PD-L1 Checkpoint Inhibitors Indicates Activity against Aggressive MTC

Release Date: 23-Sep-2019

PD-L1’s association with the medullary thyroid cancer (MTC) is responsible for more aggressive clinicopathological features and also gives indication of structural and biochemical recurrences. This report was according to the results of a retrospective Chinese study.

The author of the study suggests that according to the result of these findings, immune checkpoint inhibitors targeting the PD-1/PD-L1 pathway could be a potential therapeutic option for patients with PD-L1andndash;positive advanced MTC. He also added that higher PD-L1 prevalence in patients who developed incurable recurrent disease may suggest a promising prospect of anti-PD-1/PD-L1 immunotherapy in the treatment of advanced MTC.

The previous studies related to the PD-L1 expression in thyroid malignancies focused on follicular histology, and those studies that did investigate MTC did not provide sufficient evidence on the prognostic significance of positive expression. Acoording to the investigator, this is the first study which demonstrates the relation of PD-L1 positivity of the structural and biochemical reoccurrence in MTC.

The case study related to this involves the method of retrospective study. In this about 201 patients with MTC were reviewed, who were surgically treated at the Fudan University Shanghai Cancer Center between January 2006 and December 2015. The patients with no previous malignancies were selected and they had tumor tissue available for immunohistochemistry (IHC) staining. Patients were followed for a median of 73 months.

PD-L1 was evaluated with the Dako PD-L1 IHC 22C3 pharmDx assay and determined by combined positive score (CPS).  This was defined as the ratio of number of stained cells of PD-L1, which involves tumor cells, lymphocytes and macrophages, to the number of viable tumor cells that was then multiplied by 100.

The investigators also suggest that the efficacy of PD-1/PD-L1 immune checkpoint inhibitors are not only affected by PD-L1 expression and noted that the potential of immunotherapy to treat patients with PD-L1andndash;positive MTC required formal demonstration in clinical trials. According to the author, the increased tumor aggressiveness and recurrence risk of the PD-L1-positive disease may explain the higher positive rate [of PD-L1 expression] in advanced disease, which suggests a potential for PD-L1 blockade in the treatment of late-stage MTC.