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Pre-fibrotic myelofibrosis (pre-PMF) and essential thrombocythemia (ET) are characterized by similarly increased rate of thrombotic events, but no study specifically analyzed risk factors for thrombosis in pre-PMF. In a multicenter cohort of 382 pre-PMF patients collected in this study, the rate of arterial and venous thrombosis after diagnosis was 1.0 and 0.95% patients/year. Factors significantly associated with arterial thrombosis were age, leukocytosis, generic cardiovascular risk factors, JAK2V617F and high molecular risk mutations, while only history of previous thrombosis, particularly prior venous thrombosis, was predictive of venous events. The risk of total thromboses was accurately predicted by the the international prognostic score for thrombosis in essential thrombocythemia (IPSET) score, originally developed for ET, and corresponded to 0.67, 2.05, and 2.95% patients/year in the low-, intermediate-, and high-risk categories. IPSET was superior to both the conventional 2-tiered score and the revised IPSET in this cohort of pre-PMF patients. We conclude that IPSET score can be conveniently used for thrombosis risk stratification in patients with pre-PMF and might represent the basis for individualized management aimed at reducing the increased risk of major cardiovascular events. Further refinement of the IPSET score in pre-PMF might be pursued by additional, prospective studies evaluating the inclusion of leukocytosis and/or adverse mutational profile as novel variables.

Essential thrombocythemia (ET) and polycythemia vera (PV) are myeloproliferative neoplasms (MPNs) characterized by an increased risk of developing venous and arterial thromboses and of evolution to myelofibrosis or acute leukemia (1). MPNs are recognized as a major cause of splanchnic vein thromboses (SVT), which include hepatic, splenic, portal and mesenteric vein thromboses (2). Patients with SVT are at an increased risk of developing bleeding events and arterial thrombotic events (3), as well as recurrent SVT and the use of anticoagulation and cytoreduction do not clearly modify this risk (3–5). Management of SVT in MPN patients remains a challenge and most therapeutic recommendations are based on retrospective analyses (6). Recently, De Stefano reported that hydroxyurea failed to prevent recurrent thromboses in the splanchnic vasculature in patients with a prior SVT (7). We conducted a prospective, open-label, multi-center phase II clinical trial of Pegylated Interferon Alfa-2a (PEG) in 20 subjects with SVT and an MPN, who represented a cohort of patients who participated in the Myeloproliferative Disorders - Research Consortium (MPD-RC) 111 trial (). MPD-RC 111 was a prospective study of patients with high-risk ET/PV who were resistant or intolerant to hydroxyurea (HU), but prior HU therapy was not a requirement for patients to enter the SVT cohort. Here we report the outcomes of the 20 SVT patients who were treated with PEG.

Among 382 patients with WHO-defined prefibrotic myelofibrosis (pre-PMF) followed for a median of 6.9 years, fibrotic or leukemic transformation or death accounts for 15, 7, and 27% of cases, respectively. A multistate model was applied to analyze survival data taking into account intermediate states that are part of the clinical course of pre-PMF, including overt PMF and acute myeloid leukemia (AML). Within this multistate framework, multivariable models disclosed older age (>65 years) and leukocytosis (>15 × 109/L) as predictors of death and leukemic transformation. The risk factors for fibrotic progression included anemia and grade 1 bone marrow fibrosis. The outcome was further affected by high molecular risk (HMR) but not driver mutations. Direct transition to overt PMF, AML, or death occurred in 15.2, 4.7, and 17.3% of patients, respectively. The risk of AML was the highest in the first 5 years (7%), but leveled off thereafter. Conversely, the probability of death from overt PMF or AML increased more rapidly over time, especially when compared to death in the pre-PMF state without disease progression. The probability of being alive with pre-PMF status decreased to 70 and 30% at 10 and 20 years, respectively. This study highlights the aspects of the clinical course and estimates of disease progression in pre-PMF.

Summary Background There is no evidence that phlebotomy alone is sufficient to steadily maintain haematocrit on target level in low-risk patients with polycythaemia vera. This study aimed to compare the efficacy and safety of ropeginterferon alfa-2b on top of the standard phlebotomy regimen with phlebotomy alone. Methods In 2017, we launched the Low-PV study, a multicentre, open-label, two-arm, parallel-group, investigator-initiated, phase 2 randomised trial with a group-sequential adaptive design. The study involved 21 haematological centres across Italy. Participants were recruited in a consecutive order. Participants enrolled in the study were patients, aged 18–60 years, with a diagnosis of polycythaemia vera according to 2008–16 WHO criteria. Eligible patients were randomly allocated (1:1) to receive either phlebotomy and low-dose aspirin (standard group) or ropeginterferon alfa-2b on top of the standard treatment (experimental group). Randomisation sequence was generated using five blocks of variable sizes proportional to elements of Pascal's triangle. Allocation was stratified by age and time from diagnosis. No masking was done. Patients randomly allocated to the standard group were treated with phlebotomy (300 mL for each phlebotomy to maintain the haematocrit values of lower than 45%) and low-dose aspirin (100 mg daily), if not contraindicated. Patients randomly allocated to the experimental group received ropeginterferon alfa-2b subcutaneously every 2 weeks in a fixed dose of 100 μg on top of the phlebotomy-only regimen. The primary endpoint was treatment response, defined as maintenance of the median haematocrit values of 45% or lower without progressive disease during a 12-month period. Analyses were done by intention-to-treat principle. The study was powered assuming a higher percentage of responders in the experimental group (75%) than in the standard group (50%). Here we report results from the second planned interim analysis when 50 patients had been recruited to each group. The trial is ongoing, and registered with ClinicalTrials.gov , NCT03003325 . Findings Between Feb 2, 2017, and March 13, 2020, 146 patients were screened, and 127 patients were randomly assigned to the standard group (n=63) or the experimental group (n=64). The median follow-up period was 12·1 months (IQR 12·0–12·6). For the second pre-planned interim analysis, a higher response rate in the experimental group was seen (42 [84%] of 50 patients) than in the standard group (30 [60%] of 50 patients; absolute difference 24%, 95% CI 7–41%, p=0·0075). The observed z value (2·6001) crossed the critical bound of efficacy (2·5262), and the stagewise adjusted p value early showed superiority of experimental treatment. Thus, the data safety monitoring board decided to stop patient accrual for overwhelming efficacy and to continue the follow-up, as per protocol, for 2 years. Under the safety profile, no statistically significant difference between groups in frequency of adverse events of grade 3 or higher was observed; the most frequently reported adverse events were neutropenia (four [8%] of 50 patients) in the experimental group and skin symptoms (two [4%] of 50 patients) in the standard group. No grade 4 or 5 adverse events occurred. Interpretation Supplementing phlebotomy with ropeginterferon alfa-2b seems to be safe and effective in steadily maintaining haematocrit values on target in low-risk patients with polycythaemia vera. Findings from the current study might have implications for changing the current management of low-risk patients with polycythaemia vera. Funding AOP Orphan Pharmaceuticals, Associazione Italiana per la Ricerca sul Cancro

A total of 410 patients with blast phase myeloproliferative neoplasm (MPN-BP) were retrospectively reviewed: 248 from the Mayo Clinic and 162 from Italy. Median survival was 3.6 months, with no improvement over the last 15 years. Multivariable analysis performed on the Mayo cohort identified high risk karyotype, platelet count 65 years and transfusion need as independent risk factors for survival. Also in the Mayo cohort, intensive chemotherapy resulted in complete remission (CR) or CR with incomplete count recovery (CRi) rates of 35 and 24%, respectively; treatment-specified 3-year/5-year survival rates were 32/10% for patients receiving allogeneic stem cell transplant (AlloSCT) (n = 24), 19/13% for patients achieving CR/CRi but were not transplanted (n = 24), and 1/1% in the absence of both AlloSCT and CR/CRi (n = 200) (p

BACKGROUND The rate of major arterial and venous thrombosis in primary myelofibrosis (PMF) and post-ET (PET) and post-PV (PPV) secondary myelofibrosis has been evaluated in a limited number of studies. In the present paper we describe the clinical epidemiology of thrombosis in a large series of patients with overt PMF and PPV/PET MF looking at the rate and risk factors. Moreover, we report findings on thrombosis rate in two cohorts of patients treated with Hydroxyurea (HU) or Ruxolitinib (Ruxo). METHODS Patients were registered in the European Registry for Myeloproliferative Neoplasms (ERNEST). This project, promoted by the European LeukemiaNet, is coordinated by FROM - Foundation for Research, Papa Giovanni XXIII Hospital, Bergamo (Italy) and supported by Novartis through a research collaboration . Patients were diagnosed in 6 Centers from Italy, Spain and Sweden, between Jan, 2001 and Dec, 2012, with the required follow-up information. Patients (n= 1010) with PMF (n=584, 59%), PET-MF (n=207, 20%) and PPV-MF (n=219, 21%) were evaluated for incident thrombosis as primary endpoint. Considering death as a competitive event, uni-and multivariate analyses were performed by applying Fine & Gray competing-risk regression models. RESULTS After a median follow-up of 3.8 years (IQR: 1.8-7.1) from diagnosis, 108 thromboses (10.7%) occurred, for an overall incidence rate of 2.0% pts-yr (95% CI: 1.7-2.5). Arterial thromboses were found in 50 patients (46.3%) including cerebral (n=21, 19.4%), myocardial infarction (n=13, 12.0%) and peripheral events (n=9, 8.3%). Venous thromboses were 58 (53.7%), of which 25 (23.0%) were DVT ± PE and 11 (10.2%) were splanchnic. Thrombosis rate was 1.91, 1.60 and 2.79% pts-yr in PMF, PET-MF and PPV-MF, respectively. In univariate analysis, factors significantly associated with an increased thrombotic risk in PMF were age (p=0.013) and the presence of the JAK2 mutation (p=0.003); in addition, a significant higher proportion of PMF patients at low and intermediate-1 vs intermediate-2 or high risk IPSS score, had thrombosis during the follow-up (p=0.008). In multivariate analysis, only JAK2 mutation retained statistical significance (SHR=3.12, 95% CI: 1.40-6.94, p=0.005). Conversely, neither in univariate nor in multivariable analysis, significant risk factors were not found.To investigate the possible interaction of IPSS score and JAK2 mutation we created a model whose results are presented in Fig. 1A: the cumulative incidence function (CIF) of thrombosis was significantly lower in patients with JAK2 wild-type and intermediate-2 or high IPSS score (CIF: 4% projected at 10 years; SHR=1 [reference category]), while patients at the highest risk for thrombosis harbored JAK2 mutation and were categorized at low or intermediate-1 by IPSS score (CIF: 20% projected at 10 years, SHR=7.13, p=0.008). Of note, thrombosis had a significant impact on mortality. After adjusting for sex, age, year of diagnosis, type of MF and IPPS, HR was 1.51, (95% CI. 1.15-1.98, p=0.003).The influence of drug exposure to incident thrombosis was investigated in two cohorts of 559 consecutive patients exposed to HU (n=470) or to Ruxo (n=89), median treatment 2.6 and 3.0 years, respectively. HU- compared to Ruxo-treated patients were older (median age 67 vs. 63 years, p=0.001), more frequently triple negatives (12% vs. 2%, p=0.036), less splenomegalic (spleen length >10 cm: 30% vs. 88%, p CONCLUSION IPSS score, in addition to the survival risk assessment, may be useful, if associated with the JAK2 mutation, to recognize patients at vascular risk and to suggest appropriate anti-thrombotic prophylaxis. The trend towards a benefit of Ruxo, compared to HU, warrants a study in larger case series. Figure 1 Figure 1. Disclosures Barbui: AOP Orphan: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding. Passamonti: 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, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; AbbVie: Speakers Bureau. Vannucchi: Incyte: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Lectures; Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Lectures; AbbVie: Membership on an entity's Board of Directors or advisory committees, Other: Lectures.

Myelofibrosis (MF) is the most aggressive form among Philadelphia negative (Ph-) myeloproliferative neoplasms (MPNs). In the last years, the mutational landscape of MF has expanded remarkably by the identification of additional recurrent mutations, called subclonal mutations. Areas covered: Here we describe the available data about the currently identified subclonal mutations and their prognostic value in MF patients. We also review the practical value of including such molecular information in available prognostic models for both outcome prediction and possibly treatment decision with regards to transplant indication. Lastly, we covered the available data on the application of molecular markers for minimal residual disease (MRD) monitoring after transplantation. Expert commentary: The demonstration of the prognostic value of additional mutations suggests to define this molecular profile at diagnosis and when an allogeneic transplant can be advised, particularly in younger patients. The presence of molecular markers might offer the possibility to evaluate the depth of remission and to monitor MRD after transplantation. Prospective clinical studies are needed to validate the use of this molecular data in the routine clinical practice.

T-cell depletion with alemtuzumab represents an effective form of graft-versus-host disease (GVHD) prophylaxis after allogeneic haematopoietic stem cell transplantation (allo-HSCT); however, little is known regarding the impact of in vivo alemtuzumab on either the incidence or clinical characteristics of acute and chronic GVHD. We therefore studied 201 consecutive adult patients who received an alemtuzumab-based, reduced-intensity conditioned (RIC) allograft. With a median follow-up of 24 months, the cumulative incidence of classic acute and late acute (persistent, recurrent and late onset) GVHD grades II-IV (grades III-IV) was 34% (13%) and 20% (8%) respectively; the cumulative incidence of classic chronic GVHD and overlap syndrome were 4% and 7% respectively. A previous diagnosis of classic acute GVHD is a risk factor for chronic GVHD (hazard ratio 10·91, 95% confidence interval 2·35-50·63, P = 0·0023) while late onset acute GVHD is not a risk factor for later development of chronic GVHD. Unrelated donor transplant is a risk factor for the development of classic acute GVHD but not for late onset or chronic GVHD. In conclusion, this study describes a distinctive pattern of GVHD following alemtuzumab-RIC allografts, identifies the risk factors for GVHD development and provides prognostic information of patients with GVHD.

We report a randomized study comparing fludarabine in combination with busulfan (FB) or thiotepa (FT), as conditioning regimen for hematopoietic stem cell transplantation (HSCT) in patients with myelofibrosis. The primary study endpoint was progression-free survival (PFS). Sixty patients were enrolled with a median age of 56 years and an intermediate-2 or high-risk score in 65%, according to the Dynamic International Prognostic Staging System (DIPSS). Donors were HLA-identical sibling (n = 25), matched unrelated (n = 25) or single allele mismatched unrelated (n = 10). With a median follow-up of 22 months (range, 1 to 68 months), outcomes at 2 years after HSCT in the FB arm versus the FT arm were as follows: PFS, 43% versus 55% (P = .28); overall survival (OS), 54% versus 70% (P = .17); relapse/progression, 36% versus 24% (P = .24); nonrelapse mortality (NRM), 21% in both arms (P = .99); and graft failure, 14% versus 10% (P = .96). A better PFS was observed in patients with intermediate-1 DIPSS score (P = .03). Both neutrophil engraftment and platelet engraftment were significantly influenced by previous splenectomy (hazard ratio [HR], 2.28; 95% confidence interval [CI], 1.16 to 4.51; P = .02) and splenomegaly at transplantation (HR, 0.51; 95% CI, 0.27 to 0.94; P = .03). In conclusion, the clinical outcome after HSCT was comparable when using either a busulfan or thiotepa based conditioning regimen.

Myeloproliferative neoplasms (MPNs) are clonal disorders that include polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF). Patients with MPNs have a higher risk than the general population of developing a lymphoid neoplasm.1 It is still unclear whether this holds true for nonhematological second primary malignancies (SPMs).2-4 However, among 20 250 MPN patients included in the Surveillance, Epidemiology, and End Results (SEER) Program database, the 10-year cumulative incidence of SPMs was 12.7%, significantly higher than that expected in the general US population.5 Ruxolitinib (RUX) is an oral JAK inhibitor (JAKi) approved for International Prognostic Scoring System (IPSS)/Dynamic IPSS (DIPSS) intermediate- and high-risk myelofibrosis (MF)6,7 and for inadequately controlled PV. More than 2600 RUX-treated MF patients have been prospectively observed for at least 2 years within the 2 pivotal COMFORT trials8,9 and the expanded-access JUMP trial.10,11 Safety data from these trials underline a possibly increased incidence of nonmelanoma skin cancers (NMSCs), but no significant increase of lymphoproliferative neoplasms, similarly to what occurs in PV.12,13 Recently, Porpaczy et al alerted, however, on the possible 16-fold increased risk of developing aggressive lymphomas in MPN patients treated with JAKis, especially in the presence of a preexisting B-cell clone.14 The publication included a total of 1555 MPN patients, 126 of whom were treated with a JAKi (ruxolitinib, gandotinib, fedratinib, momelotinib), obtained assembling 2 broad academic data sets. In the well-described Viennese cohort, 3 of 31 MF patients treated with JAKi developed lymphomas. Median time from JAKi initiation to lymphoma diagnosis was 25 months. Subsequent analyses of other large academic data sets did, however, not confirm an increased risk of aggressive lymphoma development under JAKis in MPNs15,16 and in post-PV and post-ET MF (secondary MF [SMF]).17 These contradictory results were derived either from clinical trials with strict eligibility criteria, possibly at the expense of uncertainty about the generalizability of results, or from highly selected data sets of patients evaluated at referral centers, thus highlighting the need for real-world data (RWD). We consequently set out to assess the occurrence of SPMs, including lymphoproliferative neoplasms, in RUX-treated MF patients on the basis of RWD provided by the health authority of the Lombardy Region, integrated with institutional data.

We analyzed 597 patients with myeloproliferative neoplasms (MPN) who presented transient ischemic attacks (TIA, n = 270) or ischemic stroke (IS, n = 327). Treatment included aspirin, oral anticoagulants, and cytoreductive drugs. The composite incidence of recurrent TIA and IS, acute myocardial infarction (AMI), and cardiovascular (CV) death was 4.21 and 19.2%, respectively at one and five years after the index event, an estimate unexpectedly lower than reported in the general population. Patients tended to replicate the first clinical manifestation (hazard ratio, HR: 2.41 and 4.41 for recurrent TIA and IS, respectively); additional factors for recurrent TIA were previous TIA (HR: 3.40) and microvascular disturbances (HR: 2.30); for recurrent IS arterial hypertension (HR: 4.24) and IS occurrence after MPN diagnosis (HR: 4.47). CV mortality was predicted by age over 60 years (HR: 3.98), an index IS (HR: 3.61), and the occurrence of index events after MPN diagnosis (HR: 2.62). Cytoreductive therapy was a strong protective factor (HR: 0.24). The rate of major bleeding was similar to the general population (0.90 per 100 patient-years). In conclusion, the long-term clinical outcome after TIA and IS in MPN appears even more favorable than in the general population, suggesting an advantageous benefit-risk profile of antithrombotic and cytoreductive treatment.

The use of Hydroxyurea (HU) as first line therapy in polycythemia vera (PV) has been criticized because no solid demonstration that this drug prevents thrombosis or prolongs survival has been so far produced. Here we present the outcomes of a large cohort of patients with PV included in the European Collaborative Low-dose Aspirin (ECLAP) study. We selected 1,042 patients who, during the follow-up, had received only phlebotomy (PHL) or HU to maintain the hematocrit level

To investigate the characteristics and clinical course of cerebral vein thrombosis (CVT) in patients with myeloproliferative neoplasms (MPN) we compared 48 patients with MPN and CVT (group MPN-CVT) to 87 with MPN and other venous thrombosis (group MPN-VT) and 178 with MPN and no thrombosis (group MPN-NoT) matched by sex, age at diagnosis of MPN (±5 years) and type of MPN. The study population was identified among 5,500 patients with MPN, from January 1982 to June 2013. Thrombophilia abnormalities were significantly more prevalent in the MPN-CVT and MPN-VT than in MPN-NoT group (P = 0.015), as well as the JAK2 V617F mutation in patients with essential thrombocythemia (P = 0.059). Compared to MPN-VT, MPN-CVT patients had a higher rate of recurrent thrombosis (42% vs. 25%, P = 0.049) despite a shorter median follow-up period (6.1 vs. 10.3 years, P = 0.019), a higher long-term antithrombotic (94% vs. 84%, P = 0.099) and a similar cytoreductive treatment (79% vs. 70%, P = 0.311). The incidence of recurrent thrombosis was double in MPN-CVT than in MPN-VT group (8.8% and 4.2% patient-years, P = 0.022), and CVT and unprovoked event were the only predictive variables in a multivariate model including also sex, blood count, thrombophilia, cytoreductive, and antithrombotic treatment (HR 1.97, 95%CI 1.05-3.72 and 2.09, 1.09-4.00, respectively).

Background: A myeloproliferative neoplasm (MPN) is frequent underlying cause of splanchnic vein thrombosis (SVT). We reported that ruxolitinib, a JAK1/2 inhibitor, was safe in patients (pts) with MPN-associated SVT and effective in reducing spleen size at the planned primary analysis at 24 weeks (w) in an investigator-initiated phase II clinical trial (Pieri L, AJH 2016). Herein we present final long term follow up (FU) data. Methods. A total of 21 MPN-SVT entered the trial in 2012. Pts who completed the 24w core study and well tolerated the drug and had evidence of clinically-significant improvement were allowed to enter an extension phase up to w72, then entered a long term FU. The drug was provided by Novartis, that had no role in trial design nor in data analysis. Safety data were reported as cumulative incidence of adverse events (CTCAE v4.03). Clinical responses were defined according to ELN and IWG-MRT criteria. Results. Patients disposition. Eighteen patients were alive at last follow-up at a median of 5.5y, range 3.7-6.5y. Two pts died before w72 (hepatocarcinoma; unknown cause), 1 pt died at w252 (sepsis). Diagnosis of the 18 pts was: PMF 8 (44%), PV 5 (28%), ET 4 (22%), PET-MF 1 (6%). The DIPSS risk score of the 8 pts with PMF was low in 4 and intermediate-1 in 4. At last FU, 14 patients are still on ruxolitinib (78%), 10 pts still on clinical trial, 4 pts shifted to commercial drug. Four pts (22%) withdrawn treatment after w72 because of inefficacy, withdrawal of consent, unknown reasons, shift to observation only (1 each). Safety. Thirteen pts (72.2%) had adverse events; the median number of events per patient was 5 (range, 0-37). Five pts had G2 thrombocytopenia plus 1 pt G3 (28%), 9 had G2 anemia (50%), 1 had G2 neutropenia (6%). There were 4 non-hematologic G3 adverse events (22%), one drug-related (CPK increase) that resolved with dose reduction. Six pts developed G1-2 infections (33%), 4 had Herpes Zoster reactivation (22%), 1 developed second cancer (pheochromocytoma at w96; 6%). Efficacy. Spleen response (defined as percentage reduction of spleen length from left costal margin (LCM) from baseline value as by IWG-MRT criteria) was available in 16 of 18 pts on treatment. Of 8 pts who obtained spleen response at w72, 4 pts had a complete response, while the remaining 4 pts had a spleen reduction >50%. At last FU, 6 of 8 pts (75%) adjudicated as spleen responders at w72 maintained the response. None of the 8 pts who had not obtained a spleen response at w72 acquired it at the last FU. According to ELN/IWG-MRT criteria of disease response, 7 pts had partial response, 11 had stable disease. At abdominal vessel eco scan, thrombosis improved in 3 of 12 evaluated pts (25%) and remained stable in the remaining 9. Of the 16 pts with endoscopic evaluation at last FU, complete resolution of oesophageal varices was documented in 3/12 with baseline varices (25%), worsening in 4 (33%), stable in 5 (42%), while no de-novo formation of F1 varices was documented in the remaining 4 (33%). No pt had gastrointestinal bleeding episodes. Exploratory endpoints. Included changes in the level of JAK2V617F variant allele burden (VAF) at last FU, available in 13 of 15 JAK2V617F mutated pts. VAF remained stable in 2 pts (13%), increased by 34% (range 25-40) in 3 pts, while 8 pts (62%) had a reduction >10% (range 18-96), of whom 6 (46%) had a reduction >50% (median 82%, range 70-96). By correlative analysis of JAK2 VAF changes and spleen response, 3 of 6 pts with VAF reduction of >50% had complete spleen response, as compared to none of the 3 pts who had an increase of VAF. Conclusions. After a median follow-up of 5.5 years, ruxolitinib continues to be safe in pts with MPN-associated SVT and maintains efficacy against splenomegaly in 33% of the pts. Of note, the large majority of pts (67%) showed stabilization or improvement of oesophageal varices, supporting the hypothesis that sustained reduction of enlarged spleen might contribute to decrease the upstream venous system pressure. Significant reduction of JAK2V617F VAF>50% was documented in 40% of the pts, although it was not clearly correlated with clinical improvement. Disclosures Rumi: novartis: Honoraria, Research Funding. Vannucchi:Novartis: 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; Incyte: Membership on an entity's Board of Directors or advisory committees; Italfarmaco: Membership on an entity's Board of Directors or advisory committees; CTI BioPharma: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. OffLabel Disclosure: Ruxolitinib use in essential thrombocythemia

We retrospectively studied 181 patients with polycythaemia vera (n=67), essential thrombocythaemia (n=67) or primary myelofibrosis (n=47), who presented a first episode of splanchnic vein thrombosis (SVT). Budd-Chiari syndrome (BCS) and portal vein thrombosis were diagnosed in 31 (17.1%) and 109 (60.3%) patients, respectively; isolated thrombosis of the mesenteric or splenic veins was detected in 18 and 23 cases, respectively. After this index event, the patients were followed for 735 patient years (pt-years) and experienced 31 recurrences corresponding to an incidence rate of 4.2 per 100 pt-years. Factors associated with a significantly higher risk of recurrence were BCS (hazard ratio (HR): 3.03), history of previous thrombosis (HR: 3.62), splenomegaly (HR: 2.66) and leukocytosis (HR: 2.8). Vitamin K-antagonists (VKA) were prescribed in 85% of patients and the recurrence rate was 3.9 per 100 pt-years, whereas in the small fraction (15%) not receiving VKA more recurrences (7.2 per 100 pt-years) were reported. Intracranial and extracranial major bleeding was recorded mainly in patients on VKA and the corresponding rate was 2.0 per 100 pt-years. In conclusion, despite anticoagulation treatment, the recurrence rate after SVT in myeloproliferative neoplasms is high and suggests the exploration of new avenues of secondary prophylaxis with new antithrombotic drugs and JAK-2 inhibitors. TB and AMV were supported by a grant from Associazione Italiana per la Ricerca sul Cancro (AIRC, Milano) ‘Special Program Molecular Clinical Oncology 5 × 1000’ to AGIMM (AIRC-Gruppo Italiano Malattie Mieloproliferative). VDS was supported by an unrestricted grant from the Bruno Farmaceutici Foundation.

Because the current therapy in polycythemia vera (PV) and essential thrombocythemia (ET) is aimed at lowering the risk of thrombosis, the risk classification system in these disorders is shaped according to thrombotic risk. Patients with either PV or ET can be stratified in a "high-risk" or "low-risk" category according to their age and previous history of thrombosis. Whether novel risk factors such as leukocytosis and JAK2 mutation may be included in the prognostic stratification requires confirmation in prospective future clinical studies. The identification and appropriate management of cardiovascular risk factors and the promotion of a healthy lifestyle in chronic myeloproliferative neoplasms (MPN), as in the general population, should be considered a cornerstone of vascular prevention. Blood hyperviscosity in PV is a major cause of vascular disturbances which severely impact on morbidity and mortality. An aggressive target of hematocrit lower than 45% in males and 42% in females has been advised by the European LeukemiaNet (ELN) group, although no convincing evidence of this recommendation is currently available. The efficacy and safety of low-dose aspirin (100mg daily) in PV has been assessed in the European Collaboration on Low-dose Aspirin in Polycythemia (ECLAP) double-blind, placebo-controlled, randomized clinical trial. Translating evidence from the positive results of ECLAP to ET may be questionable. The most commonly used front-line therapy drugs for the treatment of high-risk PV and ET patients include hydroxyurea and alpha-interferon at any age while anagrelide is recommended as second line-therapy in resistant and intolerant ET patients. Busulphan is a front-line therapy in the elderly. By definition, children with ET are a population with low vascular risk unless a major thrombotic or hemorrhagic event has occurred. ELN recommends to prescribe cytoreductive drugs in children as a last resort. No results of clinical trials with JAK-2 inhibitor drugs in PV and ET are so far available.

Background Treatment of patients developing steroid-refractory acute GvHD (SR-aGvHD) after allogeneic hematopoietic cell transplantation (HCT) remains an unmet clinical need and a major therapeutic challenge. Mesenchymal stromal cells (MSC) induce immunosuppression and reduce the inflammatory status initiated by aGvHD. We performed an interim analysis of a multicenter, prospective, non-randomized, phase I/II study, planned to test the safety and activity of human umbilical cord (UC), third-party MSC given sequentially after Pentatostatin for the treatment of SR-aGvHD grade III-IV as well as the overlap syndrome (EUDRACT n. 2012-000582-21), NCT02032446). Patients and Methods Third-party UC MSC were produced under GMP conditions as previously described (Capelli C et al Cytotherapy, 2011, 13, 786-801). The treatment schedule was based on the sequential administration of Pentostatin, given iv at dose of 1 mg/m^2 for 3 consecutive days, followed by 3 MSC infusions given at weekly intervals. Between October 2013 and May 2018 (range 4.6 years) we enrolled 27 allogeneic HCT adult recipients (22 male) with SR-aGvHD (n 25) or overlap syndrome (n 2), median age 47 years (range 19-62) transplanted from HLA-identical sibling donors (6; 22%), haploidentical donors (2; 7%), unrelated donors (18; 67%) or cord blood (1; 4%). Target organ involvement included skin in 11 cases (44%), gastrointestinal tract (GI) in 23 (92%) and liver in 12 (48%). Nine patients had grade III (33%), 16 patients grade IV (60%) and 2 patients had severe overlap syndrome (7%). Most of patients exhibited multiple organ involvement (n 16, 64%). Patients started MSC therapy at median of 22 days (10-2101) after the onset of aGvHD or overlap syndrome. Results The infusions of UC MSC-infusion were always well tolerated without any immediate or late toxic event. Response to MSC therapy, by day 30 after the final MSC dose, was evaluable in 16 of 27 patients: 7 achieved CR (26%), 6 PR (22%) and 3 NR (11%). Ten patients died before reaching the evaluation time of response: 8 patients for aGvHD and 2 for haematological disease. One patient was lost to follow up after 9 days from the last UC-MSC infusion. Remarkably, the subgroup of patients with single organ involvement (8 GI, 1 liver) were all evaluable showing 6 patients in overall response (67%, 4 RC and 2 PR). No response was observed in 2 cases of severe overlap syndrome. Patients achieving CR had improved longer term OS vs patients in PR/NR (80% vs 50% at 1 year). For patients with grade III and IV SR-aGvHD, CR rates at day 30 were 67% and 31% respectively. During tapering of steroid therapy 4 out of 7 patients that obtained CR had aGvHD recurrence, at median time of 87 days. We observed relapse of underlying malignancy in 5 patients and all died with active disease. At last follow-up 8 out of 27 patients were alive with no GVHD in 5 of them; 14 patients died from TRM: aGvHD or overlap syndrome itself (n=10), infections (n= 2), cGvHD (n= 2). Two patients with uncontrolled GvHD had clinical signs of Transplant Associated Microangiopathy (TAM). A total of 17 reported AE and 12 SAE were registered. In 23 out of 27 patients infectious complications were observed, in most cases virus related (n.25; CMV followed by BK virus and EBV), and fungal infections (3 aspergillus pneumoniae). Blood-stream documented infections (5) and pneumoniae (5) were also observed. Conclusions The infusion of cord blood derived MSC proved safe in all cases. As expected in patients with steroid refractory aGvHD, a high rate of infectious complications were observed. When considering that most patients (60 %) had grade IV aGvHD, the response rate and the OS are promising and this warrants not only the completion of this Phase I/II study but also planning a future pivotal trial. Disclosures No relevant conflicts of interest to declare.

The optimal duration of treatment with vitamin K antagonists (VKA) after venous thromboembolism (VTE) in patients with Philadelphia-negative myeloproliferative neoplasms (MPNs) is uncertain. To tackle this issue, we retrospectively studied 206 patients with MPN-related VTE (deep venous thrombosis of the legs and/or pulmonary embolism). After this index event, we recorded over 695 pt-years 45 recurrences, venous in 36 cases, with an incidence rate (IR) of 6.5 per 100 pt-years (95% confidence interval (CI): 4.9-8.6). One hundred fifty-five patients received VKA; the IR of recurrent thrombosis per 100 pt-years was 4.7 (95% CI: 2.8-7.3) on VKA and 8.9 (95% CI: 5.7-13.2) off VKA (P=0.03). In patients receiving VKA, the IR of recurrent thrombosis per 100 pt-years was 5.3 (95% CI: 3.2-8.4) among 108 patients on long-term VKA and 12.8 (95% CI: 7.3-20.7) after discontinuation among the 47 who ceased treatment (P=0.008), with a doubled risk of recurrence after stopping VKA (hazard ratio: 2.21, 95% CI: 1.19-5.30). The IR of major bleeding per 100 pt-years was 2.4 (95%: CI: 1.1-4.5) on VKA and 0.7 (95% CI: 0.08-2.5) off VKA (P=0.08). In conclusion, in MPN patients with VTE recurrent thrombosis is significantly reduced by VKA and caution should be adopted in discontinuation; however, the incidence of recurrence on treatment remains high, calling for clinical trials aimed to improve prophylaxis in this setting.

Contains fulltext : 137430.pdf (Publisher’s version ) (Open Access) The clinical course of polycythemia vera and essential thrombocythemia is potentially associated with long-term severe complications, such as evolution to myelofibrosis or acute myeloid leukemia. Allogeneic stem cell transplantation is currently the only potentially curative treatment for advanced polycythemia vera or essential thrombocythemia. We analyzed 250 consecutive patients with an initial diagnosis of polycythemia vera (n=120) or essential thrombocythemia (n=130), who underwent transplantation due to progression to myelofibrosis (n=193) or acute myeloid leukemia (n=57) and who were reported to the European Group for Blood and Marrow Transplantation registry between 1994 and 2010. Their median age was 56 years (range, 22-75) and in 52% of cases the interval between diagnosis and transplantation was 10 years or more. With a median follow-up from transplantation of 13 months, the 3-year overall survival rate and relapse incidence were 55% and 32%, respectively. In univariate analysis, the main parameters that negatively affected post-transplantation outcomes were older age (>55 years), a diagnosis at transplant of acute myeloid leukemia and the use of an unrelated donor. The overall 3-year cumulative incidence of non-relapse mortality was 28%, but was significantly higher in older patients than in younger ones (>55 years, 35% versus 20%, P=0.032), in those transplanted from an unrelated donor rather than a related donor (34% versus 18%, P=0.034) and in patients with a diagnosis of acute myeloid leukemia compared to myelofibrosis (29% versus 27%, P=0.045). This large retrospective study confirms that transplantation is potentially curative for patients with end-stage polycythemia vera/essential thrombocythemia progressing to myelofibrosis or acute myeloid leukemia. Relapse and non-relapse mortality remain unsolved problems for which innovative treatment approaches need to be assessed.

Givinostat, a histone-deacetylase inhibitor (HDACi), inhibits proliferation of cells bearing the JAK2 V617F mutation and has shown significant activity with good tolerability in patients with chronic myeloproliferative neoplasms (MPN). In this multicentre, open-label, phase II study, 44 patients with polycythaemia vera (PV), unresponsive to the maximum tolerated doses (MTD) of hydroxycarbamide (HC), were treated with Givinostat (50 or 100 mg/d) in combination with MTD of HC. The European LeukaemiaNet response criteria were used to assess the primary endpoint after 12 weeks of treatment. Complete or partial response was observed in 55% and 50% of patients receiving 50 or 100 mg of Givinostat, respectively. Control of pruritus was observed in 64% and 67% of patients in the 50 and 100 mg groups, respectively. The combination of Givinostat and HC was well tolerated: eight patients (18%) discontinued, four in each treatment arm; grade 3 adverse events were reported in one patient (4·5%) in each treatment arm. The combined use of Givinostat and HC was safe and clinically effective in HC-unresponsive PV patients.

Introduction: Patients with disease relapse after allogeneic transplantation (alloHSCT) have a poor prognosis. Donor lymphocyte infusion (DLI) is one of the main clinical options to salvage patients in relapse after transplant. Cytokine Induced Killer (CIK) cells are in vitro activated and expanded T lymphocytes which have acquired NK like cytotoxicity as well as CD56 expression. CIK cells have shown Graft versus Leukemia (GvL) activity with little GvHD and therefore may represent an ideal candidate to treat post-transplant relapse. We report the final results of a phase II multicenter pilot study, whose objective was to evaluate the safety and efficacy of sequential administration of donor derived unmanipulated DLI and CIK cells in patients with recurrent hematologic cancers after alloHSCT. Methods Seventy-four patients relapsed after alloHSCT, performed using either a matched related (N=42) or unrelated donor (n= 32), were enrolled in the study. This phase II multicenter study was authorized by Istituto Superiore di Sanità, as for Advanced Therapeutic Medicinal Product (ATMP) regulations, and approved by the Agenzia Italiana del Farmaco (AIFA). The trial was registered as (EUDRACT number 2008-003185-26, ClinicalTrial.gov : NCT01186809). Results Among the 74 patients (including 16 children and 58 adults) enrolled into this study (median age 45, range 1-67), 20 had a diagnosis of ALL (27%), 41 of AML (55%), 4 of MM (5%), 3 of HD (4%), 2 of NHL (3%) and 4 of MPN (5%). All patients relapsed after matched allogeneic transplants (32 unrelated and 42 sibling), of whom 44 (59%) suffered from a hematological, 4 (5%) from a cytogenetic and 26 (35%) from a molecular relapse. The therapeutic strategy consisted of two infusions of unmanipulated DLI (each of 1 x 106/kg cells) at 3 weeks interval, followed by three infusions of donor derived CIK cells given at 3 weeks interval. The first 12 patients were treated with increasing numbers of CIK cells, in groups of three patients per dose level. Since dose limiting toxicity (DLT) was never observed (acute GVHD of grade III or more), the highest dose planned (5 x 106/kg, 5 x 106/kg and 10 x 106/kg) was then administered to all patients. Ten patients died for disease progression, 1 patient developed aGVHD (grade I, skin only) and 1 withdrawn for medical decision before or during the DLI treatment and could not proceed to the planned subsequent CIK administration. Sixty-two patients received at least one infusion of CIK cells, of whom 43 patients (61%) completed the cell therapy program, while 3 patients are still under treatment. The study flow is outlined in Figure 1. As per protocol, clinical response was determined 100 days after the last CIK administration and the study was analyzed on an intent to treat basis. An early death occurred in 24 (32%) patients (4 during the DLI), no response was observed in 18 (24%) patients, a stable disease in 1 patient (1%), a complete remission in 21 (28%) and a partial remission in 6 (8%), for an overall response rate of 36%. In 4 patients clinical response could not be evaluated (3 patients still in treatment and 1 withdrawn from the protocol). Acute GVHD was observed in a total of 11 patients (15%): grade 1 (n=4), 2 (n=2) and 3-4 (n=5). During follow up, chronic GVHD was observed in 8 patients (11 %) (3 mild, 4 moderate and 1 severe). By univariate analysis, progression free survival (PFS) and overall survival (OS) were significantly associated (p Conclusion Our study shows that administration of CIK cells is feasible in patients with recurrent hematologic cancer after alloHSCT with a relatively low toxicity in terms of GvHD. Particularly in the setting of the molecularly relapsed patients, long-term survival can be achieved. In future studies, we are planning to test CIK cells in preventing post-transplantation relapse in high risk AML. Finally, CIK cells may represent an innovative platform to transduce chimeric antigen receptors in allogeneic T cells with a reduced risk to induce GvHD. Disclosures Biondi: Cellgene: Other: Advisory Board; BMS: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board.

CALR mutation, MPL mutation and triple negativity identify patients with the lowest vascular risk in primary myelofibrosis

A phase II A study was conducted to evaluate the safety and efficacy of Givinostat, a novel Histone-Deacetylases inhibitor, in patients with Polycythaemia Vera (PV, n = 12), Essential Thrombocythaemia (ET, n = 1) and Myelofibrosis (n = 16), bearing the JAK2V617F mutation. The study was approved by the local ethics committees and all human participants gave written informed consent. Givinostat was given orally for 24 weeks at a starting dose of 50 mg twice daily. The median treatment duration was 20 weeks. Reasons for treatment discontinuation were disease progression (n = 6), grade 2 thrombocytopenia (n = 1), psychiatric symptoms (n = 1) and withdrawn consent (n = 2). A dose reduction was applied in 10 patients while a temporary interruption occurred in 15. Among 13 PV/ET patients, 1 complete, 6 partial and 4 no responses were documented at study end while 2 patients went off-study, prematurely. Three major responses were registered among 16 MF patients. Pruritus disappeared in most patients and reduction of splenomegaly was observed in 75% of PV/ET and 38% of MF patients. Reverse transcription polymerase chain reaction identified a trend to reduction of the JAK2V617F allele burden. Givinostat was well tolerated and could induce haematological response in most PV and some MF patients.

Introduction Graft-versus-Host Disease (GvHD) is one of the leading causes of mortality and morbidity following allogeneic stem cell transplant. In vivo T cell depletion by alemtuzumab as part of the transplant conditioning is an effective strategy to reduce the risk of GvHD. While it is recognised that the overall incidence of GvHD is reduced by alemtuzumab, the incidence of chronic GvHD as defined by the National Institute of Health (NIH) consensus criteria, the impact on outcome, and the pattern of organ involvement have not been defined yet in this transplant setting. Methods Consecutive patients (n = 323) undergoing allogeneic stem cell transplantation at the Queen Elizabeth Hospital, Birmingham, between January 1 2008 and June 30 2012 were reviewed in this retrospective, single centre study. Medical records were examined and data regarding the development of GvHD were collected; NIH consensus criteria for diagnosis and staging of chronic GvHD were stringently applied. Clinical characteristics of GvHD occurring in patients transplanted following T cell depletion by alemtuzumab administration (n=248) were compared with those of patients transplanted with a T cell replete graft (n=75). Patients receiving alemtuzumab were mainly treated with reduced-intensity conditioning protocols, while patients in the no-T-cell depletion group were mainly treated with a myeloablative, sibling transplant. Results After a median follow up of 38.4 months, the cumulative incidence (CI) of grade II-IV classic acute GvHD was 35% and 48% for patients transplanted respectively with or without T cell depletion by alemtuzumab (p= 0.041, Figure 1); with a CI of grade III-IV classic acute GvHD of 13% and 27% (p=0.007). The 2-years CI of grade II-IV late acute GvHD was not significantly different in the two groups (20% and 23% for patients respectively treated with or without alemtuzumab, p=0.589, Figure 2). T cell depletion by alemtuzumab significantly reduces the 3 years cumulative incidence of classic chronic GvHD (5% versus 31%, p Conclusion This retrospective analysis provides for the first time data on the incidence rates of NIH-defined GvHD categories in patients transplanted after T cell depletion by alemtuzumab. Patients transplanted with alemtuzumab experienced a lower incidence of classic acute and classic chronic GvHD compared to patients not receiving T cell depletion. In contrast, alemtuzumab conditioning appeared to have no effect on the incidence of late acute GvHD or overlap syndrome, suggesting that these two entities of GvHD are driven by different immunological mechanisms as compared to classic acute and classic chronic GvHD. We also confirmed the utility of the NIH classification of GvHD and of the NIH global severity score to predict survival in alemtuzumab-conditioned allogeneic stem cell transplant. Disclosures No relevant conflicts of interest to declare.

Background Patients with Philadelphia-negative myeloproliferative neoplasms (MPN) can develop venous thrombosis and MPN are the leading cause of splanchnic vein thrombosis. Cerebral vein thrombosis (CVT) is a rare life-threatening disease that in approximately 3% of cases encounters MPN among risk factors and tends to recur in 2-4% of patients as CVT and in 4-7% as venous thrombosis at other sites. Little or no information is available on patients with MPN who develop CVT. Objective and design To investigate the characteristics and clinical course of CVT in patients with MPN we carried out a multicenter (n=11), observational, retrospective cohort study. Patients Centers were asked to provide information on index patients with MPN who developed CVT (group MPN-CVT). For each of them, 2 patients with MPN and venous thrombosis other than CVT (group MPN-VT) and 4 patients with MPN and no venous thrombosis (group MPN-NoVT) were provided, matched by sex, age at diagnosis of MPN (+/-5 years) and type of MPN (polycytemia vera, essential thrombocytemia, myelofibrosis) with index patients. Results From January 1982 to June 2013, 48 MPN-CVT, 87 MPN-VT and 178 MPN-NoVT patients were identified in a population of 5,500 patients with MPN. Diagnosis of MPN and thrombosis coincided in 46% of MPN-CVT and 29% of MPN-VT patients (p=0.046). Compared to MPN-NoVT, MPN-CVT and MPN-VT patients had a higher prevalence of thrombophilia abnormalities (40% and 35% vs 21%, p=0.015) and, among those with essential thrombocytemia, of the JAK2 V617F mutation (76% and 78% vs 55%, p=0.059). Compared to MPN-VT, MPN-CVT patients had a higher rate of recurrent thrombosis (42% vs 25%, p=0.049) that in two-third of patients in both groups was venous, with a similar site distribution. This difference occurred despite a shorter median follow-up period (6.1 vs 10.3 years, p=0.019), a higher proportion of patients on long-term antithrombotic treatment (94% vs 84%, p=0.099) and a similar proportion of patients on cytoreductive treatment (75% vs 72%, p=0.745) among MPN-CVT than MPN-VT patients. The incidence of recurrent thrombosis was 8.8% patients/year in MPN-CVT and 4.2% patients/year in MPN-VT patients (log-rank test, p=0.022) and CVT was the only variable in a multivariate model including blood counts, thrombophilia, cytoreductive and antithrombotic treatment, that was predictive of recurrent thrombosis (HR 1.86, 95%CI 1.00-3.58). Conclusions Patients with MPN develop recurrent thrombosis in a much higher proportion than those without, particularly if they had a CVT. Patients with MPN and CVT have an approximately 2-fold increased probability to develop recurrent thrombosis than those with MPN and venous thrombosis at other sites, independently of other risk factors. Disclosures: No relevant conflicts of interest to declare.

Abstract 314 Background: Akt/mTOR activation has been found in association with dysregulated JAK2/STAT5 signaling due to JAK2V617F mutation. Increased phosphorylation of STAT5 and Akt was detected in patients (pts) with myeloproliferative neoplasms (MPN) (Grimwade LF, BJH 2009). We reported (Bogani C, ASH 2009) that RAD001, an oral inhibitor of mTOR, inhibited the proliferation of human and murine JAK2V617F-mutated cells and impaired colony formation by MPN progenitor cells, suggesting potential clinical activity. Methods: We will report final data from an investigator-initiated, multicenter phase I/II trial with RAD001 in myelofibrosis, primary (PMF) and post-polycythemia vera/essential thrombocythemia (PPV/PET MF). Inclusion criteria were intermediate/high risk score (Lille criteria) or need of treatment because of progressing splenomegaly. Phase I involved a 3+3 pts scheme in 3 sequential cohorts at 5.0, 7.5, and 10 mg daily for 3 mo to establish maximum tolerated dose (MTD). Phase II was a two-stage Simon design involving 16+14 pts at MTD for 4 mo. The protocol was approved by IRBs and pts provided informed consent. The study was supported by Agenzia Italiana per il Farmaco (AIFA) and AIRC-Gruppo Italiano Malattie Mieloproliferative (AGIMM). Results: Phase I: there was no DLT at 10 mg daily, considered as MTD; there were 2 major (MR), 3 moderate (MO) and 1 minor (MI) and 3 no (NR) responses. In part 1 of Phase II, >1/16 pts achieved MR; according to study design, 14 additional pts were enrolled in part 2 (n=30). 20 patients had low and 10 intermediate Lille score; according to IWG-MRT criteria, 5, 10, 8 and 7 were low, int-I, int-II and high risk score, respectively. There were 16 PMF, 8 PPV- and 6 PET-MF. 20 pts were JAK2V617Fpos, 3 were MPLW515pos. Patients evaluable for intention-to-treat (ITT) analysis as of aug 1st were 26; the remaining 4 pts will be updated at meeting. Therapy was discontinued in 5 pts: 1 pt's decision at d60 without evidence of any >grade-2 toxicity, 2 at d60 and d90 for physician's decision due to grade-2 toxicity, 1 death due to respiratory failure at d60, 1 at d30 for grade-3 acute renal failure. 21/26 pts (81%) were available for per-protocol analysis. Therapy was generally well tolerated; commonest toxicities were grade-2 mouth ulcers and grade-1/2 hypertrigliceridemia. Hematological toxicities: 3 grade-2 and 4 grade-3 reversible anemia, one grade-2 neuthropenia, one grade-2 and 1 grade-3 reversible thrombocytopenia. A reduction of spleen size consistent with CR, PR or NR was obtained in 8%, 46%, and 46% of the pts, respectively. 11 of 21 pts (52%) had complete resolution of systemic symptoms, and 14 of 19 pts (74%) reported disappearance of pruritus. Two pts achieved PR in anemia with decrease in transfusion requirement >50%, while in 3 pts Hb increased of 2g/dL. A CR in platelets was obtained in 3 of 19 pts and CR in leucocytes in 2 of 18 pts with abnormal blood count. Overall, according to ITT analysis: 6 major (23%), 6 moderate (23%), 2 minor (8%) and 12 NR (46%) (EUMNET criteria). According to IWG-MRT criteria, there were 6 (23%) clinical improvement. Per-protocol analysis: 33% major, 19% moderate, 5% minor, 43% NR; 24% clinical improvement. No disease progression. Changes induced by RAD001 in some biological parameters were preliminary evaluated and will be finally updated at meeting. Blood levels of CCDN1 mRNA, a target of mTOR, significantly decreased in responders (MR+MO) versus non-responders (P=0.02). In the 13 JAK2-mutated pts who completed the treatment, the V617F allele burden was 61.6+/−15.8 versus 66.6+/−19.6% at baseline. There was a trend (P=0.07) towards a reduction of granulocyte WT1mRNA copy number in responders versus non-responders. We found no correlation of circulating CD34+ cells or CXCR4 expression with clinical response. A set of 46 inflammatory protein markers and cytokines were quantified before and at d30 of treatment. Some, including IL-10 and MIP-1beta, showed significant decrease while others increased, including Factor VII, IL-8 and MMP-2. Levels of MIP-1 beta were significantly lower in responders (P=0.006). Conclusions: These data indicate that mTOR pathway targeting with RAD001 in MF pts induces an appreciable rate of response in splenomegaly, constitutional symptoms, and pruritus, with low-grade toxicity. However, effects on JAK2V617F mutational load were minimal, and should be better evaluated after longer trial duration. Disclosures: Vannucchi: Novartis: Membership on an entity's Board of Directors or advisory committees. Off Label Use: This is an investigator-initiated, non-sponsored, clinical trial with RAD001 in myelofibrosis. Paratore:Novartis: Employment.