Regeneron Pharmaceuticals, Inc. will discontinue development Suptavumab after a Phase III study evaluating suptavumab (REGN2222), an antibody to respiratory syncytial virus (RSV), did not meet its primary endpoint of preventing medically-attended RSV infections in infants. Suptavumab did show signs of efficacy in a subgroup of patients. Adverse events were generally balanced between suptavumab and placebo. Regeneron plans to discontinue further clinical development of this antibody. 

“We are disappointed in these results, as we had hoped suptavumab might offer a new option for the thousands of infants impacted by serious RSV infections every year,” said George D. Yancopoulos, M.D., Ph.D., president and chief scientific officer of Regeneron. “Regeneron has a robust pipeline across many serious diseases, and we look forward to important data readouts from other programs in the coming weeks and months.”

The double-blind, placebo-controlled Phase III study enrolled 1,149 healthy pre-term infants. Patients were randomized to one of three study groups: suptavumab 30 mg/kg as a single dose; suptavumab 30 mg/kg administered as two doses 8 weeks apart; or placebo. Patients were considered ‘medically-attended’ if they required hospitalization and/or sought medical care for a centrally-adjudicated RSV infection. Pre-term infants in the study had a gestational age of less than 36 weeks and were 6 months old or younger at the beginning of the study.