PDCD1LG2 and neoplasm: While we could not reliably assess tumor mutational burden due to limited availability of paired germline samples, we analyzed copy numbers of CD274/PDCD1LG2 and found that 29.2% (14/48) patients had shallow deletions and 12.5% (6/48) had copy gains (3–4 copies) of these genes, potentially affecting PD-L1 and PD-L2 expression (53) and sensitivity to immune checkpoint inhibitors.