T-DXd has shown promising results in clinical trials (ORR: 51%; DCR: 86%; median OS: 12.5 months; and median PFS: 5.6 months) and was approved in Japan in September 2020 for the treatment of patients with HER2-positive unresectable or metastatic G/GEJ cancer that progressed on cancer chemotherapy [16]. Here, ERBB2 is linked to cancer.