CD274 and neoplasm: Several studies have found no correlation between tumor PD-L1 expression and the clinical efficacy of ICIs, and some patients with negative PD-L1 expression have also achieved durable clinical benefit.32 33 Moreover, PD-L1 IHC staining method has several limitations,34 including the heterogeneity of PD-L1 expression, no standardized approach for PD-L1 testing, and the availability of tumor tissues.