abemaciclib + durvalumab

Abemaciclib + durvalumab is an investigational combination therapy composed of two agents: **abemaciclib**, a small molecule inhibitor of cyclin-dependent kinases CDK4 and CDK6, and **durvalumab**, a monoclonal antibody immune checkpoint inhibitor targeting PD-L1. Abemaciclib inhibits cell cycle progression by blocking phosphorylation of retinoblastoma protein, leading to G1 cell cycle arrest and antiproliferative activity especially in hormone receptor–positive breast cancer. Durvalumab blocks PD-L1 on tumor cells from binding PD-1 and CD80 on T cells, supporting antitumor immunity by enabling T-cell mediated destruction of cancer cells. This combination aims to synergize antiproliferative and immunomodulatory effects, primarily explored in oncology indications such as metastatic breast cancer and lung cancer.