Sanofi and GSK COVID-19 vaccine shows promising Phase II results

The companies plan to initiate the Phase III, randomised, double-blind study with the 10 µg dose, in combination with GSK’s pandemic adjuvant, in the coming weeks

The Sanofi and GSK adjuvanted recombinant COVID-19 vaccine candidate has achieved strong rates of neutralising antibody responses, the companies say, in line with those measured in people who have recovered from COVID-19, in all adult age groups in a Phase II study with 722 volunteers. A global pivotal Phase III study is expected to start 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) across all doses, with acceptable tolerability and with no safety concerns. The candidate reportedly elicited strong neutralising antibody levels, comparable to those generated by natural infection, with higher levels observed in younger adults (18 to 59 years old). After a single injection, high neutralising antibody levels were generated in participants with evidence of prior SARS-CoV-2 infection, suggesting potential for development as a booster vaccine, the companies say.

“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 VP and Global Head of Sanofi Pasteur. “With these favourable 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.”

Roger Connor, President of GSK Vaccines said: “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.”

The companies plan to initiate the Phase III, randomised, double-blind study with the 10 µg dose, in combination with GSK’s pandemic adjuvant, in the coming weeks. This phase is expected to enroll more than 35,000 adult participants from a range of countries to assess the efficacy of two vaccine formulations including the D614 (Wuhan) and B.1.351 (South African) variants.

At the same time, the companies plan to do booster studies with various variant formulations to assess the ability of a lower dose to generate a booster response regardless of the initial vaccine platform received.

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