Check this checkpoint inhibitor in lymphoma

摘要

In this issue of Blood, Zinzani et al(1) report that the immune check point inhibitor pembrolizumab is active against relapsed/refractory primary mediastinal large B-cell lymphoma (PMLBCL). This unique clinicopathologic entity accounts for up to 10% of all diffuse large B-cell lymphomas (DLBCLs) and is most commonly seen in females between 20 and 40 years of age. Gene expression profiling has shown that the genes expressed in PMLBCL are essentially those of Hodgkin lymphoma (HL).(2) Some of these genes are related to the signaling pathways of NF-kappa B and JAK-STAT (see figure). Of interest is that chromosome 9p24.1 alterations (see figure), which have been associated with programmed death ligand (PD-L1)/L2 upregulation in classical HL, have also been observed in PMLBCL.(3) In view of these similarities in gene expression between PMLBCL and HL, it should not come as a surprise that overexpression of the PD-L1 gene, typically seen in HL, is also observed in PMLBCL.