[Immunohistochemical study of MSI markers in breast cancer]. / Immunogistokhimicheskoe issledovanie markerov MSI pri rake molochnoi zhelezy.

OBJECTIVE: To investigate the expression of microsatellite instability (MSI) markers, which is detected by an immunohistochemical technique, and to compare the expression with the PD-L1 status in luminal B, HER2-negative and triple-negative breast cancer. MATERIAL AND METHODS: The investigation included tumors from 40 patients with triple-negative and luminal B, HER2-negative subtypes. Immunohistochemical study was performed using Ventana antibodies: anti-MLH1 (clone M1), anti-MSH2 (clone G219-1129), anti-PMS2 (clone A16-4), and anti-MSH6 (clone SP93). MSI was assessed according to the standard criteria. RESULTS: The PD-L1-positive status was present in 14 (35%) of the 40 patients. Moreover, MSI-H was detected in only 1 (2.50%) case. The two-year survival rate was 87.5%; it should be noted that the median survival rate was not reached either in the study sample or in the groups divided according to PD-L1 and MSI statuses. The overall survival rate for patients with MSI was 75% (3/4). CONCLUSION: The first comparative study of the expression of PD-L1 and immunohistochemical MSI markers, which has been conducted on a small sample, fails to draw unambiguous conclusions, but shows the need to investigate this phenomenon on large samples and by using genetic methods.

[PD-L1 status in breast cancer]. / PD-L1-status raka molochnoi zhelezy.

OBJECTIVE: To investigate the expression of PD-L1 in triple-negative and luminal B, HER2-negative breast carcinoma and to assess the association of the tumor PD-L1 status with the prognosis of the disease. SUBJECT AND METHODS: The PD-L1-status of primary tumor was studied in 72 patients with breast cancer, by using an immunohistochemical method. RESULTS: Differences were found in the incidence of carcinomas with PD-L1 expression in tumor cells depending on the molecular genetic type: there was a positive PD-L1 status in luminal B, HER2-negative tumors in 4 (14.81%) of 27 cases and in triple-negative tumors in 17 (37.78%) of 45 cases. An analysis of tumors after neoadjuvant therapy revealed a positive PD-L1-status in tumor cells in 1 of 18 patients with a moderate residual tumor load and in 6 of 13 with a high residual tumor load (5.56 and 46.15%, respectively), as estimated by the RCB system. CONCLUSION: The positive PD-L1 status in triple-negative breast cancer was determined more than 2 times as frequently as in luminal B, HER2-negative breast cancer (37.78 and 14.81%). There was a considerable correlation between the high residual tumor load and the positive tumor PD-L1 status.