CD274 and ovarian cancer: We discovered no significant differences in PD‐L2 or EGFR expression between naive and recurrent tumors, which is consistent with the findings of previous studies in HNSCC, ovarian cancer, and glioblastoma [23, 39, 40, 41] suggesting that PD‐L1, rather than PD‐L2 or EGFR, would be associated with HNSCC recurrence.