Feasibility assessment of a chemoresponse assay to predict pathologic response in neoadjuvant chemotherapy for breast cancer patients.

BACKGROUND For chemosensitivity and resistance assays to be clinically useful in predicting patient outcome, they should require small amounts of tissue and be highly reproducible and reliable. PATIENTS AND METHODS Expanded tumor cells from transcutaneous biopsies of breast lesions (n=62) were tested for chemoresponse using the cell-based ChemoFx assay. Pathologic complete response (pCR) was determined on a subset of patients (n=34). Assay score and pCR were determined independently in a blinded manner. Logistic regression models were used to select predictors for response. RESULTS Tumor cells were successfully isolated from 83.9% of patients. Chemoresponse profiles were robust and reproducible with coefficient of variance of <3%. In a limited initial patient outcome correlation, assay score of docetaxel/capecitabine significantly predicted pCR; the cross-validated model was 75% accurate. CONCLUSION It is feasible to assess the chemoresponsiveness of small breast lesions using the ChemoFx assay to assist in choosing neoadjuvant chemotherapy for breast cancer patients.