Gritstone bio Inc (NASDAQ:GRTS) shares moved downward Tuesday on word the company has shared data from the first cohort (10 µg dose) of the Phase 1 booster trial of self-amplifying mRNA (samRNA) COVID-19 vaccine.
The data demonstrated strong neutralizing antibody responses to Spike and robust CD8+ T cell responses.
A single 10 µg dose of the CORAL program's samRNA vaccine was administered to healthy adults ≥60 years (n=10) at least 22 weeks after two-dose series of AstraZeneca Plc's (NASDAQ: AZN) Vaxzevria.
CORAL's samRNA vaccine was well-tolerated and demonstrated a favorable safety profile with no grade 3/4 adverse events or unexpected reactogenicity or safety events.
The CORAL-BOOST Phase 1 study is ongoing in the United Kingdom and has now dose-escalated as planned to a 30 mg dose.
Based on the Phase 1 data, Gritstone will increase enrollment to 120 subjects and evaluate the addition of a second samRNA-Spike-TCE dose.
Immunogenicity and reactogenicity data for additional cohorts are anticipated in the coming months.
Gritstone CEO Andrew Allen said, "As we have seen with the omicron variant, viral surface proteins such as Spike are mutating at a high rate, leaving the immunity provided by Spike-dedicated vaccines vulnerable to variants containing numerous Spike mutations.
"This innovation enables inclusion of a wide array of highly conserved viral epitopes, potentially creating an immune state that may offer more robust clinical protection against current and future SARS-CoV-2 variants and be a first step toward developing a pan-coronavirus vaccine."
GRTS shares are down $1.01, or 8.3%, at $11.19 in the first hour of trade Tuesday.
