CDK4 and metastatic neoplasm: This outcome is comparable to the PFS reported for capecitabine in the DESTINY Breast-06 trial, which investigated trastuzumab deruxtecan vs the investigator’s choice of chemotherapy in pretreated patients with hormone receptor–positive, ERBB2 low and ultralow metastatic breast cancer.29 However, this PFS benefit did not translate into a similar benefit for OS, suggesting that the choice between ET and oral CT after tumor progression during ET plus CDK4/6i treatment did not significantly influence the overall course of metastatic disease in the broader population.