine candidate and, more broadly, our oral vaccine platform,” said Dr. James F. Cummings, Vaxart’s Chief Medical Officer. “These data, additional forthcoming data from this study, and the data we expect from our norovirus challenge study will help inform our selection of dosage levels in a larger Phase 2b study and support an End-of-Phase 2 meeting with the U.S. Food and Drug Administration.