Worth noting is also the dynamic nature of PD1/PD-L1 and discordance of PD-L1 expression in primary versus metastatic tumors, which has been observed in both solid tumors and sarcomas [31,32,33], and its role as a predictive biomarker may require assessment of more than one tumor from the patient. The gene discussed is PDCD1; the disease is metastatic neoplasm.