Chengdu's Clover Biopharma announced plans to start a global Phase II/III efficacy trial of its S-Trimer COVID-19 vaccine together with a Dynavax (NSDQ: DVAX) adjuvant. Previously, Clover was using a GSK adjuvant, but decided to switch based on "manufacturing considerations" for the GSK product. Also today, Clover published positive early results of the Clover-GSK combination in The Lancet. Clover's vaccine can be manufactured to produce hundreds of millions of doses and stored in a regular refrigerator, making it valuable for low-resource settings.

The Coalition for Epidemic Preparedness Innovations (CEPI) will continue to fund the development of the Clover vaccine candidate through to licensure.

The Phase II/III global trial will start testing the combination of the S-Timer vaccine and Dynavax's CpG 1018 plus alum adjuvant in the first half of 2021. It plans to conduct an interim analysis for vaccine efficacy as soon as the middle of 2021.  

Joshua Liang, CEO of Clover Biopharmaceuticals, 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 utilizing 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 that could make it attractive for a broad population of peoples."

Ryan Spencer CEO of Dynavax, 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 neutralizing antibodies and a strong Th1-biased cell-mediated immune response."

Clover said its proprietary Trimer-Tag© technology, S-Trimer, produces a trimeric SARS-CoV-2 spike (S)-protein subunit vaccine candidate. The trimeric S protein of SARS-CoV-2 is responsible for binding to host cell surface receptor ACE2 and subsequent viral entry, making it the primary target antigen for vaccine development. S-Trimer resembles the native trimeric viral spike protein and is produced via a rapid mammalian cell-culture based expression system. S-Trimer is intended to be adjuvanted.

Clover uses its proprietary Trimer-Tag© technology platform to develop novel biologics that target trimerization-dependent pathways. It has raised more than $350 million in total capital since 2016, and it has developed in-house GMP biomanufacturing capabilities.

See our other articles on Clover and Dynavax.

Disclosure: none.