Pertuzumab plus trastuzumab with or without chemotherapy followed by emtansine in ERBB2-positive metastatic breast cancer

Data from a secondary analysis of a phase 2 trial found similar 24-month overall survival rates among patients with HER2-positive locally advanced or metastatic breast cancer who received first-line trastuzumab plus pertuzumab (T+P; 79.0% [90% CI: 71.4%-85.4%]) and for patients who received T+P and chemotherapy (78.1% [90% CI: 70.4%-84.5%]). Median PFS was longer in the chemotherapy group (23.3 months [95% CI: 18.9-33.1]) compared with the non-chemotherapy group (8.4 months [95% CI: 7.9-12.0]). OS and PFS did not markedly differ between populations with ERBB2-enriched and ERBB2-nonenriched cancer.