ReViral

The company's lead product candidate was sisunatovir, an orally administered small-molecule inhibitor designed to block the fusion of the RSV virus with a host cell. This mechanism prevents viral entry and replication. Sisunatovir was granted Fast Track designation by the U.S. Food and Drug Administration (FDA) and was being evaluated in global Phase 2 clinical trials for both pediatric and adult patient populations. ReViral also had a second program in Phase 1 clinical development focused on inhibiting RSV replication by targeting the N-protein.

In April 2022, Pfizer entered into a definitive agreement to acquire ReViral, a deal that was completed in June 2022. The total consideration for the acquisition was up to $525 million, including upfront payments and development milestones. Pfizer anticipated that, if successful, the annual revenue from these programs could exceed $1.5 billion. The acquisition was seen as a strategic move for Pfizer to enhance its anti-infective pipeline and complement its own RSV vaccine program. However, as of early 2025, development of sisunatovir has been discontinued.