Better activation of innate and adaptive immune responses was achieved with CV2CoV, resulting in faster response onset, higher titers of antibodies, and stronger memory B and T cell activation as compared to the first-generation candidate, CVnCoV, according to the partners.
Higher antibody neutralizing capacity was observed with CV2CoV across all selected variants, including the Beta, Delta and Lambda variants, they added.
The study, conducted in collaboration with Harvard Medical School, assessed primates - cynomolgus macaques - vaccinated with 12µg of either the first or second-generation vaccine candidate.
The preclinical data has not been peer reviewed yet, but has been published on the pre-print server, bioRxiv.
Extended protein expression
CV2CoV was engineered with specifically optimized non-coding regions to exhibit improved mRNA translation for increased and extended protein expression compared the first-generation mRNA backbone.
During a challenge with the original SARS-CoV-2 virus, the animals vaccinated with CV2CoV were found to be better protected based on highly effective clearance of the virus in the lungs and nasal passages, confirmed the companies.
“In this animal model, CV2CoV is shown to induce broad antibody and cellular immune responses very similar to the breadth of the immune responses observed after infection with SARS-CoV-2,” reported Dr Igor Splawski, CSO, CureVac.
He continued: “The current study shows that the immune responses and resulting protection produced by our second-generation candidate, based on our mRNA technology featuring targeted optimizations, are substantially improved in non-human primates against both, the original SARS-CoV-2 virus as well as the Beta and Delta Variants of Concern and the Lambda Variant of Interest.”
The optimized mRNA backbone that is being used in the collaborative effort between GSK and CureVac, has the potential for a multivalent or combination approach to address multiple emerging variants in one vaccine, said the partners.
Date set for clinical trials on second generation shot
A Phase 1 clinical trial on CV2CoV is expected to start in Q4 2021.
Rino Rappuoli, chief scientist and head of GSK vaccines R&D, said “The mRNA technology is a key strategic priority for us, and we are investing significantly in a number of mRNA programs focused on the collaboration with CureVac. The strong immune response and protection in pre-clinical testing of this second-generation mRNA backbone are very encouraging and represent an important milestone for its further development.”