CD274 and cancer: PD-L1 is located on Chromosome 9p24.1, and when this genomic region is amplified, the expression of PD-L1 is significantly increased, as evidenced by poor prognosis and short progression-free survival for patients with Hodgkin's lymphoma, small cell lung cancer (SCLC), non-small cell lung cancer (NSCLC), and other malignant tumors [56–58].