Using TILs to Predict Therapeutic Effect of Chemotherapy (Pertuzumab, Trastuzumab, Docetaxel) on HER2-positive Breast Cancer.

Recently, reports of the clinical implications of tumor-infiltrating lymphocytes (TILs) in breast cancer treatment have increased. We evaluated that chemotherapy with a TPD regimen (trastuzumab, pertuzumab, docetaxel) against HER2-positive breast cancer, using TILs as indicators. The subjects were 24 patients who had received TPD-chemotherapy. A semi-quantitative evaluation of lymphocytes invading the stroma in needle biopsy specimens prior to treatment as TILs was conducted, after which, sensitivity to chemotherapy and patient prognosis were evaluated. Overall response rate was significantly higher in the high-TILs group than in the low-TILs group. Significant extension of the progression-free survival (PFS) and overall survival was found in the high-TILs group compared to the low-TILs group. In addition, high TILs numbers significantly contributed to the extension of PFS. Monitoring antitumor immune response using TILs might be a useful indicator for predicting the curative effects of TPD chemotherapy for HER2-positive breast cancer.