Comparison of Immune Checkpoint Molecules PD‐1 and PD‐L1 in Paired Primary and Recurrent Glioma: Increasing Trend When Recurrence

Abstract

Purpose: This study aims to investigate PD‐1/PD‐L1 expression patterns in paired primary and recurrent gliomas. Methods: From January 2008 to December 2014, 42 patients who underwent surgical resections of primary and recurrent gliomas were retrospectively included. PD‐1/PD‐L1 protein expression in tumors was evaluated through immunohistochemistry. Results: In primary gliomas, PD‐1 and PD‐L1 expression was evident in 9 (22.0%) and 14 (33.3%) patients. In the paired recurrent glioma, PD‐1 and PD‐L1 expression was evident in 25 (61.0%) and 31 (74.0%) lesions. Both PD‐1 and PD‐L1 showed significantly enhanced expression after recurrence (p < 0.005; p < 0.005). For PD‐L1 expression in recurrent gliomas, the adjuvant therapy group showed significantly increased expression compared to primary gliomas (p < 0.005). For PD‐1‐ primary gliomas, if the matched recurrent gliomas showed PD‐1+, the PFS became worse than the remaining recurrent gliomas PD‐1‐ (12.7 vs 25.9 months, p = 0.032). Interestingly, for PD‐L1‐ primary gliomas, if the matched recurrent gliomas showed PD‐L1+, the OS became better than the remaining recurrent gliomas PD‐L1‐ (33.8 vs 17.5 months, p < 0.001).Conclusions: In the study, we found the expression of PD‐1/PD‐L1 increased significantly in recurrent gliomas and the elevated level of PD‐L1 was tightly associated with adjuvant treatment, suggesting the potential therapeutic and predictive value of PD‐1 and PD‐L1 in the treatment of recurrent gliomas.