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Introduction : Chronic lymphocytic leukemia (CLL) is the most common type of leukemia in Western populations, being rarer in Asian and African people. It has been suggested that patients with CLL from Africa might have a more aggressive disease compared with Causasien patients. In this study, we aimed to identify genetic factors that may account for this difference Methods: We collected peripheral blood mononuclear cells (PBMCs) from a total of 75 patients with CLL, 25 from Senegal (Africa), and 50 from Siena. Since it is well known that there are differences in germline IGH repertoires between different populations, we also collected PBMCs from five healthy Senegalese individuals as control. We analyzed immunoglobulin heavy chain (IGH) genes mutational status by performing next-generation sequencing in these 2 groups of patients. Results: We found that Senegalese patients more frequently had adverse prognostic factors and an unmutated profile. Furthermore, we documented that IGHV1 (IGHV1-69), IGHD3, and IGHJ6 were significantly more frequent in Senegalese patients, whereas IGHV3-30 was common and limited to the Italian cohort. Stereotyped receptors commonly detected in the white population were not recorded in our Senegalese series. Conclusion: The different IGH repertoire we observed in the Senegalese cohort may reflect the diverse genetic and microenvironmental (ie, polymicrobial stimulation) background. Disclosures Gozzetti: Takeda: Honoraria; Amgen: Honoraria; Janssen: Honoraria, Research Funding.

To ascertain the genetic basis of pediatric Burkitt lymphoma (pBL), we performed clinical-grade next-generation sequencing of 182 cancer-related genes on 29 formalin-fixed, paraffin embedded primary pBL samples. Ninety percent of cases had at least one mutation or genetic alteration, most commonly involving MYC and TP53. EBV(−) cases were more likely than EBV(+) cases to have multiple mutations (P < .0001). Alterations in tumor-related genes not previously described in BL were identified. Truncating mutations in ARID1A, a member of the SWI/SNF nucleosome remodeling complex, were seen in 17% of cases. MCL1 pathway alterations were found in 22% of cases and confirmed in an expanded panel. Other clinically relevant genomic alterations were found in 20% of cases. Our data suggest the roles of MCL1 and ARID1A in BL pathogenesis and demonstrate that comprehensive genomic profiling may identify additional treatment options in refractory disease.

Abstract 4826 Background: Hodgkin Lymphoma (HL) is a highly curable malignancy that mostly affects young adults; currently, considering all patients more than 75% of them will be cured and the ones diagnosed with early stage disease have a chance of cure over 90%. However, despite these very satisfactory results, about 20% of patients still die from progressive disease and non-specific related Hodgkin's mortality, mostly due to late toxic effects, continues to rise with time. Consequently, the optimal treatment should be designed based on prognostic models, but currently all of them predict the outcome of treatment with imperfect accuracy. Since from recent studies “early FDG–PET” and lately tissue macrophages infiltration seem to be powerful predictors, we hypothesized that macrophage infiltration could be the shadow of the inflammatory microenvironment that FDG-PET identifies in HL and that persist at early assessment in patients who will fail to respond to treatment. Consequently we decided to verify this hypothesis analyzing a group of patients with HL diagnosed and treated at our institution. Patients and methods: on the basis of availability of paraffin embedded diagnostic specimen and “early PET” assessment, we selected a cohort of 24 patients (M/F: 12/12) with Hodgkin Lymphoma, diagnosed and treated at our institution between February 2007 and February 2010. Before starting treatment all patients completed staging with whole body CT scan, FDG-PET and bone marrow biopsy. Ten patients had stage II disease, 10 patient stage III and 4 patients stage IV; median age was 33 years. Programmed treatment consisted of 4–6 cycles of ABVD and, if indicated, involved-field radiation therapy. Patients repeated CT scan and FDG-PET after two cycles and after completion of therapy. Macrophage infiltration in paraffine-embedded diagnostic specimen was retrospectively determined by immunohostochemistry. Results: After two cycles of ABVD, FDG-PET was negative in 18/24 patients (75%), while FDG-PET was positive in the six remaining patients (25%). Overall 20 out of 24 patients (83%) achieved a CR, however two of them had an early relapse (within 6 months), so they underwent 2nd line therapy plus autologous stem cell transplantation (ASCT), both obtaining a second CR. Among the four remaining patients, one achieved only a PR and entered salvage protocol with 2nd line treatment plus ASCT, two achieved a CR after second line treatment and the last one was refractory to 3 lines of treatment and finally was enrolled in an investigational protocol. With a median follow up of 18.5 months, 21 out of 24 patients are alive in CR, a patient is alive in PR and two patients died, due respectively to pulmonary thromboembolism and ARDS (after mediastinal irradiation). Five out six patient (83%) with persistent positive “early FDG-PET” failed their first line treatment. About macrophage percentage in the diagnostic specimen, evaluated and classified according to the criteria reported in the recent paper by Dr Steidl and coworkers, one patient (4%) was classified with score 1, twelve (50%) with score 2 and eleven (46%) with score 3. Among the six patients with persistent positive “early-FDG-PET”, one of them had score 1 (and never obtained CR), three had score 2 and two score 3. Conclusions: with the limitation of a small cohort of patients and the lack of gene-expression assays, our data do not seem to support our hypothesis neither to confirm the recently reported prognostic impact of macrophage infiltration in diagnostic specimen. Disclosures: No relevant conflicts of interest to declare.

Immunoglobulin (Ig) gene analysis delineates critical features of the clonal history of a B-cell tumor. After antigen interaction, mature B-cells undergo somatic mutation of the V-genes and isotype switch recombination, generally in the germinal center (GC). Receptor revision by secondary recombination of the V-genes with re-expression of recombination activating gene (RAG) enzymes rarely occurs at this stage. From a small series, we have reported that most hairy cell leukemias (HCL) carry mutated VH genes, with low levels of intraclonal heterogeneity, while a minor subset have unmutated VH genes. Both subsets commonly have ongoing Ig isotype switch events and express activation induced cytidine deaminase (AID). However HCL lack the GC markers CD27 and CD38, and CD23, a chemokine essential for lymph node entry. In order to probe more fully the differentiation status of the cell of origin, both VH and VL tumor-derived genes were evaluated in an expanded series of 38 HCL. From analysis of VH, the VH3 family usage was most common (24/38, 63%), with significant preference of the VH3-30 member in 10/38 cases (26%, p=0,00001), and JH4b segment utilised in 50% of cases. Most HCL (35/38) carried variable tiers of mutations (87–98.6% homology to germline), with low level of intraclonal heterogeneity also in cases with These data confirm heterogeneity in the cell of origin in terms of mutational status, with a minor subset with unmutated V-genes. Restricted V-gene segment usage, low levels of ongoing mutations with AID activated, and the new observation of receptor revision with re-expression of RAG enzymes indicate that selection by antigen could be a promoting factor in HCL development. Lack of novel glycosylation sites is in favour of interaction with antigenic stimuli occurring at extrafollicular sites.