The emerging biotech Gritstone Bio (NSDQ:GRTS) has dosed the first patient with its second-generation COVID-19 vaccine known as GRT-R910. The University of Manchester and Manchester University NHS Foundation Trust are jointly overseeing the U.K.-based Phase 1 study.
The GRT-R910 vaccine uses self-amplifying mRNA (SAM), which could optimize antigen expression at lower doses relative to conventional mRNA. The GRT-R910 vaccine targets antigens from the spike protein and highly conserved non-spike proteins on the SARS-CoV-2 virus.
Emeryville, California–based Gritstone believes the vaccine could offer a strong and durable immune response to various SARS-CoV-2 variants. It may also eliminate the need for repeat boosters, the company concluded.
The company believes that the technology will outperform the first generation of mRNA COVID-19 vaccines in those 60 and older.
“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,” explained Dr. Andrew Allen, CEO of Gritstone, in a statement. “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.”
Gritstone anticipates initial data from the Phase 1 trial to be available in the first quarter of 2022.
In an FDA advisory panel meeting last week, two physicians questioned why Pfizer was not seeking authorization of a COVID-19 vaccine booster targeting the Delta variant.
“I wonder whether or not boosters would be best if they matched the variants that are causing so many challenges now,” said Dr. James Hildreth, a temporary voting member of the Vaccines and Related Biological Products Advisory Committee (VRBPAC). “mRNA technology should make that reasonably easy to do,” Hildreth added.
Dr. Cody Meissner shared that opinion, recommending that COVID-19 boosters be seasonally adjusted as flu vaccines are.
In the meeting, Pfizer argued that it had not yet observed a variant that escapes its vaccine.
Its partner BioNTech is developing a booster vaccine that targets the Delta variant.