Furthermore, treatment with neratinib overcame endocrine resistance in ER+/ERBB2-mutant breast cancer cell lines, derived from metastatic biopsies from patients with ER+ metastatic breast cancer who developed endocrine resistance to tamoxifen or fulvestrant, thus suggesting enhanced tumor growth inhibition when combining neratinib with fulvestrant54,63. The gene discussed is ESR1; the disease is breast carcinoma.