Respiratory vaccine duel sees Pfizer come short of GSK – possibly

Secrecy surrounds the datasets for GSK’s and Pfizer’s duelling adult respiratory syncytial virus (RSV) vaccines, but signs are that the latter’s is not very good. Pfizer today unveiled topline results of PF-06928316’s Renoir study that appeared to miss analysts’ baseline expectations of 70% efficacy. The group trumpeted PF-06928316’s 85.7% efficacy in preventing severe disease, a secondary endpoint, while burying the fact that overall efficacy was just 66.7%. Investors will want to compare PF-06928316 against GSK3844766A from GSK, which revealed nothing about its pivotal Aresvi 006 trial beyond calling its topline result “exceptional”. GSK had earlier set 80% as the benchmark for “outstanding” efficacy, so analysts expect something in the 80-90% range – better than Pfizer’s, if true. Infant RSV is a separate battleground; here Sanofi/Astrazeneca’s fusion antibody nirsevimab is awaiting EU approval based on 75% efficacy, GSK3844766A has been discontinued and PF-06928316 is due to yield data in the second half. In adults PF-06928316 might still be approvable with below-70% efficacy, and unlike GSK3844766A the Pfizer vaccine is not adjuvanted, possibly making it safer, but with low efficacy it might soon be superseded. Data from the Evergreen trial of Johnson & Johnson’s Ad26.RSV.preF are due in the second half.

Duelling RSV vaccines in ≥60 year olds
  GSK Pfizer
Candidate vaccine GSK3844766A RSVpreF (PF-06928316)
Pivotal study Aresvi 006 Renoir
Key primary endpoint PCR-confirmed RSV-associated lower respiratory infection in first RSV season (2wk after vaccination until ≥56 cases accrued (assessed over 7-10mth) PCR-confirmed RSV-associated lower respiratory infection in first RSV season (day 15 after vaccination until the end of season 1 visit (avg 6 mth)
Outcome "Exceptional", statistically significant & clinically meaningful efficacy vs placebo 66.7% efficacy vs placebo
Source: company statements &

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