Sanofi and GSK COVID-19 Vaccine Shows Positive Interim Results in Phase 2 Study

On Monday, the pharmaceutical companies Sanofi and GlaxoSmithKline (GSK) announced that their adjuvanted recombinant COVID-19 vaccine candidate produced strong rates of neutralizing antibodies in all adult age groups in a phase 2 study.

The 2 companies now plan to move onto a global pivotal phase 3, randomized, double-blind, study as soon 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,” Roger Connor, president of GSK vaccines said. “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.”

The phase 2, randomized, double-blind, multi-center dose-ranging study included 722 participants aged 18 years and older, including some with high risk medical conditions. The study took place in the United States and Honduras and began in February of 2021.

The study aimed to evaluate the safety, reactogenicity, and immunogenicity of two injections of the vaccine given 21 days apart, with 3 antigen dose levels of 5, 10 and 15 µg.

Results from the study demonstrated that the adjuvanted recombinant vaccine candidate produced a significant immune response amongst the participants with a 95% to 100% seroconversion rate. Levels of neutralizing antibodies were found to be comparable to those generated by a natural COVID-19 infection.

Additionally, high titers in the non-naïve population after a single dose suggest that the vaccine candidate could potentially be used as a booster dose.

If the vaccine produces positive results in the phase 3 study and passes regulatory reviews, the Sanofi and GSK expect it to be approved in the fourth quarter of 2021.

"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,” Thomas Triomphe, executive vice president and head of Sanofi Pasteur said. “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."