Pfizer to acquire rights to RSV candidate sisunatovir in China

When in April this year US pharma giant Pfizer (NYSE: PFE) acquired ReViral for $525 million, along with its portfolio of respiratory syncytial virus (RSV) therapeutic candidates, it did not include development and commercialization rights for ReViral lead candidate sisunatovir in China and certain other Asian markets, which China’s LianBio (Nasdaq: LIAN) had already in-licensed in March 2021.

Yesterday however, Pfizer announced a deal with LianBio, opting to take up the rights to develop and commercialize sisunatovir, an RSV therapeutic candidate, in Mainland China, Hong Kong, Macau, and Singapore, with the news sending the Chinese firm’s shares rocketing more than 25% to $1.69.

Sisunatovir is an investigational, orally administered fusion inhibitor designed to block RSV replication by inhibiting F-mediated fusion with the host cell. Sisunatovir is being evaluated for the potential treatment of RSV infection in pediatric and adult patients. It will complement Pfizer’s experimental RSVpreF vaccine, which has been shown to be 85.7% effective at protecting older adults against severe illness, and later  showed 81.8% efficacy in infants when given during pregnancy.