Values of tumor-infiltrating lymphocytes (TILs), CD8+ TILs, and PDL-1 for predicting pathological complete response and prognosis in HER2-positive breast cancer receiving neoadjuvant chemotherapy with trastuzumab.

589Background: The predictive and prognostic values of tumor-infiltrating lymphocytes(TILs) in neoadjuvant chemotherapy have also been demonstrated in triple negative as well as HER2-positive breast cancer (BC). In the present study, we investigated the relationship between the expression and degree of stromal (str)-TILs, CD8+ TILs, and PDL-1 positive cancer cells, and evaluated the values of these 3 factors for predicting pCR and prognosis in HER2-positive BC patients receiving neoadjuvant chemotherapy with trastuzumab. Methods: A total of 128 Japanese HER2-positive BC received taxanes followed by FEC, with the concomitant administration of trastuzumab. The grades of str-TILs were evaluated using the criteria of the International Working Group for TILs in BC, with a high grade being defined as > 40%. Immunohistochemically, positive cancer cells for PDL-1 was defined as > 1%, and high CD8+ was defined as the number of CD8+ TILs > 25 / 1 high power field. The relationship between the expression and degree ...