These data are supported by recently published research identifying activating mutations in HR+ breast cancer, which similarly appears to confer resistance to hormonal therapy, but sensitivity to neratinib.35 Similarly, this study describes mutations found in a relatively small population, eight patients, thus our work compliments these findings and supports the principle of acquired activating mutations conferring both endocrine resistance, as well as a new sensitivity to HER2-targeted therapy. The gene discussed is ERBB2; the disease is breast cancer.