April 7, 2022 – Pfizer and ReViral Ltd. announced that the companies have entered into a definitive agreement under which Pfizer will acquire ReViral, a privately held, clinical-stage biopharmaceutical company focused on discovering, developing, and commercializing novel antiviral therapeutics that target respiratory syncytial virus (RSV).
RSV is a respiratory pathogen, which can lead to severe and life-threatening lower respiratory tract infections (LRTIs) in high-risk populations, including young infants, immunocompromised individuals, and older adults. It is estimated to cause infections in approximately 64 million people, resulting in about 160,000 deaths, globally each year.
ReViral has a portfolio of promising therapeutic candidates, including sisunatovir, an orally administered inhibitor designed to block fusion of the RSV virus to the host cell. Sisunatovir significantly reduced viral load in a phase 2 RSV human challenge study in healthy adults and is currently in phase 2 clinical development in infants. The development program for sisunatovir is expected to continue in both adult and pediatric populations. A second program is focused on the inhibition of RSV replication targeting the viral N protein. The lead candidate in this program is currently in phase 1 clinical development.
Sisunatovir has been granted Fast Track designation by the U.S. Food and Drug Administration (FDA). In June 2021, ReViral announced the successful completion of Part A of the phase 2 REVIRAL1 study of sisunatovir for the treatment of RSV infections in hospitalized infants. REVIRAL1 is a global three-part adaptive study to evaluate the safety, tolerability, pharmacokinetic (PK) profile, antiviral effects, and clinical effect of single and multiple oral doses of sisunatovir in otherwise healthy infants between the ages of 1 and 36 months hospitalized with RSV LRTIs. Following a thorough review by the REVIRAL1 Data Safety Monitoring Committee, sisunatovir showed a favorable safety and PK exposure profile to advance to Part B, the double-blind, placebo-controlled stage of the study where patients receive drug or placebo twice a day for five days.