CDK4 and breast carcinoma: In addition, testing newer endocrine therapy agents that may possess different biochemical activity and potentially overcoming resistance to older-generation agents might help provide new options for treatment in patients with ET-resistant HR+/HER2− breast cancer, as an example; a phase III (EMBER 3) trial will evaluate the efficacy of a novel SERD “Imlunestrant” with or without abemaciclib, compared to investigator choice of ET in patients with disease progression beyond AI-CDK4/6 inhibitor combinations (44).