CD274 and neoplasm: Immunohistochemistry (IHC) staining of tumor specimens showed that PIK-93 treatment induced a substantial increase in the number of CD4+ and CD8+ TILs (Fig. 6, H and I), suggesting that PIK-93 may have prompted the activation and/or recruitment of CD4+ T helper and CD8+ cytotoxic T cells to the TME via PD-L1 degradation.