Sanofi, GSK delay Covid vaccine program to improve immune response

New Delhi: Sanofi and GSK have announced a delay in their adjuvanted recombinant protein-based Covid-19 vaccine programme to improve immune response in older adults.

Interim results of the Phase 1/2 study showed an immune response comparable to patients who recovered from Covid-19 in adults aged 18 to 49 years, but a low immune response in older adults likely due to an insufficient concentration of the antigen.

A recent challenge study in non-human primates performed with an improved antigen formulation demonstrated that the vaccine candidate could protect against lung pathology and lead to rapid viral clearance from the nasal passages and lungs within 2 to 4 days. These results increased the companies' confidence in the capacity of the adjuvanted recombinant platform to deliver a highly efficient vaccine for all adults.

Sanofi's recombinant technology and GSK's pandemic adjuvant are established vaccine platforms that have proven successful against influenza. The recombinant technology 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.

"We care greatly about public health which is why we are disappointed by the delay announced today, but all our decisions are and will always be driven by science and data. We have identified the path forward and remain confident and committed to bringing a safe and efficacious Covid-19 vaccine. Following these results and the latest encouraging new preclinical data, we will now work to further optimise our candidate to achieve this goal. No single pharma company can make it alone; the world needs more than one vaccine to fight the pandemic," said Thomas Triomphe, Executive Vice President and Head of Sanofi Pasteur.

Roger Connor, President of GSK Vaccines, said: "The results of the study are not as we hoped. Based on previous experience and other collaborations, we are confident that GSK's pandemic adjuvant system, when coupled with a Covid-19 antigen, can elicit a robust immune response with an acceptable reactogenicity profile. It is also clear that multiple vaccines will be needed to contain the pandemic. Our aim now is to work closely with our partner Sanofi to develop this vaccine, with an improved antigen formulation, for it to make a meaningful contribution to preventing Covid-19."

The companies plan a Phase 2b study expected to start in February 2021 with support from the Biomedical Advanced Research and Development Authority (BARDA), part of the HHS Office of the Assistant Secretary for Preparedness and Response (ASPR). The study will include a proposed comparison with an authorised Covid-19 vaccine. If the data are positive, a global Phase 3 study could start in Q2 2021. Positive results from this study would lead to regulatory submissions in the second half of 2021, hence delaying the vaccine's potential availability from mid-2021 to Q4 2021.

The adjuvanted recombinant protein-based vaccine candidate was selected in July 2020 by US government's Operation Warp Speed in order to accelerate its development and manufacturing. Sanofi and GSK have updated the governments and the European Commission where a contractual commitment to purchase the vaccine has been made.

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