GSK has linked its mRNA seasonal flu vaccine candidate to higher immune responses than conventional jabs in a phase 2 trial, emboldening the company to start a pivotal study this month.
The limited, variable effectiveness of flu vaccines, which has ranged from 20% to 60% over the past 15 years, presents an opportunity for new shots to disrupt the multibillion-dollar market. GSK’s pursuit of the opportunity centers on mRNA vaccines targeting hemagglutinin (HA) and neuraminidase (NA). While licensed flu shots primarily target HA, there is evidence that engaging NA can boost protection.
GSK put that idea to the test in a trial that enrolled 971 adults. Participants received different dose levels of one of two mRNA vaccine candidates—which differed in their optimization of B-strain HA—or licensed age-appropriate comparators.
The mRNA vaccines caused higher immune responses than standard and high-dose flu shots in younger and older adults, respectively, the company said, adding that the reactogenicity and safety profiles were acceptable. GSK’s press release lacks the numbers behind the conclusions. A researcher shared details of the phase 2 study at the Options XIII Conference for the Control of Influenza on Monday.
Based on the data, GSK plans to start a phase 3 trial of the mRNA vaccine candidate with the optimized B-strain HA, FLUm3HA.b-3NA, this month. Phase 3 success could re-energize GSK’s flu vaccine business, which shrank (PDF) by about 25% last year amid “competitive pressure” in the U.S.
The opportunity to launch the first mRNA flu vaccine has already passed, but there is room to improve on the first-generation product. Last month, Moderna won FDA approval for an mRNA-based flu vaccine, mFlusiva, that encodes for three HA proteins. Moderna tested vaccine candidates encoding HA and NA in humans, believing it could broaden protection, but paused development as part of its pipeline rethink.