Therefore, in NSCLC, it seems that mutations are the HER2-aberrations associated with benefit from T-DXd, in contrast to breast and gastric cancers where HER2 expression levels represent the main biomarker for patient selection.34,88 Preclinical studies found that, in NSCLC, ERBB2 mutations and amplifications do not generally overlap, possibly representing 2 distinct therapeutic targets,89,90 although molecular imaging showed radiolabeled trastuzumab accumulating in both ERBB2 amplified and mutant NSCLC. The gene discussed is ERBB2; the disease is gastric cancer.