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Chronic myeloid leukemia stem cells (CML LSCs) are a rare and quiescent population that are resistant to tyrosine kinase inhibitors (TKI). When TKI therapy is discontinued in CML patients in deep, sustained and apparently stable molecular remission, these cells in approximately half of the cases restart to grow, resuming the leukemic process. The elimination of these TKI resistant leukemic stem cells is therefore an essential step in increasing the percentage of those patients who can reach a successful long-term treatment free remission (TFR). The understanding of the biology of the LSCs and the identification of the differences, phenotypic and/or metabolic, that could eventually allow them to be distinguished from the normal hematopoietic stem cells (HSCs) are therefore important steps in designing strategies to target LSCs in a rather selective way, sparing the normal counterparts.

Purpose: ENESTfreedom is evaluating treatment-free remission (TFR) following frontline nilotinib in patients with chronic myeloid leukemia (CML) in chronic phase. Following our primary analysis at 48 weeks, we here provide an updated 96-week analysis. Methods: Attempting TFR required ≥ 3 years of nilotinib, a molecular response of MR4.5 [BCR-ABL1 ≤ 0.0032% on the International Scale (BCR-ABL1IS)], and sustained deep molecular response (DMR) during a 1-year consolidation phase. Patients restarted nilotinib following loss of major molecular response (MMR; BCR-ABL1IS ≤ 0.1%). Results: Ninety-six weeks after stopping treatment (3.6-year median prior nilotinib duration), 93 of 190 patients (48.9%) remained in TFR. Of 88 patients who restarted nilotinib following loss of MMR, 87 regained MMR and 81 regained MR4.5 by the data cut-off. Ninety-six-week TFR rates were 61.3, 50.0, and 28.6% in patients with low, intermediate, and high Sokal risk scores at diagnosis, respectively. Patients consistently in MR4.5 during consolidation had higher TFR rates (50.6%) than patients with ≥ 1 assessment without MR4.5 during consolidation (35.0%). In a landmark analysis, 96-week TFR rates for patients with MR4.5, MR4 (BCR-ABL1IS ≤ 0.01%) but not MR4.5, and MMR but not MR4 at TFR week 12 were 82.6, 23.1, and 0%, respectively. There were no reports of disease progression or death due to CML; overall adverse event frequency decreased following TFR. Within the follow-up period, TFR did not adversely affect disease outcomes. Conclusions: These results demonstrate the feasibility and durability of TFR following frontline nilotinib and emphasize the importance of sustained DMR for TFR.

Chronic myeloid leukemia (CML) has evolved into a chronic disease that is managed with tyrosine kinase inhibitor therapy. Now that long-term survival has been achieved in patients with CML, the focus of treatment has shifted to dose optimization, with the goal of maintaining response while improving quality of life. In this review, the authors discuss optimizing the dose of the second-generation tyrosine kinase inhibitor dasatinib. Once-daily dosing regimens for dasatinib in the first and later lines of treatment were established through long-term (5-year and 7-year) trials. Recently published data have indicated that further dose optimization may maintain efficacy while minimizing adverse events. Results obtained from dose optimization and discontinuation trials currently in progress will help practitioners determine the best dose and duration of dasatinib for patients with CML, because treatment decisions will be made through continued discussions between physicians and patients. Cancer 2018;124:1660-72. © 2018 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Introduction Treatment of chronic phase (CP) chronic myeloid leukemia (CML) with tyrosine kinase inhibitors (TKIs) proved to be almost equally effective in young and elderly patients. Three TKIs, imatinib (IM), dasatinib (DAS) and nilotinib (NIL), are approved for frontline therapy in Italy. Choice of frontline TKI is based on a combined evaluation of patient's characteristics and expectations, with age usually playing a prominent role. However, to date, few data are available on patterns of TKI selection in very elderly patients. Aim To analyse the use of frontline TKI therapy in a large and unselected cohort of very elderly CP-CML patients Methods We retrospectively evaluated 332 patients aged ≥75 year diagnosed from 1/2012 to 12/2019 at 36 Hematology Centres participating at the "Campus CML" project. Results Clinical features at diagnosis for the whole cohort and according to frontline TKI are reported in Table 1. As to frontline TKI, 285 patients (85.8%) received IM and 47 (14.2%) a 2G-TKI (DAS n=28, 59.5%; NIL n=19, 40.5%). Of the 285 IM-treated patients, 192 (67.3%) started with standard dose (400 mg/day) and 93 (32.7%) with a reduced dose (300 mg/day n=64, 22.5%; Following widespread introduction of generic IM in Italy in early 2018, patients were divided in 2 groups: among 238 patients diagnosed from 2012 to 2017, 198 (83.1%) received IM and 40 (16.9%) a 2G-TKI, while patients diagnosed in 2018-2019 were treated with IM in 87/94 (92.5%) cases and with a 2G-TKI in 7 (7.5%) cases only (p=0.028). Conclusions IM remains the frontline drug of choice in very elderly CML patients, and this trend seems to increase after the introduction of the generic formulation. However, 2G-TKI are used in a small but sizeable group of patients, without a clear correlation with baseline CML features, thus probably reflecting a physician's evaluation of patient's fitness and/or expectation. Efficacy and safety of initial reduced TKIs doses in the setting of very elderly patients warrant further analyses. Figure 1 Figure 1. Disclosures Latagliata: Novartis: Honoraria; BMS Cellgene: Honoraria; Pfizer: Honoraria. Bonifacio: Novartis: Honoraria; Pfizer: Honoraria; Amgen: Honoraria; Bristol Myers Squibb: Honoraria. 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. Iurlo: Novartis: Speakers Bureau; Incyte: Speakers Bureau; Pfizer: Speakers Bureau; Bristol Myers Squibb: Speakers Bureau. Sportoletti: AstraZeneca: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria. Stagno: Pfizer: Consultancy, Honoraria, Other: Support for attending meetings and/or travel; InCyte: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Other: Support for attending meetings and/or travel, Research Funding. Abruzzese: Pfizer: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Bristol Myers Squibb: Consultancy, Honoraria. Breccia: Bristol Myers Squibb/Celgene: Honoraria; Incyte: Honoraria; Abbvie: Honoraria; Pfizer: Honoraria; Novartis: Honoraria.

Background Tyrosine kinase inhibitors (TKIs) revolutionized treatment of chronic myeloid leukemia (CML). However, the first months of therapy are crucial, as optimal response is defined as the achievement of molecular milestones at 3, 6 and 12 months (mo.) and as many toxicities, also causing a TKI switch, are more frequent in the 1st year. Methods To evaluate achievement of early molecular response (MR) and incidence of events leading to a TKI change during the 1st year of therapy, we retrospectively studied 1650 CP-CML patients diagnosed from 2012 and 2019 at 31 Hematology Centres and treated with frontline imatinib (IM) or second-generation (2G) TKIs dasatinib or nilotinib. Optimal MR at 3, 6 and 12 mo. were assessed according to 2020 ELN recommendations. Results Frontline TKI was IM in 926 (56.1%) and 2G-TKIs in 724 (43.9%) cases: the main clinical features at diagnosis of the entire cohort and according to frontline treatment is reported in the Table 1. Commonest comorbidities were arterial hypertension (38.7%), previous neoplasm (13.6%), diabetes (11.3%), peripheral vascular diseases (7.8%), COPD (7.5%) and ischemic heart disease (6.8%). IM-treated patients were older (p Optimal MR was achieved at 3 mo. by 1186/1430 (82.9%), at 6 mo. by 1025/1352 (75.8%) and at 12 mo. by 826/1264 patients (65.3%), respectively. Total number of patients discontinuing TKI in the 1st year was 321/1650 (19.4%), being higher with IM (237/926, 25.5%) than 2G-TKIs (84/724, 11.6%) (p0.001), hematologic toxicity (1.7%, 2.0% IM vs 1.4% 2G-TKIs, p=0.25) and progression (1.0%, 1.2% IM vs 0.8% 2G-TKIs, p=0.56). Cumulative incidence of discontinuation at 3, 6 and 12 mo. were 5.6%, 10.7% and 19.3%, respectively; values for IM and 2G-TKIs at the three timepoints were 8.1%, 15.0%, 25.5% and 2.5%, 5.3%, 11.5% (p Conclusions This real-world study on over 1600 CML patients shows that almost 20% discontinue frontline TKI during the 1st year, mostly for primary resistance or toxicity. Discontinuation rates are higher with IM compared to 2G-TKIs, mostly at 3 mo. and are probably due to a lower attainment of early MR. The impact of older age, higher risks and heavier burden of comorbidities in IM patients should be considered and need deeper investigation. Figure 1 Figure 1. Disclosures Elena: GILEAD: Membership on an entity's Board of Directors or advisory committees; NOVARTIS: Membership on an entity's Board of Directors or advisory committees; PFIZER: Membership on an entity's Board of Directors or advisory committees; CELGENE: Other: funding for meeting participation. Sportoletti: AstraZeneca: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria. Stagno: InCyte: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria, Other: Support for attending meetings and/or travel; Novartis: Consultancy, Honoraria, Other: Support for attending meetings and/or travel, Research Funding. Iurlo: Pfizer: Speakers Bureau; Incyte: Speakers Bureau; Novartis: Speakers Bureau; Bristol Myers Squibb: Speakers Bureau. Bonifacio: Novartis: Honoraria; Pfizer: Honoraria; Amgen: Honoraria; Bristol Myers Squibb: Honoraria. Breccia: Pfizer: Honoraria; Incyte: Honoraria; Abbvie: Honoraria; Bristol Myers Squibb/Celgene: Honoraria; Novartis: Honoraria. Latagliata: Novartis: Honoraria; Pfizer: Honoraria; BMS Cellgene: Honoraria.

Simple Summary The introduction to clinical practice of a treatment-free remission approach in chronic myeloid leukemia patients with a stable deep molecular response highlighted how crucial it is to monitor the molecular levels of BCR–ABL1 as accurately and precisely as possible. In this context, the droplet digital PCR (ddPCR) presents an alternative methodology for such quantification. To hypothesize the introduction of this technology in routine practice, we performed a multicentric study that compares ddPCR with the standard methodology currently used. Our results demonstrate that the use of ddPCR in clinical practice is feasible and could be beneficial. Abstract BCR–ABL1 mRNA levels represent the key molecular marker for the evaluation of minimal residual disease (MRD) in chronic myeloid leukemia (CML) patients and real-time quantitative PCR (RT-qPCR) is currently the standard method to monitor it. In the era of tyrosine kinase inhibitors (TKIs) discontinuation, droplet digital PCR (ddPCR) has emerged to provide a more precise detection of MRD. To hypothesize the use of ddPCR in clinical practice, we designed a multicentric study to evaluate the potential value of ddPCR in the diagnostic routine. Thirty-seven RNA samples from CML patients and five from healthy donors were analyzed using both ddPCR QXDxTM BCR-ABL %IS Kit and LabNet-approved RT-qPCR methodologies in three different Italian laboratories. Our results show that ddPCR has a good agreement with RT-qPCR, but it is more precise to quantify BCR–ABL1 transcript levels. Furthermore, we did not find differences between duplicate or quadruplicate analysis in terms of BCR–ABL1% IS values. Droplet digital PCR could be confidently introduced into the diagnostic routine as a complement to the RT-qPCR.

// Antonella Caivano 1 , Francesco La Rocca 1 , Ilaria Laurenzana 1 , Tiziana Annese 2 , Roberto Tamma 2 , Ubaldo Famigliari 3 , Vittorio Simeon 1 , Stefania Trino 1 , Luciana De Luca 1 , Oreste Villani 4 , Simona Berardi 5 , Antonio Basile 5 , Angelo Vacca 5 , Giuseppe Saglio 6 , Luigi Del Vecchio 7, 8 , Pellegrino Musto 9 , Daniela Cilloni 6 1 Laboratory of Pre-clinical and Translational Research, Scientific Institute of Research and Cure (IRCCS), Referral Cancer Center of Basilicata (CROB), Rionero in Vulture, Italy 2 Department of Human Anatomy, Histology and Embryology, University of Bari Medical School, Bari, Italy 3 Division of Pathology, Department of Oncology, St Luigi Hospital, Turin, Italy 4 Department of Onco-Hematology, IRCCS-CROB, Rionero in Vulture, Italy 5 Department of Biomedical Sciences and Human Oncology, University of Bari Medical School, Bari, Italy 6 Department of Clinical and Biological Sciences, University of Turin, Orbassano, Italy 7 CEINGE-Biotecnologie Avanzate s.c.a r.l and Medical Biotechnologies, Federico II University, Naples, Italy 8 Department of Molecular Medicine and Medical Biotechnologies, Federico II University, Naples, Italy 9 Scientific Direction, IRCCS-CROB, Rionero in Vulture, Italy Correspondence to: Antonella Caivano, email: caivanoa@libero.it Keywords: angiogenesis, bone marrow endothelial cells, receptor tyrosine kinase, EphA3, multiple myeloma Received: September 02, 2016 Accepted: March 01, 2017 Published: March 10, 2017 ABSTRACT This study investigates the role of ephrin receptor A3 (EphA3) in the angiogenesis of Multiple Myeloma (MM) and the effects of a selective target of EphA3 by a specific monoclonal antibody on primary bone marrow endothelial cells (ECs) of MM patients. EphA3 mRNA and protein were evaluated in ECs of MM patients (MMECs), in ECs of patients with monoclonal gammopathies of undetermined significance (MGECs) and in ECs of healthy subjects (control ECs). The effects of EphA3 targeting by mRNA silencing (siRNA) or by the anti EphA3 antibody on the angiogenesis were evaluated. We found that EphA3 is highly expressed in MMECs compared to the other EC types. Loss of function of EphA3 by siRNA significantly inhibited the ability of MMECs to adhere to fibronectin, to migrate and to form tube like structures in vitro , without affecting cell proliferation or viability. In addition, gene expression profiling showed that knockdown of EphA3 down modulated some molecules that regulate adhesion, migration and invasion processes. Interestingly, EphA3 targeting by an anti EphA3 antibody reduced all the MMEC angiogenesis-related functions in vitro . In conclusion, our findings suggest that EphA3 plays an important role in MM angiogenesis.

Background: Data from the phase 2, single-arm ENESTfreedom study (NCT01784068) have demonstrated the feasibility of treatment-free remission (TFR) following front-line nilotinib (NIL) treatment, with substantial TFR rates being sustained over time among patients (pts) with chronic myeloid leukemia in chronic phase (CML-CP). Results for long-term outcomes after a 5-year follow-up are presented here. The current subanalysis evaluated the efficacy and safety of TFR after upfront treatment with NIL in older (≥65 years [yrs] at study entry) vs younger ( Methods: Adult pts enrolled in ENESTfreedom had achieved MR4.5 after ≥2 years of front-line treatment with NIL. They then entered a 52-week consolidation (CONS) phase in which they continued treatment with NIL 300 mg twice-daily; pts still in MR4.5 at the end of CONS entered the TFR phase. NIL treatment was re-initiated upon loss of major molecular response (MMR). Rates of MMR and MR4.5, as well as safety, were evaluated according to age group ( Results: The total number of pts analyzed was 215, of which 171 were Disclosures García Gutiérrez: Novartis Pharma AG: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Incyte: Consultancy, Honoraria, Research Funding. Radich:Jazz: Consultancy; Amgen: Consultancy; Bristol-Myers Squibb: Consultancy; Novartis Pharmaceuticals Corporation: Consultancy, Research Funding. Hochhaus:MSD: Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Takeda: Honoraria. Saglio:Roche: Research Funding; Ariad: Research Funding; Incyte: Research Funding; Novartis: Research Funding; Bristol-Myers Squibb: Research Funding; Pfizer: Research Funding. Conneally:Novartis: Consultancy, Research Funding; Bristol-Myers Squibb: Honoraria; Pfizer: Honoraria; Gilead: Honoraria. le Coutre:Incyte: Honoraria; Pfizer: Honoraria; Novartis: Honoraria. Gattermann:Novartis: Honoraria, Research Funding. Saussele:Pfizer: Honoraria; Incyte: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Novartis: Honoraria, Research Funding. Giles:Actuate Therapeutics Inc: Consultancy; Pfizer: Research Funding; Novartis: Consultancy, Research Funding. Aimone:Novartis: Current Employment. Li:Novartis: Current Employment. Titorenko:Novartis: Current Employment. Ross:Celgene: Research Funding; Bristol-Myers Squibb: Honoraria; Novartis: Honoraria, Other: Participated in advisory board meetings, Research Funding.

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.

Introduction: Tyrosine kinase inhibitors (TKIs) have dramatically improved the standard of care for patients (pts) with chronic myeloid leukemia in chronic phase (CML-CP). In the 5-year follow-up of the phase 3 DASISION study (NCT00481247), dasatinib was associated with faster and deeper molecular responses than imatinib as first-line therapy for CML-CP (Cortes J et al. J Clin Oncol 2016). The NCCN guidelines recommend that multiple factors independent of risk score should be considered when selecting TKI therapy, including the presence of comorbidities. More than 50% of pts with CML-CP have at least one comorbidity at diagnosis (Hoffmann et al. Leukemia 2015); as such, comorbidities may influence first-line treatment choice for most pts. In this exploratory post hoc analysis of DASISION at 5-years' follow-up, we investigated the effect of comorbidities on response outcomes with dasatinib vs imatinib. Methods: DASISION was a multinational, open-label, phase 3 trial assessing dasatinib vs imatinib for newly diagnosed CML-CP. Pts were randomized to receive 100 mg dasatinib (n = 259) or 400 mg imatinib (n = 260) once daily. Charlson Comorbidity Index (CCI) was retrospectively calculated for each pt at diagnosis. Efficacy and safety data were retrospectively stratified based on CCI score categories 2-4, 5-6, and ≥ 7 (higher scores indicate a higher comorbidity burden). Rates of major molecular response (MMR) and molecular response with a 4.5-log reduction (MR4.5) were compared between treatment groups using unstratified Cochran-Mantel-Haenszel tests. Time to MMR and MR4.5 were evaluated using Kaplan-Meier methodology with hazard ratios (HRs) based on Cox proportional hazards models and P values from unstratified log-rank tests. Confidence intervals (CI) for median time to response were calculated using the Brookmeyer and Crowley method. P values are descriptive and unadjusted for multiple comparisons. Results: In total, 14 (3%) pts had CCI 2-4 (dasatinib 7, imatinib 7), 260 (50%) had CCI 5-6 (dasatinib 132, imatinib 128), and 245 (47%) had CCI ≥ 7 (dasatinib 120, imatinib 125). Baseline characteristics and drug exposure data are shown in the Table. Dose reductions of dasatinib and imatinib occurred in 14% vs 29% (CCI 2-4 group), 23% vs 12% (CCI 5-6 group) and 54% vs 22% (CCI ≥ 7 group) of pts, respectively. In the CCI 2-4 group, the MMR rate was 85.7% with dasatinib and 57.1% with imatinib (P = 0.2542) and the MR4.5 rates were 71.4% and 14.3% (P = 0.0374), respectively. In the CCI 5-6 group, the MMR rate was significantly higher with dasatinib vs imatinib (81.1% vs 64.8%, P = 0.0033), as was the MR4.5 rate (42.4% vs 29.7%, P = 0.0329). Median time to MMR in the CCI 5-6 group was significantly shorter with dasatinib than imatinib (15.0 vs 24.0 months; HR, 1.64; 95% CI, 1.23-2.19; P = 0.0006). In the CCI ≥ 7 group, response rates were numerically higher with dasatinib than imatinib: MMR rates were 70.8% vs 64.0% (P = 0.2552) and MR4.5 rates were 45.0% vs 39.2% (P = 0.3589), respectively. Median time to MMR was significantly shorter in the CCI ≥ 7 group with dasatinib than imatinib (12.0 vs 21.4 months; HR, 1.41; 95% CI, 1.04-1.91; P = 0.0279; Figure). Grade 3-4 treatment-related adverse events (TRAEs) were reported in 0% vs 14% (dasatinib vs imatinib) of pts with CCI 2-4, 8% vs 9% of pts with CCI 5-6, and 24% vs 13% of pts with CCI ≥ 7. Grade 3-4 TRAEs leading to discontinuation did not occur in the CCI 2-4 group, and were reported with similar frequency with dasatinib and imatinib in both CCI 5-6 (1% vs 1%) and CCI ≥ 7 groups (8% vs 7%). No deaths occurred in the CCI 2-4 group; a similar percentage of pts treated with dasatinib and imatinib died in the CCI 5-6 group (8% vs 9%) and CCI ≥ 7 group (13% vs 11%). Conclusions: In this exploratory post hoc analysis, dasatinib was effective across all CCI groups, consistent with previous findings suggesting that comorbidities do not negatively affect TKI activity. Molecular response rates were significantly higher with dasatinib than imatinib in pts with CCI 5-6, and comparable between treatments in pts with CCI ≥ 7. Furthermore, time to response was significantly faster with dasatinib than imatinib in both the CCI 5-6 and CCI ≥ 7 groups, while the frequency of grade 3-4 TRAEs leading to discontinuation was similar between treatments. These findings highlight the benefit of first-line treatment with dasatinib in pts with CML-CP and a high comorbidity burden. Study support: BMS. Figure Disclosures Breccia: Bristol-Myers Squibb/Celgene: Consultancy, Honoraria; Abbvie: Consultancy; Pfizer: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Mauro:Sun Pharma/SPARC: Research Funding; Pfizer: Consultancy, Honoraria, Other: Travel, Accommodation, Expenses, Research Funding; Takeda: Consultancy, Honoraria, Other: Travel, Accommodation, Expenses, Research Funding; Novartis: Consultancy, Honoraria, Other: Travel, Accommodation, Expenses, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Other: Travel, Accommodation, Expenses, Research Funding. Jabbour:BMS: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding; Pfizer: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding. Saglio:Pfizer: Research Funding; Bristol-Myers Squibb: Research Funding; Incyte: Research Funding; Roche: Research Funding; Ariad: Research Funding; Novartis: Research Funding. le Coutre:Pfizer: Honoraria; Novartis: Honoraria; Incyte: Honoraria. DeGutis:Bristol-Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Khan:Bristol-Myers Squibb: Current Employment, Current equity holder in publicly-traded company. Sy:Bristol-Myers Squibb: Current Employment. Swanink:Bristol-Myers Squibb: Current Employment. Cortes:Amphivena Therapeutics: Research Funding; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy, Research Funding; Immunogen: Research Funding; Merus: Research Funding; Bristol-Myers Squibb: Research Funding; Arog: Research Funding; BiolineRx: Consultancy, Research Funding; BioPath Holdings: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Research Funding; Telios: Research Funding; Sun Pharma: Research Funding.

Introduction : therapy of chronic phase (CP) chronic myeloid leukemia (CML) is based on tyrosine kinase inhibitors (TKIs) in virtually all patients. Three TKIs are approved for first-line therapy in Italy: imatinib and two second-generation (2G) TKIs, dasatinib and nilotinib. Choice of the front-line TKI is based on a combined evaluation of patient's and disease characteristics, age, risk, comorbidities and concomitant medications. Treating physician's preference and, in some cases, economic considerations, particularly after the advent of generic imatinib, may play a role in TKI selection. However, to date, few data are available on TKI use in a whole nation and on the possible drivers of treatment choice. Aim of the present work was to analyse the use of front-line TKI therapy in a large, unselected cohort of Italian CP-CML patients, correlating patient's features to drug choice. Methods: in the framework of the national Campus CML program, we retrospectively evaluated 1422 patients with CP-CML diagnosed from 2012 and 2019 in 21 haematologic Centres, mostly in academic and/or tertiary hospitals, widespread through the entire Italian territory and treated frontline with imatinib, dasatinib or nilotinib. Results: median age at diagnosis was 59.9 years [interquartile range (IQR) 47.1 - 71.7], with 317 (22.3%) patients under 45 years, 552 (38.8%) between 45 and 65 years and 553 (38.9%) older than 65 years; 821 (57.7%) patients were males. Among 1364 evaluable patients, CML risk according to Sokal score was low in 540 (39.6%), intermediate in 610 (44.7%) and high in 214 (15.7%) patients respectively; the number at low, intermediate or high risk according to the novel ELTS score among 1325 evaluable patients was 759 (57.3%), 402 (30.3%) and 164 (12.4%) respectively. Considering comorbidities, 1003 (70.6%) patients had at least one active disease at the time of CML diagnosis, the most common being hypertension (n=547, 38.5%), previous neoplasms (n=185, 13.0%), diabetes (n=150, 10.6%), chronic bronchopulmonary diseases (n=114, 8.0%), acute myocardial infarction (n=95, 6.7%), previous stroke (n=36, 2.5%) and other vascular diseases (n=98, 6.9%). Among 1335 evaluable patients, 813 (60.9%) were taking at least one concomitant medication, with 280 (21.0%) taking 3-5 drugs and 140 (10.5%) taking 6+ drugs at time of TKI start. As to the frontline therapy, 794 (55.8%) received imatinib and 628 (44.2%) were treated with 2G-TKIs, (226 dasatinib and 402 nilotinib) respectively. According to age, 2G-TKIs were chosen for majority of patients aged 100,000/mm3 vs 38.2% if WBC 10 g/dl; p=0.001) and bigger spleen (65.1% if spleen >5 cm vs 44.8% if spleen 1-5 cm vs 37.3% if spleen not palpable; p5 drugs, respectively (p 45 years, intermediate or high Sokal risk, presence of some comorbidities (2nd neoplasia and stroke) and number of concomitant medications. Conclusions: preliminary results of this observational study on almost 1500 patients show that around 55% of newly diagnosed Italian CP-CML patients receive imatinib as front-line therapy, and that the use of 2G-TKI is prevalent in the younger patients and in those with no concomitant clinical conditions. The counterintuitive finding of imatinib prevalence as frontline treatment in high risk patients might be explained by the older age of these patients. Introduction of the generic formulation in 2018 seems to have fostered the use of imatinib. Figure Disclosures Breccia: Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Abbvie: Consultancy; Bristol-Myers Squibb/Celgene: Consultancy, Honoraria. Cavazzini:Pfize: Honoraria; Incyte: Honoraria; Novartis: Honoraria. Saglio:Bristol-Myers Squibb: Research Funding; Pfizer: Research Funding; Incyte: Research Funding; Novartis: Research Funding; Ariad: Research Funding; Roche: Research Funding.

INTRODUCTION: Frontline therapy with second generation (2G) tyrosine-kinase inhibitors (TKIs) in chronic phase (CP) chronic myeloid leukemia (CML) patients demonstrated higher efficacy as compared to imatinib, with less patients experiencing treatment failure and progression to advanced disease. However, limited information are currently available on the management and outcome of those CML pts not achieving an optimal response to first-line treatment with a 2G-TKI. AIM: To describe the clinical outcome of CP CML patients without an optimal response to a frontline 2G-TKI that switched to alternative TKIs. METHODS: We performed a retrospective analysis in 22 Centers cooperating within the Italian CML Campus Project. Main inclusion criteria were: 1) diagnosis of CP-CML after 2010; 2) first-line treatment with a 2G-TKI; 3) switch to second-line treatment in case of non-optimal response (either following ELN recommendations or as for clinical practice); 4) CML in CP at the time of switching to second-line treatment. The main exclusion criteria were a switch to second-line treatment for intolerance or for low adherence to therapy. RESULTS: The main findings of this analysis are summarized in the table. Seventy-one pts meeting the inclusion/exclusion criteria were identified; the median age of pts at CML diagnosis was 46 (21-80) years. Sokal risk score was low, intermediate, and high in 24 (34%), 30 (42%), and 17 (24%) pts, respectively. First-line treatment was performed with nilotinib in 47 (66%) pts and dasatinib in 24 (34%) pts. According to the ELN 2020 recommendations, 51 (72%) pts fulfilled the criteria for "failure" and 20 (28%) pts those for "warning". BCR-ABL mutations were identified in 12 of 65 (18%) evaluable pts (T315I in 1 pt). Additional chromosomal abnormalities in Ph+ cells were identified in 6 of 54 (11%) evaluable pts. Second-line treatment was started after a median time of 16 (4-72) months, with ponatinib (40 pts, 56%), dasatinib (21 pts, 30%), nilotinib (7 pts, 10%), or bosutinib (3 pts, 4%). Median follow-up from start of second-line treatment was 25 (2-90) months. Best response to second-line treatment was MR2 in 18 (25%) pts and MR3 in 37 (51%) pts. Nineteen (27%) pts (13 for resistance and 6 for intolerance) switched to third-line treatment (ponatinib, 11 pts; nilotinib, 3 pts; dasatinib, 4 pts; imatinib, 1 pt), after a median time of 8 (1-72) months. Mutations were identified in 2 of 17 evaluable pts, and both patients harbored a T315I mutation. MR3 was reached by 9 (47%) of these pts. Lastly, 7 (10%) pts switched (6 for resistance and 1 for intolerance) to fourth-line treatment (asciminib, 4pts; dasatinib, 2 pts, nilotinib, 1 pt). Overall, 44 (62%) patients reached with sequential TKI treatments a MR3 (31/51 pts among "failures"; 13/20 among "warnings"). Allogeneic stem-cell transplantation (SCT) was performed in 7 (9.5%) pts (6 among "failures"), after a median time of 20 (15-60) months from CML diagnosis. Progression to advanced phase occurred in 2 (3%) pts; both pts previously met the ELN2020 "failure" criteria. Estimated 4-y PFS was 92.5%. Death occurred in 3 (4%) pts (1 after progression to blast phase, 2 for cardiovascular adverse events). Estimated 4-y OS was 93.7% CONCLUSION Our findings show that CP-CML patients not achieving an optimal response to frontline 2G-TKI therapy, despite a complex management, still have a favorable prognosis and survival due to the availability of both multiple TKI options and SCT. Figure Disclosures Gugliotta: Novartis: Honoraria; Incyte: Honoraria; Pfizer: Honoraria. Galimberti:Novartis: Speakers Bureau; Incyte: Honoraria. Abruzzese:Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bms: Honoraria; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees. Bocchia:CELGENE: Honoraria; Incyte: Honoraria. Castagnetti:Bristol Myers Squibb: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Incyte: Consultancy, Honoraria. Di Raimondo:Amgen, Takeda, Novartis: Honoraria; Janssen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; GILEAD, Incyte: Research Funding; GSK: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Amgen: Consultancy, Honoraria. Cavo:Jannsen, BMS, Celgene, Sanofi, GlaxoSmithKline, Takeda, Amgen, Oncopeptides, AbbVie, Karyopharm, Adaptive: Consultancy, Honoraria. Rosti:Bristol-Myers Squibb: Speakers Bureau; Incyte: Speakers Bureau; Novartis: Speakers Bureau; Pfizer: Research Funding, Speakers Bureau. Foà:Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees; Novartis: Speakers Bureau; Incyte: Speakers Bureau. Saglio:Pfizer: Research Funding; Ariad: Research Funding; Roche: Research Funding; Incyte: Research Funding; Bristol-Myers Squibb: Research Funding; Novartis: Research Funding. Breccia:Abbvie: Consultancy; Pfizer: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Bristol-Myers Squibb/Celgene: Consultancy, Honoraria; Novartis: Consultancy, Honoraria.

Background: Acute lymphoblastic leukemia (ALL) is a molecularly heterogeneous disease originating from clonal proliferation of precursor B-lineage cells. In adults, ALL diagnosis is still associated with a dismal prognosis due to the lack of specific targeted therapies. This study was designed to investigate the expression of interleukin-2 receptor alpha chain CD25 in B-ALL and its biological significance, especially following the availability of specific CD25 targeting compounds. Methods:The expression of IL2RA (CD25 gene) was detected by flow cytometry (FC), immunohistochemistry and Western blot analysis, in 25 newly diagnosed ALL patients, both Philadelphia positive (12 patients) and Philadelphia negative (13 patients). Similarly, CD25 expression was assessed in four B-ALL commercially available cell lines. Infection with shRNA specifically directed against CD25 was used to evaluate apoptosis induction and cell cycle arrest in primary B-ALL cells established from two patients. Results:Our data suggest that ALL, and in particular Ph-positive ALL, aberrantly expresses the interleukin-2 receptor alpha chain, CD25. Whereas normal B cells display low amounts of CD25, primary ALL cells and ALL cell lines (over)-express CD25. While the high frequency of CD25 on the surface of many different hematological tumor cells has been established and confirmed in our study, there is little investigation focusing on the significance of CD25 expression. Indeed, CD25 may be present on ALL cells and enable oncogenic signaling pathways. In such respect, we observed that CD25 silencing in primary cells promotes cell cycle arrest and apoptosis induction. While these data support the rational to target CD25, ALL cells did not appear to be in-vitro sensitive to basiliximab, an antibody able to target the Il2RA, but in-vivo investigations are needed to better assess the effects of this therapeutic approach in ALL context. Conclusions:We concluded that CD25 expression is elevated in patients with B-ALL. Our results also demonstrate that CD25 silencing induces cell cycle arrest and apoptosis. The latter result has important implications from a therapeutic point of view. Targeting CD25 receptor with anti-CD25 antibodies or peptide mimetics could be an effective strategy for targeting leukemic cells. Additionally, high CD25 expression could be exploited for the development of CAR-T therapy Disclosures Saglio: Roche:Research Funding;Pfizer:Research Funding;Incyte:Research Funding;Novartis:Research Funding;Ariad:Research Funding;Bristol-Myers Squibb:Research Funding.

Context While some patients with chronic myeloid leukemia in chronic phase who maintain a deep molecular response (DMR) with tyrosine kinase inhibitors (TKIs) can discontinue treatment and achieve treatment-free remission (TFR), variables that reliably predict TFR are unknown. Objective Identify clinical predictors of TFR using pooled data from long-term follow-up studies (ENESTfreedom and ENESTop) of TFR following front- or second-line nilotinib. Patients In ENESTfreedom, patients with MR4.5 and ≥2 years of frontline nilotinib were enrolled and entered a 1-year nilotinib consolidation phase, after which those who maintained DMR in 4 quarterly assessments could enter the TFR phase (n=190). In ENESTop, patients with >4 weeks of imatinib followed by ≥2 years of nilotinib (≥3 years of total TKI therapy) who achieved MR4.5 on nilotinib were enrolled; patients entered a 1-year nilotinib consolidation phase, and those with no loss of MR4.5 subsequently entered the TFR phase (n=126). Main outcome measures Data from all patients who entered the TFR phases of ENESTfreedom and ENESTop were pooled. Univariate and multivariate analyses were conducted to identify predictors of durable TFR (i.e., remaining in the TFR phase with MR4.5 at 24 weeks). Variables assessed as predictors were age, sex, time since MR4.5 achievement until TFR phase entry, and duration of nilotinib prior to TFR. Results Among all patients who entered the TFR phases of ENESTfreedom and ENESTop, 180/316 achieved durable TFR at 24 weeks. In the univariate analysis, time since MR4.5 achievement until TFR phase entry (P=0.0025) and duration of nilotinib prior to TFR phase entry (P=0.0008) were significantly associated with durable TFR. Duration of nilotinib prior to TFR phase entry was the only significant predictor (P=0.0333) found in the multivariate analysis, with a 1-month increase in the duration of nilotinib treatment being associated with a 3.6% increase in the odds of durable TFR. Conclusions Pooled analyses suggest that durable TFR at 24 weeks was associated with duration of nilotinib prior to TFR. These data could help physicians with patients who are considering attempting TFR. Study sponsored by Novartis Pharmaceuticals Corporation. This abstract was accepted and previously published at the 61st ASH® Annual Meeting and Exposition.

In chronic myeloid leukemia (CML) patients, tyrosine kinase inhibitors (TKIs) may select for drug-resistant BCR-ABL1 kinase domain (KD) mutants. Although Sanger sequencing (SS) is considered the gold standard for BCR-ABL1 KD mutation screening, next-generation sequencing (NGS) has recently been assessed in retrospective studies. We conducted a prospective, multicenter study (NEXT-in-CML) to assess the frequency and clinical relevance of low-level mutations and the feasibility, cost, and turnaround times of NGS-based BCR-ABL1 mutation screening in a routine setting. A series of 236 consecutive CML patients with failure (n = 124) or warning (n = 112) response to TKI therapy were analyzed in parallel by SS and NGS in 1 of 4 reference laboratories. Fifty-one patients (22 failure, 29 warning) who were negative for mutations by SS had low-level mutations detectable by NGS. Moreover, 29 (27 failure, 2 warning) of 60 patients who were positive for mutations by SS showed additional low-level mutations. Thus, mutations undetectable by SS were identified in 80 out of 236 patients (34%), of whom 42 (18% of the total) had low-level mutations somehow relevant for clinical decision making. Prospective monitoring of mutation kinetics demonstrated that TKI-resistant low-level mutations are invariably selected if the patients are not switched to another TKI or if they are switched to a inappropriate TKI or TKI dose. The NEXT-in-CML study provides for the first time robust demonstration of the clinical relevance of low-level mutations, supporting the incorporation of NGS-based BCR-ABL1 KD mutation screening results in the clinical decision algorithms.

Myelodysplastic syndromes (MDS) are hematological malignancies characterized by ineffective hematopoiesis and increased apoptosis in the bone marrow, which cause peripheral cytopenia. Mitochondria are key regulators of apoptosis and a site of iron accumulation that favors reactive oxygen species (ROS) production with detrimental effects on cell survival. Although the energy metabolism could represent an attractive therapeutic target, it was poorly investigated in MDS. The purpose of the study was to analyze how the presence of myelodysplastic hematopoiesis, iron overload and chelation impact on mitochondrial metabolism. We compared energy balance, OxPhos activity and efficiency, lactic dehydrogenase activity and lipid peroxidation in mononuclear cells (MNCs), isolated from 38 MDS patients and 79 healthy controls. Our data show that ATP/AMP ratio is reduced during aging and even more in MDS due to a decreased OxPhos activity associated with an increment of lipid peroxidation. Moreover, the lactate fermentation enhancement was observed in MDS and elderly subjects, probably as an attempt to restore the energy balance. The biochemical alterations of MNCs from MDS patients have been partially restored by the in vitro iron chelation, while only slight effects were observed in the age-matched control samples. By contrast, the addition of iron chelators on MNCs from young healthy subjects determined a decrement in the OxPhos efficiency and an increment of lactate fermentation and lipid peroxidation. In summary, MDS-MNCs display an altered energy metabolism associated with increased oxidative stress, due to iron accumulation. This condition could be partially restored by iron chelation.

Myeloproliferative neoplasms are divided into essential thrombocythemia (ET), polycythemia vera (PV) and primary myelofibrosis (PMF). Although ruxolitinib was proven to be effective in reducing symptoms, patients rarely achieve complete molecular remission. Therefore, it is relevant to identify new therapeutic targets to improve the clinical outcome of patients. Bcl-xL protein, the long isoform encoded by alternative splicing of the Bcl-x gene, acts as an anti-apoptotic regulator. Our study investigated the role of Bcl-xL as a marker of severity of MPN and the possibility to target Bcl-xL in patients. 129 MPN patients and 21 healthy patients were enrolled in the study. We analysed Bcl-xL expression in leucocytes and in enriched CD34+ and CD235a+ cells. Furthermore, ABT-737, a Bcl-xL inhibitor, was tested in HEL cells and in leucocytes from MPN patients. Bcl-xL was found progressively over-expressed in cells from ET, PV and PMF patients, independently by JAK2 mutational status. Moreover, our data indicated that the combination of ABT-737 and ruxolitinib resulted in a significantly higher apoptotic rate than the individual drug. Our study suggests that Bcl-xL plays an important role in MPN independently from JAK2 V617F mutation. Furthermore, data demonstrate that targeting simultaneously JAK2 and Bcl-xL might represent an interesting new approach.

The therapeutic landscape of chronic myeloid leukemia (CML) has profoundly changed over the past 7 years. Most patients with chronic phase (CP) now have a normal life expectancy. Another goal is achieving a stable deep molecular response (DMR) and discontinuing medication for treatment-free remission (TFR). The European LeukemiaNet convened an expert panel to critically evaluate and update the evidence to achieve these goals since its previous recommendations. First-line treatment is a tyrosine kinase inhibitor (TKI; imatinib brand or generic, dasatinib, nilotinib, and bosutinib are available first-line). Generic imatinib is the cost-effective initial treatment in CP. Various contraindications and side-effects of all TKIs should be considered. Patient risk status at diagnosis should be assessed with the new EUTOS long-term survival (ELTS)-score. Monitoring of response should be done by quantitative polymerase chain reaction whenever possible. A change of treatment is recommended when intolerance cannot be ameliorated or when molecular milestones are not reached. Greater than 10% BCR-ABL1 at 3 months indicates treatment failure when confirmed. Allogeneic transplantation continues to be a therapeutic option particularly for advanced phase CML. TKI treatment should be withheld during pregnancy. Treatment discontinuation may be considered in patients with durable DMR with the goal of achieving TFR. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons. org/licenses/by/4.0/.

Introduction Tyrosine kinase inhibitors (TKIs) have dramatically changed the outcome of chronic phase chronic myeloid leukemia patients (CP-CML),improving the long-term outcome; indeed, life expectancy is now very close to that of age matched individuals in the general population. Imatinib (IMA) the first generation TKI, increased the overall survival(OS)by more than 80%. Second-generation TKIs, (2gen TKIs) used in first line dasatinib and nilotinib, induced faster molecular responses, rapidly reducing the disease burden, but did not change the OS of CP-CML newly diagnosed patients. Most of the available data reported were extrapolated from sponsored clinical trials. The aim of this analysis is to detail and analyze the prognostic features influencing the OS in a large Italian CML cohort of patients prospectively enrolled in the GIMEMA CML Italian study. Methods Relevant clinical, demographic, biological and treatment-related information were web-based collected during a multicenter,observational Italian study that enrolled consecutive patients in each disease phase, at 68 Italian hematologic centers belonging to the GIMEMA network from January 2013 to June 2020. We analyzed prognostic factors influencing the OS by Kaplan Meier method and Cox multivariable models. Results A cohort of 1206 patients was prospectively analyzed, 608 of them received frontline IMA and 598 2genTKIs. Median age in the IMA cohort was 69 years (range 58-77) vs 52 years in the 2genTKIs cohort (range 41-63). The male/female ratio was 1.7 in the IMA group and 1.35 in the 2genTKIs cohort. Ninety-eight percent of patients were in CP. Results of molecular analysis of the BCR-ABL transcript at baseline showed: b2a2 in 33.1 % of patients and b3a2 in 59.9%, while an atypical transcript was found in 7%. The cytogenetic analysis at baseline showed major and minor additional aberrations in 5.7% and 1.6% of patients respectively. In the IMA cohort,according to the Sokal score, 27.7%, 57.3% and 15% of patients were stratified as low, intermediate and high risk, whereas according to the ELTS score 51.3%, 35.5% and 13.3%, of patients were classified as low, intermediate and high risk. In the 2genTKIs cohort, according to the Sokal score, 44.8%, 34.5% and 20.8%, were low, intermediate and high risk, respectively, whereas according to the ELTS score, 66.9%, 22% and 11% were assigned to the respective risk groups.The Charlson comorbidity index in the IMA cohort was 2-3 and 4-5 in 74% and 26% of patients respectively; in the 2genTKIs cohort the score was 2-3 in 89% and 4-5 only in 10% of patients. Overall, median follow-up of the whole population was 24.7 months (range 13.3-39.3).Seventy-three patients (6.1%) in the overall population died, the majority of them in the IMA cohort: 56 patients (9.2%), at median age of 80.5 years,11/608 (1.8%) due to CML-related causes. Conversely,in the 2genTKIs cohort only 17 patients (2.8%) died, at a median age of 62 years, 10/598 (1.7%) for CML-related causes. Estimated 60-months OS of the overall population was 86.4% (95% CI 81.3-90.2): 75.8% (95% CI 64.5-84) in the IMA cohort and 93.8% (95% CI 87.5-97) in the 2genTKIs group (p Conclusions In this first analysis of our study different clinical behaviors were observed among Italian hematologists, who prevalently prescribed IMA to older patients,with more comorbidities, as compared to 2genTKIs.These differences explain a better OS for patients treated with 2genTKIs vs IMA, however, the risk of death for CML related causes is quite similar between the two groups, all the differences being attributable to other causes of death.Prognostic baseline features associated to an increased OS confirmed that, in addition to age, the ELTS score and the comorbidities are the main clinical factors that independently influence the long-term OS Disclosures Pregno: Incyte-Italy,: Membership on an entity's Board of Directors or advisory committees, Other: conference reports; Novartis-Italy: Membership on an entity's Board of Directors or advisory committees, Other: conference reports; Pfizer-Italy: Membership on an entity's Board of Directors or advisory committees, Other: conference reports. Breccia:Bristol-Myers Squibb/Celgene: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Abbvie: Consultancy. Castagnetti:Novartis: Consultancy, Honoraria; Bristol Myers Squibb: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Incyte: Consultancy, Honoraria. Galimberti:Novartis: Speakers Bureau; Incyte: Honoraria. Bocchia:CELGENE: Honoraria; Incyte: Honoraria. Abruzzese:Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bms: Honoraria; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees. Levato:Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Rosti:Pfizer: Research Funding, Speakers Bureau; Bristol-Myers Squibb: Speakers Bureau; Novartis: Speakers Bureau; Incyte: Speakers Bureau. Di Raimondo:GILEAD, Incyte: Research Funding; Amgen, Takeda, Novartis: Honoraria; Celgene: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; GSK: Consultancy, Honoraria. Pane:Janssen: Other: Travel Expenses; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis pharma SAS: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Jazz Pharmaceuticals: Consultancy, Other: travel expenses, Speakers Bureau; Daiichi Sankyo: Consultancy, Other: Travel Expenses; Amgen: Consultancy, Other: Travel Expenses, Speakers Bureau; AbbVie: Consultancy, Other: Travel Expenses, Speakers Bureau. Foà:Incyte: Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees; Novartis: Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Saglio:Bristol-Myers Squibb: Research Funding; Pfizer: Research Funding; Incyte: Research Funding; Roche: Research Funding; Novartis: Research Funding; Ariad: Research Funding.

Background: Acute myeloid leukemia is a heterogeneous hematological disease, characterized by karyotypic and molecular alterations. Mutations in IDH2 have a role in diagnosis and as a minimal residue disease marker. Often the variant allele frequency during follow up is less than 20%, which represents the limit of detection of Sanger sequencing. Therefore, the development of sensitive methodologies to identify IDH2 mutations might help to monitor patients&rsquo, response to therapy. We compared three different methods to identify and monitor IDH2 mutations in patients&rsquo, specimens. Methods: Performances of PNA-PCR clamping, droplet digital PCR and Sanger for IDH2 status identification were evaluated and compared in 96 DNA patients&rsquo, specimens. Results: In contrast with Sanger sequencing, our results highlighted the concordance between PNA clamping and digital PCR. Furthermore, PNA-PCR clamping was able to detect more mutated DNA with respect to Sanger sequencing that showed several false negatives independently from the allelic frequency. Conclusions: We found that PNA-PCR clamping and digital PCR identified IDH2 mutations in DNA samples with comparable results in a percentage significantly higher compared to Sanger sequencing. PNA-PCR clamping can be used even in laboratories not equipped for sophisticated analyses, decreasing cost and time for IDH2 characterization.

Leukemia is a type of hematopoietic stem/progenitor cell malignancy characterized by the accumulation of immature cells in the blood and bone marrow. Treatment strategies mainly rely on the administration of chemotherapeutic agents, which, unfortunately, are known for their high toxicity and side effects. The concept of targeted therapy as magic bullet was introduced by Paul Erlich about 100 years ago, to inspire new therapies able to tackle the disadvantages of chemotherapeutic agents. Currently, nanoparticles are considered viable options in the treatment of different types of cancer, including leukemia. The main advantages associated with the use of these nanocarriers summarized as follows: i) they may be designed to target leukemic cells selectively; ii) they invariably enhance bioavailability and blood circulation half-life; iii) their mode of action is expected to reduce side effects. FDA approval of many nanocarriers for treatment of relapsed or refractory leukemia and the desired results extend their application in clinics. In the present review, different types of nanocarriers, their capability in targeting leukemic cells, and the latest preclinical and clinical data are discussed.

Summary In addition to the best possible overall survival, discontinuation of the tyrosine kinase‐inhibitor (TKI) treatment [treatment free remission (TFR)] without observing a recurrence of the disease has become a major goal of the therapy of chronic myelogenous leukemia (CML). Many clinical studies have demonstrated that TFR is possible, although for the moment limited to a fraction of the CML patients able to achieve a stable deep molecular response (DMR). The factors associated to the possibility of remaining in TFR or of losing it, have been investigated by a number of controlled and observation clinical trials and although total TKI treatment duration, DMR duration and stability and, more recently, also the depth of the molecular response obtained at the time of discontinuation have been shown to be significant elements, most of the factors associated with a higher possibility of a successful discontinuation still remain elusive and are here reviewed.

Discontinuation of tyrosine kinase inhibitors (TKIs) therapy is now feasible for patients with chronic myeloid leukemia (CML) with deep and longstanding molecular response (MR 4/4.5); around 40–60%...

Standard first-line therapy of chronic myeloid leukemia is treatment with imatinib. In the randomized German Chronic Myeloid Leukemia-Study IV, more potent BCR-ABL inhibition with 800 mg (‘high-dose’) imatinib accelerated achievement of a deep molecular remission. However, whether and when a de-escalation of the dose intensity under high-dose imatinib can be safely performed without increasing the risk of losing deep molecular response is unknown. To gain insights into this clinically relevant question, we analyzed the outcome of imatinib dose reductions from 800 mg to 400 mg daily in the Chronic Myeloid Leukemia-Study IV. Of the 422 patients that were randomized to the 800 mg arm, 68 reduced imatinib to 400 mg after they had achieved at least a stable major molecular response. Of these 68 patients, 61 (90%) maintained major molecular remission on imatinib at 400 mg. Five of the seven patients who lost major molecular remission on the imatinib standard dose regained major molecular remission while still on 400 mg imatinib. Only two of 68 patients had to switch to more potent kinase inhibition to regain major molecular remission. Importantly, the lengths of the intervals between imatinib high-dose treatment before and after achieving major molecular remission were associated with the probabilities of maintaining major molecular remission with the standard dose of imatinib. Taken together, the data support the view that a deep molecular remission achieved with high-dose imatinib can be safely maintained with standard dose in most patients. Study protocol registered at clinicaltrials.gov 00055874.

The 60th American Society of Hematology (ASH) held in San Diego in December 2018 was followed by the 13th Post-ASH chronic myeloproliferative neoplasms (MPNs) workshop on December 4 and 5, 2018. This closed annual workshop, first introduced in 2006 by Goldman and Mughal, was organized in collaboration with Alpine Oncology Foundation and allowed experts in preclinical and clinical research in the chronic MPNs to discuss the current scenario, including relevant presentations at ASH, and address pivotal open questions that impact translational research and clinical management. This review is based on the presentations and deliberations at this workshop, and rather than provide a resume of the proceedings, we have selected some of the important translational science and treatment issues that require clarity. We discuss the experimental and observational evidence to support the intimate interaction between aging, inflammation, and clonal evolution of MPNs, the clinical impact of the unfolding mutational landscape on the emerging targets and treatment of MPNs, new methods to detect clonal heterogeneity, the challenges in managing childhood and adolescent MPN, and reflect on the treatment of systemic mastocytosis (SM) following the licensing of midostaurin.

// Valentina Rosso 1 , Jessica Petiti 1 , Enrico Bracco 2 , Roberto Pedrola 1 , Francesca Carnuccio 1 , Elisabetta Signorino 1 , Sonia Carturan 1 , Chiara Calabrese 1 , Giada Bot-Sartor 1 , Michela Ronconi 1 , Anna Serra 1 , Giuseppe Saglio 1 , Francesco Frassoni 3 , Daniela Cilloni 1 1 Department of Clinical and Biological Sciences, University of Turin, Turin, Italy 2 Department of Oncology, University of Turin, Turin, Italy 3 Department of Pediatric Hemato-Oncology and Stem Cell, Cellular Therapy Laboratory, Institute G. Gaslini, Genova, Italy Correspondence to: Daniela Cilloni, email: daniela.cilloni@unito.it Keywords: CALR, PNA, MPN, PCR clamping, diagnostic assay Received: September 14, 2016 Accepted: December 15, 2016 Published: December 23, 2016 ABSTRACT The myeloproliferative neoplasms are chronic myeloid cancers divided in Philadelphia positive (Ph+), chronic myeloid leukemia, or negative: polycythemia vera (PV) essential thrombocythemia (ET), and primary myelofibrosis (PMF). Most Ph negative cases have an activating JAK2 or MPL mutation. Recently, somatic mutations in the calreticulin gene ( CALR ) were detected in 56–88% of JAK2/MPL -negative patients affected by ET or PMF. The most frequent mutations in CARL gene are type-1 and 2. Currently, CALR mutations are evaluated by sanger sequencing. The evaluation of CARL mutations increases the diagnostic accuracy in patients without other molecular markers and could represent a new therapeutic target for molecular drugs. We developed a novel detection assay in order to identify type-1 and 2 CALR mutations by PNA directed PCR clamping. Seventy-five patients affected by myeloproliferative neoplasms and seven controls were examined by direct DNA sequencing and by PNA directed PCR clamping. The assay resulted to be more sensitive, specific and cheaper than sanger sequencing and it could be applied even in laboratory not equipped for more sophisticated analysis. Interestingly, we report here a case carrying both type 1 and type2 mutations in CALR gene.

Dasatinib was approved at 100 mg once daily for imatinib-resistant or -intolerant patients with chronic myeloid leukemia (CML) in chronic phase, based on results of the phase 3 CA180-034 (NCT00123474) study. Here we present the final 7-year analysis of this pivotal study, the longest follow-up to date of any second-generation BCR-ABL1 tyrosine kinase inhibitor (TKI). Patients (n = 670) with imatinib-resistant or -intolerant CML in chronic phase received dasatinib. Nineteen percent of patients continued on study treatment, with a greater proportion in the 100 mg once daily arm remaining on therapy. Seven-year rates for major molecular response (MMR), progression-free survival (PFS), and overall survival (OS) were similar across doses; MMR, PFS, and OS results were 46, 42, and 65% at 100 mg once daily, respectively. Improved PFS and OS rates were reported in patients who achieved BCR-ABL1 ≤10% at 3 and 6 months. No new safety signals were identified. The incidence of drug-related pleural effusion was 28% at 100 mg once daily and 35% at the other three dose groups. Incidence of drug-related pulmonary hypertension and pulmonary arterial hypertension remained low (≤3% across all doses). Arterial ischemic events occurred in ≤4% of patients across all doses. These data support the long-term efficacy and well-established safety profile of dasatinib for patients with imatinib-resistant or -intolerant CML in chronic phase. Am. J. Hematol. 91:869-874, 2016. © 2016 Wiley Periodicals, Inc.

The Wilms tumor gene WT1 is a useful marker of clonal hematopoiesis and it has been shown to be a good marker of residual disease and it reflects the response to therapy. Although myelofibrosis is characterized by mutations of JAK2 and calreticulin (CALR), these mutations are not useful to monitor response to therapy. In this study we demonstrated that in patients affected by myelofibrosis WT1 correlates with the International Prognostic Scoring System (IPSS) score at diagnosis. Furthermore WT1 is a good marker of response to JAK2 inhibitors especially for patients without blasts and for patients who develop anemia or thrombocytopenia not for progression but as therapy related toxicity. Finally, WT1 transcript reduction can mirror a benefit of therapy on the disease burden. This study demonstrated that WT1 is a good marker for monitoring the response to therapy in patients affected by myelofibrosis.

The introduction of second-generation tyrosine-kinase inhibitors (TKIs) has generated a lively debate on the choice of first-line TKI in chronic phase, chronic myeloid leukemia (CML). Despite the TKIs have different efficacy and toxicity profiles, the planned use of two TKIs has never been investigated. We report on a phase 2 study that was designed to evaluate efficacy and safety of a treatment alternating nilotinib and imatinib, in newly diagnosed BCR-ABL1 positive, chronic phase, CML patients. One hundred twenty-three patients were enrolled. Median age was 56 years. The probabilities of achieving a complete cytogenetic response, a major molecular response, and a deep molecular response (MR 4.0) by 2 years were 93%, 87%, and 61%, respectively. The 5-year overall survival and progression-free survival were 89%. Response rates and survival are in the range of those reported with nilotinib alone. Moreover, we observed a relatively low rate of cardiovascular adverse events (5%). These data show that the different efficacy and toxicity profiles of TKIs could be favorably exploited by alternating their use. Am. J. Hematol. 91:617-622, 2016. © 2016 Wiley Periodicals, Inc.

Simple Summary The diagnostic and clinical success of standardization of BCR-ABL1 p210 monitoring in chronic myeloid leukemia patients could be seen as a good example for further standardization of molecular monitoring in other gene rearrangements. In this review, we present the chronology of more than 20 years of scientific work that allowed to achieve this result. We believe that this paper will be useful for researchers who approach the chronic myeloid leukemia field. Abstract The introduction of tyrosine kinase inhibitors in 2001 as a targeted anticancer therapy has significantly improved the quality of life and survival of patients with chronic myeloid leukemia. At the same time, with the introduction of tyrosine kinase inhibitors, the need for precise monitoring of the molecular response to therapy has emerged. Starting with a qualitative polymerase chain reaction, followed by the introduction of a quantitative polymerase chain reaction to determine the exact quantity of the transcript of interest-p210 BCR-ABL1, molecular monitoring in patients with chronic myeloid leukemia was internationally standardized. This enabled precise monitoring of the therapeutic response, unification of therapeutic protocols, and comparison of results between different laboratories. This review aims to summarize the steps in the diagnosis and molecular monitoring of p210 BCR-ABL1, as well as to consider the possible future application of a more sophisticated method such as digital polymerase chain reaction.