Regeneron ends development of RSV antibody

Regeneron has ended development of its antibody suptavumab after it failed to prevent respiratory syncytial virus (RSV) infections in babies in a phase 3 trial.

RSV is a common cause of respiratory illness and, although most people recover quickly, it is much more likely to be serious in young children and older people, leading to bronchiolitis (inflammation of the small airways) and pneumonia.

The New York state-based company said suptavumab did not meet a primary endpoint of preventing medically-attended RSV infections in infants.

Adverse events were “generally balanced” between suptavumab and placebo arms, and there were signs of efficacy in a subgroup of patients, the company said.

Nevertheless, Regeneron said it plans to end development of the antibody.

The double-blind, placebo-controlled global phase 3 NURSERY pre-term study enrolled 1,149 healthy pre-term infants.

Patients were randomised in a 1:1:1 ratio 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.

Assessment of the primary endpoint occurred through to day 150 of treatment. Patients were considered 'medically-attended' if they required hospitalisation 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 six months old or younger at the beginning of the study. Data from the study will be presented at a future medical congress.

George Yancopoulos, president and chief scientific officer of Regeneron, said: “Regeneron has a robust pipeline across many serious diseases, and we look forward to important data readouts from other programmes in the coming weeks and months.”

Regeneron’s decision leaves AstraZeneca (AZ) and Sanofi as leaders in the RSV prevention field.

In March Sanofi Pasteur paid $120 million up front and could pay a further $495 million in milestone payments, to buy in to a deal with AZ to develop RSV prevention drug MEDI8897.

AZ and its MedImmune unit will continue to lead all development activity until the drug hits the market, and AZ will also continue to manufacture it. Sanofi Pasteur will then lead marketing for MEDI8897.