FDA Accepts Pfizer BLA for Maternal RSV Vaccine for Priority Review

The US Food and Drug Administration (FDA) today accepted for priority review a Biologics License Application (BLA) from Pfizer for the company’s investigational maternal respiratory syncytial virus (RSV) candidate RSVpreF, the company said in a statement.

The FDA in March 2022 granted RSVpreF Breakthrough Therapy Designation. In November the company announced positive topline data from the pivotal phase 3 MATISSE clinical trial that demonstrated 81.8% efficacy for the maternal vaccine against severe medically-attended lower respiratory tract illness (MA-LRTI) in infants from birth through first 90 days of life. Based on its priority reveiw status, FDA has set the vaccine’s PDUFA date as August 2023.

“If approved, RSVpreF would help protect infants at their first breath from the devastating effects of this infectious disease, which though well-known, has been particularly evident throughout this RSV season,” said Annaliesa Anderson, PhD, Pfizer senior vice president and chief scientific officer, Vaccine Research & Development.

“We look forward to progressing the review of Pfizer’s RSV maternal vaccine candidate with the FDA and other regulatory authorities, given its significant potential to positively contribute to global health in the prevention of RSV in infants.”

The regulatory filings submitted are supported by the results reported in November from an interim analysis of the MATISSE clinical trial (MATernal Immunization Study for Safety and Efficacy). MATISSE evaluated the efficacy, safety, and immunogenicity of RSVpreF against MA-LRTI and severe MA-LRTI among infants who were born to healthy mothers who were vaccinated during pregnancy. In addition to the 81% efficacy reported against severe MA-LRTI, investigators also found clinically meaningful efficacy of 57.1% against nonsevere MA-LRTI through the first 90 days after birth.

According to the company, findings from MATISSE will be presented on February 23 to the Center for Disease Control’s Advisory Committee on Immunization Practices (ACIP), and at the ReSViNET Foundation’s 2023 Global Conference, on Novel RSV Preventive and Therapeutic Interventions, held February 22-24, in Lisbon, Portugal.

MATISSE enrolled approximately 7,400 pregnant women aged ≤49 years of age who were randomized in a 1:1 ratio to receive a single dose of either 120 µg of Pfizer’s RSVpreF or placebo during the late second to third trimester of their pregnancy. Participants were followed for safety through vaccination and 6 months post-partum. Infants were followed for ≥1 year for safety and efficacy, with over half of the infants followed for 2 years. MATISSE was initiated in June 2020 in 18 countries and so spanned multiple RSV seasons in both the northern and southern hemisphere.