Omicron Minimally Impacts SARS-CoV-2 T Cell Epitopes Within Gritstone Bio Inc.’s (NASDAQ: GRTS) mRNA Vaccine

Gritstone Bio Inc. (NASDAQ: GRTS) has announced that the SARS-CoV-2 T Cell epitopes given within the company’s self-amplifying mRNA COVID vaccines experience minimal impact by omicron variant’s mutations enhancing the platform’s potential on variants of concern.

Omicron designated a variant of concern 

The World Health Organization (WHO) categorized the recently disclosed Omicron variation as a Variant of Concern (VOC) on November 26, 2021, after it was originally discovered in South Africa on November 9, 2021. Early evidence suggests that Omicron has a higher re-infection risk, and sequence analysis has shown many mutations in Spike, including both the receptor-binding domain (RBD) and the N terminal domain (NTD), which could reduce the clinical efficacy of existing vaccines and/or therapeutic antibodies.

CEO Andrew Allen said, “Our value proposition in immunotherapy has always centered around two core pillars – cutting-edge TCE identification and delivering potent vaccines that can elicit strong, broad, and durable immune responses. Strong neutralizing antibody responses to Spike-based vaccines have been shown to be highly protective against COVID-19. However, the possibility of substantial viral resistance arising from Spike mutations has always been present, and Omicron may represent the embodiment of this threat.”

Omicron has minimal impact on the company’s TCEs

According to sequence analysis, Omicron has a minor impact on Gritstone’s TCEs. Only three (2%) of the 146 non-Spike TCE given in Gritstone’s vaccine now in clinical studies in the US and UK are affected by Omicron. Omicron had a similar low influence on two new TCE vaccine designs that are slated to enter clinical trials in South Africa before the end of the year.

“While engineering an Omicron form of Spike is achievable, it is clearly ideal to both address novel Spike variants and also reduce the likelihood of further variants arising, by delivering a coordinated immune attack against both Spike and other more conserved SARS-CoV-2 genes. This is the path Gritstone has followed to date. With our trial in South Africa scheduled to begin imminently and initial clinical data from our UK trial expected in early 2022, we look forward to unlocking the immense potential of this platform,” concluded Allen.