Caribbean, and rarely encountered within the United States. ATLL is sub-divided in 5 categories: acute, lymphomatous, chronic, smoldering, and Hodgkin like. Much is still to be established with this rare disease including a standard of care. The high prevalence of patients with HTLV-1 ATLL in the Caribbean places our institution within close prox- imity as opposed to other areas of the United States. Methods: We identified HTLV-1 ATLL patients treated at Moffitt Cancer Center (MCC). Records were reviewed for demographics, disease features, and outcomes. Results: Ten ATLL patients were treated at MCC over the past 5 years. The median age was 56 years. Six patients were females and 7 were originally from the Caribbean. Seven patients were leukemic subtype, 9 patients had lymph- adenopathy, 7 patients had bone marrow involvement, 5 had skin rash, 1 patient had bone disease, and none of the patients had hepatosplenomegaly, nor CNS disease. The mean hemoglobin was 12 g/dl, WBC 17/mcl, and platelets 266/mcl. All patients had hypercalcemia (mean serum calcium 11.7mg/dl), the mean serum LDH was 1238 U/L. By immunophenotype, all cases were CD3+, 90% CD5+, 80% CD25+, and 10% CD30+. Seven patients received CHOP regimen as first line therapy, and 2 patients interferon/zidovudine, 1 patient had VCAP-AMP-VECP. Only 1 patient had complete response (CR) to first line therapy, 4 had partial responses, and 3 had progressive disease. Subsequent therapy included interferon/zidovudine in 2 patients, HyperCVAD 2 patients, ESHAP 2 patients, and ICE, IGEV, pralatrexate, and denileukin difitox in 1 patient each. Three patients proceeded to allogeneic stem cell transplant (ASCT). The median overall survival (OS) was 51 months (mo). The median OS was 88 mo among those who underwent ASCT versus 34 mo for those who did not. Conclusion: HTLV-1 ATLL is associated with poor outcomes. Response to CHOP chemotherapy is poor. Best outcomes were achieved if patients proceeded to ASCT in CR1. 928 The clinical significance of cereblon expression, as an effective therapeutic target, in patients with diffuse large B-cell lymphoma Zijun Y. Xu-Monette, 1 Ruifang Sun, 1 Yi Xia, 1 Xiaoxiao Wang, 1 Xin Li, 1 Ken H. Young 1 1 Department of Hematopathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA Corresponding author: Ken H Young, UT MD Anderson Cancer Center, 1515 Holcombe Blvd, Unit 72, Houston, TX 77030, Phone: 713-745-2598; Fax: 713-792-7273, Email: khyoung@mdanderson.org Background: Cereblon (CRBN) mediates the activity of immunomodulatory drug and CRBN expression has been found to correlate with better survival for patients with multiple myeloma, activated B-cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL), and chronic lymphocytic leukemia treated with lenalidomide-containing regimen. The molecular mechanism un- derlying the critical role of CRBN includes induction of p21 which promotes cell cycle arrest and downregulation of interferon regu- latory factor 4 (IRF4) via ubiquitination activities resulting in decreased levels of many proteins downstream the B-cell receptor signaling including Myc. Objective: To evaluate the clinical sig- nificance of CRBN expression in DLBCL patients treated with standard chemotherapy rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP) and to determine the predictive value related to its signaling pathway. Approaches: We assessed CRBN expression by immunohistochemistry in 462 de novo DLBCL patients treated with R-CHOP and analyzed corre- lations between CRBN expression and other clinicopathologic fac- tors and patient survival outcomes. Gene expression profiling is analyzed for potential molecular mechanism. Results: We did not observe correlation of CRBN expression with IRF4, Myc, p53 or p21 expression. However, CRBN expression correlated with significantly better survival outcomes in DLBCL, especially the ABC subtype. This favorable prognostic impact of CRBN expres- sion depends on TP53 being wild type genetic status, and was most apparent in patients with Myc overexpression. Gene expression profiling is performed to define the CRBN-driven signature be- tween the subgroups. Conclusions: CRBN expression correlated with better survival outcomes in patients with DLBCL with WT- TP53, more apparent in patients with Myc overexpression. This study helps identify a subgroup of patients with better prognosis among patients who have ABC-DLBCL or DLBCL with Myc overexpression. Understanding the mechanism for the correlation of CRBN expression with survival outcomes in DLBCL is necessary. Enhancing CRBN expression may be a novel therapeutic strategy for targeted intervention of DLBCL patients. 929 Characteristics, Treatment and Outcomes of Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN): A single institution experience Erwin Grussie, 1 Neha Mehta-Shah, 2 Raajit Rampal, 2 Ahmet Dogan, 2 Alison Moskowitz, 2 Craig Sauter, 2 Parastoo Dahi, 2 Matthew Lunning, 3 David Straus, 2 Janine Pichardo, 2 Kurt Bantilan, 2 Patricia Myskowski, 2 Steven Horwitz 2 1 Icahn School of Medicine at Mount Sinai - St. Luke’s Roosevelt Hospital CenterInstitution; 2 Memorial Sloan-Kettering Cancer Center; 3 University of Nebraska *both authors contributed equally to this work Context: BPDCN is a rare and aggressive disorder that shows disappointing results using multi-agent chemotherapies. There is no standard treatment and transplantation seems to be the only cura- tive option. Objective: Assess a large single institution experience treating patients with BPDCN including subjects treated with pralatrexate. Design: Retrospective series of patients diagnosed with BPDCN at Memorial Sloan Kettering Cancer Center (MSKCC) Abstracts S74 - Clinical Lymphoma, Myeloma & Leukemia September 2015