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Background. The Philadelphia (Ph) chromosome (chr.) is the hallmark of chronic myeloid leukemia (CML) and typically results from the reciprocal translocation t(9;22)(q34;11.2). Complex variant translocations (CVT) involving one or more additional chr. are identified in less than 5% of newly diagnosed CML. There are conflicting reports about the prognostic impact of CVT in the achievement of optimal response to tyrosine kinase inhibitor (TKI), and very few studies addressed the role of frontline treatment with imatinib or second generation (2G)-TKI in patients with CVT. Aims. To assess the response to imatinib or 2G-TKI in a large cohort of newly diagnosed CML with CVT, and to explore the impact of the different chr. translocations on outcome. Methods. This observational retrospective study was conducted in 19 hematologic centers in the framework of Campus CML, a network of Italian physicians involved in the management of CML patients. All newly diagnosed CML from 2000 to 2019 were evaluated and patients with CVT were selected for the present analysis. Karyotypes were defined according to the 2016 International System for Human Cytogenetic Nomenclature. Responses to frontline treatment were retrospectively categorized according to the 2013 ELN recommendations, as they include cytogenetic milestones. Deep molecular response (DMR, i.e. MR4or better) was defined as BCR-ABLIS ratio ≤0.01% or undetectable disease with ≥10,000 ABL copies. Patients with DMR lasting ≥2 years and at least a Q-PCR test every 6 months were defined as stable DMR responders. Failure-free survival (FFS) was calculated from the start of frontline TKI treatment to progression to advanced phase, death, or switch to other treatments for resistance. For FFS calculation, patients were censored at TKI stop for treatment-free remission (TFR) or in case of switch for intolerance only. Differences between subgroups according to the partner chr. were presented for descriptive purposes. Results. CVT were identified in 109 (3.2%) patients from a whole population of 3,361 subjects with newly diagnosed CML. Ninety-five out of 109 patients (87%) exhibited three-way translocations, with chr. 1, 4, 6, 10, 11, 12, 14, 15 and 17 representing the most common additional partners (figure). Four- and five-way translocations were identified in 13 and 1 patients, respectively. Additional chr. abnormalities (ACA) in the Ph+ cells were observed in 15/109 (13.8%) patients and were more common in older individuals (p=0.018). Overall, median age at diagnosis was 50.6 years (range 20-90). Risk distribution according to the ELTS score was 54%, 28% and 8% for L, I and H risk, respectively (10% missing). Cytogenetic result was available before the choice of frontline treatment in 45% of cases and represented a decisive factor in 28% of them (i.e. clinicians selected a 2G-TKI or high-dose imatinib, according to the available options). Frontline TKI treatment was imatinib in 80 cases (73%) and 2G-TKI (nilotinib n=22, dasatinib n=6, bosutinib n=1) in the remaining cases. The frequency of optimal response at 3, 6 and 12 months was 48%, 45% and 53%, respectively, for imatinib-treated patients, and 76%, 83% and 76%, respectively, for the 2G-TKI cohort (p The subtype of CVT had an impact on response and long-term outcome. Patients with CVT involving chr. 1, 4, 6, 11 or 12 had a higher frequency of MMR at 12 months than patients with CVT involving chr. 10, 14, 15 or 17 (75.8% vs 30.4%, respectively, p=0.001), higher frequency of stable DMR (48.7% vs 22.2%, respectively; p=0.04) and tended to have better median FFS (p=0.07), regardless of the type of frontline TKI and of the ELTS score. Conclusions. Due to its retrospective nature, this study does not allow to define which is the optimal therapy for CML harboring CVT at diagnosis. However, our data reinforce the usefulness of bone marrow karyotyping in CML. The observed differences between partner chr. may also depend on the breaking points, which are variable. Further dissection of CVT will help to identify which are associated to a poor response to TKIs. Figure Disclosures D'Adda: Incyte: Other: Advisory board; Novartis: Other: Advisory board; Pfizer: Other: Advisory board. Galimberti:Novartis: Speakers Bureau; Incyte: Honoraria. Crugnola:Celgene: Honoraria; Janssen: Honoraria; BMS: Honoraria; Novartis: Honoraria. Bocchia:Incyte: Honoraria; CELGENE: Honoraria. Krampera:Janssen: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Breccia:Incyte: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Abbvie: Consultancy; Bristol-Myers Squibb/Celgene: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Saglio:Novartis: Research Funding; Ariad: Research Funding; Pfizer: Research Funding; Bristol-Myers Squibb: Research Funding; Incyte: Research Funding; Roche: Research Funding.

Background. Comorbidities have a well-established prognostic value in the majority of hematologic neoplasms. However, the impact of comorbidities on adult patients with acute lymphoblastic leukemia (ALL) has been poorly investigated to date. Aims. In this retrospective study of a monocentric cohort of 112 adults with Philadelphia-negative (Ph-neg) ALL consecutively diagnosed between 1990 and 2018 we aimed to assess the association between comorbidities at diagnosis and remission rate, the frequency and severity of adverse events (AE) during frontline treatment, and long-term outcome. Patients and methods. Patients were included, regardless of age, if treated within or according to clinical protocols aimed at curing. Patients initially treated with low-intensity/palliative care were not considered. Ph-positive patients were excluded, as their treatment modalities markedly changed over years due to the availability of tyrosine kinase inhibitors. Patients were defined as high risk if one or more of the following features were present: WBC >30x109/L for B-cell precursor (BCP) or >100x109/L for T-cell precursor (TCP), pro-B, early or mature T ALL phenotype, high risk cytogenetics (according to the ESMO 2016 guidelines), or central nervous system involvement. Comorbidities recorded at diagnosis were classified according to the Charlson Comorbidity Index (CCI). Classification and grading of AE was performed according to the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Responses were defined according to the ESMO 2016 guidelines. Minimal residual disease (MRD) was assessed by 6- or 8-colour flow cytometry with a 10-4 sensitivity. Variables tested for association with complete remission (CR) and MRD-negative status were: age group (stratified into quartiles), gender, phenotype (BCP or TCP), WBC, karyotype, risk class, and CCI score. Event-free survival (EFS) was calculated from the first CR to relapse or death. Overall survival (OS) was calculated from diagnosis until death. EFS and OS were estimated using the Kaplan-Meier method. Results. Median age at diagnosis was 43 years (range 14-75). BCP and TCP were 78% and 22%, respectively. Overall, 51 patients (46%) were considered as standard risk, 46 (41%) as high risk, and 15 (13%) were unclassifiable due to the lack of cytogenetics. CCI score distribution was as follows: 0 (n=66; 59%), 1 (n=18; 16%), 2 (n=9; 8%), and ≥3 (n=19; 17%). CR after induction therapy was obtained by 95/112 patients (85%). CCI was the only variable significantly associated to CR achievement (0-1 vs ≥2: 91% vs 68%; p=0.012). MRD status at the end of induction was evaluable in 64 out of 95 patients in CR and was negative in 28 (44%). No pretreatment variable predicted for the achievement of MRD complete response. Eight patients (7%) died before the first response evaluation; early death rate was significantly higher in patients with CCI ≥2 than in patients with CCI 0-1 (21% vs 2%; p=0.003). Conversely no differences in AE frequency and severity were observed according to CCI (p=0.847) or age group (p=0.881). After a median follow-up of 35 months, 46 patients (41%) were alive. OS was significantly longer in patients with CCI 0-1 as compared to CCI ≥2 (median 87 months, 95%CI: 31 to not reached vs 13 months, 95%CI: 5-36; p43 years: 81% vs 44%; p=0.014) and tended to be higher in patients treated with blinatumomab or inotuzumab rather than with standard chemotherapy (82% vs 55%, p=0.17). While there were no differences in CR2 according to CCI group, median survival after first relapse was 12.1 months (95%CI: 7.83-15.24) for CCI 0-1 vs 6.92 months (95%CI: 2.49-12.59) for CCI≥2(p=0.021). Conclusions. Comorbidities have a significant prognostic impact in intensively-treated adults with Ph-neg ALL. Patients with low comorbidities (CCI 0-1) had superior CR rates and less incidence of toxic death after induction, and pre-treatment high risk features did not have a detrimental impact in this group. Figure Disclosures Krampera: Novartis: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees. Bonifacio:Incyte: Honoraria; Pfizer: Honoraria; Novartis: Honoraria, Research Funding; Amgen: Honoraria.

The prognosis of patients affected by myelofibrosis (MF) is usually dismal and allogeneic hematopoietic stem cell transplantation (HSCT) remains the only cure. The number of HSCTs in MF patients has recently increased. However, a major obstacle is still represented by primary graft failure (PGF). Currently there are no definitive guidelines for the treatment of PGF and a second HSCT can be performed only when an allogeneic donor is rapidly available. Herein we report on a MF patient with PGF after an unrelated HSCT, who was rescued by a non-myeloablative, unmanipulated, haploidentical HSCT that resulted in persistent engraftment and bone-marrow fibrosis regression, but not in a long-term disease control. Based on this experience we briefly review the role of different conditioning regimens and hematopoietic stem cell sources in the setting of HSCT for MF patients with PGF. The role of haploidentical donors in MF patients lacking HLAmatched relatives is also discussed.

TNF-like ligand 1A (TL1A) and its unique receptor death receptor 3 (DR3) acts as broad T-cell costimulator involved in regulatory mechanisms of adaptive immune response under physiological and pathological settings. Moreover, we have recently shown that TL1A negatively regulates B-cell proliferation. Despite increasing interest on the TL1A/DR3-axis functions, very little is known on its expression and role in leukemia. In this study, we investigated the expression and function of TL1A/DR3 axis in chronic lymphocytic leukemia (CLL). DR3 was differentially expressed in activated CLL cells and predominantly detected in patients with early clinical stage disease. Soluble TL1A has been revealed in the sera of CLL patients where higher TL1A levels were associated with early stage disease. T cells, monocytes and leukemic B cells have been identified as major sources of TL1A in CLL. The relevance of these findings has been sustained by functional data showing that exogenous TL1A reduces CLL proliferation induced by stimulation of the B cell receptor. Overall, these data document the expression of the TL1A/DR3 axis in early-stage CLL. They also identify a novel function for TL1A as a negative regulator of leukemic cell proliferation that may influence the CLL physiopathology and clinical outcome at an early-stage disease.

A twin pair affected by juvenile myelomonocytic leukemia (JMML) with the same somatic PTPN11 mutation and abnormal chromosome 7 in bone marrow samples but distinct prognostic gene expression signatures, received a matched-unrelated donor and matched-unrelated cord blood transplant, respectively. Both twins fully engrafted, but after 6 months, the twin with an acute-myeloid-like (AML-like) signature at diagnosis rejected the graft and had an autologous reconstitution. A second transplant with an unrelated 5/6-HLA-matched-loci cord blood performed after 4 months from rejection was unsuccessful. After 25 months from diagnosis, the twin with the AML-like gene expression signature died of liver failure while on progression of his JMML. The other twin, who had a non-acute-myeloid-like (non-AML-like) gene expression signature at diagnosis is in complete hematological remission with full donor chimera. This observation suggests a biological diversity of JMML also in patients with a common genetic background.

Patients with Systemic Mastocytosis (SM) need a highly sensitive diagnostic test for D816V detection of the KIT receptor gene.Along with histology/cytology and flow cytometry evaluation, bone marrow (BM) from 110 consecutive adult patients referred with a suspicion of SM to Multidisciplinary Outpatient Clinic for Mastocytosis in Verona were tested both by Amplification Refractory Mutation System Reverse Transcriptase quantitative real time Polymerase Chain Reaction (ARMS-RT-qPCR) and RT-PCR. +. Restriction Fragment Length Polymorphism (RFLP) followed by Denaturing-High Performance Liquid Chromatography (D-HPLC) and Sanger sequencing.ARMS-RT-qPCR identified D816V mutation in 77 patients, corresponding to 100% of cases showing CD25+ mast cells (MCs) whereas RT-PCR+RFLP/D-HPLC+sequencing revealed D816V mutations in 47 patients.According to the 2008 WHO criteria 75 SM, 1 Cutaneous Mastocytosis (CM), 1 monoclonal MC activation syndrome (MMAS), and 1 SM Associated with Haematologic Non-Mast Cell Disorder (SM-AHNMD) were diagnosed. Seventeen out 75 SM patients (23%) would have not satisfied sufficient WHO criteria on the basis of the sole RT-PCR+RFLP: these patients had significantly lower serum tryptase levels and amount of CD25+ MCs.Therefore, ARMS-RT-qPCR might result particularly useful, in patients that do not fulfil major BM histological criterion, for the recognition of indolent SM with a very low MC burden.

Juvenile myelomonocytic leukemia is a rare neoplastic disorder occurring in early childhood often showing an aggressive progression. We report a case of a twin pair with concordant JMML but an extremely different disease course. Both twins presented with somatic aberrations of chromosome 7 and mutations in PTPN11. Analysis of sorted BM and PB cell populations revealed the clonal nature of the disease and indicated that genomic aberrations arise from common hematopoietic precursor cells. PTPN11 mutations in oral swab specimens of both patients during the active phase of the disease were attributed to monocytes infiltrating the oral mucosa and not to the presence of mosaic tissue mutations. This study provides evidence that the discordant clinical disease course in the twins is associated with a distinct gene expression profile.

Most patients affected by chronic lymphocytic leukemia are diagnosed by flow cytometry. Several immunophenotypic markers have been identified as significant and independent prognostic variables, especially from retrospective cohorts. However, while attractive because their detection is inexpensive and feasible in most laboratories, only few have been validated by independent series. The expression of leukocyte-associated immunoglobulin-like receptor-1 (also known as LAIR1, LAIR-1 or CD305), an inhibitor of B-cell receptor-mediated signaling, has been reported to be lacking in high-risk chronic lymphocytic leukemia. However, its correlation with biological variables and its prognostic significance remain unknown. We investigated 311 consecutive patients, prospectively enrolled since 2007. Methods for studying patients were standardized and included clinical assessment, immunophenotype, fluorescence in situ hybridization, and status of immunoglobulin heavy chain variable region genes. Overall, 22.1% of patients had Binet stage B or C disease, 38.5% had unmutated immunoglobulin genes, 15.1% had high-risk cytogenetic abnormalities, 23.4% were CD38(+), 37.8% CD49d(+), and 59.8% LAIR1(+). Expression of LAIR1 was inversely related to that of CD38 (P=0.0005), but was not associated with CD49d expression (P=0.96). A significantly lower expression of LAIR1 was observed in patients with Binet stage B or C disease (P=0.023), and in the presence of high-risk cytogenetic abnormalities (P=0.048) or unmutated immunoglobulin heavy chain variable region genes (P

The trisomy 8 found in malignancies may derive from a constitutional trisomy 8 mosaicism (CT8M), and in these cases the trisomy itself may be regarded as the first mutation in a multistep carcinogenetic process. To assess the frequency of CT8M in hematological dysplastic and neoplastic disorders with trisomy 8, an informative sample of 14 patients was collected. The data ascertained included chromosome analyses of fibroblast cultures and of PHA-stimulated blood cultures in patients with normal blood differential count, as well as possible CT8M clinical signs. One patient showed trisomy 8 in all cell types analyzed and undoubtedly has a CT8M; a second patient consistently showed trisomy 8 in PHA-stimulated blood cultures when no immature myeloid cells were present in blood and should be considered as having CT8M; a third patient, with Philadelphia-positive chronic myelocytic leukemia, was more difficult to interpret, but the possibility that she had CT8M is likely. A few clinical signs of CT8M were also present in these three patients. Our data indicate that the frequency of CT8M in hematological dysplastic and neoplastic disorders with trisomy 8 is approximately 15-20%.

Background small B-cell neoplasms can show plasmacytic differentiation and may potentially progress to aggressive lymphoma (DLBCL). Epstein-Barr virus (EBV) infection may cause the transformation of malignant cells in vitro. Design and Method we established VR09 cell line with plasmacytic differentiation, obtained from a case of atypical, non-CLL B-cell chronic lymphoproliferative disease with plasmacytic features. We used flow cytometry, immunohistochemistry, polymerase chain reaction, cytogenetic analysis and florescence in situ hybridization in the attempt at thoroughly characterizing the cell line. We showed VR09 tumorigenic potential in vivo, leading to the development of activated DLBCL with plasmacytic features. Results VR09 cells displayed plasmacytic appearance and grew as spherical tumors when inoculated subcutaneously into immunodeficient Rag2−/− γ-chain−/− mice. VR09 cell line and tumors displayed the phenotype of activated stage of B cell maturation, with secretory differentiation (CD19+ CD20+ CD79a+ CD79b+/− CD138+ cyclin D1- Ki67 80% IgM+ IgD+ MUM1+ MNDA+ CD10- CD22+ CD23+ CD43+ K+, λ- Bcl2+ Bcl6-) and they presented episomal EBV genome, chromosome 12 trisomy, lack of c-MYC rearrangement and Myd88 gene mutation, presence of somatic hypermutation in the VH region, and wild-type p53. Conclusion This new EBV-positive cell line may be useful to further characterize in vivo activated DLBCL with plasmacytic features.

Abstract 2668 Introduction. Diffuse large B cell lymphoma (DLBCL) represents a group of aggressive lymphoid neoplasms with morphological variants. Plasmablastic lymphoma has been recently classified as a clinical-pathological variant with plasmablastic features and terminal B-cell differentiation. Diffuse large B-cell lymphoma with both plasmablastic and plasmacytic features has been previously reported, but cell lines and animal models have been never described. However, the use of human lymphoma cell lines and animal models contributes significantly to a better understanding of the pathophysiology of hematopoietic tumors. We established and characterized a new plasmablastic lymphoma cell line with plasmacytic differentiation and we tested its tumorigenicity in vivo. Methods. Mononuclear cells from human DLBCL bone marrow, were seeded at concentration of 1×106/mL in RPMI 10% FBS medium added with 1% of antibiotics. Cells showed spontaneous proliferative capacity and a cell line (VR09) was established after a few months of continuous culture. VR09 cells were evaluated by May-Grünwald-Giemsa staining, flow cytometry, immunohistochemistry, molecular biology, standard karyotyping and fluorescence in situ hybridization (FISH). Epstein-Barr Virus (EBV) positivity was also tested. Moreover, cells were inoculated subcutaneously into 6 immunodeficient Rag2−/−γ-chain−/− mice. Subcutaneously-growing tumors were evaluated by immunohistochemistry and FISH. Disaggregated cells from masses were cultured again to confirm their biological features and proliferative capacity. Results. Cells in suspension formed large clumps with round shape by ten weeks of continuous culture. Cells appeared morphologically as medium/large-size cells with plasmablastic/plasmacytic appearance and, sometimes, bizarre shape. They had a round-ovoid or irregular nucleus with compact chromatin, no nucleoli and an abundant basophilic cytoplasm. When subcutaneously injected in mice, VR09 cells grew as an isolated spherical tumor (100% incidence). Moreover, cells maintained their proliferative capacity once disaggregated from mass and re-cultured. Cells displayed the phenotype of plasmablastic lymphoma with secretory differentiation (CD19+ CD3- CD5- CD20+ CD79a+ CD79b+/− CD138+ CD38+ cycline D1- Ki6780% IgM+ IgD+ MUM1+ MDNA+ CD10- CD22+ CD23+ CD43+ K+, λ- Bcl2+ Bcl6-). The same markers were detected on tissues derived from growing tumors and cell suspension. FISH analysis revealed the trisomy of chromosome 12 and the negativity for the MYC rearrangement both in VR09 cell line and in tumors. Cell suspension from mass showed an additional structural chromosome aberration involving chromosomes 7 and 9. EBER probe detected episomal EBV genome in both VR09 cell line and tumors. Genetic analysis in VR09 cell line showed the somatic hypermutation in the VH region, wild type p53 and a novel synonymous mutation of CD79B-variant 2, involving the insertion of alanine in the exon 2. Conclusions. We have established and characterized a new plasmablastic EBV-positive cell line with focal plasmacytic differentiation and with tumorigenic potential in immunodeficient mice. VR09 cell line represents a model for in vitro and in vivo studies regarding pathogenesis and drug sensitivity. Disclosures: No relevant conflicts of interest to declare.

A major karyotypic conversion following interferon-alpha treatment delays or prevents blastic crisis in patients with chronic myeloid leukemia. We report here a 12-year-old boy with Ph1+ chronic myeloid leukemia who, after achieving a major karyotypic conversion following 12 months interferon-alpha treatment, developed an early lymphoid blastic transformation 7 months later while still under interferon-alpha therapy. A number of possible explanations for this quite unexpected event are discussed.