Clover Biopharmaceuticals and Dynavax Technologies are set to begin a global Phase II/III efficacy trial of S-Trimer Covid-19 vaccine candidate adjuvanted with CpG 1018 plus alum.

S-Trimer uses Clover’s Trimer-Tag technology and is a trimeric SARS-CoV-2 spike (S)-protein subunit vaccine candidate.

The trial will begin in the first half of this year with an interim analysis for vaccine efficacy to be carried out mid-year.

The Coalition for Epidemic Preparedness Innovations (CEPI) will provide the fund to develop the vaccine candidate, including the Phase II/III trial, through licensure.

In June, Clover Biopharmaceuticals started dosing participants in a Phase I clinical trial of its Covid-19 S-Trimer subunit vaccine candidate, SCB-2019.

According to Phase I clinical trial data, Clover’s protein-based Covid-19 S-Trimer vaccine candidates plus either Dynavax or GlaxoSmithKline (GSK) adjuvant, performed well and induced high levels of neutralising antibodies.

In addition, the vaccine candidates showed favourable safety and tolerability profiles.

Clover anticipates producing hundreds of millions of doses of the vaccine this year and up to one billion vaccine doses in peak annual production as per the demand globally.

Clover Biopharmaceuticals CEO Joshua Liang said: “Given the encouraging results of our adjuvanted S-Trimer Covid-19 vaccine candidate to-date, we are enthusiastic about progressing to a global Phase II/III efficacy study utilising Dynavax’s advanced adjuvant CpG 1018 plus alum.

“We believe this vaccine candidate could be efficacious while potentially having a differentiated, beneficial reactogenicity and safety profile, which could make it attractive for a broad population of peoples.”

Furthermore, Clover and GSK have agreed to terminate their collaboration evaluating the S-Trimer Covid-19 vaccine candidate with GSK’s pandemic adjuvant system.

Dynavax CEO Ryan Spencer said: “We are excited to be rapidly progressing to an efficacy trial to support filing for emergency use and approval.

“Clover’s S-Trimer antigen adjuvanted with CpG 1018 plus alum demonstrated low reactogenicity while providing high levels of neutralising antibodies and a strong Th1-biased cell-mediated immune response.”