Diffuse large B cell lymphoma (DLBCL), the most common lymphoid malignancy in adults, is a clinically and genetically heterogeneous disease that is further classified into transcriptionally defined activated B cell (ABC) and germinal center B cell (GCB) subtypes. We carried out a comprehensive genetic analysis of 304 primary DLBCLs and identified low-frequency alterations, captured recurrent mutations, somatic copy number alterations, and structural variants, and defined coordinate signatures in patients with available outcome data. We integrated these genetic drivers using consensus clustering and identified five robust DLBCL subsets, including a previously unrecognized group of low-risk ABC-DLBCLs of extrafollicular/marginal zone origin; two distinct subsets of GCB-DLBCLs with different outcomes and targetable alterations; and an ABC/GCB-independent group with biallelic inactivation of TP53, CDKN2A loss, and associated genomic instability. The genetic features of the newly characterized subsets, their mutational signatures, and the temporal ordering of identified alterations provide new insights into DLBCL pathogenesis. The coordinate genetic signatures also predict outcome independent of the clinical International Prognostic Index and suggest new combination treatment strategies. More broadly, our results provide a roadmap for an actionable DLBCL classification.

Purpose Programmed death ligand 1 (PD-L1) is an immunomodulatory molecule expressed by antigen-presenting cells and select tumors that engage receptors on T cells to inhibit T-cell immunity. Immunotherapies targeting the PD-1/PD-L1 pathway have shown durable anti-tumor effects in a subset of patients with solid tumors. PD-L1 can be expressed by Reed-Sternberg cells comprising classical Hodgkin lymphoma (CHLs) and by malignant B cells comprising EBV-positive post-transplant lymphoproliferative disorders (PTLDs). We sought to determine whether the expression of PD-L1 represents a general strategy of immune evasion among aggressive B-cell lymphomas and virus- and immunodeficiency-associated tumors. Experimental Design Using novel antibodies and formalin-fixed, paraffin-embedded (FFPE) tissue biopsies, we examined 237 primary tumors for expression of PD-L1 protein. Results Robust PD-L1 protein expression was found in the majority of nodular sclerosis CHL, mixed cellularity CHL, primary mediastinal large B-cell lymphoma, T-cell/histiocyte-rich B-cell lymphoma, EBV-positive and -negative PTLD, and EBV-associated diffuse large B-cell lymphoma (DLBCL), plasmablastic lymphoma, extranodal NK/T cell lymphoma, nasopharyngeal carcinoma, and HHV8-associated primary effusion lymphoma. Within these tumors, PD-L1 was highly expressed by malignant cells and tumor-infiltrating macrophages. In contrast, neither the malignant nor the non-malignant cells comprising nodular lymphocyte-predominant Hodgkin lymphoma, DLBCL-not otherwise specified, Burkitt lymphoma, and HHV8-associated Kaposi sarcoma expressed detectable PD-L1. Conclusion Certain aggressive B-cell lymphomas and virus- and immunodeficiency-associated malignancies associated with an ineffective T-cell immune response express PD-L1 on tumor cells and infiltrating macrophages. These results identify a group of neoplasms that should be considered for PD-1/PD-L1-directed therapies, and validate a method to detect PD-L1 in FFPE tissue biopsies.

Background-Malignant cells of classical Hodgkin lymphoma (cHL) are characterised by genetic alterations at the 9p24·1 locus. This leads to overexpression of the programmed death 1 (PD-1) ligands and enables tumour cells to evade immune surveillance. A phase 1b study showed that nivolumab, a PD-1-blocking antibody, produced a high response rate in patients with relapsed and refractory cHL, with an acceptable safety profile. This phase 2 study assessed the clinical benefit of nivolumab monotherapy in patients with cHL after autologous stem-cell transplantation and brentuximab vedotin failure.

Summary Diffuse Large B-Cell Lymphoma (DLBCL) is a biologically heterogeneous and clinically aggressive disease. Here, we explore the role of BET bromodomain proteins in DLBCL, using integrative chemical genetics and functional epigenomics. We observe highly asymmetric loading of BRD4 at enhancers, with approximately 33% of all BRD4 localizing to enhancers at 1.6% of occupied genes. These super-enhancers prove particularly sensitive to bromodomain inhibition, explaining the selective effect of BET inhibitors on oncogenic and lineage-specific transcriptional circuits. Functional study of genes marked by super-enhancers identifies DLBCLs dependent on OCA-B and suggests a strategy for discovering unrecognized cancer dependencies. Translational studies performed on a comprehensive panel of DLBCLs establish a therapeutic rationale for evaluating BET inhibitors in this disease.