After an initial defeat against the biggest barrier to mRNA flu vaccines—namely, B strains of influenza—GSK has returned with a reformulated candidate that has delivered the goods in the all-important population of older adults.
The British pharma already demonstrated in a previous phase 2 trial in April that its candidate was able to beat licensed flu vaccines when it came to triggering an immune response against influenza A strains. But the company had to admit that it couldn’t manage the same feat against “historically challenging” B strains of influenza.
CureVac, which had been developing the vaccine with GSK, said at the time that they would work on “targeted optimizations” to improve the shot’s protection against the B strains, and it seems like that has finally done the trick. GSK has returned Wednesday morning with fresh phase 2 data that show new formulations of the vaccine “demonstrated positive A and B strain immune responses relative to standard of care in both younger and older adults.”
The study enrolled 250 healthy adults aged 18 to 64 years and another 250 aged 65 to 85 years. The companies tested a range of mRNA formulations and dose levels of their own vaccine against age-appropriate, approved flu shots, showing that their candidate induced acceptable immune responses for both A and B strains.
Interim data also suggest the various formulations tested had “an acceptable safety and reactogenicity profile,” GSK said.
The Big Pharma bought out the full rights to CureVac’s flu and COVID mRNA candidates for $430 million in July. Today’s results “confirm the mRNA platform elicits strong overall antibody titres with an acceptable safety profile,” said GSK, which will now move its vaccine into phase 3.
“This marks a significant advancement in our mRNA programme and these data support moving into late-stage development,” GSK Chief Scientific Officer Tony Wood, Ph.D., said in the Sept.12 release. “Ultimately, our goal is to develop a new best-in-class vaccine to bring greater protection to people through the influenza season.”
A spokesperson told Fierce Biotech this morning that the company is not yet able to set out a timeline for when the vaccine will enter phase 3, but further updates will be provided at the next quarterly earnings.
GSK’s peers in the race to get the first mRNA flu vaccine to market have all encountered the same problem when it comes to B strains. Moderna is the only competitor to have already secured full success—showing a year ago that a reformulated version of its candidate was able to induce higher antibody levels for major B strains than GSK’s approved flu vaccine Fluarix in a phase 3 trial.
Meanwhile, Sanofi’s executives were so disheartened by the failure of their own candidate to neutralize B strains that they proclaimed last year that the first generation of mRNA vaccines for flu “will not win.”
Pfizer and BioNTech have managed to overcome B strains with their own mRNA candidate in a phase 3 study—but so far only against under-65s. The companies revealed last month that their combo COVID-flu mRNA vaccine didn’t manage to neutralize B strains in older adults.
Like Pfizer, GSK also has plans to work on its own COVID-flu combination vaccine, and today’s results should ease the path toward that development.