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Management of systemic mastocytosis is an emerging challenge which requires a multidisciplinary diagnostic approach and personalized treatment strategy. Midostaurin can rapidly reduce the disease burden, also in cladribine refractory cases.

Systemic mastocytosis (SM) is characterized by extreme heterogeneity of manifestations and prognosis. Several disease-related biomarkers, including clinical, hematological and molecular variables, have been correlated with prognosis. Although relevant, the mutation profile closely reflects the WHO classification that has per se prognostic value. High-risk mutations (HRM) are largely confined to advanced forms, and thus fail in providing information regarding progression and outcome in the not-advanced variants. In this work, we studied hematopoietic cells by multi-parameter flow cytometry (MFC) in order to highlight dysplastic traits that might provide insights into outcome. A score previously validated for myelodysplastic syndromes, with high reproducibility in standard diagnostics, was used. The application of an MFC score to a cohort of 71 SM cases, concurrently genotyped for configuring a HRM category, resulted in the identification of two separate patients' categories (MFC+ and MFC-) characterized by significantly different clinical and laboratory features at presentation. The extent of dysplasia by MFC tended to parallel WHO-category and genotype-related stratification. MFC+ patients had shorter survival compared to MFC- ones, for whom the incidence of progression and/or death was virtually null. Of note, MFC score remained prognostically informative in unadvanced subsets. Furthermore, the integration of MFC and HRM was an independent predictor for outcome, also overcoming WHO-categories in multivariate analysis for EFS. Our results support the use of MFC analysis in the evaluation of patients with SM, alone and in combination with HRM, for refinement of prognosis assessment.

Systemic mastocytosis (SM) is a hematological malignancy characterized by extracutaneous infiltration by atypical mast cells. Together with indolent SM, aggressive SM, and mast cell leukemia, the World Health Organization (WHO) recognizes another major disease subgroup: SM with an associated hematological neoplasm, which is characterized by the presence of a concurrent neoplasm, more commonly, a chronic myelomonocytic leukemia. While KIT D816V is commonly regarded as the driver mutation, the clinical presentation of SM is extremely varied. Treatment of SM might not be simple, but now more specific therapies tailored toward prognostic subgroups of patients have been developed. Here, we report a detailed description of clinical management and biological features of a systemic mastocytocis case associated with multiple hematologic non-mast cell lineage diseases.

Context: Constitutively active KIT tyrosine kinase harboring the D816V mutation is the major driver of systemic mastocytosis (SM) pathogenesis. We have previously reported that the loss of function of SETD2 histone methyltransferase due to reduced protein stability is a common cooperating event in advanced SM (advSM). Objective: To dissect the mechanisms of action of midostaurin in advSM and to explore the potential of SETD2 as a marker of response to therapy. Materials: The mast cell (MC) leukemia cell line HMC-1 (negative for SETD2) and primary neoplastic MCs from 10 advSM patients, collected at regular time points during midostaurin treatment. Results: This study started from our preliminary observations indicating that aurora kinase A (AKA) is overexpressed and hyperactivated in advSM and is implicated in SETD2 proteasomal degradation. The new gold standard of therapy in advSM is midostaurin, which targets KIT andseveral other kinases, including AKA. We, thus, investigated whether midostaurin treatment may result in efficient AKA inhibition and subsequent SETD2 rescue. To this purpose, the HMC-1 cell line was treated with 5 µM midostaurin for 24 h, and phospho-AKA (T288), SETD2, and H3K36me3 (surrogate marker of SETD2 activity) were evaluated by WB. Midostaurin reduced AKA phosphorylation by 60%, partially restoring SETD2 expression and activity. We next wondered whether the same happens in patients treated with midostaurin. We, thus, collected and performed WB analysis on neoplastic mast cells from advSM patients before and during midostaurin treatment. We found that midostaurin may target AKA and rescue SETD2 expression and function in vivo and that SETD2/H3K36me3 rescue correlates with the clinical response to midostaurin and the reduction of KIT D816V allele burden, as assessed by digital PCR at 3, 6, and 12 months. In 8 patients who responded to midostaurin, SETD2/H3K36me3 rescue was detected by WB as early as 3 months after treatment onset, whereas 2 refractory patients did not show any increase in SETD2/H3K36me3 and maintained an unaltered KIT allele burden. Conclusions: Midostaurin treatment induces AKA partial dephosphorylation and consequent rescue of SETD2 expression and function in vitro and in vivo SETD2/H3K36me3 may serve as a biomarker of response to midostaurin. Supported by AIRC project 23001

In spite of an increasing array of investigations, the relationships between viral infections and allogeneic hematopoietic stem cell transplantation (HSCT) are still controversial, and almost exclusively regard DNA viruses. Viral infections per se account for a considerable risk of morbidity and mortality among HSCT recipients, and available antiviral agents have proven to be of limited effectiveness. Therefore, an optimal management of viral infection represents a key point in HSCT strategies. On the other hand, viruses bear the potential of shaping immunologic recovery after HSCT, possibly interfering with control of the underlying disease and graft-versus-host disease (GvHD), and eventually with HSCT outcome. Moreover, preliminary data are available about the possible role of some virome components as markers of immunologic recovery after HSCT. Lastly, HSCT may exert an immunotherapeutic effect against some viral infections, notably HIV and HTLV-1, and has been considered as an eradicating approach in these indications.

Reduced bone mass with or without fragility fractures is a common feature of mastocytosis, particularly in adult males. However, bone mineral density does not account for all the fragility fractures, being a part of them attributable to impairment in bone quality. Aim of this study is to assess the usefulness of DXA-derived geometry and structural indexes in the assessment of bone status in mastocytosis. Ninety-six consecutive patients (46 women and 50 men) affected by cutaneous (CM) or systemic (SM) mastocytosis were studied. Mean age (± SD) was 53.3 ± 14.23. Spine lateral X-rays for Genant's scale, DXA for lumbar (L) and femoral (F) bone mineral density (BMD), bone strain index (BSI), lumbar trabecular bone score (TBS), and hip structural analysis (HSA) were performed. Among the laboratory variables, data of serum tryptase were reported. Tryptase was higher in SM (p = 0.035), inversely correlated with LBMD (r = − 0.232; p = 0.022) and TBS (r = − 0.280; p = 0.005), and directly with L-BSI (r = 0.276; p = 0.006). L-BSI remained statistically significant (p = 0.006; adjusted R2 = 0.101) together with mastocytosis (SM or CM: p = 0.034) in the multivariate regression model with tryptase as dependent variable, being LBMD and TBS not statistically significant (p = 0.887, and p = 0.245, respectively). Tryptase increased about 22 units for each unit increase of L-BSI and about 18 units for SM against CM. L-BSI was lower (p = 0.012), while FN-BSI and FT-BSI were higher in women (p

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Available studies on metabolic syndrome (MS) after hematopoietic stem cell transplantation (HSCT) are retrospective with heterogeneous inclusion criteria, and little is known about the early post-transplant phase. In our prospective study, clinical and laboratory data were collected in 100 HSCT recipients, 48 allogeneic and 52 autologous, at baseline, at + 30, + 100 and + 360 days. At baseline, MS was observed in 24 patients, significantly associated with insulin resistance and leptin on multivariate analysis. At + 30, the diagnosis of MS was confirmed in 43 patients, significantly related to insulin resistance and allogeneic transplants. If the whole series was considered, patients with MS had significantly higher mortality from any cause. The baseline presence of any MS feature was a predictor of + 30 MS. Isolated occurrences of MS features were related to hyperleptinemia and hyperinsulinemia, except in the case of low HDL cholesterol, linked to adiponectin and resistin. Our data confirm that patients undergoing HSCT have a high prevalence of MS, with hyperleptinemia playing a major role. The early peak of new MS cases is primarily attributable to insulin resistance, notably but not exclusively immunosuppression-induced; the subsequent long-term increase in MS cases may be an effect of persistent adipokine imbalance.

Introduction Hereditary alpha-Tryptasemia (HαT) is a group of genetically defined traits that share increased copy number of TPSAB1 gene encoding for both the α- and β-alleles (Lyons et al 2018). Increased copy number (CN) of the α-tryptase coding sequence in TPSAB1 on one or both alleles represents the genetic base of HαT (Lyons et al 2016). HαT is characterized by mild elevation in serum tryptase levels and a variety of mast cell (MC) activation symptoms, including recurrent anaphylaxis. Prevalence in the general population is up to 5%, that increases up to 20% in systemic mastocytosis (SM); it has been suggested that HαT might be a germline variant predisposing to SM development. In SM, HαT correlated with higher incidence of mediator-related symptoms (Greiner G et al, Blood 2021). Due to its complexity, the assay for TPSAB1 CN is performed in few centers and the actual prevalence of HαT in selected subsets is still to be elucidated. To this end, we screened for HαT 2 groups of subjects, the first with MC activation symptoms and no evidence of SM, the second with diagnosis of SM according to WHO-2016. Methods Droplet digital PCR (ddPCR) was used to measure CN variation (CNV) in TPSAB1 by adapting standard CNV ddPCR protocol to genotype for both TPSAB1 and TPSB2 (Fig.1A). The high homology between α and β encoding isoforms and the presence of paralogous genes in a single locus makes TPSAB1 CNV detection very challenging. ddPCR was performed on genomic DNA with/without BamHI, using the PrimePCR ddPCR Copy Number reference AP3B1 (BioRad). Accuracy and precision of the ddPCR protocol was assessed by analyzing 10 samples in triplicate in 3 separate experiments. Data robustness and repeatability can be appreciated in Fig 1B. Results We studied 41 subjects with mediator-related symptoms and augmented basal serum tryptase (BST) (cohort 1) and 150 patients with ascertained diagnosis of mastocytosis (cohort 2). The BST threshold established for cohort 1 was equal or higher than 11 mcg/L. Median age was 64.7 yr, males 54%; median BST levels was 15.3 (range 12.3-21 mcg/L); 29% of the pts had history of anaphylaxis. In cohort 2, 134/150 (89.3%) pts had a diagnosis of SM, whereas 13/150 (8,6%) were Cutaneous Mastocytosis (CM). Among SM patients, 113(84.3%) presented with non-advanced SM variants. Advanced forms including aggressive SM (ASM) and SM with an associated hematological neoplasm (SM-AHN) were diagnosed in 6 (4.5%) and 8 (6%) respectively. In 3 pts, SM subtype was not available. Median age was 49 yr, males 55%; 41.7% of the pts had history of anaphylaxis. HαT was documented in 27 (65.9%) subjects in cohort 1, and 14 (9.3%) in cohort 2. In cohort 1, 3 α-tryptase (3α) copy number was observed more frequently (59.2% of HαT+ pts); conversely 3α and 2α-tryptase copy number were observed at a similar rate (42,8%) in cohort 2. HαT+ pts in cohort 1 presented significantly higher BST (17.1 vs 12.05 mgc/L, P In cohort 2, BST levels were similar in HαT+ and HαT wt pts (24.6 and 24.3 mcg/L), as were anaphylaxis episodes (50% and 41%, respectively). A trend for lower MC burden in HαT+ as assessed by flow cytometry was demonstrated (% of bone marrow MC: 0.01% in HαT+ vs 0.07%) whereas no meaningful differences emerged regarding the symptom burden. In addition, a lower prevalence of KIT 816V mutation was observed in HαT+ (71.4% vs 89.5%; p=0.073). Conclusions In our study HαT+ was observed in around 10% of patients with SM, a prevalence lower than previously reported (Greiner et al, Blood 2021) and remarkably lower than in a selected cohort of subjects with raised BTL and history of mediator-released symptoms (66%). ddPCR represents a suitable method to investigate the presence of CNV in the α-tryptase coding sequence. Genetic testing for HαT+ should be considered in the diagnostic workout of patients presenting with anaphylaxis or MC mediator-related symptoms and no suspicion/evidence of SM. The clinical correlates of HαT in SM remain to be fully ascertained. Supported by IMH no.GR-2016-02362631 and AIRC, Mynerva project no21267 Figure 1 Figure 1. Disclosures Elena: CELGENE: Other: funding for meeting participation; PFIZER: Membership on an entity's Board of Directors or advisory committees; NOVARTIS: Membership on an entity's Board of Directors or advisory committees; GILEAD: Membership on an entity's Board of Directors or advisory committees. Vannucchi: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees.

Systemic mastocytosis is a rare heterogeneous myeloproliferative neoplasm characterized by abnormal proliferation and activation of mast cells. We describe a large multicentre series of 460 adult patients with systemic mastocytosis, with a diagnosis based on WHO 2008 criteria, in a "real-life" setting of ten Italian centers with dedicated multidisciplinary programs. We included indolent forms with (n = 255) and without (n = 165) skin lesions, smouldering (n = 20), aggressive (n = 28), associated with other hematological diseases mastocytosis (n = 21) and mast cell leukemia (n = 1). This series was uniquely characterized by a substantial proportion of patients with low burden of neoplastic mast cells; notably, 38% of cases were diagnosed using only minor diagnostic criteria according to WHO 2008 classification, underlying the feasibility of early diagnosis where all diagnostic approaches are made available. This has particular clinical relevance for prevention of anaphylaxis manifestations, that were typically associated with indolent forms. In multivariate analysis, the most important features associated with shortened overall survival were disease subtype and age at diagnosis >60 years. Disease progression was correlated with mastocytosis subtype and thrombocytopenia. As many as 32% of patients with aggressive mastocytosis suffered from early evolution into acute leukemia. Overall, this study provides novel information about diagnostic approaches and current presentation of patients with SM and underlines the importance of networks and specialized centers to facilitate early diagnosis and prevent disease-associated manifestations. Am. J. Hematol. 91:692-699, 2016. © 2016 Wiley Periodicals, Inc.

Context: Histone H3 lysine 36 trimethylation (H3K36me3) by SETD2 is implicated in transcriptional regulation, splicing fidelity, and DNA damage response signaling. SETD2 non-genomic loss of function, due to proteasome-mediated protein degradation, is a common event in advanced systemic mastocytosis (advSM). Objective: To investigate the mechanisms underlying SETD2 loss of function in advSM to highlight possible druggable targets. Patients or other participants: DNA and protein samples from a retrospective cohort of 88 patients with systemic mastocytosis, classified according to WHO criteria were used for sequencing, western blotting (WB), and immunoprecipitation studies. Neoplastic mast cells (MCs) from 10 pts with advSM were used for ex-vivo drug testing. Results: Aurora kinase A (AKA) was overexpressed and hyper-activated in advSM and this inversely correlated with SETD2 protein expression. siRNA-mediated silencing of AKA and pharmacological inhibition by danusertib rescued SETD2 expression and activity, suggesting that AKA is implicated in SETD2 degradation. The new gold standard of therapy in advSM is midostaurin that targets not only mutant KIT but also other kinases, including AKA. To investigate whether midostaurin treatment may result in efficient AKA inhibition and consequent SETD2/H3K36me3 rescue, the HMC-1 cell line was treated with 5 μM midostaurin for 24 h and phospho-AKA (T288), SETD2, and H3K36me3 expression were evaluated by WB. Midostaurin reduced AKA phosphorylation by 60%, partially restoring SETD2 expression and activity, but did not induce cytotoxic effects. We next tested the efficacy of combined treatment with midostaurin and nilotinib or dasatinib in inducing cytotoxic rather than cytostatic effects. Cytofluorimetric analysis of apoptosis and clonogenic assays in HMC-1 cells and in neoplastic MCs showed an important advantage in using the midostaurin + dasatinib/nilotinib combination compared to each single agent alone, as underlined by the significant reduction of drug doses necessary to obtain cytotoxic effects and cell growth arrest. Of note, we observed that midostaurin + nilotinib completely de-phosphorylated AKA and restored SETD2 expression and activity. Conclusions: AKA overexpression contributes to SETD2 non-genomic loss of function in advSM. KIT and AKA targeting by midostaurin in combination with second-generation tyrosine kinase inhibitors is a promising therapeutic alternative in patients with SETD2/H3K36me3 deficiency. Supported by AIRC project 23001.

Context: Detection of the KIT D816V mutation in the bone marrow (BM) is one of the minor criteria for the diagnosis of systemic mastocytosis (SM). Because in most SM patients, the number of neoplastic mast cells (MCs) in the BM is low, the use of molecular techniques, such as ASO-qPCR, with elevated sensitivity is recommended. Droplet digital PCR (ddPCR) is a promising alternative to ASO-qPCR for D816V testing. Objective: We evaluated a commercial ddPCR assay for the detection of KIT D816V in SM. ddPCR was performed on a BioRad QX200 instrument using the ddPCR™ Mutation Assay: KIT p.D816V, Human (Bio-Rad). Patients: PB samples from 13 healthy donors (HDs) were used as negative controls; the D816V-positive HMC-1.2 cell line was used as positive control. Thirty-five BM samples from patients with suspected SM, either with neoplastic mast cell infiltration Results: In HMC 1.2 cells, ddPCR measured an allele burden (AB) of 50%, consistent with the heterozygous status. No D816V-positive events were detected in the HDs. Comparison between ddPCR and ASO-qPCR revealed high concordance in mutation detection and quantitation, even at low AB levels. ddPCR identified D816V in 70/151 patients prospectively evaluated for diagnosis of SM. According to WHO criteria, 49 were later diagnosed with ISM, 13 with aggressive SM, 4 with smouldering SM, 2 with SM with an associated clonal hematopoietic non-MC disease, and 2 with MC leukemia. The median AB in all positive SM patients was 0.34%. Patients with advanced SM showed a higher D816V AB (median, 15.23%) compared with patients with ISM and smouldering SM (median, 0.27%). All patients positive for D816V in BM also tested positive in the PB. Conclusion: ddPCR proved accurate and precise and was able to detect D816V in PB when the BM was positive. We propose ddPCR as a valid alternative to ASO-qPCR for straightforward and sensitive detection of D816V in SM.

Aim: We collected ‘real-life’ data on the management of patients with mastocytosis in the Italian Mastocytosis Registry. Methods: Six hundred patients diagnosed with mastocytosis between 1974 and 2014 were included from 19 centers. Results: Among adults (n = 401); 156 (38.9%) patients were diagnosed with systemic mastocytosis. In 212 adults, no bone marrow studies were performed resulting in a provisional diagnosis of mastocytosis of the skin. This diagnosis was most frequently established in nonhematologic centers. In total, 182/184 pediatric patients had cutaneous mastocytosis. We confirmed that in the most patients with systemic mastocytosis, serum tryptase levels were >20 ng/ml and KIT D816V was detectable. Conclusion: The Italian Mastocytosis Registry revealed some center-specific approaches for diagnosis and therapy. Epidemiological evidence on this condition is provided.

Key Clinical Message We present a case of severe, irreversible neurotoxicity in a 55-year-old-patient with myelofibrosis undergoing hematopoietic stem cell transplantation following a reduced intensity conditioning including fludarabine. The patient developed progressive sensory-motor, visual and consciousness disturbances, eventually leading to death. MRI imaging pattern was unique and attributable to fludarabine neurotoxicity.

Introduction: In patients with advanced stage mycosis fungoides (MF) and Sézary syndrome (SS), allogeneic hematopoietic stem cell transplantation (allo-HSCT) continues to represent the only potentially curative treatment strategy. We have previously reported long-term outcome of our reduced intensity conditioning-based allo-HSCT program in MF and SS, including 38 patients who consecutively underwent transplantation from matched sibling or unrelated donor in the 2001-2018 time interval, with a 5-yr overall and disease-free survivals of 52% and 43%, respectively, and a 1-yr non relapse mortality of 17% (ASH annual meeting, 2018). In the most recent years, haploidentical donors are considered an increasing valid alternative for patients with haematological malignancies lacking a suitable matched donor. Here we report the results of our first series of haploidentical SCT (haplo-HSCT) in patients witn MF and SS. Patients & Methods: From May 2016 to June 2019, 4 patients (2 males and 2 females) underwent haplo-HSCT from family donors (3 siblings and 1 son) in our center. Median age was 53 years (range 19-62). Two patients had stage IV refractory MF - involving nodes and lungs in one case and blood in the other one, while two patients had SS. Median number of previous treatment lines was 4 in SS and 4.5 in MF (range 2-6) while median time from diagnosis to transplantation was 21 months (range 17-101). Two patients (1 SS and 1 MF) received 24Gy total skin electron beam (TSEB) therapy as a bridge to transplant, associated to brentuximab vedotin (5 cycles) in one case showing also lung CD30+ involvement. At the time of transplant two patients were in CR and 2 were in very good partial remission, with limited nodal involvement in one SS and limited skin disease in one MF patient, respectively. The source of stem cells was bone marrow in SS and peripheral blood in MF patients. A reduced-intensity conditioning regimen including Thiotepa 10 mg/kg, Cy 30 mg/kg, Fludarabine 120 mg/m2 (over 4 days) and low dose TBI (200 cGy) was used in all patients. GvHD prophylaxis included CsA/MMF and post-transplant CTX (50 mg/kg on days +3 e +4), with the addition of ATG 2.5 mg/kg in the most recently transplanted patient for whom donor peripheral blood was the selected source of stem cells. Results: Hematologic engraftment occurred in all patients, with a median time to ANC >0.5 x 109/L of 16.5 days (range 14-18) and to PLT >20 x 109/L of 15 days (range 13-45). At +100 days after transplantation, donor chimerism was 100% in 3 patients, and 90% in one. Acute GvHD occurred in 3 patients, always of grade II (involving skin in all, gastrointestinal in 2 and liver in 1 patient), with overlap characteristics in one case. Major early infectious complications included two cases of fungal pneumonia and 1 case of bacteremia from P. aeruginosa. Chronic GvHD was observed in 2 out of the 3 evaluable patients - i.e. with a follow-up longer than 100 days - being mild in one case (with joints involvement) and severe in the other case (skin). With all patients and their donors being CMV positive at baseline, CMV reactivations occurred in 3 cases, successfully treated with preemptive valganciclovir. Following transplantation, a complete remission (CR) was achieved in all the four patients. One patient with SS who experienced a skin biopsy-proven relapse 9 months after transplant, achieved a new and durable CR following the occurrence of a severe skin chronic GvHD triggered by an inadvertent sunburn, which required steroids + ECP treatment. At the last visit, all patients were alive in CR with a follow-up of 38, 36, 6 and 3 months, respectively. Conclusions: Even though with a limited follow-up time, our preliminary experience of haplo-HSCT appears particularly safe and highly encouraging in inducing and maintaining remission in patients with advanced MF/SS eligible to allo-HSCT. Disclosures No relevant conflicts of interest to declare.

Introduction: Total skin electron beam (TSEB) therapy represents a valid treatment option in the management of patients with cutaneous T-Cell lymphoma (CTCL) with diffuse skin involvement. While the efficacy of TSEB for palliative treatment is well established, its inclusion as a debulking strategy before reduced-intensity conditioning allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been only recently reported. Due to the lack of hematopoietic toxicity, TSEB may also be effectively administered in patients relapsing after allo-HSCT. With this study we aimed to retrospectively investigate the use of TSEB among patients who underwent to allo-HSCT in our Center for advanced CTCL. Patients & Methods: As of July 2019, 45 CTCL patients (26 M and 19 F, median age 54 years, range 19-66) all having stage IIB to IV refractory Mycosis Fungoides (MF, n=33) or Sézary Syndrome (SS, n=12) underwent allo-HSCT from HLA-identical sibling (n=18), unrelated donors (n=23) or haploidentical related donors (n=4). Median time from diagnosis to HSCT was 46 months and median number of previous treatment lines was 6. Source of stem cells was peripheral blood in 40 patients, bone marrow in 4 patients and cord blood in 1 patient. Conditioning regimens included FC/TBI200, pentostatin/TBI200, fludarabine/melphalan and TT/CTX/Fluda/TBI200. Outcomes at 5-years were: OS 51% (33%-66%), DFS 40% (20%-50%), NRM 15% (4%-27%) and relapse incidence 48% (32%-65%). Clinical charts of the whole series of patients were extensively reviewed to collect information on the use of TSEB from diagnosis to the last follow up date. Results: Overall 21 patients of the series received TSEB with dose fractionation of 2 Gy in 2 days administered with the Stanford Technique as part of their treatment strategy. In six cases it was included among the lines of treatment administered over the disease course preceding transplant referral, with a total dose of 36 Gy in all of them. In 13 patients TSEB was part of the debulking strategy for patients with chemorefractory disease just prior to allo-HSCT with a median total dose of 24 Gy (range 10.8- 36). In 4 patients TSEB was administered after transplantation: as a salvage treatment for skin relapse during early post tranplant intense immunosuppression phase in 3 cases (12, 36, 21.6 Gy respectively) and as palliative treatment for disease progression in one case (36 Gy). Among patients who received TSEB as a bridge to transplant strategy, CR was achieved in 5 cases: at the last follow up visit (median time from transplantation 23 months, range 6-80) 4 were alive with persistent CR, whereas 1 patient who experienced graft failure died from disease progression 31 months after transplantation. Partial remission (PR) was documented in 7 (very good in 2): at the last follow up visit (median time from transplantation 14 months, range 6-52) 2 patients were alive in CR and 5 died: 3 from disease progression, 1 from GVHD and 1 from myocardial infarction 42 months after transplantion. In 1 patient, who only showed minimal response to TSEB therapy, death from disease progression occurred 9 months after an autologous-allogeneic tandem transplant strategy. All the 3 patients receiving TSEB after allo-HSCT for early relapse achieved a new and durable CR maintained at the last follow up date (42, 21 and 10 months after transplant respectively), suggesting the occurrence of a durable graft-versus-lymphoma effect following TSEB. As far as safety is concerned, only grade 1 skin toxicity (erythematous reactions) was observed in a minority of patients, while no case of haematological toxicity was documented. Conclusions: Our experience confirmed TSEB as a particularly safe and potentially effective treatment strategy in CTCL patients, both to induce remission prior to allo-HSCT and to rescue early post transplant relapse occurring before immunosuppression withdrawal. Disclosures No relevant conflicts of interest to declare.

Objectives and background: According to the World Health Organization (WHO) classification, the diagnosis of Systemic Mastocytosis (SM) relies on bone marrow (BM) examination and is based on a major and four minor criteria. The somatic ‘autoactivating’ point mutation D816V in the KIT receptor gene is one of the minor criteria, founded in the great majority of patients (90%) and it plays a central role in the pathogenesis of the disease. Indolent Systemic Mastocytosis (ISM) is the most common variant of SM, characterized by a very low MC burden and associated with very different clinical pictures. A highly sensitive diagnostic methods for D816V detection are required to assure an appropriate diagnosis and to reduce false-negative results. The recent development of “ultra-deep amplicon sequencing” (UDS) technologies has opened the way to a more accurate characterization of molecular aberrations with higher sensitivity of screening for known and unknown mutations. Our aims were: i) to set-up and optimize a UDS-based mutation screening strategy of the KIT gene on the Roche GS Junior Instrument; ii) to test the sensitivity of our UDS assay to detect the D816V mutation; iii) to investigate the presence of additional KIT mutations in SM. Methods: We decided to take advantage of a next generation sequencing approach to perform an UDS KIT gene mutation analysis on 20 bone marrow (BM) samples from patients whit ISM that were negative for the D816V mutation by Sanger Sequencing which has a sensitivity of 20%. Fusion primers were designed to generate ten partially overlapping amplicon covering the whole KIT transcript (exons 1-21) by RT-PCR. To determine the lower detection limit of our UDS-assay, serial dilutions of the HMC-1 cell line (harboring the D816V mutation) into an unmutated K562 cell line in ratios such as to simulate the following mutation loads were sequenced: 50%, 37.5%, 25%, 12.5%, 5%; 2.5%, 1.25%, 0.5%, 0.25%. Results and significance: UDS of cell line dilutions showed a high accuracy of D816V mutation detection and linearity of mutation calling over the entire range down to 0.25%. The UDS technology allowed to detected the D816V mutation, below the lower detection limit of Sanger Sequencing, with an abundance from 0.5% to 11%, in 12/20 ISM patients. Two additional sequence variations were detected in a large proportion of patients. These two variations included a 3bp in-frame deletion in exon 15 (GenBank X06182.1: c.2164_2166delAGC; p.S715del) found in 11/20 patients and a 12bp in frame-deletion in exon 9 in all patients, whit an abundance ranging from 83% to 97% (GenBank X06182.1: c.1550_1561delGTAACAACAAAG; p.G510_K513del). Previously published studies indicate that the KIT Gly-Asn-Asn-Lys510-513+/- alternatively spliced located immediately downstream to the extracellular KIT domain and KIT Ser715+/-, an interkinase KIT domain, are expressed in normal human hematopoietic cell, leukemic cell lines, acute myeloid leukemia blast and GISTs and represent rather a splice variant of KIT transcript. Interestingly our results showed the presence of the transmembrane domain M541L (GenBank X06182.1: c.1642A>C; p.Met541Leu) KIT-activating mutation in exon 10, with an abundance of 50%, in addition to D816V, in 2/20 ISM. This mutation is known to retain sensitivity to imatinib mesylate. Conclusions: Our preliminary results suggest that our-UDS based KIT gene mutation screening assay might be a reliable and sensitive alternative to conventional sequencing methods for the detection of the D816V. We are now planning to investigate whether the greater sensitivity of UDS allows to detect the D816V mutation in peripheral blood mononuclear cells from patients with a suspected clonal mast cell disorder. These results could represent a starting point to plan other extensive studies to better understand the exact role of KIT receptor alterations in SM. Supported by ELN, AIL, AIRC, PRIN, progetto Regione-Università 2010-12 (L. Bolondi), FP7 NGS-PTL project. Disclosures Cavo: Celgene: Consultancy, Honoraria, Speakers Bureau. Martinelli:Novartis: Consultancy, Speakers Bureau; BMS: Consultancy, Speakers Bureau; Pfizer: Consultancy; ARIAD: Consultancy.

We investigated the relationship between the International Prognostic Scoring System of the International Working Group for Myelofibrosis Research and Treatment and the European Consensus on grading of bone marrow fibrosis (MF) in patients with primary myelofibrosis. We compared them in 196 consecutive primary myelofibrosis patients (median follow-up 45.7 months; range 7.4-159). International Prognostic Scoring System classified 42 cases as low risk, 73 as intermediate risk-1, 69 as intermediate risk-2, and 12 as high risk; European Consensus on grading of bone marrow fibrosis classified 83 cases as MF-0, 58 as MF-1, 41 as MF-2, and 14 as MF-3. By the time of the analysis, 30 patients (15.3%) had died. Overall median survival was 3.8 years (95% confidence interval: 3.3-4.3). Multivariate analysis confirmed that both scoring systems independently predicted survival, with hazard ratios similar to those provided by univariate analysis (respectively, 2.40 (95% confidence interval: 1.47-3.91) and 2.58 (95% confidence interval: 1.72-3.89) but the likelihood ratio increased from 19.6 of the International Prognostic Scoring System or 29.0 of the European Consensus on grading of bone MF to 42.3 when both measures were considered together. Analysis of the overall survival curves documented that patients classified as having the most favourable rate with both prognostic scores (ie low risk and MF-0) survive longer than those with only one favourable score (ie low risk but MF >0 or MF-0, but International Prognostic Scoring System >low risk). In contrast, those patients classified as having the most unfavourable rate for both scores (high risk and MF-3) have a shorter survival than those with only one unfavourable score (ie high risk but MF

Introduction: Although a few novel drugs have recently shown promising activity in mycosis fungoides (MF) and Sézary syndrome (SS), prognosis of patients with advanced stages or refractory disease remain poor, with median survival ranging from 1.4 to 3.4 years (Agar NS et al. JCO 2010). In selected patients, allogeneic hematopoietic stem cell transplantation (allo-HSCT) represents a potential curative strategy. By decreasing transplant-related mortality, reduced intensity (RIC) and nonmyeloablative conditioning (NMA) regimens lead to better outcomes in comparison to myeloablative ones. Here we report long-term outcome of our RIC allo-HSCT experimental program, initiated in 2001. Patients & Methods: As of July 2018, in our Center 40 patients underwent RIC allo-HSCT from HLA-identical sibling (n=16), unrelated donors (UD, n=22 - fully-matched in 10, 1 or 2-mismatch in 12) or haploidentical related donors (n=2). Median age was 52 years (range 19-66). All patients (24 M and 16 F) had stage IIB/IV refractory MF (n=27) or SS (n=13). Median number of previous treatment lines was 6 (range 2-12) while median time from diagnosis to transplantation was 46 months (range 11-264). The source of stem cells has been peripheral blood in 35 patients (87.5%), bone marrow in 4 (10%) and cord blood in 1 (2.5%). Conditioning regimens included FC/TBI200, pentostatin+TBI200, and fludarabine/melphalan in transplants from HLA-identical sibling donor or UD, whereas the TT/Flu/CTX/TBI200 regimen was used in the haploidentical setting. GvHD prophylaxis included CsA/MMF in all patients, with the addition of ATG in cases with UD and post-transplant CTX (50 mg/kg giorni +3 e +4) in haploidentical setting. Results: Full donor chimerism was obtained in 32 out of 37 evaluable patients, in a median time of 2 months (range 1-12). Acute GvHD occurred in 18 patients out of the 32 evaluable (56%), being of grade III-IV in 9 (28%). Chronic GvHD was observed in 10 patients (31%), being extensive in 4 (12%). Of note, the latter were all patients transplanted from HLA-identical sibling (i.e. without ATG). Following transplantation, a complete remission (CR) was achieved in 26 out of the 37 evaluable patients (70%), of whom 4 experienced relapse at +2 (2 pts), +25 and +35 months, respectively. At the last follow-up, 19 patients were alive and 17 (89%) maintained CR after a median follow-up of 80 months (range 4-210). Out of the 11 patients who did not achieve CR, 9 died from progressive disease (median follow-up of 12 months, range 3-31), 1 from a secondary malignancy, while 1 is still alive with disease 62 months after transplant. Transplant-related death occurred in 7 patients (17%), of whom 5 were in CR. In the whole population, the 5-year OS was 52% (95% CI 34-70) [Fig.1] and the 5-year DFS was 43% (95% CI 27-62). However, when MF and SS were analysed separately, 5-yrs DFS were 30% (95% CI 12-51) and 72% (95% CI 38-99), respectively (Fig.2). Apart from diagnosis, outcome appeared to be primarily associated with chemosensitivity and status of disease at transplantation. Conclusions: After a median follow-up longer than 6.5 years, we confirm the efficacy of RIC allo-HSCT as a powerful therapeutic strategy in inducing and maintaining remission in selected patients with chemosensitive advanced-stage CTCL, with results particularly encouraging in SS. Disclosures Cortelezzi: roche: Consultancy; abbvie: Consultancy; novartis: Consultancy; janssen: Consultancy.

Systemic mastocytosis (SM) is a heterogeneous disease of the bone marrow characterized by abnormal growth, accumulation and activation of clonal mast cells (MCs). We report a case of SM with multi-organ involvement. A 30-year-old man presented with diarrhea, flushing, maculopapular rash with itching and weight loss. The upper and lower gastrointestinal endoscopies showed macroscopic involvement of stomach and duodenum; mucosal samples from stomach, duodenum, colon and distal ileum showed mucosal infiltration by large, spindle-shaped MCs with abnormal surface molecule expression (CD2 and CD25), a picture fully consistent with SM, according to the World Health Organization diagnostic criteria. A computed tomography scan showed diffuse lymphadenopathy, hepatosplenomegaly and diffuse small bowel involvement. Bone marrow aspirate and biopsy were diagnostic for SM; serum tryptase levels were increased (209 ng/mL, normal values < 20 ng/mL). The conclusive diagnosis was smouldering SM. There were no therapeutic indications except for treatment of symptoms. The patient was strictly followed up because of the risk of aggressive evolution.

We compared the recovery profile and postoperative SpO(2) after the administration of general anesthesia with either sevoflurane-remifentanil or sevoflurane-sufentanil in 30 healthy patients undergoing upper abdominal surgery. They were randomly allocated to receive general anesthesia with sevoflurane and small doses of either remifentanil (n = 15) or sufentanil (n = 15), followed by postoperative epidural analgesia. The median sevoflurane minimum alveolar anesthetic concentration-hour was 2.3 (1.2-6.3) in group Remifentanil and 2.6 (1.4-5.2) in group Sufentanil (P: = 0.39), while the median consumption of remifentanil was 1.3 mg (0.7-3.4 mg) and sufentanil 0.09 mg (0.05-0.6 mg). Tracheal extubation required 10 min (6-18 min) with remifentanil and 14 min (8-24 min) with sufentanil (P: = 0.05); however, no differences in time to discharge from the recovery area were reported (24 min [12-75 min] with remifentanil and 30 min [12-135 min] with sufentanil; P: = 0. 35). From the first to seventh hour after surgery, SpO(2) was decreased more in the sufentanil than in the remifentanil group (P: = 0.001), and seven patients in the sufentanil group showed at least one episode with SpO(2)or = 90% for more than 1 min (P: = 0.006) (median: 1 episode; range: 0-17 episodes; P: = 0.003). When added to sevoflurane, remifentanil is as effective as sufentanil during the intraoperative period, but provides shorter time to tracheal extubation and fewer effects on postoperative SpO(2) in the first 7 h after surgery.In this double-blinded study, we evaluated the effects of adding small infusions of either remifentanil or sufentanil to sevoflurane in combination with postoperative epidural analgesia for upper abdominal surgery. We demonstrated that remifentanil is as effective as sufentanil during the intraoperative period, but that it provides shorter time to extubation and fewer effects on postoperative SpO(2) in the first 7 h after surgery.

Systemic mastocytosis (SM) is a rare myeloproliferative neoplasm characterized by proliferation and hyperactivation of clonal mast cells. Clinical manifestations are heterogeneous and encompass cutaneous lesions, gastrointestinal alterations, osteoporosis, anaphylaxis and involvement of bone marrow and other organs due to neoplastic mast cells (MC) infiltration. As consequence, diagnosis may be difficult and patients (pts) are often evaluated by different specialists before the disease is recognized. To date, only few studies (Lim 2009, Escribano 2009, Cohen 2014) described relatively large series of pts with SM. We performed a multicentre retrospective study to evaluate clinical and biological features and therapeutic management in a large series of pts from 10 Italian centres experienced in management of SM and organized in multidisciplinary groups of specialists. We collected 455 pts diagnosed with SM according to WHO criteria. Additionally 26 pts with mastocytosis in the skin (MIS) evaluated with BM examination did not fulfil criteria for SM, leading to diagnosis of Cutaneous Mastocytosis (CM); however 2/26 pts with CM had both cKITD816V mutation and CD2/CD25 expression on MC in BM, additional 3 showed either cKITD816V or CD2/CD25. Moreover, we found 22 pts without MIS but with features of monoclonal mast cell activation syndrome. Of the 455 pts with WHO-SM (male 56%), 252 (55%) had MIS: median age at MIS diagnosis (dg) was 37 years (y) (range 0-79), while at SM dg it was 46.5 (range 18-82). Time from onset of MIS to dg of SM was 9 y (range 0-43). In 18/252 pts (7%) MIS occurred before age of 18 y (median 9, range 0-17) and persisted over childhood. Median age at dg of SM without MIS (203/455 pts, 45%) was older: 54 y, range 19-79 (p Disclosures Martinelli: Novartis: Consultancy, Speakers Bureau; BMS: Consultancy, Speakers Bureau; Pfizer: Consultancy; ARIAD: Consultancy.