CD274 and neoplasm: A central focus is placed on biomarker-based immune monitoring strategies, encompassing both tissue-based biomarkers—such as programmed cell death ligand 1 (PD-L1) expression, microsatellite instability, tumor mutational burden, tumor-infiltrating lymphocytes (TILs), and gene expression signatures—and blood-based biomarkers, including gene expression profiling, comprehensive immunophenotyping, and cytokine profiling.