Pfizer falls short with infant respiratory vaccine

Pivotal data from Beyfortus, Sanofi and Astrazeneca’s preventative respiratory syncytial virus antibody for infants, left the door open for Pfizer and its candidate, RSVpreF. But mixed topline results from a maternal protection trial suggest that Pfizer has failed to capitalise on the opportunity. The Matisse study only met one of its two co-primary endpoints, evaluating severe medically attended lower respiratory tract illness, failing on less severe illness. As ever, cross-trial comparisons are tricky, particularly as it is unclear how Pfizer defined severe versus less severe disease. But on the face of it RSVpreF looks to have fallen short of the bar set by Beyfortus. Pfizer did not give details on hospitalisations, a secondary endpoint of its study. The infant RSV market is expected to be smaller than the adult segment, with SVB analysts seeing peak sales of $2.7bn versus $6bn respectively; Pfizer and GSK are already fighting it out in adults. If Sanofi and Astra are to prevail commercially it will take a shift in mindset, but the groups are adamant that any infant could receive Beyfortus, regardless of risk. And Sanofi’s head of vaccines, Jean-Francois Toussaint, previously told Evaluate Vantage that Beyfortus would be “priced like a vaccine”.

Cross-trial comparison of RSVpreF vs Beyfortus
  RSVpreF, Matisse Beyfortus, Melody
  90 days 6 months 150 days
Reduction in medically attended LRTI 57%* 51%* 75%
Reduction in severe medically attended LRTI 82% 69% N/A
Reduction in hospitalisations N/A N/A 62%*
*Not statistically significant vs placebo. Source: Company release & NEJM.


Late-stage infant RSV prevention pipeline 
Project Company Description Details 
Nirsevimab (SP0232) Sanofi/Astrazeneca Fusion antibody EU CHMP recommendation Sep 2022; FDA filing due Q4 2022
RSVpreF (PF-06928316) Pfizer Protein subunit vaccine, unadjuvanted Matisse toplined Nov 2022, FDA filing due Q4 2022
Clesrovimab (MK-1654) Merck & Co Fusion antibody Ph3 MK-1654-007 in high-risk infants ends 2025; ph2/3 MK-1654-004 in healthy infants, ends 2024
RSVPreF3 (GSK3888550A) GSK Protein subunit vaccine, unadjuvanted Discontinued
Source: Evaluate Pharma &

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