Twenty breast cancer PDX models were generated from different molecular subtypes (overall success rate, 17.5%; 3.6% for HR+/HER2−, 21.4% for HR+/HER2+, 21.9% for HR−/HER2+ and 22.5% for triple-negative breast cancer (TNBC)). The gene discussed is ERBB2; the disease is triple-negative breast carcinoma.