PDCD1 and neoplasm: Serum biomarkers identified through biopsy, such as human epidermal growth factor receptor 2, programmed cell death protein 1/programmed death-ligand 1 (PD-1/PD-L1), microsatellite instability, NTRK mutation, and somatic mutations, defined as tumor mutational burden, have predictive implications and can further dictate therapeutic measures.