Pre-operative systemic (neo-adjuvant) therapy with trastuzumab and docetaxel for HER2-overexpressing stage II or III breast cancer:: results of a multicenter phase II trial

Background: Trastuzumab plus chemotherapy has become the standard of care for women with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer. Trastuzumab-based pre-operative systemic (neo-adjuvant) therapy (PST) also appears promising, warranting further investigation. Patients and methods: Patients with HER2-positive, stage II/III non-inflammatory, operable breast cancer requiring a mastectomy (but who wished to conserve the breast) received weekly trastuzumab and 3-weekly docetaxel for six cycles before surgery. The primary end point was pathological complete response (pCR) rate, determined from surgical specimens. Results: Thirty-three patients were enrolled. The majority (79%) had T2 tumors, with 42% being N1/2. Twenty-nine patients completed six cycles of therapy and one patient withdrew prematurely due to progressive disease. A complete or partial objective clinical response was seen in 96% (73% and 23%, respectively) of patients. Surgery was performed in 30 patients, breast conserving in 23 (77%). In an intention-to-treat analysis, tumor and nodal pCR was seen in 14 (47%) patients. Treatment was generally well tolerated. Grade 3/4 neutropenia occurred in 85% of patients while febrile neutropenia was encountered in 18%. Only three patients withdrew prematurely due to toxicity. No symptomatic cardiac dysfunction was reported. Conclusions: PST with trastuzumab plus docetaxel achieved promising efficacy, with a high pCR rate and good tolerability, in women with stage II or III HER2-positive breast cancer.