Pfizer to Acquire BioPharma Company to Develop RSV Therapeutics

Pfizer will acquire clinical-stage biopharmaceutical company ReViral to discover, develop, and commercialize novel antiviral respiratory syncytial virus (RSV) therapeutics.  

ReViral’s portfolio contains promising therapeutic candidates, including sisunatovir, designed to block the fusion of the RSV virus to the host cell. In August 2020, FDA granted fast track designation to sisunatovir to treat patients with serious RSV infection.  

In a previous Phase 2 RSV human challenge study, sisunatovir significantly reduced viral load in healthy adults. And In June 2021, ReViral completed the first part of the global three-part adaptive Phase 2 REVIRAL1 study. Researchers studied the safety and efficacy of sisunatovir in infants hospitalized with RSV.  

Sisunatovir’s development program will continue in both adult and pediatric populations. While a second program will focus on inhibiting RSV replication by targeting the viral N protein, the lead candidate in this program is currently in Phase 1 clinical development. 

“We’re continuing to grow our pipeline — through our own research-and-development efforts, such as our investigational RSV vaccine programs, as well as strategic investments in companies like ReViral — with a focus on end-to-end capabilities to help protect patients from severe illness, hospitalization, and death,” Albert Bourla, chairman and CEO of Pfizer, said in the announcement.. 

RSV leads to nearly 58,000 hospitalizations annually among children younger than five years old, 177,000 hospitalizations among adults 65 years of age and older, and 14,000 deaths among adults 65 years and older, according to the CDC.  

In September 2021, Pfizer initiated a Phase 3 clinical trial evaluating the efficacy, immunogenicity, and safety of a single dose of its RSV vaccine candidate in adults 60 years of age and older.  

The study’s primary objective is the prevention of moderate to severe lower respiratory tract illness during the first RSV season. 

Other big pharma companies, including Moderna and AstraZeneca, have also developed promising RSV vaccine candidates over the last year.  

In July 2021, AstraZeneca’s long-acting antibody, nirsevimab, demonstrated a favorable safety profile and tolerability profile in infants at high risk of RSV in a Phase 2/3 clinical trial.  

And in August, FDA granted fast track designation to Moderna’s RSV vaccine candidate, mRNA-1345, for use in adults 60 years of age and older.