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Mast cell leukemia (MCL) is the leukemic form of SM with at least 20% mostly immature mast cells on bone marrow aspirate. MCL may develop de novo, in the absence of a prior SM, or it may represent a progression from a previous SM. MCL may be sub-divided into the more frequent, aggressive acute form with signs of organ damage (C-findings) and the chronic form lacking C-findings and presenting a more stable course, although over time, progression to acute MCL is common. The 2022 WHO subtype of MCL with an associated hematological neoplasm was renamed MCL with an associated myeloid neoplasm in the 2022 International Consensus Classification (ICC). The relevance of the distinction between the leukemic and aleukemic forms based on the percentage of circulating mast cells is a matter of debate. The current knowledge on MCL is restricted mainly to single reports or case series with a limited number of larger studies. Our aim is to provide a comprehensive overview of this rare disease in terms of clinical manifestations, morphology, phenotype, molecular characteristics, differential diagnosis, outcome and treatment. A general overview on mastocytosis is also included.

Extramedullary Plasmacytoma (EM) disease is an aggressive presentation at diagnosis and relapse for multiple myeloma (MM) patients. EM plasmacytoma is divided into two groups: the first group comprises tumors that are extending directly from osteolytic bone lesions while the second results from plasmacytoma infiltration into soft tissues, with no relationship to the bone. Despite new therapies and monoclonal antibodies the survival for patients with EM plasmocytoma is poor. The involvement pleural is uncommon in Multiple Myeloma.

Decitabine, a DNA hypomethylating agent, was approved for use in adults with acute myeloid leukemia (AML) not eligible for standard chemotherapy and is now widely accepted as standard treatment. Although a number of clinical trials demonstrated its benefits in elderly AML patients, older adults and patients with frequent comorbidities are typically under-represented in such settings. Thus, the aim of the present study is to evaluate, in a real-world setting, the effectiveness and toxicity of decitabine administered as a single agent in unselected previously untreated elderly AML patients not eligible for intensive chemotherapy. In nine hematological departments of the Apulian Hematological Network (REP), we enrolled 199 patients (median age: 75.4 years; range: 61–91) with de novo (n = 94) or secondary/therapy-related (n = 105) AML treated with decitabine 20 mg/m2 for five days every 4 weeks. Hazard ratios (HR) and their 95% confidence intervals (CI) were estimated using multivariate Cox regression. The average number of cycles administered per patient was 6.3 (SD: 6.0; median: 5 cycles). Complete response was achieved by 31 patients (15.6%) and partial response by 57 (28.6%), for a total of 88 responders overall (44.2%). After a median follow-up of 33.6 months, median OS was 8.7 months (95% CI: 7.4–10.3), and the 6-month, 1-year, and 3-year OS rates were 62.7%, 37.0%, and 7.1%, respectively. Mortality was increased in AML patients with ≥3 comorbidities (HR = 2.45; 95% CI: 1.18–5.08) vs. no comorbidities and in those with adverse karyotype (HR = 1.58; 95% CI: 1.05–2.38) vs. favourable or intermediate profile. Infection was the main registered adverse event (46.0%). In conclusion, this REP real-life study demonstrates, after a follow-up of almost 3 years, how decitabine administered to AML patients not suitable for intensive chemotherapy is effective and well tolerated, even in a population of truly elderly patients with frequent comorbidities.

The outcome of relapsed or refractory (R/R) T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/T-LBL) in adults is poor, with less than 20% of patients surviving at 5 years. Nelarabine is the only drug specifically approved for R/R T-ALL/T-LBL, but the information to support its use is based on limited available data. The aim of this observational phase 4 study was to provide recent additional data on the efficacy and safety of nelarabine in adults with R/R T-ALL/T-LBL and to evaluate the feasibility and outcome of allogeneic hematopoietic stem cell transplant (SCT) after salvage with nelarabine therapy. The primary endpoints were overall response rate (ORR) and overall survival (OS). Additional endpoints were safety, SCT rate and post-SCT OS. Between May 2007 and November 2018, 118 patients received nelarabine salvage therapy at 27 Italian hematology sites. The median age was 37 years (range 18-74), 73% were male, 77 had a diagnosis of T-ALL and 41 of T-LBL, and 65/118 (55%) had received >2 lines of therapy. The median number of nelarabine cycles was 2 (range 1-4); 43/118 (36%) patients had complete remission (CR), 16 had partial remission (14%) and 59 (50%) were refractory, with an ORR of 50%. The probability of OS, from the first dose of nelarabine, was 37% at 1 year with a median survival of 8 months. The OS at 1 year was significantly better for the 47 patients (40%) who underwent SCT after nelarabine salvage therapy (58% vs. 22 %, log-rank P=0.0001. The probability of OS at 2 and 5 years from SCT was 46% and 38%, respectively. Seventy-five patients (64%) experienced one or more drug-related adverse events (AE). Grade III-IV neurologic toxicities were observed in 9/118 (8%) of cases and thrombocytopenia or/and neutropenia (grade III-IV) were reported in 41% and 43% of cases, respectively. In conclusion, this is one of the largest cohorts of adult patients with R/R T-ALL/T-LBL treated in real life with nelarabine. Taking into account the poor prognosis of this patient population, nelarabine represents an effective option with an ORR of 50% and a CR rate of 36%. In addition, 40% of cases following nelarabine salvage therapy could undergo SCT with an expected OS at 2 and 5 years of 46% and 38%, respectively. The safety profile of nelarabine was acceptable with only 8% of cases showing grade III-IV neurological AE. This article is protected by copyright. All rights reserved.

Background Role of erythropoietin (EPO) in the treatment of late anemia in patients with Chronic Myeloid Leukemia (CML) is still undefined. Methods Fifty CML patients treated at 14 institutions with frontline imatinib for at least 12 months and in stable complete cytogenetic response who developed a late chronic anemia treated with EPO were retrospectively evaluated. Results Median time from imatinib start to EPO treatment was 42.2 months [interquartile range (IQR) 20.8-91.9]. Median Hb value at EPO starting time was 9.9 g/dL (IQR 8.9-10.3): Eleven patients (22.0%) were transfusion dependent. Alpha-EPO (40 000 UI weekly) was employed in 37 patients, beta-EPO (30 000 UI weekly) in 9 patients, zeta-EPO (40 000 UI weekly) in 2 patients, and darbepoetin (150 mcg/weekly) in the remaining 2 patients. On the whole, 41 patients (82.0%) achieved an erythroid response, defined as a stable (>3 months) improvement >1.5 g/dL of Hb level, and 9 patients (18.0%) indeed resulted resistant. Among responding patients, 10 relapsed after a median time from EPO start of 20.7 months (IQR 10.8-63.7). No EPO-related toxicity was observed. Conclusions Results of EPO treatment for late chronic anemia during long-lasting imatinib therapy are encouraging, with a high rate of response.

Therapy with Tyrosine Kinase Inhibitors (TKIs) changed the fate of Philadelphia-positive Chronic Myeloid Leukemia (CML). At present, the therapeutic strategy aims to improve the management of the disease and the quality of life of the patients. In July 2015, we started a prospective multicentric randomized trial with the aim to validate the policy of the intermittent de-escalation treatment and to explore the impact of this strategy on the Quality of Life. To this purpose, CML patients older than 60 years in stable (≥2 years) MR3.0 or MR4.0 molecular response were randomized to receive a FIXED intermittent TKIs regimen (one month ON and one month OFF), as previously published (Russo D, Blood 2013; Russo D, BCJ 2015), versus a PROGRESSIVE intermittent TKIs regimen (one month ON and one month OFF for the 1st year; one month ON and two months OFF for the 2nd year; one month ON and three months OFF from the 3rd year) (OPTkIMA study, ClinicalTrials.gov: NCT02326311). Molecular monitoring was performed according to the 2015 ELN guidelines, every 3 months by RT-PCR on peripheral blood (Baccarani M,Blood 2013). In case of MR3.0 (MMR) loss, checked in two monthly consecutive RT-PCR analysis, patients were planned to exit the study and to resume TKIs daily. This first interim report have been focused on the patients who, by intention to treat, have completed the first year of the study for an historical comparison with the previous INTERIM trial (Russo D, Blood 2013; Russo D, BCJ 2015). During the first year, both the patients randomized in the FIXED and in the PROGRESSIVE arms were given the TKIs treatment one month ON and one month OFF. Up to June 2018, 177 patients have been enrolled by 26 Italian Hematological Centers (first patient randomized in July 2015) and 121/177 patients (68%) completed the first year of OPTkIMA study. The median age was 71 years (range 60-89) and 64% of the patients were belonging to the Sokal intermediate/high risk goup. 96/121 (79%), 14/121 (12%) and 11/121 (9%) patients were receiving imatinib (IMA), nilotinib (NILO) and dasatinib (DAS), at the time of enrollment. Overall, 59/121 (49%) and 62/121 (51%) patients have been randomized in the FIXED and PROGRESSIVE arm, respectively. 41/62 patients (66%) randomly assigned to the PROGRESSIVE arm have entered the second year of therapy. 34/121 patients (28%) went out of the study during the first year. The reasons for protocol discontinuation were: informed consent withdrawn (2 cases), second cancer (4 cases), loss of MR3.0 (28 cases). (Table 1). Among the 28 patients who lost the MMR, 17 and 11 were in MR4.0 and MR3.0, respectively, when they were enrolled into the study. Thus the probability of loosing the MR3.0 while on OPTkIMA was 21,7% at one year (Figure 1). All the 28 patients resumed TKIs continuously and all obtained at least the MR3.0 response, within 6 months and are currently included in the study follow up. The intermittent treatment was well tolerated, with 4 serious adverse events (1 appendicitis, 1 atrial fibrillation, 1 cardiac failure, 1 hip fracture) and 3 adverse events (1 diarrohea, 1 pruritus and 1 fever), none of which have been considered treatement-related. None of the patients experienced the TKI withdrawn syndrome. According to this first interim report, we found that a policy of intermittent TKIs administration in elderly patients is safe and well tolerated. Analysis of patient-reported QoL outcomes is ongoing and will further add information on the overall treatment effectivness of the new PROGRESSIVE intermittent TKI administration. After the 1st year, 28/121 patients (23%) lost MR3.0 and all of them re-gained the major molecular response within 6 months from resumption of continuous treatment. The probability of MR3.0 loss while on OPTkIMA at 1 year was 21,7% and this is quite comparable with the 20% MR3.0 loss observed in the previous INTERIM trial (Russo D, Blood 2013; Russo D, BCJ 2015). Disclosures Efficace: Bristol Meyers Squibb: Consultancy; Seattle Genetics: Consultancy; Lundbeck: Research Funding; TEVA: Research Funding; AMGEN: Research Funding; Incyte: Consultancy; Amgen: Consultancy; TEVA: Consultancy; Orsenix: Consultancy. Abruzzese:Novartis: Consultancy; BMS: Consultancy; Pfizer: Consultancy; Ariad: Consultancy. Bonifacio:Incyte: Consultancy; Pfizer: Consultancy; Amgen: Consultancy; Novartis: Research Funding; Bristol Myers Squibb: Consultancy. Castagnetti:Incyte: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Bristol Meyers Squibb: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Giai:Novartis: Consultancy; Pfizer: Consultancy.

Chronic myeloid leukemia (CML) patients in sustained “deep molecular response” may stop TKI treatment without disease recurrence; however, half of them lose molecular response shortly after TKI withdrawing. Well-defined eligibility criteria to predict a safe discontinuation up-front are still missing. Relapse is probably due to residual quiescent TKI-resistant leukemic stem cells (LSCs) supposedly transcriptionally low/silent and not easily detectable by BCR-ABL1 qRT-PCR. Bone marrow Ph+ CML CD34+/CD38− LSCs were found to specifically co-express CD26 (dipeptidylpeptidase-IV). We explored feasibility of detecting and quantifying CD26+ LSCs by flow cytometry in peripheral blood (PB). Over 400 CML patients (at diagnosis and during/after therapy) entered this cross-sectional study in which CD26 expression was evaluated by a standardized multiparametric flow cytometry analysis on PB CD45+/CD34+/CD38− stem cell population. All 120 CP-CML patients at diagnosis showed measurable PB CD26+ LSCs (median 19.20/μL, range 0.27–698.6). PB CD26+ LSCs were also detectable in 169/236 (71.6%) CP-CML patients in first-line TKI treatment (median 0.014 cells/μL; range 0.0012–0.66) and in 74/112 (66%), additional patients studied on treatment-free remission (TFR) (median 0.015/μL; range 0.006–0.76). Notably, no correlation between BCR-ABL/ABLIS ratio and number of residual LSCs was found both in patients on or off TKIs. This is the first evidence that “circulating” CML LSCs persist in the majority of CML patients in molecular response while on TKI treatment and even after TKI discontinuation. Prospective studies evaluating the dynamics of PB CD26+ LSCs during TKI treatment and the role of a “stem cell response” threshold to achieve and maintain TFR are ongoing.

First-line nilotinib in chronic myeloid leukemia is more effective than imatinib to achieve early and deep molecular responses, despite poor tolerability or failure observed in one-third of patients. The toxicity and efficacy of tyrosine kinase inhibitors might depend on the activity of transmembrane transporters. However, the impact of transporters genes polymorphisms in nilotinib setting is still debated. We investigated the possible correlation between single nucleotide polymorphisms of hOCT1 (rs683369 [c.480C>G]) and ABCB1 (rs1128503 [c.1236C>T], rs2032582 [c.2677G>T/A], rs1045642 [c.3435C>T]) and nilotinib efficacy and toxicity in a cohort of 78 patients affected by chronic myeloid leukemia in the context of current clinical practice. The early molecular response was achieved by 81% of patients while 64% of them attained deep molecular response (median time, 26 months). The 36-month event-free survival was 86%, whereas 58% of patients experienced toxicities. Interestingly, hOCT1 and ABCB1 polymorphisms alone or in combination did not influence event-free survival or the adverse events rate. Therefore, in contrast to data obtained in patients treated with imatinib, hOCT1 and ABCB1 polymorphisms do not impact on nilotinib efficacy or toxicity. This could be relevant in the choice of the first-line therapy: patients with polymorphisms that negatively condition imatinib efficacy might thus receive nilotinib as first-line therapy.

BACKGROUND: Compared with imatinib, nilotinib is a potent breakpoint cluster region/v-abl Abelson murine leukemia viral oncogene (bcr-abl) kinase inhibitor, and it induces higher rate and rapid complete cytogenetic response (CCyR), yet no clinical data are available regarding its efficacy against chronic myeloid leukemia (CML) stem cells. Earlier studies demonstrated that clusters of differentiation 34–positive, Philadelphia chromosome–positive (CD34+Ph+) cells are detectable in about 45% of patients with CML, despite being on long-term imatinib therapy and having achieved sustained CCyR. METHODS: CD34+ cells from bone marrow of de novo CML patients in the chronic phase (n = 24) treated with nilotinib (median duration of therapy, 22 months) were isolated and scored for BCR-ABL by fluorescent in situ hybridization (FISH) analysis. Similar analysis was also performed in 5 de novo CML chronic phase patients who achieved CCyR within 3 months of nilotinib therapy. RESULTS: FISH evaluation of a median of 100 CD34+ nuclei per patient revealed that only 1 of 20 (5%) evaluable patients showed residual Ph+ progenitor cells. In this patient, just 1 of 140 (0.7%) CD34+ interphase nuclei was found to be positive for BCR-ABL. Surprisingly, no CD34+Ph+ cells were found even in those 5 patients evaluated after 3 months of nilotinib treatment. CONCLUSIONS: This study assessed for the first time the persistence of CD34+Ph+ cells during nilotinib first-line treatment. Preliminary results showed that in patients in CCyR, even after short-term nilotinib therapy, residual leukemic progenitors are very rarely detected compared with imatinib-treated CCyR patients. It is yet to be determined if these findings will have an impact in the path to a cure of CML with tyrosine kinase inhibitors. Cancer 2012. © 2012 American Cancer Society.

// Monica Bocchia 1 , Sara Galimberti 2 , Lara Aprile 1 , Anna Sicuranza 1 , Antonella Gozzini 3 , Francesca Santilli 4 , Elisabetta Abruzzese 5 , Claudia Barate 2 , Barbara Scappini 3 , Giulia Fontanelli 2 , Monika Malgorzata Trawinska 5 , Marzia Defina 1 , Alessandro Gozzetti 1 , Alberto Bosi 3 , Mario Petrini 2 and Luca Puccetti 1 1 Department of Hematology, University of Siena, Azienda Ospedaliera Universitaria Senese, Siena, Italy 2 Department of Clinical and Experimental Medicine, U.O. Hematology, University of Pisa, Pisa, Italy 3 Functional Unit of Hematology, University of Florence, Florence, Italy 4 Department of Medicine and Aging, University of Chieti, Chieti, Italy 5 Hematology Unit, S. Eugenio Hospital, Tor Vergata University, Rome, Italy Correspondence: Monica Bocchia, email: // Keywords : PAOD, TKI, CML, inflammation, atherothrombotic risk Received : March15, 2016 Accepted : July 18, 2016 Published : August 05, 2016 Abstract Several reports described an increased risk of cardiovascular (CV) events, mainly atherothrombotic, in Chronic Myeloid Leukemia (CML) patients receiving nilotinib. However, the underlying mechanism remains elusive. The objective of the current cross-sectional retrospective study is to address a potential correlation between Tyrosine Kinase Inhibitors (TKIs) treatment and CV events. One hundred and 10 chronic phase CML patients in complete cytogenetic response during nilotinib or imatinib, were screened for CV events and evaluated for: traditional CV risk factors, pro/anti-inflammatory biochemical parameters and detrimental ORL1 gene polymorphisms (encoding for altered oxidized LDL receptor-1). Multivariate analysis of the whole cohort showed that the cluster of co-existing nilotinib treatment, dyslipidaemia and G allele of LOX-1 polymorphism was the only significant finding associated with CV events. Furthermore, multivariate analysis according to TKI treatment confirmed IVS4-14 G/G LOX-1 polymorphism as the strongest predictive factor for a higher incidence of CV events in nilotinib patients. Biochemical assessment showed an unbalanced pro-inflammatory cytokines network in nilotinib vs imatinib patients. Surprisingly, pre-existing traditional CV risk factors were not always predictive of CV events. We believe that in nilotinib patients an induced “inflammatory/oxidative status”, together with a genetic pro-atherothrombotic predisposition, may favour the increased incidence of CV events. Prospective studies focused on this issue are ongoing.

Despite the crucial aid that newly developed target therapies are providing to chemotherapy and stem cell transplant, the cure for many hematological malignancies is still an unmet need. Although available therapies are able to induce an effective debulking of the tumor, most of the time, an insidious minimal residual disease survives current treatments and it is responsible for an immediate or delayed relapse. Peptide-derived antitumor vaccines have been developed with the idea that an artificially “educated” immune system may exert an active specific antitumor response able to control and ultimately eradicate underlying post-treatment residual disease. This review will summarize current knowledge of peptide vaccines for hematological malignancies, trying to analyze promises and pitfalls of a safe and intelligent tool that after many years from its first appearance has not yet established its potential role as alternative immune mediated therapeutic approach for hematopoietic tumors.

Introduction Recently there have been some reports of Peripheral Arterial Occlusive Disease (PAOD) in chronic myeloid leukemia (CML) patients treated with second generation Tyrosine Kinase inhibitor (TKI) nilotinib. PAOD is mainly caused by atherosclerosis, which is a multifactorial disease of the vessels involving lipid accumulation, thrombogenic components, cell death and inflammatory responses in the arterial wall. With the intent to elucidate a potential correlation between TKIs treatment and mechanisms underlining PAOD or other atherotrombotic events, we investigated a previously described (and confirmed in different settings) genetic and biochemical trait associated with vascular events, in a series of CML patients treated in with TKIs. Patients and Methods Seventy-five CML patients referring to three Italian Hematology Centers (Siena, Pisa and Firenze), of which 39 treated with imatinib and 36 with nilotinib (median treatment time 10 years, range 3-13ys and 3 years, range 2-6ys, respectively), all in complete cytogenetic response and with various degree of molecular response, entered the study. During a routine follow-up visit the patients were evaluated for: classical risk factors (Diabetes Mellitus, Dyslipidemia, Arterial Hypertension, Body Mass Index, Cigarette Smoking, Familiarity); sCD40L level and Endogenous Thrombin Potential (ETP) as markers of platelets and coagulation activation; oxidized LDL (oxLDL) level as early stage atherogenesis promoter; IL6, IL10, TNFα cytokines network as indicator of pro/anti-inflammatory balance; 3'UTR polymorphism of OLR1, encoding for the oxidized LDL receptor 1 (LOX-1), as independent genetic predisposition for atherotrombotic events. In addition the patients were screened for PAOD a/o other atherotrombotic episodes. Results The distribution of classical risk factors was homogeneous in the two groups of patients. On the contrary we noted significant differences in several biochemical parameters evaluated (Table 1). Evaluation of events (i.e. PAOD, Acute Coronary Syndrome and Cerebral Ischemia) showed a statistically significant difference in the two groups with 9/36 (25%) atherotrombotic events occurring in the nilotinib group and 3/39 (7.6%) events occurring in the imatinib group (p=0.019). Multivariate analysis showed that the most strictly related factors to the increased risk of events in this series of CML patients were: nilotinib treatment, oxLDL level (O.R.3.8 95% C.I. 1.8-6.9, p< 0.001, β 1.61), IL10 level (O.R.3.3 95% C.I. 1.9-5.1, p< 0.001, β 1.55) and the presence of an intermediate or high risk OLR1 variant allele (O.R.3.1 C.I. 1.6-4.8, p< 0.001, β 1.59). Discussion These preliminary data suggest that an unbalance of pro/anti-inflammatory cytokines network observed in nilotinib treated patients, together with genetic pro-atherothrombotic predisposition conferred by LOX-1, may have a role in the increased incidence of vascular events. The pro-inflammatory condition could be responsible of the pro-atherotrombotic activation, mainly by enhanced lipid peroxidation, as confirmed by altered sCD40L, ETP and oxLDL levels, despite the use of anti-atherothrombotic drugs. The link between pro-inflammatory stimuli and lipid peroxidation is a well established trigger of accelerated atherogenesis in the general population. As such, in a condition of potential increased lipid peroxidation as described in carriers of detrimental SNPs of LOX-1, the enhanced inflammatory milieu observed during nilotinib treatment could be an additional factor of accelerate atherothrombosis. Further studies are needed to both elucidate the mechanism underlining nilotinib-induced pro-inflammatory status and confirm LOX-1 mutations as a useful genetic tool to identify nilotinib-treated patients at potential increased atherothrombotic risk. Disclosures: Galimberti: Novartis and Bristol Mayer Squibb: Honoraria. Gozzini:Novartis and Bristol Mayer Squibb: Honoraria. Baratè:Novartis and Bristol Mayer Squibb: Honoraria. Scappini:Novartis and Bristol Mayer Squibb: Honoraria. Bosi:Novartis and Bristol Mayer Squibb: Honoraria. Petrini:Novartis and Bristol Mayer Squibb: Honoraria. Bocchia:Novartis and Bristol Mayer Squibb: Honoraria.

Introduction: In chronic myeloid leukemia (CML), tyrosine Kinase Inhibitors (TKIs) treatment is a potentially life-time therapy for the majority of patients (pts), as few of them, only after achieving a deep and stable molecular response, may discontinue TKIs without recurrence of disease. Available data suggest that relapse after TKIs discontinuation is due to the persistence of leukemic stem cells (LSCs) intrinsically resistant to TKIs. Survival of CML LSCs may be the consequence of activation of several pathways BCR-ABL1 independent. qRT-PCR, the most sensitive assay to monitor disease status in CML pts, may be inappropriate to quantify residual quiescent CML LSCs that are transcriptionally silent. Therefore, the possibility to easily quantify LSCs during TKIs treatment is a great opportunity to better understand the behavior of residual LSCs and potentially to identify those pts candidates to safely discontinue TKIs. Recently, Valent et al described that CD34+/CD38-/Lin- CML LSCs specifically co-express dipeptidylpeptidase IV (CD26) and that CD26 is a potential biomarker for the quantification and isolation of CML LSCs, in bone marrow samples of CML patients. Furthermore, Culen et al. quantified CD26+ LSCs bone marrow compartment in 31 CML patients at diagnosis and their number appears to correlate with response to TKIs treatment. In the present study we wanted to explore the feasibility, rate and potential implication of detecting CD26+ LSCs in peripheral blood (PB) from CML pts during TKI treatment. Methods: CML pts during first line treatment with any approved TKIs, referring to several Italian Hematology Centers, entered this non interventional cross sectional study after signing a proper informed consent. During a routine follow up visit, in which pts were checked for molecular response by standard PB qRT-PCR BCR-ABL1 analysis, additional 3 mls of PB were collected in EDTA and sent within 24 hours to Siena Hematology Lab to detect CD34+/CD38-/CD26+ LSCs by multicolor flow cytometry. After red blood cells lysis, cells were incubated with anti CD45 (BD Biosciences), CD34 (581), CD38 (HIT2), CD26 (M-A261) (BD Pharmigen). After washing, acquisition and analysis were performed by FACSCanto II (BD Biosciences, NR Nannini) using DIVA 8 software (BD, Biosciences). CD45+ cells acquired for each sample ranged from 500,000 to 1,000,000. Isotype controls were included in each staining. In 5 pts a FISH analysis of PB sorted CML LSCs population was also performed. Results: to validate our assay we first performed a FISH analysis of both PB sorted CD34+/CD38-/CD26+ and CD34+/CD38-/CD26- in 5 CML patients at 3-6 months after starting treatment, confirming Ph+ cells only in the CD26+ fraction. Afterward, we checked for circulating CML LSCs a total of 202 CML pts in first line treatment with TKIs for a median of 39 months (range 1-175). Type of TKI, length of treatment, molecular response and quantification of LSCs are summarized in Table 1. PB CML LSCs were detectable in 146/202 (72.3%) pts with a median number of CD26+ of 0,0165 cells/µL (range 0,0018-0,66). Kendall rank correlation coefficient used to analyze the relation between the measurable variables showed no correlation between BCR-ABL/ABLIS ratio (median 0,004 range 0-61) and number of residual LSCs (r 0.118 p=0.097). In 56/202 (27.7%) pts CD26+ LSCs were undetectable, yet we found no correlation with the concomitant degree of molecular response. Conclusions: this study represents the first attempt to measure in a large cohort of CML patients residual circulating LSCs during TKIs treatment. In our hands PB LSCs flow-cytometry assay appeared feasible, specific and sensitive and thus suitable for routine monitoring. As expected, the majority of CML patients, even in deep molecular response, still harbor residual LSCs and the number of PB CD26+ did not correlate with the number of BCR-ABL1 copies. This evidence suggests that the molecular response refers to transcriptionally active CML progenitor cells and not to quiescent, TKIs resistant, CML LSCs. Prospective studies evaluating the behavior of PB CML LSCs during different TKIs treatment, as well as studies monitoring PB CD26+ in CML pts that discontinued TKIs treatment are ongoing. Our goal is to rule out the impact, if any, of a "stem cell response" in addition to the standard molecular response in the management of CML patients mainly to identify those pts candidates for a safe TKI discontinuation. Disclosures Bocchia: Janssen: Honoraria; Novartis: Honoraria; Bristol-Myers Squibb: Honoraria. Aprile:Novartis: Honoraria. Castagnetti:Pfizer: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; ARIAD Pharmaceuticals: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Tiribelli:Ariad Pharmaceuticals: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Speakers Bureau. Breccia:Novartis: Consultancy, Honoraria; Bristol Myers Squibb: Honoraria; Celgene: Honoraria; Ariad: Honoraria; Pfizer: Honoraria. Rosti:Roche: Honoraria, Research Funding, Speakers Bureau; Incyte: Honoraria, Research Funding, Speakers Bureau; Pfizer: Honoraria, Research Funding, Speakers Bureau; BMS: Honoraria, Research Funding, Speakers Bureau; Novartis: Honoraria, Research Funding, Speakers Bureau.

Introduction. Drug transporters, such as ABCB1, hOCT1, and ABCG2, control both intracellular and systemic plasma concentrations of BCR-ABL1 inhibitors. Our group previously reported that the hOCT1 c.480C>G polymorphism significantly correlated with higher rates of adverse events and shorter event-free survival (EFS) of patients receiving imatinib. Even if nilotinib has less affinity than imatinib for the transmembrane transporters, no definitive data about the possible role of their polymorphisms are available from the "real life". Methods. Through an approach similar to the one previously used for imatinib, we investigated any possible influence of ABCB1 and hOCT1 polymorphisms on the nilotinib efficacy and toxicity in a series of 78 CML patients receiving nilotinib as first-line therapy in 8 Italian Centers from June 2012 to June 2016. Lack of CCyR at 12 months, stop of treatment for any cause, loss of MR3 or CCyR, appearance of mutations were computed as events in the EFS assessment. The following polymorphisms were tested by real-time PCR: hOCT1: rs683369[c.480C>G]; ABCB1: rs1128503 [c.1236C>T], rs2032582[c.2677G>T/A], and rs1045642[c.3435C>T]. Results. Forty-six patients were male and 32 female; the median age was 47 years (range, 18-79); Sokal score was low in 44%, intermediate in 37%, and high in 19% of cases; EUTOS was high in 30%. Efficacy: 97% of patients were in CHR and 82% in early molecular response (EMR) at 3 months; 85% achieved the CCyR at 6 months, and 88% the MR3 with a median time of 6.1 months; 78% achieved a deep molecular response (DMR), with 14% of MR5, with a median time of 26 months.With a median follow-up of 36 months, no patient lost CCyR and 9% lost MR3. All patients are still alive; 23% of patients stopped nilotinib (one third of them because of failure), and half of them reduced toT SNP, 56% of patients were heterozigous and 22% omozigous polymorphic; for the c1236 C>T SNP, 54% of patients were heterozigous and 12% omozigous polymorphic; finally, for the hOCT1 c.480 C>G, 41% of patients were heterozigous and 10% omozigous polymorphic.We found that ABCB1 and hOCT1 polymorphisms did not condition the achievement of CHR, CCyR, or MR3. Nevertheless, polymorphism of ABCB1 (c.3435C>T) was associated with a higher probability of achieving DMR (90% vs 65%; p=0.04).A longer 3-year EFS was conditioned by the achievement of EMR (90% vs 75%; p=0.012) and of MR3 (90% vs 65%: p=0.04). We found that polymorphic or wild-type status of transporters did not impact on EFS.Toxicities were observed in 41% of cases, with 40% of grade 3 or 4; ABCB1 and hOCT1 polymorphisms did not condition toxicities or nilotinib discontinuation. Conclusions. Our previous studies showed that polymorphic hOCT1 negatively conditioned CCyR and EFS during imatinib treatment, and that the combination of ABCB1 and hOCT1 polymorphisms were related to higher levels of toxicity.On the contrary, the present study demonstrated that the same polymorphisms did not condition toxicity when patients received nilotinib as first-line treatment. About efficacy, even if in a multicentric "real life" setting, it resulted superimposable to that reported in literature. We found that hOCT1 polymorphism did not have any impact on the quality of response; on the contrary, the ABCB1 c.3435C>T polymorphism (that induces a lower efflux from the leukemic cell and lower intestinal and renal excretion) was associated to a high rate of deep molecular response.On the basis of these results, we demonstrated that hOCT1 and ABCB1 polymorphisms, differently from the imatinib setting, are not relevant in patients receiving nilotinib, and that patients polymorphic for ABCB1 can even receive an advantage on DMR. Disclosures Saglio: Ariad: Consultancy; Pfizer: Consultancy; Bristol Myers Squibb: Consultancy.

Ph+ acute lymphoblastic leukemia (Ph+ ALL) is a high-risk acute leukemia with poor prognosis, in which the specific t(9;22)(q34;q11) translocation results in a chimeric bcr-abl (e1a2 breakpoint) and in a 190 KD protein (p190) with constitutive tyrosine kinase activity. The advent of first- and second-generation tyrosine kinase inhibitors (TKIs) improved the short-term outcome of Ph+ ALL patients not eligible for allo-SCT; yet disease recurrence is almost inevitable. Peptides derived from p190-breakpoint area are leukemia-specific antigens that may mediate an antitumor response toward p190+ leukemia cells. We identified one peptide named p190-13 able to induce in vitro peptide-specific CD4+ T cell proliferation in Ph+ ALL patients in complete remission during TKIs. Thus this peptide appears a good candidate for developing an immune target vaccine strategy possibly synergizing with TKIs for remission maintenance.

A 63-year-old woman with chronic myeloid leukemia (CML) received treatment with interferon (IFN)-α for 6 years. After achieving a complete cytogenetic response that was repetitively documented, IFN-α treatment was stopped. Despite maintenance of a complete cytogenetic response, a progressive rise of the BCR-ABL1 transcript was detected and loss of major molecular response occurred about 2 years after stopping IFN-α therapy. Disease remained at molecular level.Peripheral blood quantitative real-time PCR every 3 months and periodical bone marrow aspirate were performed to monitor disease.Chronic-phase, Philadelphia-positive CML that was still detectable after complete cytogenic response 2 years after cessation of IFN-α therapy.The patient was treated with a target immune approach receiving a therapeutic vaccine that consisted of an immunogenic 25-mer b2a2 breakpoint-derived peptide (CMLb2a2-25) with binding properties for several HLA-DR molecules. After nine boosts of vaccine the patient developed an adequate b2a2-25 peptide-specific CD4(+) T-cell response and BCR-ABL1 transcript started to decline in peripheral blood. No hematological or extrahematological effects were documented during therapy. At the last evaluation, 39 months since vaccinations commenced, the patient is in complete molecular response with an undetectable level of BCR-ABL1 transcript both in peripheral blood and in bone marrow and she continues to receive boosts of vaccine every 3 months as the only treatment.

Abstract 3413 Introduction Imatinib mesylate is highly effective in inducing rapid hematologic and cytogenetic responses in the vast majority of chronic myeloid leukemia (CML) patients. Yet, discontinuation of treatment is associated with disease relapse probably due to the persistence of resistant leukemic stem cells representing a reservoir of the disease. On this regard it has been reported that BCR-ABL positive progenitor cells can still be detected in patients in complete cytogenetic response (CCyR) after short term of imatinib treatment (Bhatia R, et al. Blood. 2003;101:4701-4707) but also after a stable long lasting CCyR (Bocchia M, et al. Leukemia. 2008;22:426-428). Compared to imatinib, the second generation Tyrosin Kinase Inhibitor (TKI) nilotinib appears to eradicate more rapidly the bulk of CML cells, inducing high rate of CCyR and major molecular response (MMolR) after a very short period of treatment (78% CCyR and 52% MMolR at 3 months) (Rosti G, et al. Blood. 2009;114(24):4933-8). Despite nilotinib is a more potent TKI, it didn't appear to be more effective in eliminating in vitro CML progenitors than imatinib (Konig H, et al Leukemia. 2008;22:748-755). Up to date no data evaluating the persistence of Ph+ stem cells in early chronic phase CML patients during first line treatment with nilotinib have been reported. Patients, materials and methods We investigated the presence of residual CD34+/Ph+ cells in 24 CML patients in CCyR during first line nilotinib treatment. Patients were enrolled in 2 clinical trials (GIMEMA CML0307 and CAMN107A2303) and evaluation of residual leukemic stem cells was performed during a routine bone marrow aspirate after receiving specific patients informed consent. Bone marrow purified CD34+ cells were evaluated for BCR-ABL fusion gene by fluorescent in situ hybridization (FISH) analysis. A minimum of 100 interphase nuclei of purified CD34+ cells was considered optimal for FISH analysis. Results All 24 patients have been treated exclusively with nilotinib since diagnosis (17/24 at 400mg bid; 5/24 at 300mg bid; 2/24 at 400mg/day). At the time of analysis all 24 patients were in CCyR for a median time of 27 months (range 6–29) after being treated for a median time of 30 months (range 9–30) with this second generation TKI. Regarding molecular response 20/24 (83%) were in MMolR while only 1/24 (4%) was in CMolR. Harvest, purification and subsequent FISH analysis of bone marrow CD34+ cells was optimal in 15/24 (63%) patients, suboptimal in 5/24 (21%) patients (less than 100 interphase nuclei analyzed) and not adequate in 4/24 (16%) patients (less than 50 interphase nuclei). With respect to leukemic stem cells, residual CD34+/Ph+ cells were found only in 1/20 (5%) evaluable patients. Of note, in this patient 140 CD34+ interphase nuclei were analyzed and only 1 was found bcr-abl positive (0.7%). Conclusion Our study shows for the first time that in patients in CCyR during front line Nilotinib treatment residual CD34+/Ph+ stem cells are very rarely detected. These results quite differ from what was previously found in imatinib treated patients (Bocchia M, et al. Leukemia. 2008;22:426-428). In fact in the present series, only 1/20 (5%) patients treated with nilotinib in CCyR for a median time of 27 months showed residual CD34+/Ph+ cells, while in our prior study residual leukemic CD34+ cells were still detectable in 14/31 (45%) imatinib treated patients in stable CCyR (median of 39 months). Despite the limited number of patients studied, this novel evidence may support the better short term clinical results observed with nilotinib as first line treatment in CML. Disclosures: Rosti: Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bristol Myers Squibb: Honoraria, Speakers Bureau; Roche: Speakers Bureau.

Abstract 4147 Background Standard induction chemotherapy for Acute Myeloid Leukaemia (AML) is represented by a combination of cytarabine and antracyclin with or without the addition of a third drug (e.g. etoposide), with a Complete Remission (CR) rate of about 60-65%. Aim The main goal of adding further drugs to induction therapy is to increase the CR rate in order to extend the opportunity of intensification therapies (e.g. autologous or allogeneic stem cell transplantation). Design and methods Eighty-four consecutive AML patients younger than 65 yrs were treated with a four-drug induction regimen Fludarabine (25 mg/sqm), Ara-C (2 g/sqm), Etoposide 100 mg/sqm on days 1-5, Idarubicin (6 mg/sqm) on days 1, 3, and 5, between 2002 and 2008 in two Italian Hematological Centres. The median age of this series of patients was 45 years (range 18-65), 39 were males and 44 were females. According to karyotype at diagnosis, white blood count (WBC > 30.000/mmc) and secondary disease, 58/84 patients (69%) were considered at high risk Patients were evaluated for response rate and treatment-related adverse events. Stem cell transplantation was performed according to the risk stratification and donor availability. Results After induction with FLAIE, CR occurred in 62 of 84 patients (74%). There were two death during induction (DDI 2 %). Six out of 22 resistant patients (7%) achieved CR after the second course of therapy, that was HD-Ara-c (2 g/sqm) on days 1-5 + idarubicine (12 mg/sqm) on days 1-3. Three patients were lost to follow up after induction, while in CR. The toxicity of FLAIE was acceptable, with grade III/IV hematological and extra-hematological adverse events comparable with standard induction therapy. Fifty-five patients of the 81 evaluable (68%) underwent transplant procedures while in first CR (22/81, 27 %, auto-SCT and 33/81, 41 %, allo-SCT). Five patients received allo-SCT in second CR, after early relapse. Three patients received allo-SCT with active disease and died because of disease progression. Sixteen patients (20%) received only chemotherapy-based consolidation because of either resistant disease or lack of donors or unsuccessful peripheral blood harvestt. After a median follow-up of 46 months (range 1-81), 40 of 81 evaluable patients (49%) are alive (40/40 in CR). Relapse rate is 32% at 4 yrs. These results suggest that a four drugs induction chemotherapy is feasible in young AML patients and can effectively permit intensification chemotherapy in at least 2/3 of the patients. A larger number of patients, in the context of a randomized trial may better define its efficacy with respect to standard 2 – 3 drugs induction therapy. Disclosures: Baccarani: Novartis Pharma: Consultancy, Honoraria, Research Funding, Speakers Bureau; Bristol-Mayer Squibb: Consultancy, Honoraria, Research Funding, Speakers Bureau.

Abstract 648 Introduction: Imatinib (IM) 400mg daily is the standard treatment for chronic myeloid leukemia (CML) patients and a complete cytogenetic response (CCyR) is achieved in the majority of patients within one year of treatment. In addition, a considerable number of patients reach a major molecular response (i.e BCR-ABL/ABL ratio Results: Current interim analysis shows that vaccinations (a total of over 400 shots) were very well tolerated, with CMLVAX100-GMCSF toxicity consisting exclusively of some redness and itching at the site of injection and with only 4/43 patients (9%) experiencing a mild fever. Regarding immune response induced by vaccination, 29/43 patients (67%) showed a significant in vitro b3a2-peptide-specific CD4+ T cell proliferation. With respect to MRD response, we observed a reduction of at least 50% of pre-vaccine BCR-ABL/ABL values after 6 months of treatment (i.e. after 9 vaccinations) in 22/43 (51%) patients and the reduction was confirmed in 14/29 (48%) patients who reached the 9th month evaluation (i.e. after 10 vaccinations); 14/43(32%) patients had at least one documented undetectable transcript during this time period. In 2/43 patients we observed a significant raise of BCR-ABL transcript level, after 3 and 18 months from starting vaccinations with subsequent loss of CCyR. Conclusions: CMLVAX100 vaccine appears to induce a reduction of long lasting molecular MRD surviving IM in about half of vaccinated CML patients, thus confirming preliminary results. If this BCR-ABL-specific immune control of MRD will have a substantial impact on the rate of BCR-ABL mutations, disease evolution and ultimately survival needs longer observation time to be determined. Disclosures: Baccarani: Novartis Pharma: Consultancy, Honoraria, Research Funding, Speakers Bureau; Bristol-Mayer Squibb: Consultancy, Honoraria, Research Funding, Speakers Bureau.

In recent years there has been a great improvement in molecular characterization of acute myeloid leukemia (AML) allowing the stratification of patients in different rate of risk. Patients with FLT3 mutated AML have poor prognosis because of resistance to induction chemotherapy or early relapse. Several first and second generation molecules, able to inhibit FLT3 signaling have been developed and many single agent or combination studies are ongoing. Of these, quizartinib seems to have the best clinical activity. Unfortunately, resistance to FLT3 inhibitors has been observed and many scientists are currently investigating new strategy to restore sensitivity to FLT3 inhibitors.