Tucatinib is an oral selective TKI against HER2 that was combined with trastuzumab in patients with RAS wild-type CRC harboring an amplification or overexpression of HER2 in the MOUNTAINEER trial, resulting in an ORR of 55%, median PFS of 6.5 months, and median OS of 17.3 months [20]. The gene discussed is ERBB2; the disease is colorectal carcinoma.