CD274 and neoplasm: Recently, new PET tracers, such as 89Zr-C4 and 18F-BMS-986192, that visualize tumor PD-L1 expression have been developed and show good correlation with tumor PD-L1 expression as measured by IHC and responses to immunotherapy.41 42 Since these PET images can reveal the heterogeneity of PD-L1 expression between different tumor lesions, they may predict dissociated responses prior to treatment initiation.