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Abstract T cell lymphoma (TCL) is a heterogeneous group of malignant lymphomas and is subdivided in three major subgroups, (i) cutaneous (mycosis fungoides (MF), sezary syndrome (SS) and primary CTCL), (ii) nodal (peripheral T-cell lymphoma, PTCL NOS, anaplastic large cell lymphoma (ALCL), angioimmunoblastic (AITL)) (iii) and extranodal. Because of this broad morphological spectrum and immunophenotypic variation the pathogenesis of most of the TCL is poorly understood. Constitutive STAT3 signaling provides growth-promoting signals in many forms of malignancy; however in-vivo activation of phosphorylated STAT3 and its clinical correlation in subtypes of TCLs has not been extensively studied. In this study we examined constitutive STAT3 activation in various subtypes of TCL tumors and performed pre-clinical testing to determine whether STAT3 inhibitors will be effective. First, we assessed the STAT3 activation (pSTAT3Tyr705) by immunohistochemistry (IHC) on a tissue microarray (TMA) from 169 untreated TCL patient samples. Using a cutoff of ≥30% pSTAT3 nuclear staining, 38% (64/169) of TCL tumors were pSTAT3+. Interestingly, pSTAT3 was differentially expressed among the various TCL subgroups. 27% (16/59) PTCL NOS, 29% (11/38) AITL, 93% (14/15) ALK+ ALCL, 57% (13/28) ALK- ALCL, 50% (6/12) extranodal NK/T cell tumors and 17% (1/6) primary cutaneous showed pSTAT3 positivity. Using either a 30% or 80% cut-off, pSTAT3 positivity was associated with inferior event free survival for AITL, PTCL NOS and ALK neg ALCLs TCLs. Due to small sample size within each group statistical significance (p=0.03) was met only for ALK neg ALCL (80% cutoff). Further analysis in the human TCL cell lines and normal control T-cells also revealed differential expression of pSTATs. ALCL cell lines, Karpas 299 and SR786 were pSTAT3 positive but pSTAT5 negative. Both the CTCL (SS) cell lines HuT78 and SeAx were pSTAT3 negative, however MyLa a cell line of MF origin was strongly pSTAT3+ and pSTAT5+. The normal control CD4 T-cells was pSTAT3- and pSTAT5+. These data clearly suggest that pSTAT3 is differentially expressed among the TCL tumors and is a potential therapeutic target. Potential mechanisms for STAT3 activation could be aberrant secretion of cytokines/chemokines produced by the tumor itself or the tumor microenvironment. We compared the cytokine profile of the culture supernatant from pSTAT3 positive SUDHL1 and pSTAT3 negative HuT78 TCL cell lines using a 30-plex ELISA. The most significantly different cytokines among these 2 cell lines were interleukin -10 (IL-10) and soluble interleukin-2 receptor alpha (sIL-2Ra). The SUDHL1 was found to secrete a very high level (1700 pg/ml) of IL-10, in contrast to only 167 pg/mL in the HuT78 supernatant. Moreover, SUDHL1 secretes 3.5 times more sIL-2Ra (6600 pg/ml) than the pSTAT3 negative cell line HuT78 (1800 pg/ml). In-vitro exposure to IL-10 but not sIL-2Ra was able to further upregulate pSTAT3 in SUDHL1 and Karpas 299. Overall, these data suggest that autocrine secretion of IL-10 but not sIL-2Ra is important for STAT3 activation in ALCL TCLs. Next we compared the cytokine profile of 2 pSTAT3 positive cells from different origin; SUDHL1 (ALCL) and MyLa (MF). In contrast to SUDHL1 (which produce high level of IL-10), MyLa was producing very little IL-10 (18pg/ml). The other most significantly different cytokines between these cells was RANTES with MyLa producing a very high level (28897 pg/ml) and SUDHL1 a very low level (8pg/ml). We also noticed differential level of IL-13 between these cells; MyLa producing 113pg/ml while SUDHL1 only 13 pg/ml. SAR302 (Sanofi, Cambridge, MA), a selective JAK2 inhibitor currently in clinical trial for myeloproliferative neoplasms was able to inhibit autocrine secretion of IL-10 but not sIL-2Ra in a dose-dependent manner followed by STAT3 dephosphorylation and decreased lymphoma cell survival. In summary, our data provide first evidence of in-vivo STAT3 activation in AITL, PTCL NOS, ALK negative ALCL TCLs using TMA from patient samples. Comprehensive cytokine analysis determined IL-10 as an autocrine factor driving STAT3 activation in ALCLTCLs, while RANTES and IL-13 might be important drivers for STAT3 activation in MF TCLs. Finally our data provide a mechanistic basis of selecting and targeting TCL tumor cells with high IL-10 levels and/or constitutive STAT3 activity with potent and novel JAK2 inhibitors such as SAR302 or other STAT3 inhibitors. Disclosures: No relevant conflicts of interest to declare.

Abstract We have recently reported that event-free survival at 24 months from diagnosis (EFS24) is a robust endpoint for assessment of disease related outcome for newly diagnosed patients with diffuse large B-cell lymphoma (DLBCL) treated with anthracycline-based immunochemotherapy (IC). Patients who achieve EFS24 following IC have a subsequent overall survival that is equivalent to the age and sex matched general population. The IPI was developed in the pre-rituximab era using OS/EFS endpoints. While the IPI is associated with outcome in the IC era, the original survival estimates for the IPI risk groups are outdated. The IPI is also a discrete risk classifier, with only 6 possible groups. Here we remodel the IPI using EFS24 as the endpoint in a large international cohort of patients treated with IC. This model provides an individual level 0-100% risk of failing to achieve EFS24 for each patient and can be used for patient prognosis, treatment stratification, and risk assessment. Methods Newly diagnosed DLBCL patients treated with immunochemotherapy from the University of Iowa/Mayo Clinic SPORE Molecular Epidemiology Resource, NCCTG N0489 clinical trial, GELA LNH2003B program, and a Lyon, France based hospital registry were included in the original EFS24 study. Patients with a relapse, progression, unplanned re-treatment, or death due to any cause within 730 days of diagnosis were considered a failure for the EFS24 endpoint. Patients alive and progression/relapse free at 730 days from diagnosis with no subsequent treatment following initial IC were considered a success for the EFS24 endpoint. Variables selected for potential model inclusion were the IPI components (age, stage, ECOG PS, number of extranodal sites, and LDH), as well as standard clinical variables typically reported in studies of DLBCL: presence of B-symptoms, bone marrow involvement, bulky disease (>10 cm), and sex. The IPI24, a prognostic model for EFS24, was developed using logistic regression models. Model building began by fitting the classic IPI score (0-5), then allowing individual IPI variables to carry different model weights and number of categories, followed by dropping insignificant variables, finally adding any additional significant variables. Model performance was assessed using bias corrected c-statistics, AIC, and R2 values. Model selection was done using the complete case set with multiple imputation on the full dataset used to refine parameter estimates for the final model. Results 1596 total patients were available for modeling. The median age was 62 (range 18-93) and 53% were male; 33% were IPI 0-1, 25% were IPI 2, 25% were IPI 3, and 17% were IPI of 4-5. The failure rate for achieving EFS24 was 29%. All variables but sex (p=0.33) were univariately associated with EFS24 (p<6.4x10-5). The original IPI had good prognostic ability for EFS24 (c=0.696, p=2.2x10-32). Allowing multiple categories for ECOG PS, stage, and age (continuous) improved model fit and prognostic ability (c=0.727). The number of extranodal sites was not significant when IPI variables were modeled separately and was removed from the model. Sex and bulky disease were additional significant variables when added to the model. Thus, the final IPI24 model contained the following risk predictors: male sex, ECOG PS (0 vs. 1 vs 2 vs 3-4), stage (I vs. II, vs. III vs. IV), LDH (elevated vs. normal range), bulky disease > 10cm, and age (continuous). This model resulted in improved fit and prognostic ability (c=0.749) over the standard IPI (c=0.696, bootstrap p<0.001). Model validation was performed on an additional 158 patients from the SPORE MER and showed good concordance (c=0.697). Additional validation is planned in a larger set of independent patients. Conclusion The IPI24, generated using standard clinical variables, yields an individual risk prediction for failing to achieve EFS24 following IC for treatment of DLBCL. The IPI24 has superior prognostic ability to the standard IPI and can be implemented in the clinic using a nomogram or as a simple electronic application. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 1591 Background: The serum free light chain (FLC) assay quantitates free kappa and free lambda immunoglobulin light chains. We previously showed elevated FLC are present in approximately 1 in 3 diffuse large B cell lymphoma (DLBCL) patients from both a phase II cooperative group clinical trial and a large clinic based epidemiology cohort. Approximately 10% of DLBCL patients had elevated FLC that was monoclonal in these series. Patients with monoclonal elevated FLC have very poor outcome with almost 50% of patients progressing in the first 15 months following initial treatment with immunochemotherapy. Unlike patients with polyclonal FLC elevation, where a variety of host effects may cause a rise in both kappa and lambda, it is likely the excess FLC in monoclonal patients is directly related to the tumor. DLBCL are a heterogenous group of tumors that can be classified into germinal center (GCB) or activated B cell (ABC) groupings using immunohistochemistry (IHC) staining algorithms. Here we examine the association of monoclonal free light chains with ABC vs. GCB DLBCL tumors. Methods: Newly diagnosed DLBCL patients were prospectively enrolled in the University of Iowa/Mayo Clinic SPORE Molecular Epidemiology Resource (MER) or NCCTG clinical trial N0489. Serum FLC was quantitated from enrollment research serum draws using the Freelite FLC assay (The Binding Site, Ltd., Birmingham, UK). Monoclonal elevated FLC was defined as an elevated kappa or lambda with a corresponding abnormal FLC ratio. Immunohistochemistry (IHC) staining was performed on paraffin tissue from research tissue microarrays (TMAs). Results: IHC tissue staining was available from 12 patients with monoclonal elevated FLC unrelated to renal failure. Germinal center markers were predominantly negative: 2 of 11 were LMO2 positive (18%), 1 of 12 was CD10 positive (8%), and zero cases out of 11 were GCET1 positive. FoxP1 was positive in 5 of 9 cases (56%) and MUM1 was positive in 4 of 12 cases (33%). By the Tally algorithm, 10 of 11 cases (91%) were ABC type DLBCL The percentage of ABC patients by the Tally algorithm in the corresponding DLBCL patients without monoclonal FLC was 45% (N=108, p=0.004). Conclusions: Approximately 10% of DLBCL patients have elevated monoclonal FLC and these patients have poor prognosis. Elevated monoclonal FLC may be a serum marker for ABC-type lymphoma, as the tumors from patients are predominantly negative for germinal center stains and ABC by the Tally algorithm. The secretion of light chains by the tumor suggests an activated B cell clone and the poor prognosis is characteristic of ABC type DLBCL and. Given the likelihood of the excess monoclonal FLC being tumor related, the potential exists for tracking of tumor response and progression via serum FLC in these patients. Replication of these findings in an additional cohort of DLBCL patients is planned. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 991 Background: The outcome of patients with DLBCL has significantly improved with the addition of rituximab to CHOP chemotherapy. While standard clinical prognostic factors such as those included in the International Prognostic Index (IPI) still predict outcome in DLBCL in R-CHOP treated patients, predicting the outcome of patients might be further refined using biological factors. We therefore tested whether pretreatment serum cytokines, that measure the biological activity of the tumor as well as the host response, could provide additional prognostic information in DLBCL patients. Methods: Newly diagnosed DLBCL patients were prospectively enrolled in the University of Iowa/Mayo Clinic SPORE Molecular Epidemiology Resource (MER). Serum cytokines were measured from pre-treatment blood draws using a multiplex ELISA (Upstate Cell Signaling Solutions, Lake Placid, NY). Thirty cytokines, including pro-inflammatory, Th1 and Th2 associated cytokines, were analyzed using the Luminex-100 system Version 1.7 (Luminex, Austin, TX). Data analysis was performed using the MasterPlex QT 1.0 system (MiraiBio, Alameda, CA). The assay was also performed on research serum draws from 400 non-lymphoma epidemiology controls enrolled on a corresponding lymphoma etiology case-control study. The upper limit of normal for each cytokine was defined as the 95th percentile from the control distribution. Clinical data was abstracted using a standard protocol for the MER and patients were followed systematically for event-free (progression, retreatment, or death due to any cause) and overall survival (EFS and OS, respectively). Cox proportional hazards models were used to evaluate the association between cytokines and outcome. Principal components analysis (PCA) was performed on the combined DLBCL and control cytokine dataset, agnostic to clinical characteristics and outcome, to identify cytokine profiles. Results: 206 DLBCL patients diagnosed between September 2002 and February 2008 with available serum were included. The median age was 64 years (range 20–92) and 52% were male. At a medium follow-up of 47 months (range 5–94), 75 patients (36%) had relapsed and 63 patients had died (31%). A cytokine profile was determined based on the first two principal components (PC) of the PCA analyses with PC1 corresponding to a general (host) cytokine elevation (also seen in normal controls) and PC2 corresponding to an increase predominantly in cytokines that were commonly elevated in DLBCL patients. 75 DLBCL patients (36%) had a normal cytokine profile similar to the general population of controls; 114 DLBCL patients (55%) had elevation in tumor specific cytokines (CXCL10, CXCL9, IL-2R, IL-12, IL-8, and IL-10) and 17 (8%) had a general cytokine elevation. Patients with any elevation of cytokines (tumor specific or general elevation) had a significantly worse event-free (HR=3.96, 95% CI: 2.13–7.37, p<0.00001) and overall survival (HR=3.75, 95% CI: 1.99–7.09, p<0.0001) than those with a normal cytokine profile (see figure). While the cytokine elevations were associated with advanced stage, poor performance score and elevated LDH, they were not associated with advanced age or extranodal disease and the results remained significant after adjustment for the IPI and treatment in the Cox model (EFS HR=3.11, 95% CI: 1.66–5.85, p<0.0001; OS HR=2.93, 95% CI: 1.53–5.63, p=0.001). Elevated serum cytokines also identified patients who were unlikely to complete initial therapy or who relapsed early. In low-risk patients (IPI 0–2), only 3% of patients with normal serum cytokines relapsed in the first 12 months compared to 23% of patients with elevated cytokines. Similarly in the high-risk group (IPI 3–5), none of the patients with normal cytokines relapsed in the first year compared to 43% with elevated cytokines. Conclusion: Elevated pretreatment serum cytokines, predominantly related to the malignancy, are associated with an increased likelihood of disease relapse and an inferior survival in patients with DLBCL. Furthermore, the pretreatment cytokine profile may also identify DLBCL patients at high risk for early disease relapse. Disclosures: No relevant conflicts of interest to declare.

Abstract Gene expression profiling has shown that diffuse large B-cell lymphoma (DLBCL) clusters into three major subtypes based on similarity in expression patterns to their cell of origin (COO): germinal center B-cell-like (GCB-DLBCL), activated B-cell-like DLBCL (ABC-DBLCL) and primary mediastinal B-cell lymphoma (PMBCL). These subtypes of DLBCLs are associated with distinctly different overall survival rates after standard immunochemotherapy. However, clinical and prognostic heterogeneity remains within COO subsets and strategies are needed to further stratify patients to identify and target high-risk subsets. A comprehensive genomic analysis of COO on a clinically defined set of DLBCL cases has not been performed and the aim of this study was to use whole-exome sequencing (WES) data from 58 paired tumor-normal DLBCL samples to assess association of known DLBCL genomic alterations with cell COO as well as for identification of novel and relevant genetic biomarkers. To investigate genomic alterations associated with DLBCL subsets, we analyzed WES and genome wide copy number data from 58 paired tumor-normal DLBCL tumors. Gene expression profiling or Hans classification was performed to determine DLBCL COO subtype; 31 patients were classified as GCB and 27 as non-GCB. The WES data were used to 1) assess the association of known DLBCL genomic alterations with COO, and 2) identify novel alternations associated with COO. Statistical analysis was performed and the data were ranked by significance (p≤ 0.05) within each DLBCL subtype. In total, 45 genomic abnormalities were analyzed for their association with either GCB, non-GCB or both. Mutations in CREBBP, EZH2, MEF2B, FOXO1 and REL have also been reported as GCB driver mutations and we observed GCB patients with these mutations, but the mutation clustering was not wholly associated with GCB. MYC double-hits were exclusively found in the GCB-subtype group. For the non-GCB cases we found that mutations in MAP2K3 and MYD88 were significantly associated with this subtype(p< 0.05). In addition to mutational patterns, we identified several copy number alterations (CNA) across both groups. Chromosomal losses in GCB patients were found at chromosomes 10q11.21-10q24.23, 4q12-4q35.2, 3q12.1-3q29, 4p12-4p16.3, 10p11.21-10p15.3, and 14q11.2-14q24.3 whereas gains were localized to 7q11.1-7q36.3, 7p11.2-7p22.3, and 1q21-1q32.1 (p < 0.05). No CNA was observed to directly associate with non-GCB patients, however, a loss at 9p21 and gains at 9q24.1 and 18q21.33 trended with the non-GCB subtype, supporting previous reports. Loss at 10q23.31 or a gain in 2p13-2p12 have been reported as being specific for GCB and our data confirmed the association of 10q23.31 with GCB while a gain at 2p13-2p12 (REL)was found in both subtypes. To further understand genomic differences between DLBCL subtypes, we evaluated the relative percentage of each genomic feature. 18/45 (40%) were only observed in GCB patients whereas 2/45 (5%) were specific to the non-GCB subtype. The majority (25/45, 55%) overlapped between the two subtypes. Throughout our analysis we noted that 7 non-GCB cases lacked any of the driver mutations analyzed in the study. While all cases carried mutations, they consisted of low frequency mutations that were not specifically associated with COO. 2/7 cases had a gain at 9p24.1 that included CD274 and JAK2. Because 9p24.1 gains have not been fully defined in DLBCL, we reviewed all cases and identified 4 (7%) with a 9p24.1 gain, 3 of which were non-GCB and 1 GCB. One non-GCB case was EBV+ and none of the cases showed evidence of PMBCL. Of the 9p24.1 cases, three had RNAseq data available and we found that PDL1 and JAK2 expression was elevated (12 fold p< 0.01 and 7 fold p< 0.01, respectively) when compared to the 9p24.1 normal cases (n=32). While outcome was not the focus of the study, we did note that 6/7 cases that lacked driver mutations achieved event free survival at 24 months (EFS24). Taken together, this analysis has further characterized the genetic profile of each COO subtype and has identified novel GCB CNAs which require independent replication. Additionally, we identify a subgroup of non-GCB DLBCL patients that do not harbor known driver mutations and require further genomic study to better resolve the biology of these tumors. Together, these data provide insight on the genetic heterogeneity of DLBCL and identify genetic variants that may inform subtype specific therapy. Disclosures Nowakowski: Morphosys: Research Funding; Celgene: Research Funding; Bayer: Consultancy, Research Funding. Rimsza:NCI/NIH: Patents & Royalties: L.M. Rimsza is a co-inventor on a provisional patent, owned by the NCI of the NIH, using Nanostring technology for determining cell of origin in DLBCL..

Abstract Background: Patients (pts) with DLBCL who receive first-line anthracycline based immunochemotherapy and remain in remission at 2 years have excellent outcomes with overall survival (OS) in one study that was comparable to the age and sex matched general population in cohorts from the US and France (Maurer et al, JCO 2014). To evaluate whether these findings are robust and generalizable, we assessed OS stratified by progression-free survival at 24 months (PFS24) using individual patient data from pts with DLBCL enrolled in 14 multi-center, international randomized clinical trials as part of the SEAL consortium. Methods: Central data alignment was performed by the SEAL statistics and data center. All enrolled patients treated with rituximab-containing anthracycline-based immunochemotherapy as part of initial induction therapy were included in this analysis using an intent-to-treat approach. PFS was defined as time from initiation of first-line therapy to progression or death. PFS24 was defined as being alive and progression-free 24 months (731 days) after initiation of therapy. Overall survival from PFS24 was defined as time from achieving PFS24 until death due to any cause. OS was compared to each patient's age-, sex-, and country- matched general population using expected survival and standardized mortality ratios (SMR). Country-level population rate tables were obtained from www.mortality.org where available. A per-study average rate table was used when country information was unavailable. OS beyond 9 years from treatment initiation was only available the time of analysis from two trials (13% of cohort) and thus follow-up from PFS24 was restricted to the first 7 years after PFS24 for this analysis. Results: Fourteen studies with 7975 patients were included in the SEAL database. 5853 (73%) received rituximab as part of induction therapy and used in this analysis. Median age was 62 years (range 18-92) with 56% >60 years, 54% were male, 57% had elevated LDH, 63% had stage III/IV disease, 13% had ECOG PS 2-4, and IPI was 0-1 in 36%, 2 in 25%, 3 in 23%, and 4-5 in 16%. At a median follow-up of 4.4 years, 1337 (23%) had disease progression, 1489 patients (25%) had died, and 5101 patients were evaluable for PFS24. 1423 (28%) of evaluable patients failed to achieve PFS24. These patients had poor outcomes after progression with median OS of 7.2 months (95% CI 6.8-8.1), 5-year OS of 19%, and SMR of 32.1 (95% CI: 30.0-34.4). Outcome was excellent (median unreached) in the 3678 patients who were progression-free at 24 months, with subsequent OS after achieving PFS24 approaching the age and sex matched general population (Figure). The observed vs. expected OS at 3, 5, and 7 years after achieving PFS24 was 93.1% vs. 94.4%, 87.6% vs. 89.5%, and 80.0% vs. 83.7%, respectively, the SMR was 1.22 (95% CI: 1.09-1.37). In subset analyses examining pts achieving PFS24, adverse prognostic characteristics at baseline (elevated LDH, advanced stage, ECOG PS 2-4, high IPI) were associated with greater decrement in OS from the general population based expected survival (Table). Conclusions: PFS24 from the start of initial therapy stratifies DLBCL pts into populations with distinct outcomes. DLBCL pts treated with rituximab containing anthracycline-based immunotherapy on large randomized clinical trials who are alive without progression at 24 months from start of initial therapy have excellent outcomes with survival that is marginally lower but clinically indistinguishable from the age-, sex-, and country-matched background population for at least 7 years after achieving PFS24. Further follow-up time will be needed to assess any long-term impact of late relapse and survivorship issues in this population. Table Table. Figure Figure. Disclosures Shi: Mayo Clinic: Employment. Cunningham:Amgen: Research Funding; Astra-Zeneca: Research Funding; Bayer: Research Funding; Celgene: Research Funding; Merrimack: Research Funding; Medimmune: Research Funding. Seymour:AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel support, Speakers Bureau; Genentech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Jaeger:Roche: Honoraria, Research Funding; Celgene: Honoraria, Research Funding. Haioun:Sandoz: Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees. Ghesquieres:Mundipharma: Consultancy; Roche France: Research Funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees. Merli:Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Teva Pharmaceuticals Industries: Membership on an entity's Board of Directors or advisory committees. Herbrecht:Servier: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Cell Therapeutics, Inc: Membership on an entity's Board of Directors or advisory committees. Flament:Celgene: Employment, Equity Ownership. Fu:Celgene: Employment, Equity Ownership. Flowers:Gilead: Consultancy, Research Funding; Roche: Consultancy, Research Funding; Acerta: Research Funding; ECOG: Research Funding; Mayo Clinic: Research Funding; Pharmacyclics, LLC, an AbbVie Company: Research Funding; Millenium/Takeda: Research Funding; Infinity: Research Funding; TG Therapeutics: Research Funding; Genentech: Consultancy, Research Funding; NIH: Research Funding; AbbVie: Research Funding. Ou:Mayo Clinic: Employment. Sargent:Celgene: Research Funding. Coiffier:MorphoSys: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy; Celltrion: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Abstract Introduction: "High grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements" (HG DH/THL) is a new diagnosis per the revised 2016 WHO classification. It has been colloquially called "double hit/triple hit lymphoma" and is significant for its aggressive clinical course. However, under this umbrella diagnosis there are several morphologic and cytogenetic variants with either controversial or unknown clinical significance. Herein, we investigate the prognostic significance of several of these parameters, including morphology, immunoglobulin gene (IG) vs non-IG MYC translocation partners, and BCL2/BCL6 translocation status in HG DH/THL in the Mayo Clinic Rochester practice. Materials and methods: All cases, which were identified through the Mayo Clinic Lymphoma Database, University of Iowa/Mayo Clinic SPORE Molecular Epidemiology Resource (MER), and the Mayo Clinic Cytogenetics Laboratory, had diffuse large B-cell lymphoma (DLBCL) or high grade B-cell lymphoma (HGBCL) morphology, were CD20-positive, and had a MYC translocation with concurrent BCL2 and/or BCL6 translocations. Morphology was re-reviewed by four hematopathologists when possible. Cell of origin (germinal center B-cell (GCB) vs non-GCB phenotype) was determined by paraffin section immunohistochemistry using the Hans classifier. Interphase FISH was performed on either tissue paraffin sections or bone marrow aspirate smears using a breakapart probe for MYC, followed by dual fusion probes for IGH/MYC, IGL/ MYC and IGK/MYC, a BCL6 breakapart probe, and either a BCL2 breakapart probe or an IGH/BCL2 dual fusion probe. Outcome analysis was restricted to patients with de-novo HG DH/THL or HG DH/THL at transformation of a previously diagnosed low-grade lymphoma and who were treated with anthracycline-based chemotherapy. Overall survival (OS) was defined as time from DH/THL diagnosis to death from any cause. Results: There were 100 patients with a median age of 61 years (range 29-87). The consensus re-review morphologic diagnosis (n=65) was HGBCL in 39 (60%) and DLBCL in 26 (40%). The HGBCL group had inferior survival (2-year OS = 35%) compared to DLBCL (2-year OS=62%, p= 0.058). By interphase FISH, the MYC translocation partner was an IG gene (IG/MYC) in 52 cases (60%; 39 IGH, 6 IGK and 7 IGL) and a non-IG gene (non-IG/MYC) in 35 cases (40%). No difference in OS was identified between IG/MYC and non-IG/MYC cases (p=0.85, Figure 1). By FISH, 87 cases (87%) had a BCL2 translocation (59 MYC/BCL2, 20 MYC/BCL2/BCL6, and 8 MYC/BCL2/[BCL6 unknown]) and 13 (13%) lacked a BCL2 translocation (MYC/BCL6). Those with a BCL2 translocation were all of GCB phenotype (N=85), while 6 of 12 of the MYC/BCL6 cases (50%) were of non-GCB phenotype (p <0.0001). All 13 MYC/BCL6 cases were de novo diagnoses, while 38% of cases with a BCL2 translocation represented either transformation (n=22) or recurrence (n=11) events (p=0.025). The MYC/BCL6 group had better survival (2-year OS=73%) than those with BCL2 translocation (2-year OS=43%, p= 0.13). Conclusion: As HG DH/THL's frequently have morphologic characteristics of DLBCL (40% in this series), it is important to perform complete interphase FISH analysis on all cases with DLBCL or HGBCL morphology to exclude the possibility of HG DH/THL. Furthermore, within the diagnosis of HG DH/THL, there are several morphologic and cytogenetic subtypes that are biologically and clinically significant. High grade morphology (HGBCL) tends to predict for a more aggressive clinical course independent of all other parameters (p= 0.058). Unlike a recent report (Blood 2015;126:2466), our data suggest MYC translocation partner (IG versus non-IG) may have no impact on overall survival (Figure 1). HG DH/THL's with a BCL2 translocation appear restricted to GCB phenotype, frequently represent either transformation or recurrence events, and tend to have inferior OS. In contrast, those without BCL2 translocations may be of either GCB or non-GCB phenotype, typically arise de novo, and tend to have a superior OS. Careful morphologic review and complete interphase FISH studies are essential in all HG DH/THL for prognostic and potential therapeutic purposes. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Abstract Background: DLBCL without an event (disease progression, retreatment or death) within 24 months post diagnosis have a subsequent overall survival equivalent to that of the age- and sex-matched general population. In contrast, patients with an event with 24 months post diagnosis have poor survival. Patients experiencing early events are a heterogeneous group, consisting of patients with primary refectory disease and responding patients who later developed relapse. While the outcome of patients with primary refractory disease have been recently studied, little is known about or patients who have a response following immunochemotherapy (IC) and proceed to surveillance. These patients are the subject of recently completed and ongoing post-IC maintenance trials. To provide perspective, we analyzed outcomes of patients from a prospective observational study entering post IC. Methods: Newly diagnosed patients with DLBCL and treated with anthracycline-based immunochemotherapy were enrolled in the University of Iowa/Mayo Clinic SPORE Molecular Epidemiology Resource (MER) from 2002-2009. End of immunochemotherapy (EOIC) was defined as the date the patient entered surveillance after completion of anthracycline-based IC as per our previous study of surveillance imaging. Response status at EOIC was abstracted as reported from the clinical and radiographic (CT and/or PET) reports. EFS24 was defined being event-free at 24 months from diagnosis, where events consisted of progression, re-treatment, or death (any cause) after initial immunochemotherapy. Survival from EOIC was compared to the general United States population using standardized mortality ratios (SMR) and expected survival. Logistic regression with EFS24 as the endpoint was used to identify pretreatment variables that inform prognosis at the time of EOIC, using Odds ratios (ORs) and 95% confidence intervals (CI) as the measure of association. A subset analysis was performed in the patients aged 60-80 with aaIPI 1-3. Results: 680 patients with DLBCL were enrolled in the MER and initiated R-CHOP or comparable IC from 2002-2009. 552 pts (81%) completed therapy and proceeded to surveillance. Median age of the 552 patients was 61 years (range 18-92) and 51% were male. At a median FU of 89 months from EOIC (range 5-156), 146 pts (26%) had died, and 467 (86%) achieved EFS24. From EOIC, the 5 year overall survival was 82% compared to 91% expected based on age and sex matched general population; SMR was 1.88 (95% CI: 1.60-2.22). In the patients age 60-80 with aaIP1 1-3, (N=203), 79% achieved EFS24 and the 5-year OS from EOIC was 75% compared to 89% expected; SMR was 2.08 (95% 1.65-2.61). When examining all 552 patients proceeding to surveillance at end of EOIC, several high-risk disease characteristics at diagnosis were associated with higher risk of failing EFS24 after completion of therapy: ECOG PS 2-4 (OR = 2.72, 95% CI: 1.55-4.78) , LDH> ULN (OR = 3.54, 95% CI: 1.99-6.31), Stage III/IV (OR=2.43, 95% CI: 1.41-4.16), and aaIPI (per-point OR = 2.02, 95% CI: 1.54-2.64). Patients reported to be in CR at EOIC were more likely to achieve EFS24 (90%) compared to patients not in CR (72%, p<0.001). Conclusion: Patients entering surveillance after IC have shortened overall survival when compared with the general US population, with significant proportion of patients having an event within 24 months of diagnosis. Increased aaIPI and response less than CR are risk factors for inferior EFS24 in this group. Assessment of the prognostic value of EOIC response (PR vs. CR based on central review) is ongoing. Disclosures Nowakowski: Celgene: Research Funding; Morphosys: Research Funding; Bayer: Consultancy, Research Funding. Maurer:Celgene: Research Funding; Kite Pharma: Research Funding. Howlett:Celgene: Employment, Equity Ownership. Ansell:BMS, Seattle Genetics, Merck, Celldex and Affimed: Research Funding.

Abstract Background: There are a number of ongoing clinical trials assessing next-generation immunochemotherapy (IC) regimens (i.e. RX-CHOP) in DLBCL. In addition to standard clinical trial workup, some trials require central pathology review and/or molecular phenotyping before treatment assignment and/or initiation of therapy. There is concern that these studies may be biasing patient selection due to missing patients with aggressive disease who require immediate therapy and cannot delay their treatment to enroll on a study. Here we examine clinical characteristics and outcome stratified by the time from diagnosis to initiation of therapy from a large observational cohort of patients with DLBCL from the R-CHOP era. Methods: Patients were prospectively enrolled in the University of Iowa / Mayo Clinic SPORE Molecular Epidemiology Resource (MER) within 9 months of diagnosis and followed for relapse, retreatment, and death. Clinical management at diagnosis and subsequent therapies were per treating physician. This analysis includes patients with stage II-IV DLBCL or primary mediastinal B-cell lymphoma (PMBCL) who underwent front-line anthracycline based IC; patients with primary CNS lymphoma, PTLD, or a component of low-grade lymphoma were excluded. Time from diagnosis to treatment was defined as the time from date of first lymphoma-containing biopsy to the initiation of IC therapy; delayed therapy was defined as initiating therapy more than 14 days after diagnosis. Event-free survival was defined as time from diagnosis until progression, retreatment, or death due to any cause. EFS24 was defined as progression free status 24 months from diagnosis. Results: 720 patients with stage II-IV newly diagnosed DLBCL or PMBCL and treated with IC were enrolled in the MER from 2002-2012. Median age at diagnosis was 62 years (range 18-92) and 399 patients (55%) were male. 541 patients (75%) had stage III/IV disease and IPI at diagnosis was 0-1 in 166 patients (23%), 2 in 221 patients (31%), 3 in 222 patients (31%) and 4-5 in 111 patients (15%). 233 of 395 patients (59%) were GCB per Hans. At a median follow-up of 73 months, (range 0-163), 349 (49%) patients had an event and 267 patients died (37%); 37% of patients failed to achieve EFS24. Median time from initial lymphoma diagnosis to initiation of IC was 14 days (range 0-79, IQR=8-23). Patients with delay in therapy (>14 days from diagnosis) were more frequently female (50%, p=0.0051) and older than patients who initiated therapy within 14 days from diagnosis (median age at diagnosis of 63 years vs. 60 years, p=0.0008). Patients with delay in treatment initiation had universally less aggressive disease characteristics, including earlier stage, non-elevated LDH, 0-1 extranodal sites, absence of B-symptoms, lower ECOG PS, and lower IPI (see table). In addition, patients with delayed therapy were enriched for GCB subtype per Hans algorithm (p=0.056). Patients with initiation of therapy within 14 day of diagnosis had significantly worse outcome (EFS24 failure=44%) compared to patients with delayed time to initiation of therapy (EFS24 failure=28%, p<0.0001, figure), which remained significant after adjusting for either IPI or aaIPI (both p<0.005). The association between delayed time to initiation of therapy and EFS24 was observed in both GCB (EFS24 failure = 42% vs. 27%, p=0.019) and non-GCB (EFS24 failure = 46% vs. 27%, p=0.014) subsets by Hans. The lower event rate in delayed therapy patients results in an approximately 10% loss of power if the study was powered based on all patients regardless of timing from diagnosis to therapy. Conclusions: Patients with delayed therapy from diagnosis have less aggressive clinical characteristics compared to patients who initiate treatment within 14 days from diagnosis. Studies with a lengthy trial work-up including central pathology review period may be selecting patients with less aggressive disease based on the patient's ability to delay treatment to complete study enrollment requirements. Furthermore, selection of patients with less aggressive disease may result in underpowered studies due to a lower event rate (fewer events) than expected. This retrospective analysis would suggest that trials in DLBCL should consider streamlined enrollment and therapy initiation to avoid potential selection bias and loss of power. Further assessment of implications on trial design and outcomes by cell of origin in this setting is ongoing. Table Table. Figure Figure. Disclosures Maurer: Kite Pharma: Research Funding; Celgene: Research Funding. Ansell:BMS, Seattle Genetics, Merck, Celldex and Affimed: Research Funding. Nowakowski:Morphosys: Research Funding; Bayer: Consultancy, Research Funding; Celgene: Research Funding.

Abstract Background: B-cell lymphomas with a MYC/8q24 rearrangement coupled with translocations involving BCL2 and/or BCL6, often referred to as double hit or triple hit (DH/TH) lymphomas, typically have an aggressive clinical course. A new WHO subtype, "high grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements", has been established for this entity (Swerdlow et al. Blood; 127: 2375-2390, 2016). Herein we report the treatment and outcomes of DH/TH patients at our institution. Materials and Methods: Cases were identified through the Mayo Clinic Lymphoma Database, University of Iowa/Mayo Clinic SPORE Molecular Epidemiology Resource (MER), and the Mayo Clinic Cytogenetics Laboratory. Interphase FISH was performed clinically on either paraffin sections of the tissue specimens or on smears of the bone marrow aspirate specimens using break-apart probes for MYC and BCL6, dual fusion probes for IGH/MYC, IGL/MYC, and IGK/MYC, and either a BCL2 break-apart probe or an IGH/BCL2 dual fusion probe. Consensus pathology re-review was performed to define morphology as diffuse large B-cell lymphoma (DLBCL) vs. high-grade B-cell lymphoma (HGBCL). Patients with de-novo DH/TH or diagnosis of DH/TH at the time of transformation of a previously diagnosed low-grade lymphoma and who were treated with anthracycline-based chemotherapy were included in this analysis. Patients with DH/TH first identified at the time of recurrent aggressive B-cell lymphoma were excluded. Overall survival (OS) was defined as time from DH/TH diagnosis to death from any cause. EFS12 was defined as event-free status 12 months from diagnosis of DH/TH. Results: Clinical outcome analysis was performed on 71 patients (Table 1). The median age was 61 years (range 29-82). 60 patients had de-novo DH/TH and 11 patients had transformation of a previously diagnosed low-grade lymphoma. In 65 cases in which there was consensus morphology on pathology re-review, there were 39 (60%) with HGBCL morphology and 26 (40%) with DLBCL morphology. At a median follow-up of 21 months (range 1-87), the event free survival at 12 months was 43%, and the median overall survival (OS) was 22 months (95% CI: 13-NA). The OS at 5 years was 48% (95% CI: 36%-63%). Patients with DH/TH at transformation of previously diagnosed low-grade lymphoma had a very poor outcome (median OS=10.8 months, EFS12 = 10%), which was inferior to patients with de-novo DH/TH (P=0.0069). When compared to all other therapies, patients treated with R-CODOX-M/IVAC had better EFS12 (p=0.03) with a trend in improved OS (p=0.08) though this may be confounded by patient selection bias as these patients were significantly younger (p=0.0001) than patients treated with other anthracycline based regimens (table 1). Conclusion: In "high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements", induction failure occurs early. Although transformation to DH/TH from previously diagnosed low-grade lymphoma is associated with a particularly poor outcome, the overall survival for the entire cohort at 5 years was 48%, suggesting long-term cures in a subset of patients. Treatment with R-CODOX-M/IVAC may result in superior outcomes in patients less than 60 years of age. Table 1 Table 1. Figure Figure. Disclosures Ansell: BMS, Seattle Genetics, Merck, Celldex and Affimed: Research Funding. Nowakowski:Celgene: Research Funding; Morphosys: Research Funding; Bayer: Consultancy, Research Funding.