Pfizer doubles down on respiratory syncytial virus

Pfizer’s purchase of the respiratory syncytial virus therapy specialist Reviral is not a sign of a lack of confidence in its late-stage RSV vaccine, the company insisted today. Instead the acquisition, worth $525m in biodollars including an undisclosed up-front sum, is “complementary” to its vaccine efforts, a spokesperson told Evaluate Vantage. Pfizer clearly hopes to repeat its success with a similar two-pronged approach in Covid. With Reviral it is getting hold of the mid-stage RSV fusion inhibitor sisunatovir and a phase 1 N-protein inhibitor. With no approved treatments for the infection, the big pharma reckons the market for these drugs could exceed $1.5bn per year. However, RSV has proven a tough nut to crack, with Gilead’s presatovir, for instance, failing to live up to promising human challenge data. And Pfizer is not the only group looking at these targets: Johnson & Johnson’s fusion inhibitor rilematovir is already in phase 3 in children, while the phase 2 RSVP adult study of Enanta’s N-protein inhibitor EDP-938 will soon yield results. It looks like efficacy data with sisunatovir will not be available until next year; before then, though, Pfizer has the small matter of pivotal results with its RSV vaccine candidate, RSVpreF.