ISM6210

ISM6210 is a potent, orally bioavailable, and highly selective small molecule inhibitor of cyclin-dependent kinase 4 (CDK4), developed by Insilico Medicine for the treatment of HR+/HER2- breast cancer. Unlike first-generation dual CDK4/6 inhibitors such as palbociclib, ISM6210 demonstrates significant selectivity for CDK4 over CDK6, which is intended to reduce CDK6-mediated hematological toxicities like myelosuppression. Mechanistically, the compound blocks the phosphorylation of the retinoblastoma (Rb) protein, thereby inhibiting the G1/S cell cycle transition and inducing growth arrest in hormone receptor-positive breast cancer cells. Preclinical evaluations have shown robust anti-tumor activity in xenograft models and a favorable safety margin in human hematopoietic stem cell assays.