ERBB2 and metastatic colorectal cancer: The recognition of HER2 (ERBB2) alterations as actionable targets has been reinforced by the phase II MOUNTAINEER trial of tucatinib plus trastuzumab and the DESTINY-CRC01/CRC02 studies of trastuzumab deruxtecan, which demonstrated durable responses and have led to inclusion of HER2-directed therapies in treatment guidelines for RAS/BRAF wild-type metastatic colorectal cancer [31, 32].