[Comment] Dalpiciclib in advanced breast cancer

Hormone receptor-positive, HER2-negative advanced breast cancer is largely not curable. Anti-oestrogen agents improve the prognosis of patients with hormone receptor-positive, HER2-negative advanced breast cancer, but resistance eventually occurs. Targeting cyclin-dependent kinase 4 (CDK4) and CDK6 increases endocrine therapy efficacy, leading to the approval of CDK4/6 inhibitors palbociclib, ribociclib, and abemaciclib in the this treatment setting.1