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.

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Key Points• Outcome prediction in DLBCL.• MYC status in concert with BCL2 and BCL6.MYC rearrangements occur in 5% to 10% of diffuse large B-cell lymphomas (DLBCL) and confer an increased risk to cyclophosphamide, hydroxydaunorubicin, oncovin, and prednisone (CHOP) and rituximab (R)-CHOP treated patients. We investigated the prognostic relevance of MYC-, BCL2-and BCL6-rearrangements and protein expression in a prospective randomized trial. Paraffin-embedded tumor samples from 442 de novo DLBCL treated within the RICOVER study of the German High-Grade NonHodgkin Lymphoma Study Group (DSHNHL) were investigated using immunohistochemistry and fluorescence in situ hybridization (FISH) to detect protein expression and breaks of MYC, BCL2, and BCL6. Rearrangements of MYC, BCL2, and BCL6 were detected in 8.8%, 13.5%, and 28.7%, respectively. Protein overexpression of MYC (>40%) was encountered in 31.8% of tumors; 79.6% and 82.8% of tumors expressed BCL2 and BCL6, respectively. MYC translocations, MYChigh, BCL2high, and BCL6low protein expressions were associated with inferior survival. In multivariate Cox regression modeling, protein expression patterns of MYC, BCL2 and BCL6, and MYC rearrangements were predictive of outcome and provided prognostic information independent of the International Prognostic Index (IPI) for overall survival and event-free survival. A combined immunohistochemical or FISH/immunohistochemical score predicts outcome in DLBCL patients independent of the IPI and identifies a subset of 15% of patients with dismal prognosis in the high-risk IPI group following treatment with R-CHOP.

IntroductionMature T-cell and natural killer (NK)-cell lymphomas are rare and heterogeneous diseases following an aggressive clinical course which necessitates immediate therapy. Outcome is generally believed poor although only 1 recent study 1 comprises all major T-cell lymphoma subtypes according to the World Health Organization classification 2,3 with spin-off studies reporting on clinical outcome and prognostic factors of various subtypes. [4][5][6] In contrast to the progress made in the treatment of aggressive B-cell lymphoma, 7-9 evidence for similar therapeutic improvements in T-and NK-cell lymphoma is largely absent. Therefore, we analyzed a large cohort of patients with T-cell lymphoma who have been treated on protocols of the German High-Grade Non-Hodgkin Lymphoma Study Group (Deutsche Studiengruppe Hochmaligne Non-Hodgkin Lymphome [DSHNHL]). We were particularly interested in the long-term results achieved with "standard" CHOP (cyclophosphamide, hydroxydaunorubicin (doxorubicin), Oncovin (vincristine), and prednisone/prednisolone) and CHOP-like therapy and wanted to define prognostic factors which should influence the decision which patients should be treated on standard or experimental protocols in the future. Methods PatientsBetween October 1993 and May 2007, 343 patients with mature nodal or extranodal T-cell or NK-cell lymphoma 2 were treated on protocols of the DSHNHL. Mandatory reference pathology was performed in 1 of the 6 German Reference Centers for Malignant Lymphomas (Berlin, Frankfurt, Kiel, Lübeck, Ulm, and Würzburg) prior to therapy. Of 343 patients, 320 could be assigned to 1 of the following subtypes: anaplastic large cell lymphoma (ALCL), anaplastic large cell lymphoma kinase-positive (ALKpositive); ALCL, ALK-negative; peripheral T-cell lymphoma unspecified (PTCLU); angioimmunoblastic T-cell lymphoma (AITL); NK/T-cell lymphoma; lymphoblastic lymphoma; enteropathy-type T-cell lymphoma; hepatosplenic ␥␦ T-cell lymphoma; or subcutaneous panniculitis-like T-cell lymphoma. In a subset of ALCL cases the ALK status had not been determined at the time of diagnosis, because antibodies were not available at that time. In these cases, the ALK status was defined retrospectively using the ALK1 antibody from DAKO (dilution 1:80, citrate buffer pH 6.0). The definition of ALK1-negative ALCL followed the current World Health Organization classification and required characteristic large cell morphology (indistinguishable from ALK-positive ALCL), strong and consistent expression of CD30 and negativity for ALK1. Moreover, most cases had expression of at least 1 cytotoxic molecule (Perforin, Granzyme B, or TIA). Twenty-three patients were excluded from the analysis because the ALK For personal use only. on May 12, 2018. by guest www.bloodjournal.org From status of some ALCL patients remained unknown (n ϭ 11) or the T-cell lymphoma subtype could not be confirmed for technical (n ϭ 3) or other reasons (n ϭ 9).All patients had thorough baseline and follow-up assessments (history, clinical evaluation, labor...

The effects of rituximab were superimposed on the effects of CHOP with no interactions between chemotherapy and antibody therapy. These results demonstrate that the IPI is still valid in the R-CHOP era.