Specific expression of PD‐L1 in RELA‐fusion supratentorial ependymoma: Implications for PD‐1‐targeted therapy

These findings in ST-RELA suggest tumor evasion and immunsuppression due to PD-L1/PD-1-mediated T-cell exhaustion. Trials of checkpoint inhibitors in EPN should be enriched for ST-RELA tumors.