Sanofi, GSK Report Positive Trial Data for COVID-19 Vaccine

In April 2020, Britain’s GlaxoSmithKline (GSK) and French drugmaker Sanofi entered a partnership to develop an adjuvanted recombinant COVID-19 vaccine, aiming for regulatory clearance in the second half of 2021. However, their plans suffered as a Phase 1/2 trial yielded mixed data. Results showed that the vaccine failed to elicit a robust immune response in people over 50 years despite promising results in the 18-49 age group.

Nevertheless, the recent Phase 2 Trial has rekindled market hopes for the duo. On May 17th, the companies announced encouraging interim results showing that the vaccine candidate achieved strong rates of neutralizing antibody responses in all age groups (18 to 95 years old), similar to those observed in recovered COVID-19 patients.

“Our Phase 2 data confirm the potential of this vaccine to play a role in addressing this ongoing global public health crisis, as we know multiple vaccines will be needed, especially as variants continue to emerge and the need for effective and booster vaccines, which can be stored at normal temperatures, increases”, said Thomas Triomphe, Executive Vice President and Global Head of Sanofi Pasteur in a statement.

“With these favorable results, we are set to progress to a global Phase 3 efficacy study. We look forward to generating additional data and working with our partners around the world to make our vaccine available as quickly as possible.”

Phase 2 Trial

The study intended to evaluate the safety, reactogenicity, and immunogenicity of two injections given 21 days apart in 722 enrolled participants in the US and Honduras. Results showed 95% to 100% seroconversion following a second injection in all age groups with all three antigen dose levels (5, 10, and 15 µg). No adverse tolerability or safety concerns were observed, the companies said.

These positive results have now provided the impetus for a subsequent global Phase 3 trial. The study projected to begin in the coming weeks will involve more than 35,000 adult participants from various countries. The trial will evaluate a 10 µg dose of the vaccine in combination with GSK’s pandemic adjuvant.

The trial will also assess the efficacy of two vaccine formulations, including the D614 (Wuhan) and B.1.351 (South African) variants. In parallel, the companies aim to conduct booster studies with various variant formulations. This will assess the ability of a lower dose of the vaccine to generate a strong booster response regardless of the initial vaccine platform received.

If the vaccine candidate shines in Phase 3 and receives favorable regulatory reviews, it is expected to be approved in the fourth quarter of 2021. Although a latecomer to the vaccine race, the rising global demands and the emergence of new variants would still render this adjuvanted recombinant vaccine valuable for patients.

“These positive data show the potential of this protein-based adjuvanted vaccine candidate in the broader context of the pandemic, including the need to address variants and to provide for booster doses. We believe that this vaccine candidate can make a significant contribution to the ongoing fight against COVID-19 and will move to Phase 3 as soon as possible to meet our goal of making it available before the end of the year,” said Roger Connor, President of GSK Vaccines.

Related Article: Sanofi/GSK Vaccine Delayed Due to Poor Immunogenicity in Older Adults

Author

Rajaneesh K. Gopinath