Link, Brian K.

Abstract Abstract 1604 Background EBV (+) DLBCL of the elderly is a lymphoproliferative disorder recently included as a provisional entity in the 2008 WHO classification of lymphoid tumors. Defined as EBV (+) DLBCL in patients over the age of 50 years without known immunosuppression, information is evolving in this entity. To date, the true incidence of EBV (+) DLBCL in adults remains imprecisely determined and may vary regionally. This study sought to determine the incidence, presenting clinical characteristics, and outcome of EBV (+) in an unselected cohort of DLBCL patients enrolled in a prospective observational study. Methods The University of Iowa/Mayo Clinic SPORE Molecular Epidemiology Resource (MER) is a prospective, longitudinal observational study designed to collect information on patterns of care and outcomes for patients with newly diagnosed lymphoma. Patients seen at the Mayo Clinic, Rochester MN and the University of Iowa within 9 months of their initial diagnosis of lymphoma are offered enrollment. HIV (+) patients are excluded. Baseline patient reported data, clinical data and initial management are collected using a standard protocol and a central pathology review is performed. After enrollment, patients are actively followed for events (disease progression, retreatment, and death) and disease related comorbidities. Tissue Micro Arrays (TMA) are constructed on available primary biopsy specimens. Epstein Barr Encoded RNA (EBER) EBV testing was performed by in-situ hybridization, and scored by an expert hematopathologist. EBER reactivity in more than 30% of malignant cells were required for EBV(+) designation. All DLBCL patients from the MER with available TMA excluding primary mediastinal DLBCL and post transplant lymphoproliferative disorders (PTLD) are included in the current analysis. Event free survival (EFS) was defined as time from diagnosis until recurrence, retreatment, or death due to any cause. Results 184 newly diagnosed DLBCL patients with available TMAs were enrolled in the MER from 2002–2009. The median age at enrollment was 62 (range 18–89) and 57% were male. 89.7% were treated with immunochemotherapy. At a median follow-up of 66 months (range 1–116), 80 patients (43%) had an event which included 59(32%) deaths. TMA testing was positive for EBV in 13 (7 %) samples with an even distribution among age groups. There was a trend toward higher percentage of stage III/IV disease (85 vs 57%, p = 0.052), and BM involvement (46 vs 16%). EBV (+) was not associated with other extranodal disease or further identifiable differences in presenting clinical characteristics. Controlling for IPI, the hazard ratio for EFS among EBV+ in DLBCL pts over 50 was 0.41 (95% CI = 0.13–1.32) p = 0.14. EFS and OS curves for pts over 50 are shown below. There were no events or deaths in the 4 EBV+ pts under age 50. Conclusions EBV+ DLBCL represents a small proportion of DLBCL patients presenting for care to our academic medical centers, consistent with reports from other regions. Substantial unique clinical characteristics at presentation for those pts with EBV+ disease were not identified, and outcomes were no worse than EBV (−) counterparts. Given the apparent regional differences in reports of EBV(+) DLBCL of the elderly, future clinical series will need to establish a more precise definition or determine more distinctive features to justify adoption of EBV(+) DLBCL of the elderly as a full entity in the WHO classification. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 1546 Background: Follicular lymphoma (FL) is an incurable disease with an undefined optimal management strategy. Global priorities in goals of care are avoidance of death and transformation to aggressive subtypes. Retrospective series, – most including patients diagnosed before ubiquitous rituximab use, - describe diverse rates of transformation with a common consensus of 3% per year, and with a median survival post transformation of less than 2 years. This study sought to characterize transformation events in a prospective observational series begun after diffusion of early rituximab use in FL. Methods: Newly diagnosed FL patients were prospectively enrolled in the University of Iowa/Mayo Clinic SPORE Molecular Epidemiology Resource (MER) from 2002–2009. Clinical data were abstracted from medical records using a standard protocol. Patients were actively followed for retreatment, transformation, and death. Inclusion criteria for this analysis were initial diagnosis of grade I-IIIa FL. Exclusion criteria for this cohort include composite diffuse large B-cell lymphoma (DLBCL), FL grade IIIb, or evidence of clinical or pathological transformation at the time of FL diagnosis. Transformation was defined as refractory/recurrent disease with either a) biopsy confirmed subtype of FLIIIb, DLBCL or higher grade B-cell lymphoma; or b) clinical indication of transformation (sudden rise in LDH, rapid discordant localized nodal growth, new involvement of unusual extranodal sites, new B symptoms or hypercalcemia). Risk of transformation was analyzed via time to transformation using a death as a competing risk. Time to transformation was defined as the date of initial FL diagnosis to date of transformation. Overall survival was defined as the date of initial diagnosis to date of death or last known follow-up for patients still alive. Results: There were 631 newly diagnosed grade I-IIIa FL patients with a median age at enrollment of 60 years (range 23–93). 54% were male. The most common types of initial therapy were observation (33%), rituximab (R) monotherapy (12%), alkylator based chemotherapy +/− R (22%), and anthracycline based chemotherapy +/− R (20%). At a median follow-up of 60 months (range 11–110), 79 patients had died, 311 patients had an event (death, progression, or retreatment), and 60 patients (9.5%) had transformed. Transformation was biopsy proven in 48 of the 60 patients (80%). The overall transformation rate at 5 years (TX5) was 10.7% (95% CI: 8.3%–13.8%) (Figure 1). Time to transformation was associated with a FLIPI score of 3–5 (HR=2.37, 95% CI 1.28–4.39, p=0.006), but was not significantly associated with other standard clinical characteristics. Risk of transformation was different in the common initial treatment groups with the highest rate in patients who were initially observed (TX5=14.4%) and lowest rate in patients who initially received R monotherapy (TX5=3.2%)(p=0.058). Outcome after transformation was inferior to MER subjects with de-novo diagnosed DLBCL (p<0.0001). The median overall survival from date of transformation was 44 months (95% CI: 22-NA). Survival after transformation was superior in patients who transformed greater than 18 months after FL diagnosis compared to patients who transformed earlier (5 yr OS =70% vs 20%) (p=7 ×10−5), and for those initially observed (median unreached) versus those patients who were initially treated with alkylator or anthracycline based chemotherapy (median survival of 11 months)( p=0.016). Conclusions: Follicular transformation rates in this modern large prospective observational study are similar to risk of death without transformation and slightly lower at 5 years than most previous reports. Post-transformation prognosis is substantially better than described in older series. These observed differences may be a function of the prospective nature of the study design, modern management strategies, or patient selection factors. Initial management strategies may influence the risk of transformation. Marked survival differences following early vs. late transformation suggest that these may be different biologic events. Disclosures: Link: Genentech: Consultancy, Research Funding; Celgene: Consultancy; Millenium: Consultancy. Johnston:Novartis: Consultancy.

Abstract Abstract 149 Background. There are few established factors that predict risk of follicular lymphoma (FL) transformation, and only two studies have evaluated the role of germline genetic variation and risk of transformation. One study reported an association of a BCL6 SNP (397C>G) with risk of transformation, and a second study reported an association with rs6457327, which is in the HLA region of 6p21. This study evaluated the risk of FL transformation in the modern treatment era with germline SNPs that were previously reported to be associated with FL transformation (BCL6SNPs and rs6457327), along with SNPs (N=45) previously associated with either risk of FL or FL prognosis. Methods. Newly diagnosed FL patients were prospectively enrolled from 2002–2009 into the Molecular Epidemiology Resource of the University of Iowa/Mayo Clinic Lymphoma SPORE. Peripheral blood for genotyping was collected at enrollment, and clinical and treatment data were abstracted from medical records. All patients were actively followed for disease progression, retreatment, transformation and death. For this analysis, only FL patients with grade I-IIIa were included. Patients with composite DLBCL, FL grade IIIb, or other evidence of transformation at diagnosis were excluded. Transformation was based on either 1) biopsy confirmation of FL grade IIIb, DLBCL, or higher grade B-cell lymphoma; or 2) clinical indicators of transformation based on the published literature, including sudden rise in LDH, rapid discordant localized nodal growth, new involvement of unusual extranodal sites, new B-symptoms, or hypercalcemia. Genotyping was conducted using a custom Illumina iSelect panel. Cox regression was used to estimate Hazard Ratios (HRs) and 95% confidence intervals (CI) for individual SNPs with time to transformation, with death modeled as a competing risk. Each SNP was modeled with the most prevalent homozygous genotype used as the reference group, and each SNP was modeled as having a log-additive (per minor allele) effect in the regression model. An ordinal test was used to assess the trend, and p<0.05 was considered statistically significant. Results. There were 631 newly diagnosed grade I-IIIa FL patients, of whom 532 had DNA and were successfully genotyped. The median age at diagnosis was 60 years (range 23–93) and 53% were male. FLIPI distribution was 42% 0–1, 34% 2 and 24% 3–5. Initial therapies included observation (32%), rituximab (R) monotherapy (13%), alkylator-based chemotherapy +/− R (20%), and anthracycline-based chemotherapy +/− R (19%). At a median of 59 months of follow-up (range, 11–110), 58 patients died, 254 had an event (death, progression or retreatment) and 54 patients (10%) transformed. Transformation was biopsy proven in 43 of the 54 patients (80%). The SNP rs6457327 on chromosome 6p that was previously reported to be associated with transformation was positively associated with risk of transformation in our data (HR=1.40; 95%CI 0.97–2.04; p=0.07), although this association was weaker but still consistent with the prior report. Further, we evaluated additional typed SNPs from the HLA region of 6p, and found additional associations (p<0.05) with HLA-DRA (3 SNPs), HLA-DQA2 (2 SNPs), HLA-DOA (2 SNPs) and HLA-DPB1/HLA-DPA2 (2 SNPs), of which rs10484569 from HLA-DPB1/HLA-DPA2 was the most strongly associated with risk of transformation (HR=3.01; 95%CI 1.48–6.09; p=0.002). None of the BCL6 or other previously reported risk SNPs were associated with transformation. Of the SNPs previously associated with FL prognosis, only the FCGR2A rs1801274 (HR=1.41; 95%CI 0.94–2.10; p=0.09) and CD46 (CD46 molecule, complement regulatory protein) rs2466571 (HR=1.72; 95%CI 1.16–2.55; p=0.007) were associated with risk of transformation. For CD46, one additional SNP (rs2796269) was also associated with transformation (HR=0.61; 95%CI 0.40–0.95; p=0.03). Further adjustment for FLIPI score and treatment (observation versus all other) did not alter these associations. Conclusions. The previously reported association of rs6457327 with risk of transformation in the modern treatment era was replicated. In addition, several HLA loci and two FL prognosis SNPs were linked to transformation risk. The remaining published FL risk or prognosis SNPs were not associated with transformation. Our results support a role for germline genetic variation in the HLA region, FCRGR2A and CD46 in transformation of FL. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 1563 Intro: Optimal treatment for non-follicular low grade B-cell lymphoma (NFLGL) is not well defined. Clinical trial design for these subtypes would be enhanced by further understanding of early presentation and management. A large prospective observational study was used to identify presenting clinical features, describe patterns of care and compare the prognostic utility of International Prognostic Index (IPI) and the Follicular Lymphoma International Prognostic Index (FLIPI). Methods: The University of Iowa/Mayo Clinic SPORE Molecular Epidemiology Resource (MER) is a prospective, longitudinal observational study designed to collect information on patterns of care and outcomes for patients with newly diagnosed lymphoma. Patients seen at the Mayo Clinic, Rochester MN and the University of Iowa within 9 months of their initial diagnosis of lymphoma are offered enrollment. Baseline patient reported data, clinical data and initial management are collected using a standard protocol and a central pathology review is performed. After enrollment, patients are actively followed for events (disease progression, retreatment, and death) and disease related comorbidities. This analysis includes 198 patients diagnosed with extranodal marginal zone (EMZL), 22 with nodal marginal zone (NMZL), 47 with splenic marginal zone (SMZL), 48 with lymphoplasmacytic lymphoma (LPL), as well as 67 patients with unclassifiable low-grade B-cell lymphoma (B-NOS). Results: 382 newly diagnosed NFLGBL patients were enrolled in the MER from 2002–2009. The median age at enrollment was 63 years (range 22–95). 52% were male. The most common types of initial therapy after diagnosis were observation (41 %), alkylator- based chemotherapy +/− rituximab (R) (17%), radiation therapy alone (15%) and R monotherapy (13%). At median follow-up of 60 months (range 1–121), 51 patients were deceased and 155 had an event. The clinical characteristics that comprise the IPI and FLIPI were similar across the subtypes. Approximately half of the cases presented at low risk (55% IPI; 48% FLIPI). A majority had a normal LDH (81%), limited nodal involvement (91% had ≤ 4 groups), normal hemoglobin (71% ≥12 g/dL), good performance status (95% 0–1), and advanced stage (57% stages III-IV). There were notable differences among the NFLGBL subtypes. Patients with SMZL and LPL presented with high risk FLIPI of 3–5 (49% and 46% respectively) and high to high-intermediate IPI of 3–5 (21% and 13%). Abnormal LDH and anemia (< 12 g/dL) were more frequent in patients with SMZL (40%; 56%) and LPL (25%; 62%). EMZL presented with lower stages (70% stage I-II) and NMZL presented with increased nodal involvement (38% >4 sites). SMZL had the highest rates of surgical resection (21%) and EMZL was more frequently treated with radiation therapy (25%). LPL (30%) and NMZL (32%) more commonly received alkylator based chemotherapy +/− R. While both IPI and FLIPI differentiated outcome in these patients, FLIPI had higher c-statistics than IPI for both EFS (0.583 vs 0.568) and OS (0.685 vs 0.661), respectively. Conclusions: This large prospective collection of data on NFLGBL patients presenting to academic medical centers provides a modern picture of presentation and management patterns useful to investigators designing clinical trials. FLIPI may have more prognostic utility than IPI in this group of patients. Disclosures: Ansell: Seattle Genetics, Inc.: Research Funding.

Abstract BACKGROUND: Diffuse large B-cell lymphoma, not otherwise specified (DLBCL), though defined as one disease entity, consists of two main cell-of-origin (COO) subtypes, germinal center B-cell like (GCB) and activated B-cell like (ABC), with the latter predicting a significantly worse prognosis using conventional chemotherapy. Up to 40% of all patients diagnosed with DLBCL will experience relapse, and outcomes are generally poor in this setting. In this study, we examine the proportion of GCB vs. non-GCB subtypes at initial diagnosis and at time of relapse, and assess the incidence of reclassification from one subtype to another. 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. All relapse events were validated by review of the medical record. This analysis includes patients diagnosed with DLBCL who underwent initial treatment and subsequently experienced relapse as confirmed by biopsy. Immunohistochemical staining data including CD10, Bcl-6, and Mum-1, were collected from available pathology reports and classified to either GCB or non-GCB subtypes as predicted by the Hans algorithm. We compared subtype classification and individual immunohistochemical data both at the time of diagnosis and relapse. The overall subtype agreement between the two diagnostic time points was assessed. RESULTS: 1023 patients with newly diagnosed DLBCL were enrolled in the MER from 2002 - 2012. Of those, 249 had documented disease relapse. Of those analyzed, a total of 43 patients had COO classification based on the Hans algorithm from tissue biopsy at both diagnosis and relapse. Thirty patients were characterized as GCB DLBCL on initial presentation, and upon relapse 28 were noted to be GCB, while 2 were noted to be the non-GCB subtype. Of the 13 that were characterized as non-GCB on initial presentation, 10 remained non-GCB while 3 were reclassified as GCB. The overall agreement of DLBCL COO phenotypes between initial diagnosis and relapse was 88%. Seven percent of those initially diagnosed as GCB were reclassified as non-GCB subtype; in contrast, 23% of those initially diagnosed as non-GCB had changed to GCB upon relapse. Similar analysis was performed on individual immunohistochemical staining factors including CD10, Bcl-6, and Mum-1, and we observed overall agreement of 88%, 87%, and 91%, respectively. CONCLUSIONS: A majority of patients with relapsed DLBCL exhibit similar COO phenotypes at initial presentation and at relapse, and the incidence of reclassification from one subtype to another is uncommon. This suggests that the initial treatment regimen for DLBCL rarely alters the basic cancer phenotype when immunohistochemistry laboratory technical factors and pathologist interpretive discrepancies are excluded as causes for this change. However, reclassification from GCB to non-GCB subtypes is observed in a minority of cases, which may affect the overall outcome and response to treatment. Further studies are needed using gene expression to categorize COO and to examine the factors surrounding the time of relapse for possible harbingers of relapse as well as the behavior and outcome of reclassified DLBCL. Table Table. Disclosures Ansell: BMS, Seattle Genetics, Merck, Celldex and Affimed: Research Funding.

Abstract Background: Peripheral T-cell lymphomas (PTCLs) comprise a group of non-Hodgkin lymphomas (NHLs) of mature T-cell origin with generally aggressive clinical behavior. Most systemic PTCLs are treated with anthracycline-based combination chemotherapy; however, outcomes remain relatively poor for most subtypes except ALK-positive anaplastic large cell lymphoma (ALCL). We have used landmark analyses based on event-free survival (EFS) to identify clinically useful endpoints in B-cell NHLs, with EFS at 24 (EFS24) months identified to stratify overall survival (OS) in aggressive B-cell NHL. Here we examined the ability of EFS24 to predict subsequent OS in a large, multinational PTCL cohort. Methods: A cohort of newly diagnosed PTCL patients treated with curative intent combination chemotherapy regimens was assembled from the University of Iowa/Mayo Clinic SPORE Molecular Epidemiology Resource (MER), Swedish Lymphoma Registry (SWE), and British Columbia Cancer Agency (BCCA). Subtypes included ALK-negative ALCL, angioimmunoblastic T-cell lymphoma (AITL), PTCL, not otherwise specified (NOS), enteropathy-associated T-cell lymphoma (EATL), extranodal NK/T-cell lymphoma, nasal type (ENKTL), and hepatosplenic T-cell lymphoma (HSTCL). Patients were followed based on local institution guidelines, and EFS was defined as time from the date of pathologic diagnosis to progression, re-treatment, or death due to any cause. EFS24 was defined as being alive and event-free 24 months from diagnosis. Subsequent OS was defined as time from achieving EFS24 (24 months from diagnosis) or time from progression in patients failing to achieve EFS24 (progression within 24 months of diagnosis). OS was compared to the age-, sex-, and country-matched general population using United States, Sweden, and British Columbia rate tables via standardized mortality ratios (SMR) and expected survival. Results: 775 patients diagnosed from 2000-2012 were included in the combined analysis with diagnosis by the WHO classification at the respective institutions (MER=138, SWE=422, BCCA=215). Median age at diagnosis was 64 years (range 18-89) and 63% were male. Patient characteristics are summarized in the table. 736 (95%) received anthracyline-based therapy at diagnosis. At a median follow-up of 77 months (range 1-185), 516 patients (67%) had died. The percentage of patients achieving EFS24 was similar across the 3 cohorts (MER=39%, SWE=35%, BCCA= 36%, combined=36%). Median survival after progression within the first 24 months was only 4.9 months (95% CI: 3.8-5.9), with a 5-year OS of 11% and SMR of 46.4 (95% CI: 41.8-51.3). In contrast, median survival after achieving EFS24 was not reached, with a 5-year OS of 78% (95% CI: 73%-84%). This was inferior to the expected survival of 92% in the age-, sex-, and country matched population (SMR=3.16; 95% CI: 2.48-3.98). In EFS24 subgroup analyses, more favorable outcomes were observed in younger patients (age <=60 years, N=137, 5-year survival of 91% vs. 98% expected) and in patients receiving autologous stem cell transplant in first remission (N=72, 5-year survival of 88% vs. 96% expected). Patients achieving EFS24 who were not transplanted in first remission (N=189) had a 5-year survival of 74% vs. 90% expected. Conclusions: Assessment of EFS24 stratifies subsequent outcome in PTCL. Patients with early relapse from PTCL have extremely poor outcomes. However, over one-third of patients with PTCL remain in remission two years from diagnosis after initial chemotherapy and have encouraging OS rates, although survival remains significantly worse than the matched general population. Subset analysis suggests that younger patients and patients who receive autologous stem-cell transplant in first CR have 5-year survival rates that approach 90%, though still below the expected survival of the background population. The marked differences in OS after failing or achieving EFS24 in PTCL patients suggest that this endpoint may be useful for patient counseling, as a clinical trial endpoint, and as an endpoint to assess novel biomarkers for risk stratification. Table Table. Figure 1. Figure 1. Figure 2. Figure 2. Disclosures Maurer: Celgene: Research Funding; Kite Pharma: Research Funding. Jerkeman:Mundipharma: Research Funding; Amgen: Research Funding; Janssen: Research Funding; Gilead: Research Funding; Celgene: Research Funding. Connors:Seattle Genetics: Research Funding; Millennium Takeda: Research Funding; NanoString Technologies: Research Funding; F Hoffmann-La Roche: Research Funding; Bristol Myers Squib: Research Funding. Ansell:BMS, Seattle Genetics, Merck, Celldex and Affimed: Research Funding.

Abstract Background: Secondary CNS involvement (SCNS) is a detrimental complication seen in ~5% of patients with diffuse large B-cell lymphoma (DLBCL) treated with modern immunochemotherapy. Data from older series report short survival following SCNS, typically <6 months. However, data in patients that develop SCNS following primary therapy that contains a rituximab-based-regimen as well as the impact of more intensified treatment for SCNS are limited. Aims: The aims of this study were to i) describe the natural history of SCNS in a large cohort of patients treated with immunochemotherapy, and ii) determine prognostic factors after SCNS. Patients and methods: We performed a retrospective study of patients diagnosed with SCNS during or after frontline immunochemotherapy (R-CHOP or equivalently effective regimens). SCNS was defined as new involvement of the CNS (parenchymal, leptomeningeal, and/or eye) in patients without known CNS involvement at the time of first pathologic diagnosis of DLBCL. Patients were identified from local databases and/or regional/national registries in Denmark, Canada (British Columbia), Australia, Israel, US (University of Iowa/Mayo Clinic SPORE), and England (Guy's and St. Thomas' Hospital, London). Clinico-pathologic and treatment characteristics at the time of SCNS were collected from medical records. Results: In total, 281 patients with SCNS diagnosed between 2001 and 2016 were included. Median age at SCNS was 64 (range 20-93) years and male:female ratio was 1.3. SCNS occurred as part of first relapse in 244 (87%) patients and 112 (40%) had documented concurrent systemic disease at the time of SCNS. The median time from initial DLBCL diagnosis to SCNS was 9 months, which was similar for patients treated with (N=76, 27%) or without upfront CNS prophylaxis (N=205, 73%) (10 vs 9 Mo; P=0.3). The median post-SCNS OS was 4 months (interquartile range 2-13) and the 2yr survival rate was 20% (95% CI 15-25) for the entire cohort. Associations between clinicopathologic features, management strategy, and post-SCNS survival are shown in Table 1, which excludes patients who did not receive any treatment against SCNS, patients treated with steroids alone, and a patient with unavailable treatment information (n=43, 15%). In multivariable analysis, performance status >1, concurrent leptomeningeal and parenchymal involvement, SCNS developing before completion of 1st line treatment, and combined systemic and CNS involvement by DLBCL were associated with inferior outcomes. Upfront CNS prophylaxis did not influence post-SCNS OS. High-dose methotrexate (HDMTX) and/or platinum based treatment regimens (i.e. ICE, DHAP, or GDP [+/- IT treatment and/or radiotherapy], N=163) for SCNS were associated with reduced risk of death (HR 0.45 [0.32-0.62, P<0.01]). The 2yr post-SCNS survival for patients treated with HDMTX and/or platinum-based regimens (N=163) was 29% (95% CI 22-37). For patients with isolated parenchymal SCNS, single modality treatment with radiotherapy resulted in 2-yr OS of 19% (95% CI 8-35). For the subgroup of 49 patients treated with HDMTX- and/or platinum-based regimens for isolated SCNS after 1st line DLBCL treatment and with performance status 0 or 1, the 2yr post-SCNS survival was 46% (95% CI 31-59). Overall, 9% of the patients received HDT with ASCT as part of salvage therapy at the time of SCNS. Amongst 36 SCNS patients without systemic involvement and in CR following intensive treatment (HDMTX and/or platinum-based treatments), 11 patients consolidated with HDT had similar outcomes to 25 patients treated without consolidating HDT (P=0.9, Fig 1) Conclusions: Outcomes for patients with SCNS remain poor in this large international cohort of patients from the immunochemotherapy era. Combined parenchymal and leptomeningeal disease, presence of systemic disease concurrent with SCNS, performance status >1, and SCNS developing during first line treatment were independently associated with inferior OS. However, a significant fraction of patients with isolated SCNS after first line DLBCL treatment and with good performance status may achieve long-term remissions after intensive regimens for SCNS. Disclosures El-Galaly: Roche: Consultancy, Other: travel funding. Cheah:Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Gilead Sciences: Membership on an entity's Board of Directors or advisory committees; Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees, Other: Speaker's Bureau. Kansara:Celgene: Honoraria. Connors:Bristol Myers Squib: Research Funding; NanoString Technologies: Research Funding; F Hoffmann-La Roche: Research Funding; Millennium Takeda: Research Funding; Seattle Genetics: Research Funding. Sehn:roche/genentech: Consultancy, Honoraria; amgen: Consultancy, Honoraria; seattle genetics: Consultancy, Honoraria; abbvie: Consultancy, Honoraria; TG therapeutics: Consultancy, Honoraria; celgene: Consultancy, Honoraria; lundbeck: Consultancy, Honoraria; janssen: Consultancy, Honoraria. Opat:Roche: Consultancy, Honoraria, Other: Provision of subsidised drugs, Research Funding. Seymour:Genentech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie Inc.: 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; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: 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. Villa:Celgene: Honoraria; Lundbeck: Honoraria; Roche: Honoraria, Research Funding.

Abstract The anti-CD20 monoclonal antibody rituximab (R) is widely used to treat B-cell malignancies including follicular lymphoma (FL). A better understanding of activity and resistance mechanisms is necessary for improving treatment outcomes. We previously reported that genetic variants in the complement pathway are associated with event-free survival of FL patients following R therapy. This correlation was particularly high for SNP rs3766404, located in intron 6 of Complement Factor H (CFH). Subjects with the minor allele of this SNP experienced inferior event-free survival. Five CFH related proteins (CFHR1-5) share a similar and sometimes overlapping function with CFH, including suppression of complement activation. Genetic variations within the CFH family locus are linked to a variety of complement-mediated disorders such as age-related macular degeneration (AMD) and atypical hemolytic uremic syndrome. Interestingly, AMD patients with the minor allele of rs3766404 frequently have deletion of CFHR3 and CFHR1, suggesting that loss of these proteins functionally impacts complement regulation. The current studies were designed to better understand the relationship between R therapy of FL and CFH family proteins. CFH and CFHR1 protein levels were quantified in serum samples from both normal subjects (n=59) and FL (n=108) subjects from the Iowa/Mayo Lymphoma SPORE Molecular Epidemiology Resource. No correlation was observed between the quantity of CFH in serum and SNP genotype in either cohort. However, in both cohorts, individuals homozygous for the minor allele in SNP rs3766404 lacked detectable expression of CFHR1. Homozygotes for the major allele expressed the highest levels of CFHR1, and heterozygotes expressed intermediate levels. Among FL subjects treated with R as a component of initial therapy, increased levels of CFHR1 were associated with improved event-free survival (hazard ratio 0.48, 95% confidence interval 0.28-0.82, p=0.0051). In contrast, CFHR1 levels had no impact on outcome among the FL subjects who did not receive R as a component of initial therapy. This subset of FL subjects included those observed off therapy. The effect of CFHR1 levels on outcome for those subjects treated with R versus those not treated with R was statistically different (p=0.0023 based on a Cox proportional hazard model). There was no correlation between CFH levels and outcome in any population. CFHR1 binds the complement component C3b, inhibiting downstream complement activation. We previously demonstrated that complement can inhibit R activity in vitro. Specifically, C3b deposition can have a negative impact on antibody–mediated tumor cell killing by interfering with R-induced NK cell activation and antibody dependent cellular cytotoxicity. Our current finding that higher CFHR1 correlates with improved outcome following R therapy provides further evidence that the effect of complement on therapeutic monoclonal antibodies is complex. These findings may have implications for predicting response to, and optimization of, anti-CD20 and other antibody therapies. Ongoing studies are exploring this possibility in additional patient cohorts, the potential role of other CFH family members, and the underlying biology associated with these observations. Disclosures: Link: Genentech: Consultancy; Millenium: Consultancy; Pharmacyclics: Consultancy; Spectrum: Consultancy; Genentech: Research Funding; Millenium: Research Funding; Pharacyclics: Research Funding.

Abstract Background. Diffuse large B-cell lymphoma (DLBCL) is curable for the majority of patients treated with anthracycline based immunochemotherapy (IC). While most patients achieve response to initial therapy, a subset of patients are refractory to initial IC or become refractory to subsequent salvage therapies. Prognosis in this setting is very poor. Here we determine the incidence of refractory disease from a large cohort of DLBCL prospectively followed from diagnosis in the IC era and assess outcomes in these patients. Methods. Patients were prospectively enrolled in the University of Iowa/Mayo Clinic Lymphoma SPORE Molecular Epidemiology Resource (MER) within 9 months of diagnosis. Patients were followed for relapse, retreatment, and death; all events were validated by medical record. This analysis includes patients with DLBCL or primary mediastinal B-cell lymphoma (PMBCL) who received initial treatment of anthracycline based immunochemotherapy; patients with primary CNS lymphoma or post-transplant lymphoproliferative disorders were excluded. Response to therapy was retrospectively classified per 2007 Revised Response Criteria for Malignant Lymphoma from available clinical and radiology records. Refractory disease was defined as having a best response to any systemic therapy of stable disease (SD), progressive disease (PD), or relapse within 12 months of autologous stem cell transplantation (SCT). We also examined patients with transient response to IC as defined by achieving an interim response (CR or PR) but having progressive disease at or prior to the end of the planned number of cycles of IC. Results. 1039 patients with DLBCL or PMBCL lymphoma were enrolled in the MER from 2002-2012 and treated with R-CHOP or comparable IC. Median age at diagnosis was 62 years (range 18-91) and 577 (56%) were male. At a median FU of 60 months (range 1-148), 136 patients developed refractory disease. The median age at diagnosis of patients with refractory disease was 62 years (range 19-87). The cumulative incidence of refractory DLBCL was 11.3% at 2 years (95%: CI: 9.5-13.4) and 13.1% at 5 years (95% CI: 11.2-15.4). The median overall survival after becoming refractory was 4.7 months (95% CI: 4.1-5.5) with a 1 year survival rate of 21% (95% CI: 15%-30%). The median number of therapies before becoming refractory was 2 with 35 patients becoming refractory following their first therapy (i.e. IC), 83 patients becoming refractory after their 2nd therapy, and 23 patients becoming refractory after their 3rd or later therapy; 27 patients had received stem cell transplant prior to becoming refractory. Outcomes were poor regardless of when patients became refractory (figure). Patients received a median (range) of 2 (0-8) treatments after becoming refractory with 40% (N=54) attempting subsequent platinum based salvage therapy and 14% (N=9) proceeding to ASCT, of which only 6 remain alive in long-term remission. 41 patients (30%) were treated on clinical trials after becoming refractory. Response rate for the first therapy after becoming refractory was 21%, while 29% of patients had a response to any subsequent therapy. Once patients became refractory, there was no difference in survival based on response at end of initial IC (p=0.33), cell of origin at diagnosis (p=0.64), IPI at diagnosis (p=0.33), or age when refractory (p=0.66). Outcomes in patients with transient response to IC (n=58) were poor, with the majority (N=37, 63%) becoming refractory to subsequent therapy. Median OS after first relapse was 6.7 months in patients with transient response to IC, which was equivalent to patients refractory to IC (p=0.99). The majority of patients with transient response to IC (69%) were next treated with platinum based salvage therapy which had a response rate of 40%. Ultimately 15 of the 58 patients (26%) proceeded to transplant, of which only 5 (9%) achieved long-term remission. Conclusions. Approximately 13% of patients with DLBCL become refractory to treatment in their disease course. Outcomes once patients become refractory are extremely poor regardless of when patients become refractory. Standard prognostic factors are no longer predictive of outcome and stem cell transplant had limited benefit in this group of patients. Patients with transient response to initial immunochemotherapy should be included when classifying patients as refractory. New therapy strategies are needed in the refractory setting. Figure 1. Figure 1. Disclosures Maurer: Kite Pharma: Research Funding. Thompson:Kite Pharma: Research Funding. Farooq:Kite Pharma: Research Funding. Cerhan:Kite Pharma: Research Funding. Ansell:Bristol-Myers Squibb: Research Funding; Celldex: Research Funding. Link:Genentech: Consultancy, Research Funding; Kite Pharma: Research Funding.

Abstract Diffuse large B-cell lymphoma (DLBCL) is a genetically heterogeneous disease characterized by multiple low-frequency alterations including somatic mutations, copy number alterations (CNAs) and chromosomal rearrangements. We sought to identify previously unrecognized low-frequency genetic events, integrate recurrent alterations into comprehensive signatures and associate these signatures with clinical parameters. For these reasons, our multi-institutional international group assembled a cohort of 304 primary DLBCLs from newly diagnosed patients, 87% of whom were uniformly treated with state-of-the-art therapy (rituximab-containing CHOP regimen) and had long term followup. Tumors were subjected to whole exome sequencing with an extended bait set that included custom probes designed to capture recurrent chromosomal rearrangements. In this cohort, 47% of samples had available transcriptional profiling and assignment to associated disease subtypes. Analytical pipelines developed at the Broad Institute were used to detect mutations (MuTect), CNAs (Recapseq+Allelic Capseq) and chromosomal rearrangements (dRanger+Breakpointer) and assess clonality (Absolute). To analyze formalin-fixed paraffin-embedded tumors without paired normals we developed a method which utilized 8334 unrelated normal samples to stringently filter recurrent germline events and artifacts. Significant mutational drivers were identified using the MutSig2CV algorithm and recurrent CNAs were assessed with GISTIC2.0. In addition, we utilized a recently developed algorithm, CLUMPS2, to prioritize somatic mutations which cluster in 3-dimensional protein structure. With this approach, we identified > 90 recurrently mutated genes, 34 focal amplifications and 41 focal deletions, 20 arm-level events and > 200 chromosomal rearrangements in the DLBCL series. Of note, 33% of the mutational drivers were also perturbed by chromosomal rearrangements or CNAs, underscoring the importance of a comprehensive genetic analysis. In the large DLBCL series, we identified several previously unrecognized but potentially targetable alterations including mutations in NOTCH2 (8%) and TET2 (5%). The majority of identified chromosomal rearrangements involved translocations of potent regulatory regions to intact gene coding sequences. The most frequently rearrangements involved Ig regulatory elements which were translocated to BCL2, MYC, BCL6 and several additional genes with known roles in germinal center B-cell biology. After identifying recurrent somatic mutations, CNAs and chromosomal rearrangements, we performed hierarchical clustering and identified subsets of DLBCLs with comprehensive signatures comprised of specific alterations. A large subset of tumors shared recurrent alterations previously associated with follicular lymphoma including mutations of chromatin modifiers such as CREBBP, MLL2, and EZH2 in association with alterations of TNFRSF14 and GNA13 and translocations of BCL2. This cluster was enriched in GCB-type DLBCLs and contained a subset with select genetic alterations associated with an unfavorable outcome. An additional cohort of tumors was characterized by alterations perturbing B-cell differentiation including recurrent BCL6 translocations or alterations of PRDM1. A subset of these DLBCLs had alterations of NOTCH2 and additional pathway components or mutations of MYD88 in association with TNFAIP3, CD70 and EBF1, a master regulator of B-cell differentiation. An additional group of DLBCLs exhibited frequent MYD88 mutations in association with alterations of CD79B, PIM1, TBL1XR1 and ETV6 and BCL2 copy gain; these tumors were highly enriched for ABC-type DLBCLs. This coordinate signature and additional alterations of p53 pathway components were associated with outcome. We explored bases for the identified genetic alterations in DLBCL by performing an in silico mutational signature analysis. The most frequent mutational signatures were those of spontaneous deamination (aging) and AID with rare cases of microsatellite instability. We also assessed the clonality of identified genetic features to define cancer cell fraction and establish the timing of specific genetic events. The comprehensive genetic signatures of clinically annotated DLBCLs provide new insights regarding approaches to targeted therapy. Disclosures Link: Kite Pharma: Research Funding; Genentech: Consultancy, Research Funding. Rodig:Perkin Elmer: Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding. Pfreundschuh:Boehringer Ingelheim, Celegene, Roche, Spectrum: Other: Advisory board; Roche: Honoraria; Amgen, Roche, Spectrum: Research Funding. Shipp:Gilead: Consultancy; Sanofi: Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees, Research Funding.