A COVID-19 vaccine candidate from Sanofi and GSK ran into trouble last week when interim results from a phase 1/2 study showed it to produce little immune response among older adults.
While the candidate showed sufficient results in those aged 18 to 49 years, researchers believe its lack of efficacy on the elderly can be credited to an insufficient antigen concentration. However, this has not decreased the companies’ confidence in the vaccine, as a separate study conducted on non-human primates showed it could rapidly clear the virus from nasal passages and lungs within two to four days and protect against lung troubles.
“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,” Thomas Triomphe, executive vice president and head of Sanofi Pasteur, said. “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 optimize our candidate to achieve this goal.”
Sanofi and GSK scientists intend to refine the concentration of antigen and try again in a phase 2b study, expected to begin in February 2021. The Biomedical Advanced Research and Development Authority (BARDA) still intends to support that study. During that trial, the candidate will be compared to an authorized COVID-19 vaccine.
“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,” Roger Conner, president of GSK Vaccines, said. “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.”
Both Sanofi’s recombinant technology and GSK’s pandemic adjuvant have previously proven successful against influenza. If data from the upcoming trial turns out positive, a global phase three study could follow in the second quarter of 2021. However, at this time, the companies have pushed back predicted product availability until at least the fourth quarter of 2021.