ESR1 and breast cancer: A third ADC datopotamab deruxtecan, which also acts against Trop-2 and uses the same payload as trastuzumab deruxtecan has had encouraging results in a phase I trial that included heavily pretreated ER+/HER2-breast cancer (Meric-Bernstam et al., 2022), and is under further assessment in the phase III TROPION-Breast-01 trial (Clinicaltrials.gov identifier NCT05104866).