Predictive value of MGMT, hMLH1, hMSH2 and BRCA1 protein expression for pathological complete response to neoadjuvant chemotherapy in basal-like breast cancer patients.

To evaluate the importance of biological markers to predict pathologic complete response (pCR) to neoadjuvant chemotherapy (NACT) in patients with locally advanced basal-like breast cancers (BLBCs).,Thirty-two BLBC patients receiving NACT with an anthracycline-based regimen plus taxane were included in this study. The immunoreactivities of MGMT, MLH1, MSH2 and BRCA1 before and after NACT were evaluated.,A pCR was obtained in 10 of 32 cases (31%). Cancer-related (P = 0.013) and disease-free (P = 0.023) survival rates were significantly higher in the pCR group than in the non-pCR group. In biopsy samples before NACT, attenuated expression of MGMT, MLH1, MSH2 and BRCA1 was observed in 12/32 (38%), 0/32 (0%), 5/32 (16%) and 28/32 (88%) cases, respectively. On evaluation of pCR, patients' characteristics (patients' age, menopausal status, or clinical and pathological stages) and immunohistochemical patterns, attenuated expression of MGMT was only found to be significantly predictive of a pCR (P = 0.018). Paired biopsy sample before NACT and a surgical tumor material after NACT were available for 19 cases of non-pCR. In these cases, decrease in expression during NACT were more frequently observed for MGMT as compared to MLH1, MSH2 or BRCA1 (P = 0.021).,MGMT status is a predictive factor for pCR with neoadjuvant anthracycline-based plus taxane combination chemotherapy, which may be helpful in the selection of appropriate NACT for Japanese patients with BLBC.