PD-L1 copy number gains: a predictive biomarker for PD-1/PD-L1 blockade therapy?

Immune checkpoint blockade has emerged as a promising and distinct treatment strategy and has caused a paradigm shift in oncology. Significant response and survival benefit have been observed in a fraction of patients who were treated with immune checkpoint inhibitors (ICIs) in several malignancies including melanoma (1-3), non-small-cell lung cancer (NSCLC) (4-7), gastric cancer (8), urothelial carcinoma (9), Hodgkin’s lymphoma (10), and head and neck squamous cell carcinoma (11).