The HER2-specific vaccine nelipepimut-S (HER2 369–377, E75, NeuVax) is a human leukocyte antigen (HLA) A2 restricted, major histocompatibility complex (MHC) class I, dominant epitope derived from the extracellular domain of HER2, and has been evaluated in the adjuvant setting to prevent breast cancer recurrence in women rendered clinically disease-free after standard-of-care therapy [7–9]. The gene discussed is ERBB2; the disease is breast carcinoma.