Sanofi, GSK continue COVID-19 booster vaccine Phase 3 trial after positive preliminary showing

With recommendations from an independent Data Safety Monitoring Board (DSMB) and positive antibody and safety showings from preliminary studies, Sanofi and GSK announced this week that their COVID-19 vaccine booster candidate will continue its Phase 3 trial.

So far, the DSMB has identified no safety concerns with the VAT0002 study candidate and recommended that its trial continues into early 2022 to gather more data. Preliminary results showed that the booster produced neutralizing antibodies 9 to 43 fold, regardless of the source of any primary vaccine regimen. That held for all age groups tested. It was also well-tolerated by participants.

“These preliminary data show we have a strong booster candidate, whatever primary vaccine you have received.” Thomas Triomphe, executive vice president of Sanofi Pasteur, said. “This is consistent with our efforts to provide relevant responses to evolving public health needs. While pursuing a phase 3 trial is a challenge in a quickly shifting pandemic environment, we look forward to seeing the results to support submissions of our booster vaccine as quickly as possible.”

Regulatory authorities will require the current global trial’s efficacy to be determined using participants who have never been infected by COVID-19. While most participants were recruited earlier this year, the number of events needed for analysis will continue to be tallied until necessary endpoints are met, particularly given the world’s increased exposure to COVID-19 variants.

Final results are expected sometime in the first quarter of 2022.

“As the pandemic threat continues with the current dominant Delta variant and Omicron rapidly gaining ground, booster vaccines will continue to be needed to help protect people over time,” Roger Connor, president of GSK Vaccines, said. “The initial booster data are promising, and we await the phase III results to determine the next steps on making protein-based adjuvanted COVID-19 vaccines available.”

The companies intend to file data with regulatory authorities following the results of the VAT0008 trial.