GSK and Sanofi Launch Phase 3 Trial of Adjuvanted Recombinant COVID-19 Vaccine Following Earlier Immune Response Setback

On May 27 local time, GSK announced that it has initiated a Phase 3 clinical trial for the adjuvanted recombinant COVID-19 candidate vaccine co-developed with Sanofi, which is expected to enroll more than 35,000 adult volunteers across multiple regions, including the United States, Asia, Africa, and Latin America.

Ten days ago, GSK released the Phase 2 clinical trial data for this COVID-19 candidate vaccine, evaluating the immunogenicity of a two-dose regimen in 722 healthy volunteers aged 18 years and older. The results showed a seroconversion rate of 95%–100% among volunteers following completion of the second dose. Additionally, high levels of neutralizing antibodies were elicited in subjects previously infected with SARS-CoV-2 after a single dose administration, indicating the vaccine's strong potential as a booster vaccine.

The primary endpoint of this newly initiated Phase 3 clinical trial is the efficacy of a two-dose vaccine regimen in preventing symptomatic COVID-19, while the secondary endpoints are its efficacy in preventing severe COVID-19 and asymptomatic infection. The study will be conducted in two stages: first evaluating the protective efficacy of the two-dose regimen against the original D614 strain, followed by an exploration of its protective efficacy against the South African mutant strain B.1.351.

In addition, GSK and Sanofi will also explore the possibility of using this vaccine as a booster in the coming weeks, which could create a larger market for this vaccine.

According to GSK's projections, the vaccine will receive approval from the U.S. Food and Drug Administration (FDA) in the fourth quarter of 2021, and GSK and Sanofi will commence production within weeks of obtaining the regulatory approval.

Notably, the vaccine developed by GSK and Sanofi encountered a major "crisis" in December 2020. Interim data from the Phase 1/2 study indicated that the vaccine's immune response in the elderly population did not meet expectations. At the time, the two pharmaceutical companies believed this might be due to an insufficient antigen concentration. Based on the previously released Phase 2 clinical data, however, this issue appears to have been effectively resolved.

One day before GSK announced the initiation of a Phase 3 clinical trial for its COVID-19 vaccine, the monoclonal antibody therapy sotrovimab, co-developed by the company and Vir Biotechnology, received Emergency Use Authorization (EUA) from the FDA for the treatment of adult and pediatric patients with mild to moderate COVID-19.

Note: The original text has been abridged.

References:

[1]https://us.gsk.com/en-us/media/press-releases/sanofi-and-gsk-initiate-global-phase-3-clinical-efficacy-study-of-covid-19-vaccine-candidate/

[2]https://www.fiercebiotech.com/biotech/sanofi-gsk-kickstart-phase-3-covid-vax-test-as-pair-target-variants-and-a-q4-approval

[3]https://us.gsk.com/en-us/media/press-releases/gsk-and-vir-biotechnology-announce-sotrovimab-vir-7831-receives-emergency-use-authorization-from-the-us-fda/