PDCD1LG2 and primary central nervous system lymphoma: Meanwhile, the STAT3 gene is found to be expressed in various types of cancer, including PCNSL.339 Amplification of chromosome 9p24.1 leads to elevated expression of PD-L1 and PD-L2, while PD-L1 and PD-L2 can participate in the immune evasion and regulatory mechanisms of PCNSL.340 Additionally, somatic hypermutation (SHM) may lead to PCNSL pathogenesis and may offer a rationale for immunotherapy.