- Two-stage design will evaluate vaccine formulations targeting original D.614 virus as well as B.1.351 variant, in diverse geographies with multiple circulating variants
- A booster study program will begin in the coming weeks to complement Phase 3 trial
- Pending positive Phase 3 outcomes and regulatory reviews, the vaccine could be approved in Q4 2021
Today, Sanofi and GSK started enrollment in their Phase 3 clinical study to assess the safety, efficacy, and immunogenicity of their adjuvanted recombinant-protein COVID-19 vaccine candidate. The global, randomized, double-blind placebo-controlled Phase 3 study will include more than 35,000 volunteers aged 18 and older from several countries, including sites in the US, Asia, Africa, and Latin America.
The primary endpoint of the study is the prevention of symptomatic COVID-19 in SARS-CoV-2 naïve adults, with secondary endpoints being the prevention of severe COVID-19 disease and prevention of asymptomatic infection. In a two-stage approach, the study will initially investigate the efficacy of a vaccine formulation targeting the original D.614 virus (Wuhan), while a second stage will evaluate a second formulation targeting the B.1.351 (South African) variant. Recent scientific evidence shows that antibodies created against the B.1.351 variant may provide broad cross-protection against other more transmissible variants. The design of the Phase 3, conducted across a broad diversity of geographies, also allows evaluation of the efficacy of the candidate against a variety of circulating variants.
Following encouraging interim results from the recent Phase 2 study, the companies will also begin clinical studies in the coming weeks to assess the ability of the adjuvanted recombinant-protein COVID-19 vaccine candidate to generate a strong booster response regardless of initial vaccine platform received.
“We are encouraged to see first vaccinations starting to take place in such an important, pivotal Phase 3 study, as we believe that our unique technology platform will provide a clinically-relevant vaccine option” said Thomas Triomphe, Executive Vice President, Global Head of Sanofi Pasteur. “We have adapted our vaccine development strategy based on forward-looking considerations as the virus continues to evolve, as well as anticipating what may be needed in a post-pandemic setting. This trial is testament to the urgency and agility in our approach to help overcome the ongoing impact of this pandemic.
Roger Connor, President of GSK Vaccines added, “We believe further solutions for COVID-19 are very much needed to help reach people around the world, especially as the pandemic evolves and variants continue to emerge. Adjusting our technology and study designs reflects this need and will further build the potential of this adjuvanted protein-based vaccine. We are grateful to the volunteers who will take part in the trials and hope the results will add to the encouraging data we’ve seen so far so we can make the vaccine available as quickly as possible.”
The Phase 3 study follows the interim Phase 2 results which showed that the adjuvanted recombinant COVID-19 vaccine candidate achieved high rates of neutralizing antibody responses in all adult age groups, with 95 to 100% seroconversion rates. After a single injection, high neutralizing antibody levels were also generated in participants with evidence of prior SARS-CoV-2 infection, suggesting strong potential for development as a booster vaccine.
Pending positive Phase 3 outcomes and regulatory reviews, the vaccine could be approved / authorized in Q4 2021. Manufacturing will begin in the coming weeks to enable rapid access to the vaccine should it be approved.