Chinese clinical-stage biotech Clover Biopharmaceuticals and Nasdaq-listed biopharmaceutical company Dynavax Technologies Corporation announced on Wednesday the first participants have been dosed in Clover's global Phase 2/3 clinical trial evaluating the efficacy, safety and immunogenicity of its protein-based S-Trimer COVID-19 vaccine candidate adjuvanted with Dynavax's CpG 1018 plus alum.

The global Phase 2/3 trial is a double-blind, randomized, controlled study of the adjuvanted S-Trimer COVID-19 vaccine candidate in a two-dose regimen, given 21 days apart. The study is expected to enroll over 22,000 adult and elderly participants at multiple sites across Latin America, Asia, Europe and Africa.

CpG 1018 is the adjuvant used in an adult hepatitis B vaccine approved by the United States Food and Drug Administration and the European Commission. Dynavax developed CpG 1018 to provide an increased vaccine immune response. CpG 1018 provides a well-developed technology and a significant safety database, potentially accelerating the development and large-scale manufacturing of a COVID-19 vaccine.

An independent external Data Safety Monitoring Board will provide safety oversight throughout the program by regular review of available efficacy and safety data. An interim analysis of the primary endpoint is expected in the middle of 2021, depending on trial enrollment and occurrence of COVID-19 cases in the study.

Joshua Liang, CEO of Clover Biopharmaceuticals, said there is still a significant need in many global communities for COVID-19 vaccines and should the Phase 2/3 interim analysis be favorable, the company will work closely with regulatory authorities worldwide to make the S-Trimer COVID-19 vaccine candidate available as soon as possible.

Ryan Spencer, CEO of Dynavax, said Clover's adjuvanted vaccine candidate has the potential to be an important additional solution to address worldwide demand, since it can be manufactured at large scale and stored at standard refrigeration temperature.

In December 2020, Clover reported positive clinical data from its Phase 1 trial, demonstrating its protein-based COVID-19 S-Trimer vaccine candidate in combination with Dynavax's CpG 1018 induces strong immune response, including neutralizing antibodies and cell-mediated immunity, as well as favorable safety and tolerability profiles in the adult and elderly participants. The vaccine candidate is expected to be stable long-term under standard refrigeration conditions and has demonstrated stability at room temperature for at least two months, making it suitable for global distribution. The Phase 1 data was shared in The Lancet in early 2021.