Combined use of a CDK4/6 inhibitor with hormonal therapy could also be a useful strategy for Br-NENs, and a case report documents a durable response to palbociclib plus fulvestrant treatment in a patient with high-grade NEC of the breast who was refractory to platinum-based chemotherapy and other hormonal therapy [49]. Here, CDK4 is linked to neuroendocrine carcinoma.