Neoadjuvant trastuzumab increases pCR rates

SAN FRANCISCO—In patients with locally advanced breast cancer, adding trastuzumab (Herceptin) to chemotherapy prior to surgery significantly increases pathologic complete response rates, compared with chemotherapy alone. Luca Gianni, MD, reported the findings for the Neoadjuvant Herceptin (NOAH) study group, a joint effort of Fondazione Michelangelo, Grupo SOLTI, and Roche, at the ASCO Breast Cancer Symposium.

In this ongoing phase III trial, 228 patients with newly diagnosed, HER2-positive, locally advanced breast cancer were randomized to receive doxorubicin/paclitaxel (AT) followed by cyclophosphamide, methotrexate, and fluorouracil (CMF), with or without trastuzumab. Results were also compared with a group of 99 HER2-negative patients receiving the same chemotherapy with no trastuzumab. After surgery and radiotherapy, patients in the trastuzumab group continued to receive the agent through week 52.

In the intent-to-treat analysis, HER2-positive patients who received trastuzu-mab had a complete response rate of 60%, compared with 51% for no trastuzumab and 25% for HER2-negative patients. The overall response rates, including partial responses, were 81%, 74%, and 66%, respectively (P = .18).

Pathological complete response rates in the breast were 43% with trastuzumab vs 23% without trastuzumab (P = .002) and 17% in HER2-negative patients. Total pCR rates (negative in the breast and axillary nodes) were 38% and 20% (P = .003) for trastuzumab vs no trastuzumab, and 16% for the HER2-negative patients.

The trastuzumab-containing regimen was well tolerated, with 15% of patients having one or more serious events and 2% having a cardiac event (CHF that responded to treatment). Dr. Gianni pointed out that 96% of patients receiving trastuzumab completed the protocol.Final analysis is expected after 106 HER2-positive patients have progressed during neoadjuvant therapy or after surgery.

Further data presented at the 2007 ECCO meeting on NOAH patients with inflammatory breast cancer (abstract 2030) showed a significant advantage for trastuzumab in pCR rate (55% vs 19%, P = .004) and total pCR rate (48% vs 13%, P = .002).