Trastuzumab Improves Efficacy of Standard Neoadjuvant Chemotherapy in Patients With HER2-Positive Breast Cancer: Presented at ASCO-Breast

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Title: Trastuzumab Improves Efficacy of Standard Neoadjuvant Chemotherapy in Patients With HER2-Positive Breast Cancer: Presented at ASCO-Breast
URL: http://www.pslgroup.com/dg/22B6FA.htm
Doctor's Guide
September 8, 2008

Lisa M. Cockrell, PhD

WASHINGTON, DC -- September 8, 2008 -- Combining trastuzumab with standard anthracycline-/taxane-based neoadjuvant chemotherapy improves the clinical response rate of patients with human epidermal growth factor receptor-2 (HER2)-positive breast cancer, according to the results of the GeparQuattro study.

Gunter von Minckwitz, MD, Centre of Gynaecology and Obstetrics, University Women's Hospital, Frankfurt, Germany, presented the research findings on September 6 here at the American Society of Clinical Oncology's Annual Breast Cancer Symposium (ASCO-Breast).

The phase 3, randomised, GeparQuattro study investigated the efficacy and safety of trastuzumab when administered concomitantly with an established neoadjuvant chemotherapy regimen combining an anthracycline and taxane agent.

A total of 1,495 patients with operable or locally-advanced breast tumours were administered 4 preoperative cycles of epirubicin plus cyclophosphamide and then were randomised to 1 or 3 treatment arms: 4 cycles of docetaxel alone; 4 cycles of concurrent docetaxel and capecitabine; or 4 cycles of docetaxel followed by 4 cycles of capecitabine.

Throughout the entire neoadjuvant therapy, all patients with HER2-positive tumours received concomitant trastuzumab therapy, regardless of treatment arm.

The primary objective of this portion of the GeparQuattro trial was to compare the rates of pathological complete response (pCR) between patients with HER2-positive tumours receiving trastuzumab concomitantly with chemotherapy and patients with HER2-negative tumours who received chemotherapy alone.

A pCR was defined as having no invasive or in situ residual tumour masses in the breast at the time of surgery.

The cohort included 445 patients with HER2-positive tumours and 1,050 patients with HER2-negative tumours. A significantly higher proportion of patients in the HER2-negative group were steroid receptor-positive (P = .003) or node-negative (P = .018). A greater proportion of patients in the HER2-positive group were diagnosed with ductal invasive carcinoma (P < .001).

Results showed that HER2-positive patients achieved significantly higher rates of pCR compared with HER2-negative patients (31.7% vs 15.7%, respectively, P < .001). Also, patients in the HER2-positive group were more likely than those in the HER2-negative group to exhibit clinical complete responses, both after the initial 4 cycles of epirubicin/cyclophosphamide (10.8% vs 4.8%) and prior to surgery (34.1% vs 19.3%).

Multivariate analysis to identify patient subgroups that could predict a pCR in HER2-positive patients showed that only hormone-receptor status (oestrogen receptor or progesterone receptor) significantly predicted a pCR (P < .001). Other subgroups tested included age, tumour size, tumour grade, and lymph-node status.

Addition of trastuzumab did not increase the incidence of haematological or nonhaematological toxicities.

Patients in the HER2-positive and -negative experienced similar rates of nonhaematological toxicities, such as diarrhoea, vomiting, mucositis, neuropathy, and hand-foot disease. Also, comparable rates of haematological toxicities were observed between both HER2 groups, including high rates of grade 3/4 leukopaenia and grade 1/2 anaemia.

According to Dr. von Minckwitz and colleagues, the positive results of this phase 3 study suggest that patients with HER2-positive breast tumours should be considered for treatment with trastuzumab concomitantly administered with neoadjuvant chemotherapy.

[Presentation title: Effect of Trastuzumab on Pathologic Complete Response Rate of Neoadjuvant EC-Docetaxel Treatment in HER2-Overexpressing Breast Cancer: Results of the Phase III GeparQuattro Study. Abstract 226]

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