Genetic basis of PD-L1 overexpression in diffuse large B-cell lymphomas

K Georgiou, L Chen, M Berglund, W Ren… - Blood, The Journal …, 2016 - ashpublications.org
K Georgiou, L Chen, M Berglund, W Ren, NFCC De Miranda, S Lisboa, M Fangazio, S Zhu…
Blood, The Journal of the American Society of Hematology, 2016ashpublications.org
Diffuse large B-cell lymphoma (DLBCL) is one of the most common and aggressive types of
B-cell lymphoma. Deregulation of proto-oncogene expression after a translocation, most
notably to the immunoglobulin heavy-chain locus (IGH), is one of the hallmarks of DLBCL.
Using whole-genome sequencing analysis, we have identified the PD-L1/PD-L2 locus as a
recurrent translocation partner for IGH in DLBCL. PIM1 and TP63 were also identified as
novel translocation partners for PD-L1/PD-L2. Fluorescence in situ hybridization was …
Abstract
Diffuse large B-cell lymphoma (DLBCL) is one of the most common and aggressive types of B-cell lymphoma. Deregulation of proto-oncogene expression after a translocation, most notably to the immunoglobulin heavy-chain locus (IGH), is one of the hallmarks of DLBCL. Using whole-genome sequencing analysis, we have identified the PD-L1/PD-L2 locus as a recurrent translocation partner for IGH in DLBCL. PIM1 and TP63 were also identified as novel translocation partners for PD-L1/PD-L2. Fluorescence in situ hybridization was furthermore used to rapidly screen an expanded DLBCL cohort. Collectively, a subset of samples was found to be affected by gains (12%), amplifications (3%), and translocations (4%) of the PD-L1/PD-L2 locus. RNA sequencing data coupled with immunohistochemistry revealed that these cytogenetic alterations correlated with increased expression of PD-L1 but not of PD-L2. Moreover, cytogenetic alterations affecting the PD-L1/PD-L2 locus were more frequently observed in the non–germinal center B cell–like (non-GCB) subtype of DLBCL. These findings demonstrate the genetic basis of PD-L1 overexpression in DLBCL and suggest that treatments targeting the PD-1–PD-L1/PD-L2 axis might benefit DLBCL patients, especially those belonging to the more aggressive non-GCB subtype.
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