Sanofi (NYSE:SNY) and Glaxo Smith Kline’s (NYSE:GSK) have confirmed a delay in their adjuvanted recombinant protein-based COVID-19 vaccine owing to an inadequate immune response in older adults in a Phase 1/2 trial.
Sanofi and GSK now plan to launch a Phase 2b study in February 2021 to investigate a new vaccine formulation.
If that study reaches primary endpoints, the companies could launch an international Phase 3 study in the second quarter of 2021 and regulatory submissions in the second half of the year.
Sanofi and GSK had planned on launching a Phase 3 trial by the end of 2020.
According to their revised timetable, the companies anticipate that the resulting vaccine would be available in the fourth quarter of 2021. By that point, vaccines would likely be available from Pfizer (NYSE:PFE) and its partner BioNTech, Moderna (NSDQ:MRNA), Janssen (NYSE:JNJ) and AstraZeneca (LON:AZN).
Sanofi’s and GSK’s initial Phase 1/2 did show some promise for younger adults. According to an interim analysis, adults aged 18 to 49 developed a similar immune response to patients who had recovered from COVID-19. Adults 50 and over, however, did not
The companies note their vaccine could be improved using a new antigen formulation that demonstrated efficacy against SARS-CoV-2 in non-human primates. In particular, the modified formulation guarded against COVID-19 pulmonary pathology and enabled viral clearance from the nasal passages and lungs within two to four days.
Sanofi’s recombinant technology and GSK’s pandemic adjuvant have shown past success in protecting against influenza.
“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,” said Roger Connor, president of GSK Vaccines in a statement.
In October, the two companies signaled their intent to provide 20 million vaccine doses to the COVAX Alliance,