Although immunotherapy is not an established treatment option in high grade glial tumors, trials are ongoing. One of the main predictive factor for response to immune checkpoint inhibitors is PD-L1 expression status and this can change over time with the effect of therapies like chemotherapy and radiotherapy. The aim of this study is to determine whether PD-L1 expression status changes in recurrent gliomas after chemoradiotherapy and the impact of this change on survival.
PD-L1 expression of 29 patients was evaluated by an expert pathologist with immunohistochemistry. PD-L1 positivity was defined as expression in ≥ 1% of tumor cells. Change in PD-L1 expression status was defined as an absolute 5% difference between two resections.
Of the 29 patients, 15 patients (51.7%) had PD-L1 expression in ≥ 1% of tumor cells and 7 patients (24.1%) had PD-L1 expression in ≥ 10% of tumor cells at diagnosis. Median survival of patients with baseline PD-L1
The PD-L1expression status changes in more than 40% of high grade glial tumors at recurrence after receiving chemotherapy and radiotherapy. So immune responsiveness of glial tumors can be modified by treatments. As the patients in this study did not receive immunotherapy after recurrence, the change in PD-L1 expression probably did not affect survival.
Clinical trial identification
Legal entity responsible for the study
Basak Oyan, Seyma Eren, Ozlem Sonmez
Yeditepe University Hospital
All authors have declared no conflicts of interest.