Vaxart Inc. (NASDAQ: VXRT) has received US FDA clearance for its Investigational New Drug application for its S-only oral COVID-19 vaccine candidate. The vaccine candidate showing S-only protein triggered higher serum antibodies than a construct showing S and N in the NHP study.
Vaxart to explore several S-only constructs in trials
CEO Andrei Floroiu said, “This is great news because it allows us to move forward with our first S-only vaccine construct. As we said at the end of the first quarter, we will explore multiple S-only constructs in clinical trials alongside the S+N construct that has already completed its Phase I trial. Together, the S-only and S+N constructs are part of our unique oral tablet COVID-19 vaccine candidate portfolio, which we believe could make a significant contribution to the fight against COVID-19 globally.”
Vaxart reported in February that its oral S+N SARS-CoV-2 vaccine had completed a Phase 1 clinical trial. The investigational oral vaccination elicited numerous immune responses against COVID-19 antigens while meeting primary and secondary endpoints of immunogenicity and safety, respectively, according to the findings of that trial. As a result, the company plans to commence a Phase II clinical trial of the S-only construct in the second half of 2021.
S-only vaccine produced more antibodies
The company’s Chief Scientific Officer said, “Preliminary data from our current Non-Human Primate study indicates that the S-only vaccine produced much higher serum antibodies than the one expressing both S and N proteins. Our Phase I results from the S+N vaccine candidate showed remarkable T-cell responses and a mucosal antibody response, but not as strong serum antibody responses. This new clinical trial will allow us to compare the S-only and S+N vaccine candidates and put us in a position to decide which approach offers the best way forward for our COVID-19 vaccine development program, particularly in the face of emerging variant strains.”