Gritstone bio, Inc. announced results from a preclinical study evaluating a self-amplifying mRNA (samRNA) vaccine candidate against SARS-CoV-2 were published in Nature Communications, in an article titled “Low-dose self-amplifying mRNA COVID-19 vaccine drives strong protective immunity in non-human primates against SARS-CoV-2 infection”. The results of the study, which were previously pre-printed in bioRxiv, show that the samRNA vaccine candidate induced broad and potent neutralizing antibodies and T cell immune responses following administration to non-human primates (NHP) at low doses, and that these immune responses were protective against SARS-CoV-2 challenge. Since the pre-publication of these data in November 2021, Gritstone disclosed initial results from a Phase 1 study of a samRNA vaccine candidate demonstrating similar outcomes against SARS-CoV-2. The company is currently evaluating samRNA vaccines for coronaviruses and other infectious diseases.

Gritstone is currently evaluating four distinct SARS-CoV-2 product candidates across three different Phase 1 clinical trials containing various Spike variants plus additional highly conserved non-Spike T cell epitope sequences (and also full-length nucleocapsid) within its CORAL program. These studies include homologous and heterologous prime-boost regimens. All three of these studies are ongoing, and data from all are expected during the second half of 2022.