Discovery of 3 ({5 Chloro-1 [3 (methylsulfonyl)propyl]-1H indol-2 yl}methyl)-1 (2,2,2 trifluoroethyl)-1,3 dihydro-2H imidazo[4,5-c]pyridin-2 one (JNJ-53718678), a potent and orally bioavailable fusion inhibitor of respiratory syncytial virus.

: Respiratory syncytial virus (RSV) is a seasonal virus that infects the lungs and airways of 64 million children and adults every year. It is a major cause of acute lower respiratory tract infection and is associated with significant morbidity and mortality. Despite the large medical and economic burden, treatment options for RSV-associated bronchiolitis and pneumonia are limited and mainly consist of supportive care. This publication covers the medicinal chemistry efforts resulting in the identification of JNJ-53718678, an orally bioavailable RSV inhibitor which showed to be efficacious in a phase 2a challenge study in healthy adult subjects and which is currently being evaluated in hospitalized infants and adults. Co-crystal structures of several new derivatives helped rationalizing some of the structure activity relationship (SAR) trends observed.