Pfizer Terminates Development of Oral RSV Medication Sisunatovir Due to Ongoing Challenges

Termination of Sisunatovir Development:
Pfizer has ended the development of sisunatovir, an oral inhibitor designed to treat respiratory syncytial virus (RSV), due to ongoing challenges including drug-drug interactions with antacids.

Acquisition Background:
Pfizer acquired ReViral in 2022 for up to $525 million to expand its anti-infective pipeline and strengthen its capabilities in infectious disease research and development.

RSV Impact:
RSV is a significant respiratory pathogen causing severe and life-threatening lower respiratory tract infections (LRTIs) in high-risk populations, including young children, immunocompromised individuals, and older adults, with approximately 64 million infections and 160,000 deaths globally each year.

Sisunatovir Details:
Sisunatovir was granted Fast Track designation by the U.S. Food and Drug Administration (FDA) and showed promising results in reducing viral load in a phase 2 RSV human challenge study in healthy adults and was in phase 2 clinical development in infants before its termination.