The pCR rate in patients with HR+/HER2+ BC, who received 18 weeks of trastuzumab plus lapatinib plus letrozole (n = 77), was 18%, compared with 43% in those with HR−/HER2+ BC (n = 74), who received only trastuzumab plus lapatinib (p = 0.0015). The gene discussed is ERBB2; the disease is breast cancer.