Pfizer to acquire ReViral and its Respiratory Syncytial Virus therapeutic candidates

Pfizer and ReViral announced yesterday that the companies have entered into a definitive agreement under which Pfizer will acquire ReViral, a privately held, clinical-stage biopharma company focussed on discovering, developing and commercialising novel anti-viral therapeutics that target Respiratory Syncytial Virus (RSV), according to a statement by Pfizer.

The statement mentioned that under the terms of the agreement, Pfizer will acquire ReViral for a total consideration of up to $525 million, including upfront and development milestones. If successful, Pfizer believes annual revenue for these programmes has the potential to reach or exceed $1.5 billion. The proposed transaction is subject to customary closing conditions, including receipt of regulatory approvals.

It also said that 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-II RSV human challenge study in healthy adults, and is currently in phase-II clinical development in infants. The development programme for Sisunatovir is expected to continue in both adult and pediatric populations. A second programme is focussed on the inhibition of RSV replication targetting the viral N protein. The lead candidate in this programme is currently in phase-I clinical development.

Sisunatovir has been granted fast track designation by the US Food and Drug Administration (FDA). In June 2021, ReViral announced the successful completion of Part A of the phase-II Reviral study of Sisunatovir for the treatment of RSV infections in hospitalised infants. Reviral is a global three-part adaptive study to evaluate the safety, tolerability, PharmacoKinetic (PK) profile, anti-viral effects and clinical effect of single and multiple oral doses of Sisunatovir in otherwise healthy infants between the ages of one and 36 months hospitalised with RSV LRTIs. Following a thorough review by the Reviral Data Safety Monitoring Committee, Sisunatovir showed a favourable 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, the statement added.