PARIS.- Sanofi and GSK announced the initiation of a new Phase 2 study with 720 volunteers aged 18 and over to select the most appropriate antigen dosage for Phase 3 evaluation of their adjuvanted recombinant protein COVID-19 vaccine candidate.

“Over the past few weeks, our teams have worked to refine the antigen formulation of our recombinant-protein vaccine, based on learnings from our initial Phase 1/2 study.” said Thomas Triomphe, Executive Vice President and Head of Sanofi Pasteur. “We are confident that our vaccine candidate has strong potential and we are very encouraged by the latest preclinical data. This new Phase 2 study will enable us to identify the final vaccine formulation for adults of all ages. We have demonstrated our commitment to focusing efforts and capabilities towards the global fight against the pandemic, and this new study takes us a step closer to achieving our primary goal of developing a COVID-19 vaccine with a good efficacy and safety profile.”

Roger Connor, President of GSK Vaccines added: “We are pleased to be starting this new Phase 2 study. The world needs multiple vaccines and we are confident that combining our proven pandemic adjuvant system with this improved antigen formulation will have significant potential as the pandemic evolves. We look forward to further progressing this vaccine candidate to Phase 3 in Q2 2021, if this Phase 2 study is successful.”

In parallel to the new Phase 2 study and recognizing the global emergence of new SARS-CoV-2 variants and their potential impact on vaccine efficacy, Sanofi has commenced development work against new variants, which will be used to inform next stages of the Sanofi/GSK development program.

Phase 2 study
The new Phase 2 trial is a randomized, double-blind, multi-center dose finding study conducted in adults aged 18 years of age and older to evaluate the safety, reactogenicity, and immunogenicity of two injections given 21 days apart. The trial will include equal numbers of adults 18 to 59 years and those 60 years and above.




Three different antigen doses with a fixed dose of adjuvant will be tested in a total study population of 720 volunteers, in the United States, Honduras and Panama. Results of the Phase 2 trial will inform the Phase 3 protocol.

In December 2020, Phase 1/2 study results showed an immune response comparable to patients who had recovered from COVID-19 in adults aged 18 to 49 years, but a lower immune response in older adults, likely due to an insufficient concentration of the antigen. If data from the new Phase 2 trial are positive, a global Phase 3 study is planned for Q2 2021. Positive results from the Phase 3 study would lead to regulatory submissions in the second half of 2021, with the vaccine expected to be available in Q4 2021, if approved.

The advancement of the trial program is supported by the United States’ Biomedical Advanced Research and Development Authority (BARDA), part of the HHS Office of the Assistant Secretary for Preparedness and Response under contract W15QKN-16-9-1002. Sanofi and GSK’s adjuvanted recombinant protein-based COVID-19 vaccine candidate was selected in July 2020 by the U.S. government in order to accelerate its development and manufacturing.

GSK / Sanofi partnership
In the partnership between the two Companies, Sanofi provides its recombinant antigen and GSK contributes its pandemic adjuvant, both established vaccine platforms that have proven successful against influenza. The recombinant technology combined with GSK’s adjuvant offers the advantages of stability at temperatures used for routine vaccines, the ability to generate high and sustained immune responses, and the potential to prevent virus transmission.

On the front line in the fight against the COVID-19 pandemic
In addition to the recombinant protein-based vaccine in collaboration with GSK, Sanofi is developing a messenger RNA COVID-19 vaccine in partnership with Translate Bio. Encouraging preclinical data showed that two immunizations of the mRNA vaccine induced high neutralizing antibody levels that are comparable to the upper range of those observed in infected humans. Sanofi and Translate Bio are planning to start a phase 1/2 study in Q1 2021.

Sanofi earlier announced an agreement with Pfizer-BioNTech under which Sanofi will support the manufacturing and supply of more than 125 million doses their COVID-19 vaccine.