Several factors may explain this: (i) PD-L1 expression is spatially heterogeneous, varying across different tumor regions or between biopsy specimens; (ii) its predictive value is limited, as other elements of the TME also influence therapeutic response; (iii) variability in assay platforms and testing protocols can lead to inconsistent results; and [92,93]; (iv) tissue-based biomarkers are dynamic and may evolve during treatment. The gene discussed is CD274; the disease is neoplasm.