PDCD1LG2 and primary central nervous system lymphoma: Indeed, nivolumab showed single-agent activity in relapsed and refractory PCNSL patients, and frequent copy-number alterations in 9p24.1/PD-L1/PD-L2 of tumor cells leading to the expression of PD-L1 and PD-L2 were found in PCNSL [17, 18].