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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.

We showed in a phase I trial that the maximum tolerated dose of the ProMACE-CytaBOM regimen in patients with aggressive lymphoma was 200% (Gordon et al, J Clin Oncol 14:1275, 1996). Based on these observations, we initiated a phase II trial designed to determine response, toxicity, and dose intensity using this regimen. We analyzed 74 patients with advanced-stage (III or IV) or bulky stage II aggressive lymphoma. The overall complete response rate was 69% (72% in evaluable patients). With a median follow-up of 4.5 years, the median survival has not yet been reached. The 4-year survival rate is 73% (95% confidence interval [CI] 62, 83%) and no difference was observed among International Prognostic Index (IPI) groups. The 4-year disease-free survival was 71% (95% CI 58, 84%) with no statistical difference between patients with IPI 0 to 1 versus 2 to 4. The toxicity was acceptable, though the grade 4 hematologic toxicity rate for this regimen was 100%. Grade 4 nonhematologic toxicity was 36%. Three cases of either myelodysplastic syndrome or acute leukemia occurred at 7 months, 3.4 years, and 4.2 years after registration. Cytogenic analysis was available in two cases, showing inv(16) without French American British classification (FAB) M4 EO histology in one patient and a 5q-syndrome in the other. These data suggest that 200% ProMACE-CytaBOM with either granulocyte-macrophage colony-stimulating factor (GM-CSF) or G-CSF results in a high complete remission rate and a disease-free survival comparable to any prior risk-based analysis in aggressive lymphoma. Before using this regimen in general practice, phase III clinical trials should be conducted.

Abstract Abstract 1534 + equal contributions Diffuse large B-cell lymphoma (DLBCL) is a clinically and biologically heterogeneous disease with a high proliferation rate and infrequent somatic mutations of TP53 and genes encoding cell cycle pathway components. Despite recent advances in the molecular understanding of DLBCL pathogenesis, clinical models such as the International Prognostic Index (IPI) are still used to identify high-risk patients. By integrating high-resolution high-density SNP array data with transcriptional profiles and performing pathway analysis in 180 primary DLBCLs, we identified a comprehensive set of copy number alterations (CNAs) that decreased p53 activity and perturbed cell cycle regulation. Primary DLBCLs with single copy loss of 17p13.1 (TP53/RPL26/KDM6B) often had CNAs of an additional p53 modifier – 9p21.3 (CDKN2A/ARF), 19q13.42 (BCL2L12), 12q15 (MDM2) or 1q23.3 (MDM4/RFWD2). CNAs of the respective p53 modifiers, CDKN2A (ARF, 9p21.3), MDM2 (12q15) and MDM4/RFWD2 (1q23.3), occurred in largely separate groups of tumors. DLBCLs with CNAs of p53 pathway members frequently exhibited concurrent alterations of additional cell cycle components such as CCND3 (6p21.32), CDK6 (7q22.1), CDK2/CDK4 (12q15) and/or RB1 (13q14.2) or RBL2 (16q12.2). When the primary DLBCLs were clustered in the space of CNAs that perturb p53 pathway and cell cycle components, 66% of tumors had multiple alterations (“complex” pattern) whereas the remaining 34% of tumors lacked these lesions (“clean” signature). Tumors with “complex” alterations of p53 pathway and cell cycle components also had more total CNAs and more frequent TP53 mutations, highlighting the association between p53 deficiency, cell cycle deregulation and increased genomic instability in DLBCL. The patterns of “complex” vs. “clean” CNAs of p53 pathway and cell cycle components and the association between the “complex” signature and total CNAs were confirmed in an independent series of primary DLBCLs. To further characterize DLBCLs with “complex” vs. “clean” CNA patterns, we performed gene set enrichment analyses with publicly available series of p53 target genes and a RB-deficiency gene set which included multiple E2F targets. The p53 target transcripts were significantly less abundant in “complex” DLBCLs, directly linking their genetic signature of p53 deficiency with decreased p53 activity. Furthermore, the RB-deficiency gene set was significantly enriched in “complex” DLBCLs suggesting that these tumors had increased E2F-mediated cell cycle progression. Consistent with these observations, DLBCLs with “complex” CNA patterns also had significantly higher proliferation indices as determined by Ki67 immunostaining. We next assessed the prognostic significance of the “complex” CNA pattern in the subset of patients who were treated with R-CHOP (rituxan, cyclophosphamide, adriamycin, oncovin, prednisone) and had long-term follow-up. R-CHOP treated patients with “complex” CNA patterns had a 5-year overall survival of only 62%; in contrast, those with “clean” CNA signatures had an 100% overall survival (p =.001). The association between CN complexity and outcome was independent of transcriptionally defined categories and additive to the clinical IPI risk model. Taken together, these data provide a structural basis for deregulated cell cycle, increased cellular proliferation and unfavorable outcome in DLBCL and suggest targeted treatment strategies. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 1527 Interim Positron-Emission Tomography (PET-scan), as a functional imaging test for tumor activity, has been shown to be a predictor for progression-free survival (PFS) and time to progression (TTP) in classical Hodgkin lymphoma (HL). The peripheral blood absolute lymphocyte/monocyte ratio (ALC/AMC) at diagnosis, as a surrogate marker of host immunity (i.e., ALC) and tumor microenvironment (i.e., AMC), has been recently reported [Porrata et al, Hematologica 2012; 97(2): 262–9] and confirmed [Koh et al, Oncologist 2012; 17(6): 871–80] to be also a predictor for PFS and TTP in classical HL. Therefore, we evaluated the combination of ALC/AMC ratio at diagnosis and the interim PET-scan to further stratify the clinical outcomes of PFS and TTP in patients with classical HL. To participate in the studies, patients were required to be diagnosed, treated, and followed at Mayo Clinic, Rochester, Minnesota. The treatment consisted of adriamycin, bleomycin, vinblastine, and dacarbazine (ABVD) with or without radiation therapy. Patients were required to have an interim PET-scan performed. An ALC/AMC ratio ≥1.1 cut-off was used in the study based on our previous publication [Porrata et al, Hematologica 2012; 97(2): 262–9]. From 2000 until 2008, 111 classical HL patients qualified for the study. The cohort included 54% males and 46% females. The median age at diagnosis was 37 years (range: 18–83 years). The median follow-up was 2.8 years (range: 0.3–10.4 years). Patients with a negative interim PET-scan (N=98) presented with a higher ALC/AMC ratio at diagnosis (median of 2.32, range: 0.26–37.5) compared with patients with a positive interim PET-scan (N = 13) (median of 0.9, range: 0.29–3.10), p < 0.004. By univariate analysis, the ALC/AMC ratio at diagnosis and the interim PET-scan were predictors for PFS [ ALC/AMC ratio, R =0.13, 95% CI (0.05–0.35), p < 0.0002; and interim PET-scan, HR = 0.13, 95% CI (0.05–0.37), p < 0.0003] and TTP [ALC/AMC ratio, R =0.07, 95% CI (0.02–0.24), p < 0.0001; and interim PET-scan, HR = 0.05, 95% CI (0.01–0.18), p < 0.0003]. By multivariate analysis, ALC/AMC ratio at diagnosis and the interim PET-scan were independent predictors for PFS [ ALC/AMC ratio, R =0.13, 95% CI (0.07–0.63), p < 0.006; and interim PET-scan, HR = 0.11, 95%CI (0.02–0.47), p < 0.003] and TTP [ALC/AMC ratio, R =0.11, 95% CI (0.02–0.71), p < 0.02; and interim PET-scan, HR = 0.10, 95% CI (0.02–0.46), p < 0.003] when compared to the International Prognostic Score, limited versus advanced stage, and radiation. Patients were stratified into four groups: group 1 included patients with a negative interim PET-scan and ALC/AMC ratio at diagnosis ≥1.1 (N = 88); group 2 included positive interim PET-scan and ALC/AMC ratio at diagnosis ≥1.1 (N = 5); group 3 included negative PET-scan and ALC/AMC ratio at diagnosis < 1.1 (N = 10); and group 4 included positive PET-scan and ALC/AMC ratio at diagnosis <1.1 (N = 8). The three year PFS rates for each group were for goup1 95% (Events = 6); group 2 40% (Events = 3); group 3 56% (Events = 4); and group 4 50% (events = 4), p < 0.0001. The three year TTP rates for each group were: for group1 was 100% (Events = 0); for group 2 of 40% (Events = 3); for group 3 of 65% (Events = 3); and group 4 of 50% (events = 4), p < 0.0001. In conclusion, the ALC/AMC ratio at diagnosis is independent of the interim PET-scan to predict PFS and TTP in classical HL. Further studies are warranted to confirm our findings and to assess if the combination of the ALC/AMC ratio at diagnosis and interim PET can be use for planning of risk-adapted treatment. Disclosures: Ansell: Seattle Genetics, Inc.: Research Funding.

Abstract Abstract 1618 Introduction: Primary breast lymphoma is a rare type of non-Hodgkin lymphoma (NHL), representing about 1% of breast tumors and 2% of extranodal NHL. Diffuse large B-cell lymphoma (DLBCL) is the most common primary subtype presenting in the breast. Due to the low incidence of primary breast DLBCL, outcome data is limited. The aim of this study was to retrospectively assess the natural history of primary breast DLBCL in the pre and post rituximab eras, with specific emphasis on the incidence of local, systemic and central nervous system (CNS) relapses. Methods: Data was retrospectively collected on patients with primary breast DLBCL from seven USA academic medical centers. Institutional review board approval was obtained at each participating site. Patients were identified through institutional databases and tumor registries at each site. Charts were reviewed to obtain demographic and clinical variables including treatment history and dates of relapse and death when applicable. Only patients with stage I/II disease (involvement of breast and localized lymph nodes) were included. All histologies apart from primary DLBCL were excluded. Overall survival (OS) was calculated from the diagnosis date to the date of death or last follow-up. Time to Progression (TTP) was calculated from diagnosis data until the date of pathological evidence of recurrence or death. Data were summarized using descriptive statistics, and survival was analyzed using the Kaplan-Meier method. Results: Between 1984 and 2012, 75 patients were identified who met the eligibility criteria. The median age was 62 years (range 17–87); 81% presented with a palpable mass; 12% had their disease detected incidentally by mammography; 4% presented with B-symptoms; 59% had right breast involvement; 67% had stage I and 33% had stage II disease. The stage-adjusted international prognostic index (IPI) score was 0 in 28% of patients, 1 in 41%, 2, in 25%, 3 in 4% and 4 in 1%. 91% of patients were treated with chemotherapy; 31% of these were treated in the pre-rituximab era and 69% received rituximab. Radiation therapy (RT) was utilized in 68% of patients and was the only treatment modality in 8% of those receiving RT. 8% of patients received CNS prophylaxis with intrathecal chemotherapy. After a median follow-up of 4.5 years (range 0.6 – 20.6 years), the Kaplan-Meier estimated median TTP was 10.4 years (95% CI 6.2 – 14.6 years) and the median OS was 14.6 years (95% CI 6.5 – 22.6 years). The 5-year TTP and 5-year OS were 65% (95% CI 53–77%) and 75% (95% CI 64–86%) respectively. Among the patients who relapsed, 67% occurred within the first 2 years. A total of 7 relapses in the breast were observed, none in patients treated with combination of chemotherapy and RT. In univariate analysis, rituximab exposure was not associated with any difference in TTP or OS. The stage-adjusted IPI was associated with OS; the 5-year OS was 88% (95% CI 79–98%) in patients with a score of 0–1 versus 48% (95% CI 25–71%) in those with a score of 2–4 (log rank p < 0.001). The very limited-disease group with a stage-adjusted IPI of 0 had a 5-year OS of 94% (95% CI 83–100%) compared to all others who had a 5-year OS of 67% (95% CI 52–81%; log rank p = 0.001). There was no difference in TTP and OS in patients with solitary versus multiple breast masses or between patients with tumors less than versus more than 7cm. Patients receiving RT in addition to chemotherapy had a longer TTP than those who did not (log rank p = 0.03), but RT was not associated with an improved OS. Patients who relapsed and underwent stem cell transplant (SCT) had similar OS to those who never relapsed. Ten patients (13%) had CNS relapse (3 with leptomeningeal disease, 5 with brain parenchymal disease and 2 with both). All CNS relapses occurred within the first 2.8 years from the time of diagnosis. There was no difference in the rate of CNS relapse in the patients who received IT prophylaxis versus those who did not. Conclusions: In this multicenter study, the largest published to date, primary breast DLBCL appears to have a worse prognosis than early-stage DLBCL in nodal or other extranodal sites. RT was associated with improved TTP. Patients who relapsed were successfully salvaged with SCT, and had similar survival times to those who never relapsed. A high CNS relapse rate (∼1 in 8 patients, including parenchymal disease in 70%) was observed. The small numbers preclude definitive conclusions on the value of intrathecal prophylaxis or the utility of rituximab. 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 Background: CLL patients (pts) treated with novel targeted therapies continue to experience disease progression. Approximately 7-15% of relapsed CLL treated with ibrutinib or venetoclax developed Richter's syndrome (RS), an aggressive high grade lymphoma transformation. Standard chemotherapy has limited efficacy in RS. We hypothesized that checkpoint blockade would re-establish anti-tumor immune response in progressive CLL/RS and here we aim to update the clinical data and correlative analysis of MC1485: a phase 2 study of PD-1 blocking antibody pembrolizumab in relapsed/refractory CLL and RS. Methods: Relapsed/refractory CLL including RS enrolled in the CLL arm of MC1485 trial was reported here. The primary end point of this study is overall response rate (ORR). Pts with prior allogeneic stem cell transplant were excluded. Pembrolizumab 200 mg was administered intravenously every 3 weeks. NCI CTCAE v4.0 and IWCLL 2008 criteria were used for non-hematological adverse events (AE) and for CLL grade hematological AE. Tumor expression of PD-1 and PD-L1 were assessed with standard immunohistochemical (IHC) staining. Percentage expressions of individual antigens were analyzed with whole-slide scanning followed by image analysis with Image-Pro software (Media Cybernetics). Fluorescence in situ hybridization (FISH) was performed on available CLL/RS tissue sections to assess copy number of chromosome 9p region that contains PD-L1 and PD-L2. Results: 25 pts including 16 CLL and 9 RS (biopsy-proven large cell lymphoma) were enrolled in CLL arm. The median age was 69 years (46-81). Twelve (48%) pts had del(17p) or monosomy 17 or TP53 mutation. The median number of prior therapies was 4 (1-10). 96%, 72% or 48% of pts had received alkylator and anti-CD20 antibody, purine analog or anthracycline. Fifteen (60%) pts had prior ibrutinib and 12 (48%) progressed clinically while receiving ibrutinib, including 6 who progressed to RS and 6 who developed progressive CLL. The median number of pembrolizumab doses that pts received was 3 (1 to 21), administered over a median treatment duration of 11 weeks (1 to 56). Drug-related AE occurred in 21 pts (88%) with the most common ones being neutropenia in 9 (37%), cough in 7 (29%) and dyspnea in 6 (25%) pts. Drug-related grade 3 or above AE occurred in 9 (38%) pts with most common ones being thrombocytopenia (5, 21%), dyspnea (2, 8%), and fatigue (2, 8%). The most common immune-related AE was liver enzyme elevation (12%, 8% G3) and was reversible with therapy interruption or steroid therapy. Based on investigator assessment using the Revised Response Criteria for Lymphomas and IWCLL 2008 criteria, one RS pt had complete response (CR, 4%), 3 RS had partial responses (PR, 12%). Among 9 RS pts, 1 CR (11%), 3 PR (33%), 3 SD (33%) and 2 PD (22%) were observed. Thus the ORR in RS was 44%. No CLL pts achieved a CR/PR, 3 had SD and 9 had progressive disease (PD). The ORR of all pts was 16%. Of the 4 RS who had CR/PR, responses occurred early after 2 cycles of therapy and median duration of therapy for CR/PR pts was 8.3 months with data cut-off by June 30th 2016 (Figure 1A). The causes for therapy discontinuation in RS were PD (3, 33%), alternate therapy (2, 22%), and thrombocytopenia due to increased marrow CLL (1, 11%). Increased marrow CLL was observed in 2 RS pts with PR to RS phase of disease assessed by PET, thus the protocol was amended to allow addition of idelalisib/ibrutinib to control the underlying marrow CLL. For RS pts who had a CR/PR or SD, variable nodal responses were observed (Figure 1B). In particular, 6 RS who had prior ibrutinib experienced CR or PR or SD with nodal responses. After a median follow-up of 10.2 (1.9 to 16.1) months, the median overall survival (OS) for all pts was 10.7 months (95% confidence interval [CI], 5.4 to not reached). The 6 month OS rate for RS and CLL pts were 73% and 59%, respectively. Biomarker assessment using IHC analysis on 10 pts with available tumor/nodal tissues (6 RS and 4 CLL) showed an increased expression of PD-L1 (p = 0.02) and a trend for an increased expression of PD-1 (p = 0.1) in the group of pts with CR/ PR versus pts in the group with no clinical response. One out of 10 tested showed polysomic for chromosome 9p. Conclusion: Pembrolizumab had an acceptable safety profile in CLL and RS patients. We confirmed that pembrolizumab has substantial therapeutic activity in RS. Single-agent pembrolizumab does not appear to have clear activity in CLL. Disclosures Ding: Merck: Research Funding. Parikh:Pharmacyclics: Honoraria, Research Funding. Shanafelt:GlaxoSmithKline: Research Funding; Genentech: Research Funding; Janssen: Research Funding; Pharmacyclics: Research Funding; Celgene: Research Funding; Cephalon: Research Funding; Hospira: Research Funding.

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 1525 Background: Nodular lymphocyte predominant Hodgkin Lymphoma (NLPHL) is a more indolent form of Hodgkin Lymphoma that is usually associated with favorable outcomes. However, a number of reports have shown a tendency of transformation to more aggressive types of lymphoma, typically diffuse large B-cell lymphoma (DLBCL). Long-term data on the incidence and outcomes of transformed NLPHL is lacking in the literature. The aim of this study was to evaluate incidence, risk factors and outcomes of DLBCL transformation in NLPHL in a cohort of patients followed at a single institution. Methods: The actively maintained Mayo Clinic Lymphoma Database includes all consenting consecutive patients with lymphoma seen at Mayo Clinic Rochester. This was used to retrospectively identify patients with NLPHL. The study was approved by the Institutional Review Board. Pathology was reviewed by a hematopathologist and all transformations were histologically confirmed by WHO criteria. The clinical characteristics, therapy and outcomes of patients with NLPHL and DLBCL transformation were analyzed. The chi-square test was used to compare variables. Risk of progression was calculated using a person-year approach. Survival and freedom from transformation were estimated and compared using the Kaplan Meier method and log rank tests, respectively. Results: Between 1970 and 2010, 222 consecutive adult patients with NLPHL were identified. The median follow-up was 20 years. Of these, 17 (7.7%) developed a transformation to DLBCL during the course of the disease (Figure 1). The median time to transformation was 35 (6–248) months. Of these 17 patients, 13 (76.5%) were male, 11 (64.7%) had stage I/II and 6 (35.3%) had stage III/IV NLPHL. Transformation was the first relapse in most patients (12 patients, 70.6%) while five patients (29.4%) developed one or more relapses of NLPHL before transformation. Prior therapies for NLPHL were as follows: radiation therapy in 5 (29.4%), chemotherapy in 5 (29.4%) and combined chemotherapy and radiation in 6 (35.3%) patients. The median age at transformation was 45 years (30–87). Most patients (10 patients, 58.8%) presented with signs (palpable lymph nodes) or “B” symptoms. Eight patients (47.1%) had stage III/IV disease at the time of transformation. The most commonly used regimens for treatment of DLBCL were R-CHOP or CHOP (9 patients, 52.9%). Platinum based therapy was administered in 4 (23.5%) patients. Five patients (29.4%) required more than one line of therapy, and autologous stem cell transplant was utilized in two (11.7%) patients. Based on the observed 17 transformations during 2304 patient-years of follow-up, the rate of transformation was 0.74 per 100 patient-years. The five-year overall survival (OS) of patients with transformed disease (calculated from time of transformation) was 76.4%. The most common cause of death was lymphoma (75%). Following treatment for transformation, 5 patients (29.4%) relapsed. The OS in transformed patients was independent of prior therapies, and transformation did not adversely affect overall survival in our cohort (median survival of in 129 months in transformed versus 120 in non-transformed patients, P=0.33). In a univariate analysis of prior therapies, use of radiation therapy was associated with a significant delay in time to transformation (P= 0.0035) (Table 1, figure 2). Conclusions: The risk of transformation in NLPHL is 0.74% per year in this large single institution case series of NLPHL, and appears to be lower than that observed in follicular and other types of low grade lymphoma. The outcomes of patients with transformation were significantly better than reported in other types of transformed lymphoma and did not adversely affect OS. 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.