RP6503

RP6503 is a novel, potent, and selective small molecule inhibitor of the delta (PI3Kδ) and gamma (PI3Kγ) isoforms of phosphoinositide 3-kinase (PI3K). It was developed for inhalation delivery with the aim of treating respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), and pulmonary fibrosis. The drug demonstrated strong anti-inflammatory and anti-fibrotic activity in preclinical models, including enhanced efficacy when combined with pirfenidone in pulmonary fibrosis models. Its high selectivity for PI3Kδ/γ isoforms was expected to provide improved safety over less selective PI3K inhibitors. Despite promising preclinical data, development has been discontinued[1][5][7].