Benzinga | Sep 20, 2021 07:03AM EDT

Gritstone Announces Dosing Of First Volunteer In Trial Evaluating Self-Amplifying mRNA As A COVID-19 Vaccine Booster And Immunogenicity Enhancer

Gritstone bio, Inc. (NASDAQ:GRTS), a clinical-stage biotechnology company developing next generation cancer and infectious disease immunotherapies, today announced that the first volunteer has been dosed in a Phase 1 trial evaluating the ability of GRT-R910, a self-amplifying mRNA (SAM) second generation SARS-CoV-2 vaccine to boost and expand the immunogenicity of first-generation COVID-19 vaccines in subjects 60 years of age or older. This single-center study is being conducted in collaboration with The University of Manchester and Manchester University NHS Foundation Trust in the United Kingdom.

GRT-R910 is part of Gritstone's CORAL program, a second-generation COVID-19 vaccine platform that uses a SAM vector formulated with lipid nanoparticles to deliver a broad set of antigens against SARS-CoV-2 that includes both stabilized spike protein and highly conserved viral protein regions containing T cell epitopes. By virtue of self-amplification, extended duration and magnitude of antigen production with SAM vaccines may offer the opportunity of lowering vaccine doses or eliminate the need for repeat administrations, and has potential to safely elicit strong, durable and broad immune responses across SARS-CoV-2 variants.

"Our SAM COVID vaccine is designed to drive robust CD8+ T cell responses, in addition to strong neutralizing antibody responses, offering the promise of longer lasting immunity, especially in more vulnerable populations," said Andrew Allen, M.D., Ph.D., co-founder, president and chief executive officer of Gritstone. "Additionally, since viral surface proteins like the spike protein are evolving and sometimes partially evading vaccine-induced immunity, we designed GRT-R910 to have broad therapeutic potential against a wide array of SARS-CoV-2 variants by also delivering highly conserved viral proteins that may be less prone to antigenic drift."

Professor Andrew Ustianowski, who is Clinical Lead for the NIHR COVID Vaccine Research Programme, Consultant in Infectious Diseases and Tropical Medicine at North Manchester General Hospital (part of MFT) and Honorary Clinical Chair at The University of Manchester, will be the local lead investigator for this study. Professor Ustianowski is Chief Investigator for the study and MFT is the chief site.

He added, "The observed waning of vaccine-elicited immune responses, particularly in older individuals, coupled with the prevalence of emerging variants, highlights the need for continued vigilance to keep COVID-19 at bay. Using GRT-R910 as a boost vaccination is expected to elicit strong, durable, and broad immune responses, which are likely critical to maintaining protection in this vulnerable elderly population with increased mortality risk. We look forward to working with Gritstone in the clinical development of this promising next generation COVID vaccine."

Professor Ian Bruce, from The University of Manchester, is Chair of the Manchester COVID-19 Research Rapid Response Group (RRRG), Consultant Rheumatologist at Manchester Royal Infirmary's Kellgren Centre, and Director of the NIHR Manchester Biomedical Research Centre. He commented: "We're tremendously excited that this promising vaccine is to be trialed here in Manchester. As the only European site for this study, it is testament to the way our academic and clinical researchers have come together as part of the 'One Manchester R&I' approach to answer the questions the world needs answers to. Though the vaccine is being evaluated in the over 60s, future studies will also examine its efficacy in other-vulnerable populations. If successful, we feel it has the potential to play a significant role in the battle against COVID-19, which has so devastated vulnerable populations across the globe. We look forward to working with Gritstone in the clinical development of this promising next generation COVID-19 vaccine."

The Gritstone sponsored Phase 1 trial, which is initially expected to enroll 20 volunteers, will explore the ability of GRT-R910 to boost and expand the immunogenicity of AstraZeneca's first-generation COVID-19 vaccine AZD1222 (Vaxzevria) in healthy adults ? 60 years. This open-label dose-escalation design study will examine dose, safety, tolerability, and immunogenicity of GRT-R910 at two dose levels at least 4 months after the second administration of their initial vaccine. GRT-R910 is also being investigated as part of a National Institutes of Health sponsored Phase 1 study in the United States. Additional trials of the CORAL platform, including an additional Phase 1 trial in collaboration with the Coalition for Epidemic Preparedness Innovations (CEPI) are planned. Data from these studies will inform the future development of CORAL, Gritstone's SARS-COV-2 second generation vaccine program.