Gritstone bio has signed a funding agreement of up to $20.6m with the Coalition for Epidemic Preparedness Innovations (CEPI) to expedite the development of its CORAL Covid-19 vaccine programme focusing on South African markets initially.

CORAL programme is a second-generation Covid-19 vaccine platform offering spike and other SARS-CoV-2 T cell epitopes for potentially broad and long-lasting protection against variants of the virus.

Chimpanzee adenovirus, self-amplifying messenger ribonucleic acid (mRNA) or both can be the delivery vectors used.

As per the deal, CEPI will provide funds to conduct a multi-arm Phase I clinical trial of the CORAL programme’s self-amplifying mRNA (SAM) vaccine in naïve, convalescent and human immunodeficiency virus-positive (HIV+) patients.

Furthermore, the funding will facilitate pre-clinical studies, scale-up and development of a formulation to offer a stable drug product.

The trial will analyse two different SAM vaccine constructs that act on both the spike protein and additional SARS-CoV-2 targets. These are made to induce strong B as well as T cell immune responses.

Gritstone noted that the trial is anticipated to commence before this year-end.

In addition, CEPI and Gritstone bio will make the vaccine candidate available to the COVAX Facility for purchase and supply, on validating safety and efficiency.

Gritstone bio co-founder, president and CEO Andrew Allen said: “Our unique approach combines our self-amplifying mRNA platform with a broad set of viral antigens beyond spike intended to drive robust and durable immune responses comprising both neutralising antibodies and CD8+ T cells.

“With this unique antigenic breadth, our CORAL vaccine may offer protection against emerging spike variants of SARS-CoV-2 that appear challenging for first-generation vaccines.”

Sponsored by the National Institute of Allergy and Infectious Diseases (NIAID), a Phase I trial is presently analysing the reactogenicity and immunogenicity of CORAL in healthy subjects and as a booster shot for already vaccinated people.

Additional Phase I studies sponsored and performed by Gritstone in some populations are expected to launch before the end of this year.

The company noted that these trials will evaluate four different vaccine candidates and determine optimal dosing and antigenic content for the CORAL programme in youngsters, elderly, already vaccinated and immunocompromised individuals.