ALBERT

Description: Diffuse large B cell lymphoma (DLBCL) comprises two distinct molecular subtypes: germinal center B cell (GCB) subtype and activated B cell (ABC) subtype. The pathogenesis of ABC-DLBCL is characterized by two processes - the activation of NF-KB and a block in terminal B-cell differentiation. However, in GCB-DLBCL only a few biologically relevant pathways have been identified, which has hampered the development of targeted therapies with specific efficacy in this subtype. Recurrent genetic alterations involved in PI3K-AKT signaling pathway have been identified in the patients with solid cancers, and dramatic responses have been observed to PI3K inhibitors in clinical trials. The prevalence and clinical significances of genetic alterations in PI3K-AKT pathway have not been well studied in DLBCL. Previous studies have reported that loss of PTEN expression was observed in almost half of GCB-DLBCL cases but were largely absent in the ABC-DLBCL. In addition, functional studies have recently shown that the inactivation of Gα13 signaling pathway genes may also activate AKT in germinal center driven lymphoma, raising the possibility that additional genes within these pathways are affected in GCB-DLBCL. Herein, we identified genetic alterations involved in the PI3K-AKT pathway and evaluated their clinical impact. We analyzed biopsies from 347 patients newly diagnosed with de novo DLBCL uniformly treated with R-CHOP at the BC Cancer Agency. High-resolution copy number analyses were performed using Affymetrix SNP 6.0 arrays. Mutation status was determined using deep targeted re-sequencing of the coding exons of 61 genes with a Truseq Custom Amplicon assay (Illumina) and/or Fluidigm Access Array chips, and RNAseq. Immunohistochemical staining of phospho-AKT (pAKT) was performed on tissue microarrays (n=332). Cell-of-origin (COO) was assigned by gene expression (Lymph2Cx assay) in 323 cases - 183 GCB, 104 ABC and 36 unclassifiable. GISTIC analysis revealed several COO-specific peaks with copy number changes. Among them, focal 10q23.3 deletion including PTEN was detected in GCB-DLBCL (q-value=1.7e-7), but not in ABC-DLBCL. We also identified two focal amplification peaks in GCB-DLBCL containing microRNAs MIR17HG (13q31.1;q=1.01e-24) and MIR21 (17q23.3; q=1.45e-6), which are known to down-regulate PTEN and result in activation of PI3K-AKT signaling. Furthermore, we detected recurrent INPP4B deletion (4q21.23) in GCB-DLBCL (q= 0.004) only. Of note, the lipid phosphatase INPP4B has been shown to play a role as a tumor suppressor that controls the levels of PI3K lipid products leading to AKT activation and metastasis of some solid cancers. This is consistent with the observation that PTEN and INPP4B deletions were individually associated with increased pAKT protein expression in our cohort (p=0.015 and p

Description: Introduction: Grey zone lymphoma (GZL), a B-cell lymphoma with features intermediate between large B-cell lymphoma (LBCL) and classical Hodgkin lymphoma (cHL), is a rare and poorly defined entity. To decipher its mutational landscape and discover new therapeutic targets, we performed exome sequencing of 31 GZL cases. Methods: GZL cases from the LYSA group (N=139) and BC Cancer (N=30) were centrally reviewed and classified as previously published (Sarkozy et al, Am J Surg Pathol 2019). Whole-exome sequencing was performed on 31 cases with available fresh frozen tissue, using laser micro-dissection (LMD, MMI technology) to enrich for tumor cells and obtain matching normal DNA from microenvironment cells. DNA was extracted (Agencourt® DNAdvance kit) and genomic libraries were constructed with the Ovation ultra-low kit (Nugen®). Exome capture was performed using Agilent SureSelectXT V6+UTR followed by paired-end sequencing (NextSeq®). Somatic nucleotide variants (SNVs) and indels were identified using VarScan, Strelka and Mutect. Parameters affecting the sensitivity and specificity of variant calling were optimized using 7 "gold standard" cases for which DNA from peripheral blood cells was additionally available. Possible oncogenic drivers were identified based on rate of recurrence, MutSigCV and literature review. Results: Among the 31 GZL cases, the median age was 41 y (14-83) with a sex ratio of 15M:16F; 21 cases had mediastinal involvement, including 15 within the thymic area; EBER in-situ hybridization (ISH) was positive in 8 cases. Seven (23%) cases were classified as group-0 (cHL morphology with 100% CD20 expression), 22 (71%) with an intermediate morphology as group-1 (N=9, cHL-like morphology) or group-2 (N=13, LBCL-like morphology) and 2 (6%) as group-3 (LBCL with 100% of CD30 expression). The mean coverage was 96X (42-203) for tumor samples. One case was excluded due to failure in the LMD process. Among the 30 cases, 6628 variants across 4826 genes were found, including 2903 coding mutations (325 indels and 2808 SNVs, mean of 104/sample, range: 15-678), 721 affecting the 5' UTR and 2774 the 3' UTR. A total of 152 genes were identified as being potential oncogenic drivers, with a mean of 11 mutated genes per case (range 2-36). The most recurrently mutated genes were SOCS1 (33%), B2M (23%), GNA13 (20%), LRRN3 (17%), and ZNF217, NCOR1, ITPKB, IRF2BP2, CSF2RB, and CSMD3 (13% each). The epigenetic SWI/SNF and transcription regulation pathway (including NCOR1/2, ARID1A, KMT2D, KMT2A) was affected in 73% of the cases, JAK/STAT in 70% and NF-kB in 19%. As assessed by CNVkit and GISTIC, the most recurrent gains/amplifications identified were in 9p24.1 (JAK2, CD274, PDCD2LG2; 69%) and 2p16.1 (REL, BCL11A; 62%), and losses in 11q14.3 (ATM; 48%) and 12q24.33 (NCOR2; 48%). Based on mutational signature analysis, individual base substitutions were linked to mutagenic processes, with the highest contributions associated with aging (29%) and defective DNA mismatch repair (27%); moreover, mutations attributable to AID/APOBEC activity (5%), were found to be significantly enriched in EBV- vs. EBV+ cases (p = 0.013). EBV+ cases had fewer total variants (mean 98 vs 258, p=0.08) and potential oncogenic variants (mean 7 vs 15, p=0.03) compared to EBV- cases. EBV+ cases also lacked mutations in the NF-kB pathway and MHC-class I components (B2M and HLA-B: 0% vs 43% in EBV-, p=0.06) but had mutations in STAT3, DHX58, ACTB and ATP13A4 (6/7 cases) not present in the 23 EBV- cases. LRRN3 and GNA13 mutations were significantly associated with thymic area involvement (40% vs 0%, p=0.01). Furthermore, fluorescence-ISH indicated that 20% (1/5) of EBV+ cases had a rearrangement in the CIITA locus (16p13.13) vs 53% (9/17) in EBV- cases. Patients with an intermediate morphology had more oncogenic variants than those in group 0 and 3 (mean of 15 vs 6 variants/case, p=0.01 affecting 12 vs 5 genes, p=0.004). Finally, NCOR1 (N=4) and NCOR2 (N=2) mutations were exclusively found in cases with intermediate morphology (23% vs 0% for those with group 0 or 3 morphology). Conclusion: These data suggest that GZL is a highly heterogenous disease harboring somatic driver events shared with PMBCL and HL. We also discovered novel gene mutations pointing to the importance of previously unrecognized pathways in the pathogenesis of GZL. The distinct mutational pattern in EBV+ GZL suggests divergent evolutionary trajectories. Disclosures Sarkozy: Takeda: Research Funding. Salles:Merck: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis, Servier, AbbVie, Karyopharm, Kite, MorphoSys: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Educational events; Autolus: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Educational events; Epizyme: Consultancy, Honoraria; BMS: Honoraria; Amgen: Honoraria, Other: Educational events; Roche, Janssen, Gilead, Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Educational events. Savage:BMS, Merck, Novartis, Verastem, Abbvie, Servier, and Seattle Genetics: Consultancy, Honoraria; Seattle Genetics, Inc.: Consultancy, Honoraria, Research Funding. Scott:Celgene: Consultancy; Roche/Genentech: Research Funding; Janssen: Consultancy, Research Funding; NanoString: Patents & Royalties: Named inventor on a patent licensed to NanoSting [Institution], Research Funding. Steidl:Juno Therapeutics: Consultancy; Tioma: Research Funding; Roche: Consultancy; Bristol-Myers Squibb: Research Funding; Nanostring: Patents & Royalties: Filed patent on behalf of BC Cancer; Seattle Genetics: Consultancy; Bayer: Consultancy.

Description: Key Points HGBL-DH/TH makes up 8% of de novo DLBCL, with HGBL-DH/TH with BCL2 rearrangement being a GCB phenomenon. Restricting FISH testing to tumors with dual protein expression and GCB subtype results in testing

Description: Primary mediastinal large B-cell lymphoma (PMBL) represents a clinically and pathologically distinct subtype of large B-cell lymphomas. Furthermore, molecular studies, including global gene expression profiling, have provided evidence that PMBL is more closely related to classical Hodgkin lymphoma (cHL). Although targeted sequencing studies have revealed a number of mutations involved in PMBL pathogenesis, a comprehensive description of disease-associated genetic alterations and perturbed pathways is still lacking. Here, we performed whole-exome sequencing of 95 PMBL tumors to inform on oncogenic driver genes and recurrent copy number alterations. The integration of somatic gene mutations with gene expression signatures provides further insights into genotype–phenotype interrelation in PMBL. We identified highly recurrent oncogenic mutations in the Janus kinase-signal transducer and activator of transcription and nuclear factor κB pathways, and provide additional evidence of the importance of immune evasion in PMBL (CIITA, CD58, B2M, CD274, and PDCD1LG2). Our analyses highlight the interferon response factor (IRF) pathway as a putative novel hallmark with frequent alterations in multiple pathway members (IRF2BP2, IRF4, and IRF8). In addition, our integrative analysis illustrates the importance of JAK1, RELB, and EP300 mutations driving oncogenic signaling. The identified driver genes were significantly more frequently mutated in PMBL compared with diffuse large B-cell lymphoma, whereas only a limited number of genes were significantly different between PMBL and cHL, emphasizing the close relation between these entities. Our study, performed on a large cohort of PMBL, highlights the importance of distinctive genetic alterations for disease taxonomy with relevance for diagnostic evaluation and therapeutic decision-making.

Description: Background: Diffuse large B-cell lymphoma (DLBCL) is a highly heterogeneous neoplasm with 40% of patients experiencing treatment failure following immuno-chemotherapy (R-CHOP). Both cell-of-origin (COO) and presence of concurrent MYC/BCL2 rearrangements (DHIT) are significantly associated with distinct inferior outcome. Recently, next-generation sequencing (NGS) studies have uncovered distinct genetic subtypes, including a sizable ABC/GCB-independent group characterized by more frequent TP53 abnormalities. The patterns of TP53 mutations and the prognostic significance in DLBCL have been previously reported. However, such information is rarely available at the time of diagnosis as diagnosis of DLBCL for most patients is based on morphology and phenotype, assessed by immunohistochemistry (IHC). To bridge the gap between genotype and phenotype, we examined the TP53 mutational status and TP53 protein over-expression (IHC) in a large population-based DLBCL cohort uniformly treated with R-CHOP (Ennishi et al. Blood 2017 129:2760-2770). Methods: We analyzed 347 newly diagnosed de novo DLBCL cases uniformly treated with R-CHOP in British Columbia. Comprehensive clinical annotation was available through the BC Cancer Lymphoid Cancer Database. Deep targeted re-sequencing of the coding exons of TP53 was performed using a Truseq Custom Amplicon assay (Illumina) on the Miseq platform. IHC staining for TP53 (DO7), TP21, COO (Hans) and break-apart FISH assays for MYC and BCL2 were performed on tissue microarrays (n=332). COO classification was also performed using the Lymph2Cx assay (NanoString) (n=324). Strong TP53 expression (TP53+) was defined as high intensity (3/3) expression in 〉50% of the malignant cells. Results: TP53 mutations (p53mut) were present in 72 cases (22.2%) with 84% being missense and 64% localized to the DNA binding-motifs. There were 54 TP53+ tumors by IHC (17%), of which 51 (94%) had p53mut, with a sensitivity of 70% for detection of p53mut. All but one TP53+ with p53mut (50/51 cases) had missense mutations. All TP53+ with missense p53mut (85% of all missense p53mut) showed strong nuclear expression, one recurrent nonsense p53mut showed combined cytoplasm/nuclear TP53+, while all splice site and frameshift variants were TP53+-negative. All TP53+ cases were negative for TP21; 30 (56%) cases were GCB (Hans) while 24 (44%) cases were non-GCB (Hans) and only 4 (16%) cases were DHIT. Both p53mut and TP53+ were associated with poor overall survival (OS) (p=0.004 and p=0.007, respectively) and disease-specific survival (DSS) (p=0.003 and p=0.001, respectively). In multivariate analysis with IPI, COO (Hans) and DHIT status, both p53mut and TP53+ were independent predictors of OS (HR=0.6, 95%CI=0.4-0.9, p=0.008 and HR=0.6, 95%CI=0.4-0.9, p=0.011, respectively) and DSS (HR=0.6, 95%CI=0.4-0.9, p=0.01 and HR=0.5, 95%CI=0.3-0.8, p=0.004, respectively). These results were consistent when the Lymph2Cx was used to assign COO (n = 324). Importantly, patients with TP53+ tumors showed significantly poorer outcome (OS and DSS) when compared with patients with tumors negative for TP53 stratified by both Hans COO subtypes (p=0.001 and p

Description: Key Points MYC and BCL2 genetic alterations are associated with COO subtype-specific clinical effect in R-CHOP-treated DLBCL.

Description: Introduction : Follicular lymphoma (FL) remains an incurable malignancy as patients eventually experience progressive disease. A subset of patients is at risk of early lymphoma-related mortality due to histological transformation (TFL) to aggressive lymphoma (2-3% of patients per year) or early progression after immuno-chemotherapy, each of which leads to shortened survival. Mutations associated with transformation and/or early progression have been reported in the literature (e.g. CDKN2A, TP53, B2M) and the m7-FLIPI clinico-genetic risk model defines a high-risk patient group with poor failure-free survival after first-line treatment. However, the current knowledge of genetic alterations underlying transformation and/or early progression is inadequate to explain the majority of transformed cases and accurately predict early progressive disease. Materials and Methods: We performed targeted capture-based sequencing of 94 genes in a large cohort of fresh-frozen and formalin-fixed and paraffin-embedded patient specimens (402 samples in total). This cohort comprised 277 samples from 159 patients that experienced transformation (including 128 samples at T1 (the time of FL) and 149 samples at T2 (the time of transformation) with 118 paired biopsies) and 125 samples from 125 patients (pre-treatment samples only) presenting with either early progression within 2.5 years after starting immunochemotherapy (n=41) or late or never progression for at least 5 years after starting immunochemotherapy or observation (n=84). Mutations were called using MutationSeq and putative single nucleotide polymorphisms were filtered out using either matching germline samples (n=84) or dbSNP (v147). Bayesian proportion tests were used to compare the prevalence of gene mutations between groups. Results : We first compared T1 (n=128) and T2 (n=149) samples from 159 patients experiencing transformation. Eleven genes were more commonly altered in transformed lymphoma. These included genes that had previously been associated with transformation, such as TP53, B2M, MYC and EBF1, as well as genes that have not yet been implicated as contributing to this process, for example EZH2, CCND3, PIM1 and ITPKB. Moreover, mutations in GNA13, S1PR2 and P2RY8, that have been implicated in dissemination of germinal centre B cells, were enriched in T2 samples. In addition, cell-of-origin classification was available for 108 of the TFL cases with DLBCL histology, 18 and 90 of which were of the ABC and GCB subtype, respectively. Although the number of ABC-TFL cases was small, we observed higher percentages of BCL10 (16% versus 1%, Fisher P=0.004), CD79B (22% versus 4%, Fisher P=0.005) and MYD88 mutations (28% versus 9%, P=0.006) in ABC-TFL than in GCB-TFL, suggesting that B-cell receptor signaling and NF-κB signaling are important contributors to the ABC phenotype in TFL. Next, we assessed the association of gene mutations with patient outcomes contrasting early progressers (n=41) and late or non-progressers (n=84). Eleven genes were mutated more commonly in early progressers than in late progressers, including KMT2C, TP53, BTG1, MKI67, XBP1 and SOCS1. Overall, 32 out of 41 early progressers (78%) had mutations in at least one of the 11 early progression-associated genes, but none of the individual early progression-associated genes were mutated at a frequency 〉 22%. Thus, early progression appears to be related to relatively infrequent genetic alterations. None of the early progression-associated gene mutations form part of the m7-FLIPI outcome predictor. Furthermore, in our cohort that was enriched for clinical extremes, the m7-FLIPI was similarly associated with early progression when compared to the FLIPI but it was not superior, having higher specificity (89% versus 76%), but lower sensitivity (36% versus 63%). Conclusions: We found novel associations of gene mutations with transformation and showed that TFL is molecularly heterogeneous, with the ABC subtype being characterized by differential gene mutation when compared to the GCB subtype. With regards to progressive disease after immuno-chemotherapy, our approach identified early progression as a distinct clinico-genetic disease category that is imperfectly captured by traditional prognostic tools. Disclosures Connors: Seattle Genetics: Research Funding; Bristol Myers Squib: Research Funding; F Hoffmann-La Roche: Research Funding; NanoString Technologies: Research Funding; Millennium Takeda: Research Funding. Scott:NanoString Technologies: Patents & Royalties: named inventor on a patent for molecular subtyping of DLBCL that has been licensed to NanoString Technologies.

Description: Background: Diffuse large B cell lymphoma (DLBCL) is divided into two distinct molecular subtypes, germinal center B cell (GCB) subtype and activated B cell (ABC) subtype. Genetic landscape studies of DLBCL have revealed several GCB-DLBCL specific mutations, including CREBBP, GNA13, EZH2, TNFRSF14, BCL2 and MEF2B. Functional studies have recently shown that the inactivation of Gα13 signaling pathway genes, including GNA13, together with BCL2 over-expression, allows GC B-cells to escape the germinal center niche and widely disseminate. Although these findings revealed a critical role of genetic alterations of Gα13 signaling pathway in GC-driven mouse models of lymphomagenesis, clinical correlation is lacking. Here we analyzed the clinical impact of genetic alterations of Gα13 signaling pathway in a large population-based DLBCL cohort. Methods: We analyzed 347 newly diagnosed de novo DLBCL cases that were uniformly treated with R-CHOP at the BC Cancer Agency. Comprehensive clinical annotation was available through the BCCA Lymphoid Cancer Database. Deep targeted re-sequencing of the coding exons of GNA13, P2RY8, ARHGEF1, S1PR2 and RHOA was performed using a Truseq Custom Amplicon assay (Illumina) and/or Fluidigm Access Array chips. High-resolution copy number analyses were performed using Affymetrix SNP 6.0 arrays. Immunohistochemical staining and break-apart FISH assays for MYC and BCL2 were performed on tissue microarrays (n=332). Cell-of-origin classification was available in 331 cases, according to gene expression profiling by the Lymph2Cx assay using the NanoString platform (Scott, Blood 2014; 123) in 299 patients and the Hans algorithm (Hans, Blood 2004; 103) in 32 cases with low tumor content (

Description: Background: MYC and BCL2 are critical driver genes for non-Hodgkin lymphoma including diffuse large B-cell lymphoma (DLBCL). However, the clinical impact of MYC and BCL2 genetic alterations, apart from translocations, has not been comprehensively investigated using high-resolution genetic assays, such as next generation sequencing and high-resolution SNP arrays. Moreover, correlations with cell of origin (COO) subtype, determined by gene expression profiling, have not been widely studied in a large homogeneously treated cohort. We determined the frequency and clinical impact of MYC and BCL2 genetic aberrations in DLBCL in a large population-based cohort uniformly treated with R-CHOP. Methods: We analyzed 347 newly diagnosed de novo DLBCL cases that were treated with R-CHOP in BC. Comprehensive clinical annotation was available through the BCCA Lymphoid Cancer Database. Deep targeted re-sequencing of the coding exons of MYC and BCL2 was performed using a Truseq Custom Amplicon assay (Illumina) on the Miseq platform. High-resolution copy number analyses were performed using Affymetrix SNP 6.0 arrays. Immunohistochemical staining and break-apart FISH assays for MYC and BCL2 were performed on tissue microarrays (n=332). Dual positivity for MYC (cut off; 40%) and BCL2 (cut off; 50%) proteins identified a dual protein expresser (DPE) phenotype. COO classification was achieved using the Lymph2Cx assay based on NanoString technology in 299 patients and the Hans algorithm in 32 cases with low tumor content (

Description: Recognizing biological heterogeneity in diffuse large B-cell lymphoma (DLBCL), significant effort has been made to define distinct molecular subgroups of prognostic importance which harbor potentially targetable biology. Reflecting this, in the recent revision of the WHO classification, DLBCL was divided into cell-of-origin molecular subtypes and a new entity was defined - high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements (HGBL-DH/TH). ~8% of tumors with DLBCL morphology are HGBL-DH/TH and all HGBL-DH/TH with BCL2 translocations (HGBL-DH/TH-BCL2) are of the GCB molecular subtype. To explore specific biology operating in HGBL-DH/TH-BCL2, we analyzed RNAseq data from 157 de novo GCB DLBCL tumors (25 being HGBL-DH/TH-BCL2) with the aim of defining gene expression signatures that distinguish such cases from other GCB-DLBCLs. We identified 104 genes that were most significantly differentially expressed between HGBL-DH/TH-BCL2 and other GCB-DLBCLs, defined as having a 95% confidence interval of the Importance Score that did not cross 0. A model constructed from the expression of these genes clustered 42 tumors into one group ("double-hit signature" positive - DHITsig pos), and 115 tumors into the DHITsig neg group. 22 tumors were HGBL-DH/TH-BCL2 within the DHITsig pos group compared with only 3 tumors in the DHITsig neg group. We next assessed the clinical impact of the DHITsig within a uniformly R-CHOP treated cohort of de novo GCB-DLBCL drawn from a population-based registry, which included the discovery cases. The DHITsig pos group had significantly inferior outcomes for time to progression (TTP) and overall survival (OS) (P 〈 0.001 and P = 0.01, respectively) similar to ABC-DLBCL (Figs A, B). Notably, the non-HGBL-DH/TH-BCL2 cases sharing the DHITsig showed the same poor prognosis as the HGBL-DH/TH-BCL2 cases. A multivariate Cox model of TTP revealed that DHITsig remained prognostic, independent of IPI and MYC/BCL2 dual protein expression (HR = 3.1 [1.5 - 6.4], P = 0.002). We then applied this gene expression model to GCB-DLBCL in an independent dataset (n = 262 GCB-DLBCLs; Reddy et al,Cell 2017). Validating the prognostic significance, the DHITsig pos group had significantly inferior OS compared with other GCB-DLBCLs (P 〈 0.001) similar to ABC-DLBCL (Fig C). We then sought to determine whether differentially expressed genes, according to DHITsig, could inform on the biology of the DHITsig pos group. Gene set enrichment analysis (GSEA) strongly suggested a germinal centre dark-zone (DZ) cell-of-origin for the DHITsig pos tumors with significant enrichment of DZ and light-zone (LZ) gene signatures (Victora et al, Blood 2012) in DHITsig pos and neg tumors, respectively (FDR = 0.002 and 〈 0.001). Furthermore, the DHITsig pos group had up-regulation of pathways related to mitochondrial metabolism and RNA synthesis (both FDR 〈 0.001). We separately identified mutations associated with DHITsig pos cases within GCB-DLBCL. In addition to the expected enrichment of MYC and BCL2 mutations, chromatin modifiers EZH2 and CREBBP, as well as RFX7 and DDX3X (mutated in Burkitt lymphoma), were more frequently mutated in DHITsig pos tumors. In contrast, mutations of TNFAIP3, MYD88 and IRF4, more typical of ABC-DLBCLs, were more prevalent in DHITsig neg tumors. To enable application to FFPE biopsies, the DLBCL90 NanoString assay was developed by translating the DHIT gene expression signature into a 30-gene module that was then added to the Lymph2Cx assay. The DLBCL90 assay was applied to 171 DLBCL tumors (including 156 from the discovery cohort), yielding 26% DHITsig pos, 64% DHITsig neg, and 10% unclassified, with a frank misclassification rate of 3% against the RNAseq comparator. The prognostic significance of the groups was maintained (Fig D). Importantly, the DHITsig neg group had a disease specific survival of 91% at 5 years. To validate the association between the DHITsig and HGBL-DH/TH-BCL2 tumors, the DLBCL90 assay was applied to 113 transformed follicular lymphoma tumors. Within the DHITsig pos group, 19/34 tumors were HGBL-DH/TH-BCL2 compared with 0/58 in the DHITsig neg group. In conclusion, we have identified a clinically and biologically distinct subgroup of GCB-DLBCL tumors that are defined by the HGBL-DH/TH-BCL2 gene signature. The translation to an assay applicable to FFPE allows exploration of its utility to guide patient management within the context of clinical trials. Figure. Figure. Disclosures Sehn: Merck: Consultancy, Honoraria; TG Therapeutics: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Lundbeck: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Morphosys: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria; Roche/Genentech: Consultancy, Honoraria; Janssen: Consultancy, Honoraria. Steidl:Nanostring: Patents & Royalties: patent holding; Roche: Consultancy; Tioma: Research Funding; Seattle Genetics: Consultancy; Bristol-Myers Squibb: Research Funding; Juno Therapeutics: Consultancy. Connors:Cephalon: Research Funding; Amgen: Research Funding; F Hoffmann-La Roche: Research Funding; Roche Canada: Research Funding; Bristol Myers-Squibb: Research Funding; Janssen: Research Funding; Bayer Healthcare: Research Funding; Takeda: Research Funding; NanoString Technologies: Patents & Royalties: Named Inventor on a patent licensed to NanoString Technologies, Research Funding; Seattle Genetics: Honoraria, Research Funding; Merck: Research Funding; Genentech: Research Funding; Lilly: Research Funding. Gascoyne:NanoString: Patents & Royalties: Named Inventor on a patent licensed to NanoString Technologies. Scott:Roche: Research Funding; Celgene: Consultancy, Honoraria; NanoString: Patents & Royalties: Named Inventor on a patent licensed to NanoString Technologies, Research Funding; Janssen: Research Funding.