Pfizer Inc. has announced positive top-line data from the Phase 3 clinical trial (NCT04424316) MATISSE (MATernal Immunization Study for Safety and Efficacy) investigating its bivalent RSV prefusion vaccine candidate, RSVpreF or PF-06928316, when administered to pregnant participants to help protect their infants from RSV disease after birth.
The pre-planned, interim efficacy analysis conducted by an external and independent Data Monitoring Committee (DMC) met the success criterion for one of two primary endpoints. The observed efficacy for severe medically attended lower respiratory tract illness (severe MA-LRTI) was 81.8% (CI: 40.6%, 96.3%) through the first 90 days of life. Substantial efficacy of 69.4% (CI: 44.3%, 84.1%) was demonstrated for infants over the six-month follow-up period.
Although the statistical success criterion was not met for the second primary endpoint, clinically meaningful efficacy was observed for MA-LRTI of 57.1% (CI: 14.7%, 79.8%) in infants from birth through the first 90 days of life. Efficacy for MA-LRTI of 51.3% (CI: 29.4%, 66.8%) was observed over the six-month follow up period.
Pre-planned safety reviews conducted at regular intervals throughout the duration of the study by the DMC also indicate the investigational vaccine is well-tolerated with no safety concerns for both the vaccinated individuals and their newborns.
“We are thrilled by these data as this is the first-ever investigational vaccine shown to help protect newborns against severe RSV-related respiratory illness immediately at birth,” said Annaliesa Anderson, Ph.D., Senior Vice President and Chief Scientific Officer, Vaccine Research & Development, Pfizer. “These data reinforce Pfizer’s resolve to bring our expertise in the research and development of innovative vaccines to address critical public health needs using new approaches and technologies. We look forward to working with the FDA and other regulatory agencies to bring this vaccine candidate to expectant mothers to help protect their infants against severe RSV during their most vulnerable first six months of life, which has the highest burden of RSV illness in infants. We would like to thank the pregnant women who volunteered for this trial, along with their infants, and all the investigators around the world who participated in the study for their contribution to this landmark research.”
At the recommendation of the DMC, and in consultation with the U.S. Food and Drug Administration (FDA), Pfizer has stopped enrollment in the study. Based on these positive results Pfizer plans to submit a Biologics License Application (BLA) to the FDA by the end of 2022 for the vaccine candidate followed by other regulatory authorities in the coming months.
“Every year we see high levels of RSV cases among babies in the U.S. with some regions reporting hospital admission rates higher than normal this year,” said Eric A.F. Simões, M.D., Clinical Professor, Pediatrics-Infectious Diseases, University of Colorado School of Medicine and Children’s Hospital Colorado, Aurora. “A maternal vaccine with high efficacy that can help protect infants from birth could substantially reduce the burden of severe RSV among newborns through six months of age, and, if approved by regulatory authorities, will likely have a significant impact on disease in the U.S. and globally.”