Although PD-L1 IHC has some limitations as a predictive biomarker [8] and other biomarkers, such as tumor mutational burden and microsatellite instability, have been proposed [16], the establishment of a sensitive and robust PD-L1 IHC for feline tumors is of particular importance for informed selection of cat subjects that are most likely to benefit from anti-PD-1/PD-L1 therapies. Here, CD274 is linked to neoplasm.