Regrettably, the results of nelipepimut (an E75 HER2 peptide vaccine) plus trastuzumab versus trastuzumab plus placebo were negative in the adjuvant setting of HER2-low breast cancer (disease-free survival (DFS) was similar in the two groups of treatment: HR, 0.62; 95% CI 0.31–1.25; p = 0.18) (Clifton et al., 2020). This evidence concerns the gene ERBB2 and breast cancer.