Sanofi and GSK Report Strong Immune Response with COVID-19 Vaccine Candidate

Published on: 

Sanofi and GlaxoSmithKline reported that their adjuvanted recombinant COVID-19 vaccine candidate demonstrated strong immune responses across all adult age groups in a Phase II trial.

Sanofi and GlaxoSmithKline (GSK) announced on May 17, 2021 that their adjuvanted recombinant COVID-19 vaccine candidate achieved strong rates of neutralizing antibody responses in all adult age groups in a Phase II study with 722 volunteers. These results are in line with those measured in people who have recovered from COVID-19, the companies stated in a press release. The partners intend to start a global pivotal Phase III study in the coming weeks.

The Phase II interim results showed 95% to 100% seroconversion following a second injection in all age groups (18 to 95 years old) and across all doses. Further, there was acceptable tolerability and no safety concerns. Overall, the vaccine candidate elicited strong neutralizing antibody levels that were comparable to those generated by natural infection. Higher levels of antibodies were observed in younger adults (18 to 59 years old). After a single injection, high neutralizing antibody levels were generated in participants with evidence of prior SARS-CoV-2 infection, suggesting strong potential for development as a booster vaccine.

Based on these positive Phase II interim results, the companies plan to initiate a global Phase III, randomized, double-blind study with the 10-µg dose, in combination with GSK’s pandemic adjuvant, in the coming weeks. The companies plan to enroll more than 35,000 adult participants from a broad range of countries in this Phase III trial and will assess the efficacy of two vaccine formulations, including the D614 (Wuhan) and B.1.351 (South African) variants.

The companies also intend to conduct booster studies with various variant formulations in parallel to the Phase III study to assess the ability of a lower dose of the vaccine. The aim of the booster studies is to generate a strong booster response regardless of the initial vaccine platform received. Pending positive Phase III outcomes and regulatory reviews, the companies expect that the vaccine will be approved in the fourth quarter of 2021, according to the press release.


“Our Phase [II] 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, the global vaccines business unit of Sanofi, in the press release. “With these favorable results, we are set to progress to a global Phase [III] 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.”

“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 [III] as soon as possible to meet our goal of making it available before the end of the year,” added Roger Connor, president of GSK Vaccines, in the press release.

Source: Sanofi