IDO1 and neoplasm: Of note, this subtype also displayed upregulation of immune checkpoints such as CTLA4, TIGIT, and IDO1. Although we did not observe differential expression of PD-L1, prior studies reported high PD-L1 expression in dysgerminomas, correlating with dense tumor-infiltrating lymphocytes (TIL), including cytotoxic CD8+ T cells (20).