Witzig, Thomas E.

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 Introduction: With approval of Daratumumab (Dara), targeting CD38 has become an attractive therapeutic option for various B cell cancers including WM. Using preclinical models of WM we investigated CD38 expression patterns, the impact of drug-resistance and the anti-WM effects of Dara, in vitro. An important aspect of our evaluation was the identification of optimal CD38 expression that correlates with maximal cytotoxic effects of Dara; such an approach has not been attempted previously in WM. Methods: WM cell lines (BCWM.1, MWCL.1 and RPCI.WM1) with isogenic proteasome inhibitor-resistant (CR, resistant to carfilzomib, bortezomib and ixazomib) and ibrutinib-resistant subclones (IR) were used. CD38 expression was measured by flow cytometry and a grading system was developed based on increasing CD38 MFI values with 1+= <50,000, 2+ = >50,000 and 3+ = >100,000. Daratumumab-induced specific lysis due to antibody dependent cell cytotoxicity (ADCC) or complement dependent cytotoxicity (CDC) was measured using the Calcein AM assay at an effector to target ratio (E:T) of 100:1. Peripheral blood mononuclear cells (PBMCs) and complement-containing serum were obtained from healthy human donors. Daratumumab, carfilzomib and ibrutinib were obtained from commercial sources. Results: Expression of CD38 (MFI) was highest in RPCI-WM1 (91295.6) > BCWM.1 (13865.3) > MWCL-1 (9804.19) (Figure 1A.). Intriguingly we observed an interesting change in CD38 expression with induction of drug resistance; all CR clones showed a decrease in MFI (RPCI-WM1/CR; øMFI 55960.5 > MWCL-1/CR; øMFI 3890.0 > BCWM.1/CR; øMFI 1381), while decreased expression was noted in all IR clones except one (MWCL-1/IR; øMFI 6272.96, BCWM.1/IR; øMFI 3076 vs. RPCI-WM1/IR; _MFI 461784.6) (Figure 1B). When we applied our CD38 expression grading system, RPCI-WM1/IR cells classified as Grade 3+, RPCI-WM1 and its CR clones as Grade 2+, while all other WM cells were Grade 1+. We noted that utilization of this grading system was helpful in correlating the extent of cytotoxicity to the level of CD38 expression (Table 1). We next treated WM cells with Dara and observed direct lysis in only RPCI-WM1/CR (43%) > BCWM.1/CR (19%) and RPCI-WM1 (11%) cells. However, when Dara-treated WM cells were cocultured with PBMCs, significantly increased ADCC was noted in RPCI-WM1 (90.3%), RPCI-WM1/IR (88.3%) and RPCI-WM1/CR (68.0%) cells (Figure 1C). Although CDC has been reported as a mechanism of mAb-mediated cell death in WM our evaluation of CDC as a potential effector mechanism in daratumumab-treated WM was negative as expected, highlighting ADCC rather than CDC as the primary cytotoxic mechanism. Conclusion: Our analysis of CD38 in WM preclinical models highlights several important findings: 1.) Expression of CD38 changes as WM tumor clones evolve with induction of drug-resistance; an effect that may also be cell-type specific as evidenced by increased CD38 expression in RPCI-WM1/IR cells, 2.) Daratumumab can exert a direct lethal effect in WM cells but this effect is variable and cell line dependent, 3.) Expression of CD38 is an important factor directing cytotoxicity of Dara however antigen density appears to be an important factor and a grading system can be beneficial for future preclinical and/or clinical studies, 4.) ADCC and not CDC appear to be the prominent mechanism of action and 5.) ADCC-mediated cytolytic activity of Dara is contingent on CD38 expression as evidenced by the most specific lysis being noted in CD38 Grade 2+ and 3+ expressing WM cells (Table 1.). These observations can help direct optimal design of clinical studies with Dara in WM where drug resistance and CD38 expression should be further explored as factors contributing to the clinical efficacy of this new agent. Disclosures Ailawadhi: Pharmacyclics: Consultancy; Novartis: Consultancy; Amgen Inc: Consultancy; Takeda Oncology: Consultancy. Ansell:BMS, Seattle Genetics, Merck, Celldex and Affimed: Research Funding.

Abstract Abstract 3652 Purpose: Gene expression profiling has shown biologically distinct cell of origin categories for diffuse large B-cell lymphoma (DLBCL): germinal center B-cell like (GCB), and activated-B-cell like (ABC). GCB, DLBCL patients experienced better clinical outcomes compared with ABC, DLBCL patients. However, gene microarray technology is not broadly available in a non-research setting. Absolute lymphocyte count (ALC) at diagnosis is a prognostic factor for survival in DLBCL. Recently, gene-expression profiling and immunohistochemistry-based studies in non-Hosgkin's lymphoma demonstrate the important role of monocytes and their progeny, particularly lymphoma-associated macrophages, in promoting lymphomagenesis. thus, we studied if the peripheral blood absolute lymphocyte count/absolute monocyte count at diagnosis (ALC/AMC-DX), as a surrogate biomarker of the host response against the cell of origin in DLBCL, affects survival in DLBCL. Patients and Methods: We perfromed a retrospective analysis of the association between ALC/AMC-DX and survival in 131 consecutive DLBCL patients that were followed at Mayo Clinic from 2004 to 2010, with available tissue immunostaining for CD10, BCL6, MUM 1, and BCL 2 (Hans' algorithm) to identified GCB and ABC DLBCL patients. Receiver operating characteristic (ROC) and area under the curve (AUC) analyses were used for ALC/AMC-DX cut-off value determientaion and proportional-hazards models wee used to compare survival based on the ALC/AMC-DX. Results: The cohort included 91 (70%) GCb DLBCL patients and 40 (30%) ABC, DLBCL patients. All patients were treated with rituximab, cyclosphosphamide, adriamycin, vincristine, and prednisone (R-CHOP-21). The median follow-up period was 2.1 years (range 0.1–6.9 years). An ALC/AMC-DX >= 1.5 was the best cut-off value for survival with an empircal AUC of 0.83 (95% CI, 0.77 to 0.89), a sensitivity of 83% (95% CL, 72% to 92%) and specificity of 79% (95%CI, 72% to 85%). The cut-off value for ALC/AMC-DX >= 1.5 was validated by the k-fold cross validation method, showing a cross validation ROC with an AUC of 0.89 (95%CI, 0.80 to 0.95) for an ALC/AMC-DX >=1.5. Using Kaplan-Meier analysis, the overall survival (OS), defined as the time from diagnosis to last follow-up or death due to any cause; and progression-free survival (PFS), defined as the time from diagnosis to death of any cause, relapse, progression, or last follow-up, based on ALC/AMC-DX >= 1.5 were evaluated. patients with an ALC/AMC-DX >=1.5 experienced a superior OS and PFS compared with patients with an ALC/AMC-DX < 1.5: [OS: median was not reached vs 20.8 months, 5-years OS rates of 83% (95%CI, 70% to 95%) vs 36% (95%CI, 20% to 55%), p < 0.0001, respectively; and PFS: median was not reached vs 10.8 months, 5-years PFS rates of 70% (95%CI, 58% to 88%) vs 28% (95% CI, 17% to 46%), p < 0.0001, respectively]. Multivariate Cox stepwise regression analysis identified cell of origin, International Prognostic Index (IPI) and ALC/AMC-DX as the strongest predictors for OS and PFS, with ALC/AMC-DX out-performing cell of origin and IPI: OS [HR = 0.17, 95%CI, 0.07 to 0.36, p < 0.0001] and PFS [HR=0.21, 955CI, 0.11 to 0.39, p < 0.001]. conclusion: ALC/AMC-DX is independent of the cell of origin to predict survival and provides a single biomarker to predict clinical outcomes in DLBCL. Confirmatory studies are required. Disclosures: No relevant conflicts of interest to declare.

Abstract Background: The PI3K/mTORC pathway is upregulated in DLBCL and can be targeted with mTORC1 inhibitors such as everolimus. Everolimus has demonstrated single agent activity in relapsed DLBCL (Leukemia. 2011; 25(2):341-7). These data provide the rationale to combine everolimus with standard RCHOP-21 to improve the effectiveness of upfront therapy for DLBCL. Methods: A phase I study was designed to determine the maximum tolerated dose of everolimus on days 1-10 or 1-14 in combination with RCHOP-21 along with a feasibility cohort to examine response in patients with newly diagnosed CD20+ DLBCL. Response assessment was evaluated using PET/CT and standard criteria. Results: We previously reported (J Clin Oncol 33, 2015 suppl; 8518) that in the phase I portion of trial N1085 that the dose of everolimus recommended for further study was everolimus 10 mg daily days 1-14; RCHOP day 1 and pegfilgrastim 6 mg day two for each of six 21-day cycles. The trial has now completed enrollment with a total of 26 patients. Two phase I patients were replaced during cycle 1 for personal, non-medical issues leaving 24 eligible patients for response assessment. The median age was 59.5 years (23 - 78); 42% were female; 18 (75%) stages III/IV; 12 (50%) had an elevated LDH; 29% had a high IPI score; and 4 (17%) had B-symptoms. Genotype was performed by immunohistochemistry using the Hans algorithm and 54% (13/24) were non-GCB; 13 (5 GCB, 8 non-GCB) had FISH for double hit and all were negative. Twenty-one (88%) patients received everolimus at 10 mg d1-14; the other three patients received 10 mg d1-10. Twenty-two (92%) patients received all 6 cycles. All patients have now completed therapy and the overall response rate was 96% (23/24) with 23 patients attaining functional CR by PET/CT. The remaining patient went off study for refusal in cycle 1, received further RCHOP-21 off study, and attained a CR off study. The median follow-up for the 24 patients is now 16.8 months (7.3 - 35.7) with 20 patients having ≥12 months of follow-up and 8 patients having ≥24 months of follow-up. To date, none of the 24 patients have died and none have experienced relapse with DLBCL. One patient relapsed 16 months from DLBCL diagnosis with a biopsy-proven follicular grade 1 NHL and received off-study Zevalin and achieved a second CR. The most common grade 3/4 toxicity was hematologic with 71% of patients having grade 4. Five (21%) patients had febrile neutropenia. Only 1 patient had grade 3 hyperglycemia and 3 patients had grade 3 hypertriglyceridemia. Reversible rash and pneumonitis were observed in 1 case each. Conclusions: The mTORC1 inhibitoreverolimus at 10 mg daily d1-14 of a standard RCHOP-21 cycle is tolerable with a 96% CR rate in both GCB and non-GCB DLBCL. With a median follow-up of 16.8 months and 8 patients out ≥24 months, the lack of DLBCL relapse is encouraging. Longer follow-up and a larger trial will be necessary to confirm the benefits of this novel combination. Clinical trial information: NCT01334502 Disclosures Off Label Use: Everolimus is an mTOR inhibitor which has activity in B cell lymphomas. It is being investigated in combination with SOC therapy for newly diagnosed DLBCL to examine potential toxicity as well as potential for enhanced disease response.. Ansell:Bristol-Myers Squibb: Research Funding; Celldex: Research Funding.

Abstract Abstract 2687 Background: Patients with early stage (Stages I, II) diffuse large B cell (DLBCL) have been traditionally treated with either CHOP x6 alone or with CHOP followed by involved field external beam radiotherapy (IFRT). With the demonstration of the superiority of rituximab CHOP (RCHOP) in advanced stage DLBCL, RCHOP has been adopted as the chemoimmunotherapy standard of care in early stage disease with or without IFRT. Radioimmunotherapy (RIT) has the advantage of delivering high-energy, short path length radiation in a targeted approach using an anti-CD20 antibody as the carrier. Thus, radiation is potentially targeted to microscopic sites outside of known disease. Goals: To evaluate the complete response (CR) rate and functional CR rate (CR or CRu/PR and PET negative) to a treatment regimen of RCHOP followed by 90Y-ibritumomab tiuxetan (Zevalin, Spectrum Pharmaceuticals) radioimmunotherapy (RIT); only patients not achieving PET negative status after RIT were to be given IFRT. The study goal was to achieve a functional CR rate of ≥75%. Patients and Methods: Eligible patients were those with new, untreated Stages I or II DLBCL as determined by standard CT scanning, adequate blood counts, creatinine and bilirubin <2.0 mg/dl, cardiac ejection fraction >45%, and a performance status 0–2. Stage I patients were required to have ≥1 adverse risk factor (≥60 years, bulky disease, elevated LDH or PS2). Patients received standard RCHOP21 × 2 cycles and then were restaged. Patients in CR received 2 additional cycles; those in PR or CRu received 4 additional cycles. At end of RCHOP a PET scan was repeated and centrally reviewed; those with a PR or functional CR proceeded to Zevalin RIT 0.4 mCi/kg (maximum 32 mCi) within 12 weeks of the last RCHOP. Patients were restaged 12 weeks post-RIT; PET negative patients were observed without maintenance; PET positive patients received 30Gy involved field radiation and then were restaged. Descriptive statistics were used to summarize the patient characteristics, treatment and response. The Kaplan-Meier method was used to estimate failure rates. Results: Between Dec 2004 and Nov 2008, 62 patients were enrolled; after pathology review 53 were considered eligible. 42% (22/53) patients were stage I/IE; 58% (31/53) were stage II/IIE. 57% (30/53) received 6 cycles of RCHOP; 40% (21/53) received 4 cycles; and 2 patients received 1 and 2 cycles, respectively. After immunochemotherapy, 79% (42/53) were in functional CR and 19% (10/53) PR; 1 was unevaluable. Of the 53 eligible patients who completed RCHOP therapy 91% (48/53) proceeded to RIT. After RIT, 87% (46/53; 95% CI: 75–95) were in CR/CRu and 89% (47/53; 95% CI:77–96%) were in functional CR. One patient proceeded to IFRT. The median follow-up is now 4.3 years. Seven (13%) of patients have had tumor progression but only 2 have died (1 of disease). At 4 years, 88% of patients remain progression free and 98% remain alive (Fig 1,2). The median has not been reached for either PFS or OS. There has been one case of myelodysplastic syndrome. Conclusions: Combination immunochemotherapy and RIT is an active regimen for patients with early stage DLBCL. Nearly all patients will achieve functional CR without the requirement of IFRT. The regimen of RCHOP and RIT for early stage DLBCL is worthy of further study. Disclosures: Witzig: Spectrum: Membership on an entity's Board of Directors or advisory committees, Research Funding, uncompensated Other. Off Label Use: Use of Zevalin in treating patients with Stage I-II DLBCL. Kahl:Roche: Consultancy; Genentech: Consultancy, Research Funding. Horning:Genentech: Employment; Roche: Equity Ownership.

Abstract Background: High risk CLL patients treated with novel targeted therapies continue to experience disease progression (PD), and more than 50% of these PD patients evolve into Richter's syndrome (RS), (Maddocks, Jama Oncol 2015). Standard chemotherapy for large cell lymphoma has limited efficacy (median overall survival <12 months) in RS. Novel immunotherapy using a PD-1 antibody to block immune checkpoint signals to activate the cytotoxic T -cell has significant efficacy in relapsed Hodgkin lymphoma (Ansell, NEJM 2015). We conducted a phase 2 trial to test the safety and clinical efficacy of the anti-PD-1 antibody pembrolizumab in patients with relapsed/refractory CLL and relapsed low grade B non-Hodgkin lymphoma (B-NHL) (MC1485 trial). Methods: MC1485includes two arms: patients with relapsed/refractory CLL (including RS) and patients with relapsed B-NHL. The main end points of this study are safety and overall response rate. The first 6 patients enrolled in either arm were included in a designed safety interim analysis. Here we report the initial interim analysis from the CLL arm. Relapsed/refractory CLL including RS who had ECOG performance 0-2 and normal organ function were included. Patients with active autoimmune disease or interstitial lung disease were excluded. Pembrolizumab 200 mg was administered intravenously every 3 weeks until progression, excessive toxicity, or completion of 2 years of therapy. Soluble plasma PD-L1 levels were measured in these 6 patients using an established ELISA assay (Frigola, Clin Cancer Res, 2011). CD8+ T cell subsets were assessed for their functional status using an established analysis (Liu, Oncoimmunology. 2013) at baseline and after 2 cycles of therapies. Results: As of July 27th, 2015, 16 relapsed/refractory CLL patients including 5 RS patients were enrolled. The median age was 71 years (58-81). The median number of prior therapies was 3 (1-6). All CLL patients had received chemoimmunotherapy (FCR/PCR). 4 out of 5 RS patients had received anthracycline-containing chemotherapy. 5 out of 8 patients who had received prior ibrutinib therapy progressed on ibrutinib. 8 patients had 17p-/TP53 mutation. Herein, we report preliminary results from the interim analysis of CLL arm including 4 RS and 2 CLL as well as the 5th RS who had response evaluation by PET. The median cycles of therapy administered was 4 (3-7). One patient experienced grade 2 cytokine release syndrome with transient febrile neutropenia, grade 3 headache and skin rashes. These symptoms resolved with steroid therapy. One patient experienced grade 3 myalgia and was also treated with steroids. The other patients in this safety cohort tolerated pembrolizumab well. The most common drug-related adverse events were grade 1 dyspnea (33%, 2/6) and grade 1 anemia (33%, 2/6). Based on investigator assessment using the Cheson 2007 International Working Group Criteria, 4 out of 5 RS patients had responded to therapy. One patient had a complete remission after 2 cycles and remains in remission. One patient had almost complete PET response after two cycles and is classified as PR as her bone marrow have not been re-evaluated yet. Two patients had notable responses with nodal and skin lymphoma improvements before they showed potential evidence of progressive diseases. The remaining 1 RS and 2 CLL had stable disease and continued on therapy at the last follow-up. Soluble PD-L1 levels (sPD-L1, n=6) were measured at baseline and after 2 cycles of therapies. 3 RS patients who had responded to therapy had decreased or stable sPD-L1 levels. The 4th RS and two CLL had increased sPD-L1 levels and had not demonstrated clinical response. CD8 T-cell subset analyses performed blindly (n=4) showed increased CD8 T cell function in one of the 4 patients tested. This patient who demonstrated CD8 T cell functional enhancement is the only patient in the 4 tested patients who had notable response to pembrolizumab. Conclusion: Pembrolizumab is tolerated in relapsed CLL and RS patients. Early efficacy observed in heavily pretreated RS patients including patients progressed on both anthracycline-based treatment and ibrutinib indicate PD-1 inhibition is a promising novel approach in patients with RS. Our CD8 T cell subset analysis may be used as a biomarker assay to predict clinical response in the era of novel immunotherapy. This trial and further correlative analysis is ongoing and will be presented at the ASH meeting. Disclosures Ding: Merek: Research Funding. Shanafelt:Cephalon: Research Funding; Pharmactckucs: Research Funding; Janssen: Research Funding; Hospira: Research Funding; Polyphenon E Int'l: Research Funding; Celgene: Research Funding; Glaxo-Smith_Kline: Research Funding; Genentech: Research Funding. Kay:Tolero Pharma: Research Funding; Hospira: Research Funding; Pharmacyclics: Research Funding; Genentech: Research Funding; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding. Ansell:Bristol-Myers Squibb: Research Funding; Celldex: Research Funding.

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.