Taxotere and Adriamycin/Cytoxan (AC) Validation in Breast Cancer Patients

Large clinical trials have confirmed the value of systemic adjuvant therapy in decreasing the risk of recurrence and death in patients with early breast cancer. However, the need to identify breast cancer patients who will benefit from adjuvant therapy, while sparing others from the side effects of futile treatment, is spurring research into predictive markers of chemotherapy sensitivity and resistance. In the adjuvant setting, extremely large trials and long follow-up would be required to prospectively validate the predictive value of biomarkers of chemotherapy sensitivity or resistance. In part this is because response is not directly observable. Preoperative chemotherapy for large tumors (\>3cm) or inoperable breast cancer is well established and is the standard of care for locally advanced breast cancer. Data from large series of patients have demonstrated that preoperative (neoadjuvant) chemotherapy leads to significant reduction of tumor size (downstaging) and improves both the rate and the cosmetic results of breast- conserving surgery. The degree of response to neoadjuvant therapy has been shown to predict improved overall survival. This is therefore an attractive setting to study predictors of response because tissue is accessible from pre- therapeutic biopsies and tumor response is directly observable. In an early proof-of-principle pilot study of single agent neoadjuvant docetaxol, we identified a predictive gene expression pattern, and, using leave-one-cross validation, a method of internal validation, we demonstrated that the pattern was likely to accurately discriminate between responders and non-responders (Chang, J.C., et al., Gene expression profiling for the prediction of therapeutic response to docetaxel in patients with breast cancer. Lancet, 2003. 362(9381): p. 362-9). A similar pilot study of neoadjuvant AC undertaken by a collaborator in the UK suggests that different profiles will be predictive for AC response. In order to definitively determine predictive patterns for both regimens (T and AC) using improved technology for RNA preparation and a larger, more comprehensive gene expression array, we undertook a randomized Phase II trial of these two widely used regimens (Protocol H-11624 - A RANDOMIZED MULTICENTER TRIAL OF NEOADJUVANT TAXOTERE AND ADRIAMYCIN/CYTOXAN (AC): A BIOLOGIC CORRELATIVE STUDY). The trial is nearing completion, having recruited more than 90 patients out of an expected 120 patients. To date, the risks associated with this study have been modest, and there have been no unexpected adverse events. The laboratory work is well underway and gives every indication that clinically useful classifiers to predict treatment efficacy will result.