Phase II study of preoperative systemic treatment with the combination of docetaxel and trastuzumab in patients with locally advanced HER-2-overexpressing breast cancer

We conducted a phase II study using docetaxel and trastuzumab as preoperative systemic treatment for locally advanced HER-2-overexpressing breast cancer (stage IIIB or IIIC) to evaluate the efficacy and safety, and to perform a subset analysis based on tumor biomarkers. Patients received 4 mg/kg trastuzumab on day 1, followed by weekly treatments of 2 mg/kg, in addition to 75 mg/m² docetaxel every 3 weeks for 4 cycles before surgery. The primary end point was clinical response rate measured by MRI or CT. Twenty-five patients were enrolled. The median age was 54 years and median tumor size was 63 mm. The overall clinical response rate was 68% [95% CI: 47–85%] and the pCR rate was 22% [95% CI: 8–44%]. The clinical response and the pCR rates of patients with ER- and PgR- tumors were 79% and 31%, respectively, while they were 55% and 10%, respectively, in the patients with ER+ and/or PgR+ tumors (p = 0.34, p = 0.34, respectively). Cardiac toxicity was well tolerated; there was no evidence of clinical cardiac events in any patient. The combination of docetaxel and trastuzumab produced highly favorable clinical and pathological responses for locally advanced HER-2-overexpressing breast cancer. Subgroup analysis suggests that ER/PgR negative tumors might be associated with pathological response in locally advanced breast cancer.