Gritstone bio Announces Publication of Interim Results from Phase 1 Study of Self-amplifying mRNA (samRNA) Vaccine Against COVID-19 in Nature Communications
-- Potent and durable immunogenicity achieved with low dose self-amplifying mRNA vaccine (samRNA) candidate --
-- Immunity boosted for at least 6 months in previously vaccinated-older adults (administration post-primary series of Vaxzevria®, Comirnaty® or Spikevax®) --
-- Data underscore the potential of Gritstone’s samRNA candidates to serve as next-generation vaccines against COVID-19 and other infectious diseases --
“Publication of these results in
The publication details interim analyses from a Phase 1 dose-escalation trial evaluating Gritstone's samRNA candidate (GRT-R910) in previously vaccinated healthy older adults (CORAL-BOOST/NCT05148962). Results demonstrate a favorable safety and tolerability profile in this vulnerable population. Most adverse events (AEs) following dosing were mild to moderate and transient with no treatment-related serious AEs observed. With respect to immunogenicity, neutralizing antibody titers against ancestral Spike and variants of concern were boosted by the samRNA candidate, and contrasting to authorized vaccines, persisted through at least 6 months following the booster dose. Furthermore, Gritstone's samRNA increased and potentially broadened functional Spike-specific T cell responses and primed T cell responses to conserved non-Spike epitopes.
“The ability of a next-generation vaccine candidate to drive more potent, durable, and broad neutralizing antibodies and T cell responses against variants of concern not included in the vaccine is key to delivering long-term variant-proof protection,” said
About Self-amplifying mRNA (samRNA)
Gritstone’s samRNA vector is based on a synthetic RNA molecule derived from a wild-type Venezuelan Equine Encephalitis Virus (VEEV) replicon with the goal of extending the duration and magnitude of immunogen expression to drive potent and durable immune responses. The samRNA is delivered in a lipid nanoparticle (LNP) formulation. Like traditional mRNA vaccines, samRNA vaccines use the host cell’s transcription system to produce target antigens to stimulate adaptive immunity. Unlike traditional mRNA, samRNA has an inherent ability to replicate by creating copies of the original strand of RNA once it is in the cell. Potential benefits of samRNA may include extended duration and magnitude of antigen expression, strong and durable induction of neutralizing antibody and T cell immunity (CD4+ and CD8+), dose sparing, and a refrigerator stable product.
About the CORAL Program
Gritstone’s CORAL program is applying Gritstone’s infectious disease approach, which aims to drive both B cell and T cell immunity using self-amplifying mRNA (samRNA), against SARS-CoV-2. CORAL currently includes three ongoing Phase 1 trials: CORAL-BOOST, which is evaluating one construct in a boost setting (following primary series of currently-approved COVID-19 vaccines); CORAL-CEPI, which is evaluating multiple constructs in virus-naïve, convalescent, and HIV+ subjects in
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