Despite these early positive signals, NSABP B-47, a large randomized phase 3 trial that enrolled 3270 patients with HER2-low BC to adjuvant trastuzumab plus chemotherapy vs. chemotherapy alone, failed to prove any beneficial effect of trastuzumab (HR for invasive DFS, 0.98; 95% CI, 0.76 to 1.25) (Table 1) [18]. Here, ERBB2 is linked to breast cancer.