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Mitochondrial DNA (mtDNA) is a highly potent inflammatory trigger and is reportedly found outside the cells in blood in various pathologies. Platelets are abundant in blood where they promote hemostasis. Although lacking a nucleus, platelets contain functional mitochondria. On activation, platelets produce extracellular vesicles known as microparticles. We hypothesized that activated platelets could also release their mitochondria. We show that activated platelets release respiratory-competent mitochondria, both within membrane-encapsulated microparticles and as free organelles. Extracellular mitochondria are found in platelet concentrates used for transfusion and are present at higher levels in those that induced acute reactions (febrile nonhemolytic reactions, skin manifestations, and cardiovascular events) in transfused patients. We establish that the mitochondrion is an endogenous substrate of secreted phospholipase A2 IIA (sPLA2-IIA), a phospholipase otherwise specific for bacteria, likely reflecting the ancestral proteobacteria origin of mitochondria. The hydrolysis of the mitochondrial membrane by sPLA2-IIA yields inflammatory mediators (ie, lysophospholipids, fatty acids, and mtDNA) that promote leukocyte activation. Two-photon microscopy in live transfused animals revealed that extracellular mitochondria interact with neutrophils in vivo, triggering neutrophil adhesion to the endothelial wall. Our findings identify extracellular mitochondria, produced by platelets, at the midpoint of a potent mechanism leading to inflammatory responses.

Erdheim–Chester disease (ECD) pathophysiology remains largely unknown. Its treatment is not codified and usually disappointing. Interferon (IFN)-α therapy lacks efficacy for some life-threatening manifestations and has a poor tolerance profile. Because interleukin (IL)-1Ra synthesis is naturally induced after stimulation by IFN-α, we hypothesized that recombinant IL-1Ra (anakinra) might have some efficacy in ECD. We treated 2 patients who had poor tolerance or contraindication to IFN-α with anakinra as a rescue therapy and measured their serum C-reactive protein, IL-1β, IL-6, and monocytic membranous IL-1α (mIL-1α) levels before, under, and after therapy. Another untreated ECD patient and 5 healthy subjects were enrolled as controls. After treatment, fever and bone pains rapidly disappeared in both patients, as well as eyelid involvement in one patient. In addition, retroperitoneal fibrosis completely or partially regressed, and C-reactive protein, IL-6, and mIL-1α levels decreased to within the normal and control range. Beside injection-site reactions, no adverse event was reported. Therefore, our results support a central role of the IL-1 network, which seemed to be overstimulated in ECD. Its specific blockade using anakinra thereby opens new pathophysiology and therapeutic perspectives in ECD.

Background Patients with myocardial iron overload require effective cardiac iron removal to minimize the risk of cardiac complications. The 3 year EPIC cardiac sub-study showed that the oral iron chelator, deferasirox (DFX), effectively reduced cardiac iron overload. Previous reports demonstrate that cardiac iron removal is slow and suggest that liver iron concentration (LIC) may affect cardiac iron removal rate by chelators (Pennell et al., 2012; Blood). The objective of these analyses was to evaluate the impact of the severity of the liver iron overload on the change in myocardial T2* (mT2*) for patients receiving up to 3 years of DFX treatment in the EPIC sub-study. Methods Inclusion and exclusion criteria have been described previously (Pennell et al., 2012; Haematologica). Patients were categorized into LIC ≤15 and >15 mg Fe/g dry weight (hereafter mg/g) at baseline (BL) and by LIC 15 mg/g at 12, 24, and 36 months to assess the impact of BL LIC and changes in LIC overtime on mT2*, respectively. During study, LIC and mT2* were measured every 6 months. Efficacy was assessed in per-protocol population that entered third year extension. Here, mT2* is presented as the geometric mean (Gmean) ± coefficient of variation (CV) unless otherwise specified. Statistical significance was established at α-level of 0.05 using a 2-sided paired t-test for within group comparisons and ANOVA for multiple group comparisons. All p-values were of exploratory nature for this post-hoc analysis. Results Of the 71 patients, who continued into study year 3, 68 patients considered evaluable were included in this analysis (per protocol population); 59 patients had LIC values available at end of study (EOS). Mean age was 20.5 ±7.35 years and 61.8 % of patients were female. Mean actual dose of DFX (mg/kg/day) was 32.1 ±5.5 and 35.1 ±4.9 in patients with BL LIC ≤15 and >15 mg/g, respectively. At EOS, mean actual doses were 32.9 ±5.4 (LIC 15 mg/g). Overall, patients had high BL LIC (Mean, 29.0 ±10.0 mg/g); 61 patients had LIC >15 (30.8 ±8.8) mg/g, only 7 patients had LIC ≤15 (12.7 ±1.1) mg/g, and no patients had LIC 15 mg/g, respectively. Notably, 51.9% of patients with BL LIC >15 mg/g achieved EOS LIC Overall, mean mT2* was 12.8 ±4.6 ms. The impact of BL LIC on mT2* and LIC response was as follows: in patients with LIC ≤15 mg/g (Mean BL mT2*, 14.2 ±3.6 ms) and >15 mg/g (BL mT2*, 12.7 ±4.7 ms), mT2* increased by 52% (Mean abs. change, 7.5 ±4.1 ms, p=0.0016) and 46% (7.3 ±7.3 ms, p15 mg/g, (20.1 ±10.6 ms) displaying a lag of nearly 12 months. The relation between post-BL LIC on mT2* response at 12, 24 and 36 months is shown in the figure. At 12 months, there was no significant difference in mT2* that had occurred in patients with LIC 15 mg/g (13% increase; 1.9 ±3.2 ms). However, at 24 months, there was a statistically significant difference amongst the 3 subgroups in percent increase in the mT2* that had occurred; patients with LIC 15 mg/g had 54% (Mean abs. change, 8.3 ±7.3 ms), 33% (5.2 ±5.2 ms) and 10% (2.1 ±4.3 ms) increase (p 15mg/g group. At all-time points, in patients who achieved an LIC Discussion Overall, DFX treatment resulted in a significant decrease in LIC and improved mT2*. A greater difference in mT2* improvement was shown to have occurred in patients who achieved lower end-of-year LIC after treated with DFX. This divergence was progressive with time, being maximal at 36 months. Thus, a therapeutic response in LIC with DFX is associated with a greater likelihood of improving mT2*. This may assist in monitoring liver and cardiac response to DFX. Prospective evaluation of this relationship is indicated. Disclosures: Porter: Novartis Pharma: Consultancy, Honoraria, Research Funding; Shire: Consultancy, Honoraria; Celgene: Consultancy. Taher:Novartis Pharma: Honoraria, Research Funding. Aydinok:Novartis Oncology: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau; Shire: Membership on an entity’s Board of Directors or advisory committees, Research Funding. Cappellini:Novartis Pharma: Honoraria, Speakers Bureau; Genzyme: Honoraria, Membership on an entity’s Board of Directors or advisory committees. Kattamis:Novartis: Research Funding, Speakers Bureau; ApoPharma: Speakers Bureau. El-Ali:Novartis Pharma: Employment. Martin:Novartis Pharma: Employment. Pennell:Novartis: Consultancy, Honoraria, Research Funding; ApoPharma: Consultancy, Honoraria, Research Funding; Shire: Consultancy, Honoraria.

Abstract 5182 Background: The 1-yr open-label, single-arm, multicenter EPIC (Evaluation of Patients' Iron Chelation with Exjade®) trial assessed the efficacy and safety of deferasirox in patients with transfusion-dependent iron overload, including patients with thalassemia and with myelodysplastic syndromes (MDS). The most frequent adverse events (AEs) in the EPIC trial were gastrointestinal (GI) disturbances. Here, we qualitatively examine concomitant medication (con med) use in thalassemia and MDS patients with/without GI events to consider the impact of con med use on GI events. Methods: Thalassemia and MDS patients from the EPIC study were included. A GI event was defined as an investigator-reported AE with the system organ class ‘GI disorders’ after start of treatment. Data are reported here for the most frequently received con meds of interest, by preferred term, which also had notable differences in their frequency among patients with/without GI events; con meds that may have been prescribed to treat GI events are excluded from interpretation: propulsives, antipropulsives, proton pump inhibitors, laxatives and electrolyte solutions. Results: Among thalassemia patients (n=1115; 48. 3% male; aged 18. 2 yrs [range 2–72]), 345 (30. 9%) patients experienced a GI event. Mean deferasirox dose was 23. 8 ± 5. 4 mg/kg/d in patients with a GI event and 24. 3 ± 5. 5 mg/kg/d in patients with no GI event; median serum ferritin (SF) at end of study (EOS) was 2734 ng/mL (391–23997) and 3223 ng/mL (259–17644), respectively. 28. 9% of thalassemia patients did not receive any con meds; 15. 7% received ≥7 different types of con meds. Thalassemia patients with a GI event received a mean of 6. 0 different types of con meds, vs 2. 1 in patients without a GI event. Con meds were received in 91. 9% of patients with a GI event vs 61. 8% of patients without a GI event. Anti-inflammatory, antibiotic or antifungal con meds were more frequent in thalassemia patients who experienced a GI event (Figure A). The con med with the largest relative difference in frequency among patients with vs without a GI event was paracetamol/codeine phosphate (7. 2 vs 0. 5%, respectively). Among MDS patients (n=341; 59. 8% male; aged 67. 9 yrs [11–89]), 248 (72. 7%) patients experienced a GI event. Deferasirox dose was 18. 8 ± 4. 9 mg/kg/d in patients with a GI event and 20. 4 ± 6. 4 mg/kg/d in patients with no GI event; SF at EOS was 1977 ng/mL (254–9835) and 2045 ng/mL (141–10155), respectively. 12. 3% of MDS patients did not receive any con meds; 37. 8% received ≥7 different types. Patients with a GI event received a mean of 9. 6 different types of con meds vs 4. 5 in patients without a GI event. Con meds were received in 89. 5% of patients with a GI event, vs 82. 8% of patients without a GI event. In patients with MDS, antibiotic, antifungal or opioid medications were more frequent in patients with GI events (Figure B). The con med with the largest relative difference in frequency among patients with vs without a GI event was tramadol hydrochloride (7. 7 vs 1. 1%, respectively). Most frequent con med in both populations was paracetamol (acetaminophen; Figure). In patients receiving paracetamol who had a GI event, the most frequent types of GI events in thalassemia patients were diarrhea, abdominal pain and nausea; in MDS patients these were diarrhea, constipation and abdominal pain. In patients receiving paracetamol, mean alanine aminotransferase level at EOS in thalassemia patients with a GI event was 49. 0 vs 46. 3 U/L in patients with no GI event; and 38. 9 vs 27. 2 U/L in MDS patients, respectively. Discussion: In both thalassemia and MDS patients, concomitant use of antifungal and antibiotic medications was more frequent in patients with GI events, although it should be considered that GI events are also the most frequent AEs of, for eg, amoxicillin/potassium clavulanate and ciprofloxacin. Paracetamol use was higher in patients who had GI events; types of GI events were typical of those observed during deferasirox treatment and did not appear related to liver toxicity. Anti-inflammatory medications were more frequent in thalassemia patients with GI events, as were opioid medications in MDS patients. Con meds may affect the frequency of GI AEs reported with deferasirox. Further investigation is needed to determine whether these observations result from a potential interaction of the metabolic pathways of con meds and deferasirox – eg, CYP450 metabolism of paracetamol – or the action of the con meds alone. Disclosures: Cappellini: Novartis: Speakers Bureau. Porter:Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Kattamis:Novartis: Honoraria, Research Funding, Speakers Bureau. Louw:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. El-Ali:Novartis: Employment. Martin:Novartis: Employment. Gattermann:Novartis: Honoraria, Research Funding, Speakers Bureau.

Abstract 2125 Background: Young children typically receive more blood transfusions per kg body weight compared with adults, increasing the risk of iron overload. Iron overload may lead to endocrine abnormalities that can affect growth and development. Data from clinical trials of the iron chelator deferasirox (Exjade®) have demonstrated tolerability and efficacy in transfused patients with a range of underlying anemias. The registration clinical trials included 52 patients aged 2– Methods: Patients aged 2– Results: As of October 31, 2011, 247 patients (mean age 3.1 years; 1.2% 4–≤6 years) with β-thalassemia (n=160, 64.8%), sickle cell disease (n=48, 19.4%), Diamond–Blackfan anemia (DBA; n=11, 4.5%) and other anemias (n=28, 11.3%) were enrolled and received ≥1 deferasirox dose. Patients received deferasirox for a mean ± SD of 30.0 ± 15.2 months. Mean dose was 25.4 ± 6.9 mg/kg/day; 169/243 (69.5%) of these patients had no dose adjustments for a period of ≥1 year, despite a mean percentage weight change of +16.6 ± 12.0% (range −8.9 to 59.1%) during that time. 63/243 (25.9%) had no dose adjustments for a period of ≥2 years and percentage weight increased by +22.5 ± 16.1% (range −1.2 to 72.4%) during that time. At baseline (n=214), median serum ferritin was 1757 ng/mL (range 334–9577), decreasing to 1489 ng/mL (range 156–5102) in patients reaching the 30-month evaluation point (n=57). Mean iron intake was high and remained stable throughout (∼0.6 mg/kg/day). 5/247 patients (2.0%) had SCr increases >age-adjusted ULN and >33% increase from baseline on two consecutive measurements (baseline range 20–39 μmol/L); none of these five patients discontinued. Increased ALT >5 × ULN was confirmed in 11/247 patients (4.5%); most abnormalities were transient, five of these patients discontinued (increased ALT [n=3], protocol deviation [n=1] and vomiting [n=1]). The most common (≥4 patients) investigator-reported drug-related AEs were investigations and GI disorders; these are shown in the Table as investigator-reported preferred terms. The majority of investigations were mild-to-moderate in severity. Overall, 178/247 patients (72.1%) are continuing the study. Main reasons for discontinuation were protocol deviation (n=12, 4.9%) and AEs (n=7, 2.8%: increased ALT; proteinuria; hepatic AE [increased ALT/AST for second time after drug administration]; abdominal pain/vomiting/hypokalemia/transaminase elevation; vomiting; reversible increase of ALT of 239 U/L reported as hepatic cytolysis; transaminase elevation/lack of efficacy; all n=1). One patient with DBA died (severe pancytopenia and sepsis following bone marrow transplantation). Conclusions: The safety profile of deferasirox in very young pediatric patients was consistent with the available evidence in adult patients, including the rate of creatinine and liver enzyme changes which did not appear to be progressive. Many patients did not have appropriate dose adjustments during the study, despite substantial increases in weight. In addition to safety and efficacy parameters, weight change in pediatric patients should be considered during dose adjustments to optimize efficacy and safety. Disclosures: Vichinsky: Novartis: Consultancy, Research Funding; ApoPharma: Consultancy, Research Funding; ARUP Research lab: Research Funding. Bernaudin:Novartis: Research Funding. El-Ali:Novartis: Employment. Arrowsmith:Novartis: Employment. Martin:Novartis: Employment.

Abstract 1028 Background: To prevent complications associated with iron overload in patients with transfusion-dependent anemias, iron chelation therapy is required throughout life starting from early childhood. Long-term studies of iron chelation therapy are therefore required, particularly in pediatric patients. The 1-year open-label, single-arm, multicenter EPIC (Evaluation of Patients' Iron Chelation with Exjade®) trial evaluating the efficacy and safety of deferasirox in patients with transfusion-dependent iron overload enrolled 577 pediatric patients across 23 countries. In an extension period of up to 18 months, or until deferasirox was available locally, patients completing the core study could continue to receive deferasirox, thus providing long-term efficacy and safety data of deferasirox in iron-overloaded pediatric patients. Methods: At enrolment, transfusion-dependent pediatric patients (defined as ≥2–20 transfusions or >100 mL/kg red blood cells transfused) and liver iron concentration >2 mg Fe/g dw confirmed by R2 magnetic resonance imaging. Deferasirox starting dose was 10–30 mg/kg/day depending on frequency of blood transfusions, with protocol-specified adjustments of 5–10 mg/kg/day (range 0–40 mg/kg/day) based on 3-monthly serum ferritin trends and safety. Biochemistry analysis including serum ferritin was performed on a monthly basis, and growth was monitored every 12 weeks, with continuous assessment of safety parameters. Creatinine clearance was calculated using the Schwarz formula for pediatric patients. Changes from the start of deferasirox treatment (core baseline) are presented. Results: 267 pediatric patients aged 2– Overall, 257/267 (96.3%) patients completed the extension; main reasons (more than two patients) for discontinuation were unsatisfactory therapeutic effect (n=4, 1.5%) and consent withdrawal (n=3; 1.1%). The most common (>5%) investigator-assessed drug-related AEs were increased alanine aminotransferase (ALT; n=47, 17.6%), increased aspartate aminotransferase (AST; n=44, 16.5%), increased blood creatinine (n=24, 9.0%) and rash (n=23, 8.6%). ALT and AST increases were mostly mild in severity, transient, non-progressive and managed with dose adjustments. There were no reported drug-related serious AEs and no deaths occurred. 45/267 (16.9%) patients had two consecutive ALT values >5 × upper limit of normal (ULN). Of these 45 patients, 40 had high ALT levels at baseline and 30 had ALT or AST >2.5 × ULN at baseline; 13/45 had a history of hepatitis B and/or C. 6/267 (2.2%) patients had two consecutive serum creatinine values >33% above baseline and >ULN; all had normal values at baseline. The relative change in creatinine clearance from baseline to end of the extension was between –10 and –20% for the majority of patients (n=52, 19.5%), although changes in both directions were variable. Stature, growth and weight assessments indicated positive growth velocity. For all patients combined, mean ± SD growth velocity at end of extension was 5.9 ± 43.3 cm/year (median 2.6 cm/year). Conclusions: Deferasirox therapy for up to 3 years in pediatric patients significantly decreased serum ferritin, similar to previous reports. The majority of patients with elevated liver enzymes during the study also had elevated levels at baseline; renal safety was consistent with previous reports. While patient age and gender will influence individual growth rates, positive growth velocity was nonetheless maintained during treatment. Disclosures: Lin: Novartis: Honoraria. Aydinok:Novartis: Honoraria, Research Funding, Speakers Bureau; Ferrokin: Research Funding. Galanello:Novartis: Research Funding, Speakers Bureau; Apopharma: Research Funding, Speakers Bureau; Ferrokin: Research Funding. El-Ali:Novartis: Employment. Martin:Novartis: Employment. Cappellini:Novartis: Speakers Bureau.

Abstract 2126 Background: In patients with transfusion-dependent anemias, monitoring the efficacy of iron chelation therapy (ICT) using serum ferritin (SF) alone can sometimes be challenging; therefore, additional serum markers would be helpful. Furthermore, any differences between different anemias for the relationship between SF and other serum markers both before and in response to ICT may be useful to predict relative risk of iron-mediated toxicity between these conditions. Data from the 1-yr EPIC (Evaluation of Patients' Iron Chelation with Exjade®) trial allows assessment of iron parameters in a large cohort of patients with thalassemia, myelodysplastic syndromes (MDS) and sickle cell disease (SCD). Here we evaluate trends in liver iron concentration (LIC), transferrin saturation (TfSat) and labile plasma iron (LPI) in their relation to SF levels and assess systematic differences between underlying anemias. Relationships were assessed at baseline (BL), reflecting iron accumulation at study entry, and also at end of study (EOS), with changes reflecting iron excretion after 1 yr treatment with deferasirox. Methods: LIC, TfSat and LPI were measured at BL and at EOS for each underlying disease. Changes in these parameters as well as relationships between these parameters and SF were assessed by SF categories at BL and at EOS. For EOS measurements, last observation carried forward was used for all parameters (last post-BL available value), except for LPI, for which 1-yr visit was used. Pre-deferasirox dose LPI levels are reported. Results: Data from 1114 thalassemia patients, 336 MDS patients and 80 SCD patients were available for analysis. For all underlying anemias, LIC was higher at higher SF categories; in thalassemia patients for eg, with BL SF categories 5000 ng/mL, the mean LIC values at BL were 4.9, 9.0, 15.3, 22.1, 27.2, 32.5 mg Fe/g dw, respectively. Overall, mean TfSat was 89.6% (n=755) in thalassemia patients at BL and 96.1% (n=955) at EOS, compared with 82.5% (n=116) and 83.8% (n=171) in MDS patients, respectively. In SCD patients, TfSat was 61.3% (n=71) at BL and 64.1% (n=74) at EOS. TfSat was lowest in SCD patients across the full range of SF categories examined (Figure). At BL, TfSat was higher at higher SF categories in all diseases, with a similar trend at EOS, although at EOS this trend was more evident in MDS and SCD (Figure). Overall, mean LPI levels at BL and EOS were 1.25 μmol/L (n=472) and 0.59 μmol/L (n=818) in thalassemia patients, 0.53 μmol/L (n=221) and 0.14 μmol/L (n=147) in MDS patients, and 0.11 μmol/L (n=55) and 0.10 μmol/L (n=46) in SCD patients, respectively. LPI levels were highest in patients with thalassemia and lowest in SCD patients across SF categories (Figure). After 1 yr treatment with deferasirox, LPI levels were reduced in thalassemia and MDS patients, but there was no difference in patients with SCD. LPI was higher at higher SF categories in MDS patients at both BL and EOS, with a similar trend in SCD patients at EOS, although there was little relationship in thalassemia patients (Figure). Discussion: At matched SF levels and across a wide range of SF values, TfSat was lower in SCD patients, in comparison to thalassemia and MDS patients, both at BL and EOS. Similar observations have been reported previously and may contribute to the lower propensity for extra-hepatic iron accumulation in SCD patients. The mechanisms for this difference remain unclear, but could be attributed to sequestering of iron due to chronic inflammation in SCD. TfSat did not appear to decrease after 1 yr treatment with deferasirox, in any underlying anemia. The relationship of LPI to SF categories differed between underlying anemias; both at BL and EOS. At BL, SCD patients had low LPI values across the full range of measured SF values, whereas higher LPI levels at higher SF categories were most evident in MDS patients. Overall, LPI was highest in thalassemia patients. After 1 yr treatment with deferasirox, LPI was decreased in thalassemia and to a lesser extent in MDS patients, but there was no change from the low level at BL in SCD patients. The decrease in LPI in MDS and thalassemia at EOS may reflect the effects of residual plasma chelator 1 day after the previous dose and/or the decrease in storage iron over 1 yr of treatment. With further evaluation, LPI could become a useful marker of iron overload and chelation response in patients with MDS and possibly thalassemia. Disclosures: Porter: Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Viprakasit:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. El-Ali:Novartis: Employment. Martin:Novartis: Employment. Cappellini:Novartis: Speakers Bureau.

Abstract 1344 Background: Although reports are emerging of hematologic responses associated with iron chelation therapy in patients with myelodysplastic syndromes (MDS, eg, Gattermann et al. Blood 2010;116(21):abst 2912), there are limited studies in aplastic anemia (AA) patients. The EPIC study enrolled 116 transfusion-dependent AA patients with iron overload (Cappellini et al. Haematologica 2010; Lee et al. Blood 2010); deferasirox treatment resulted in a decrease in iron overload assessed by serum ferritin. As iron overload has a suppressive effect on erythroid progenitors (Hartmann et al. Blood 2008;112(11):abst 2694), it is of interest to evaluate hematologic responses with the iron chelator deferasirox in AA patients from the EPIC trial. Methods: Full study design and inclusion/exclusion criteria for EPIC have been described (Cappellini et al. Haematologica 2010). Deferasirox dose was initiated at 20 mg/kg/day with adjustments of 5–10 mg/kg/day up to 40 mg/kg/day based on serum ferritin trends and safety assessments. For this post-hoc analysis of hematologic response and the classification of patients, UK treatment guideline criteria for AA diagnosis (2 or 3 of the following: hemoglobin [Hb] 1.5 × 109/L and platelet count >150 × 109/L. For patients with “non-severe” AA, hematologic response was defined as: no response=worse or not meeting criteria for partial or complete response; partial response=transfusion independence (if previously dependent), or doubling or normalization of at least one cell line, or increased Hb >3 g/dL if initially 0.5 × 109/L if initially 20 × 109/L if initially Results: Of 116 iron-overloaded AA patients, 72 (62%) had evaluable hematologic parameters (according to UK criteria) at baseline and EOS; 9 (12.5%) and 63 (87.5%) were considered severe AA and non-severe AA, respectively. Thirty-five (48.6%) patients had a partial hematologic response; 33/63 [52.4%] with non-severe AA and 2/9 [22.2%] with severe AA. Forty-eight (67%) patients received at least one concomitant immunosuppressive treatment (IST); partial hematologic response was observed in 19/48 (39.6%) of these patients. As IST can influence hematologic response, analyses were focused on patients receiving deferasirox without IST. Twenty-four patients received deferasirox without concomitant IST; partial hematologic response was observed in 16/24 [66.7%] patients, all of whom became transfusion-independent, with 2 patients having an additional platelet response and 1 patient having an additional platelet and Hb response (Table). Median time to response was 42 days. For patients without concomitant IST, overall median change in serum ferritin from baseline to EOS was greater in partial hematologic responders (–2295 ng/mL, range –15,704 to 489 [n=16]) compared with non-responders (–815 ng/mL, range –8506 to 3671 [n=8]; P=0.22). Conclusions: Similar to MDS patients, alongside a reduction in iron overload, deferasirox may improve hematologic parameters in AA patients. Sixty-seven percent (16/24) of patients receiving deferasirox without concomitant IST had a partial hematologic response and became transfusion-independent. Changes in serum ferritin were more pronounced in partial hematologic responders compared with non-responders, suggesting that decrease in iron load could play a role in inducing a hematologic response. Further analyses are required to elucidate mechanisms of hematologic improvement with deferasirox. Disclosures: Lee: Novartis: Honoraria; Alexion: Honoraria. Yoon:NK Bio: Consultancy; Celgene: Consultancy. Ganser:Novartis: Honoraria, Research Funding. El-Ali:Novartis: Employment. Habr:Novartis: Employment. Roubert:Novartis: Employment. Porter, MD on behalf of the EPIC study investigators:Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.

Abstract 1753 Background: Ruxolitinib (INC424), a potent and selective oral JAK1 and JAK2 inhibitor, has demonstrated rapid and durable reductions in splenomegaly and improved disease-related symptoms, role functioning, and quality of life (QoL) in 2 phase 3 studies in patients with myelofibrosis (MF) (the COMFORT studies). These studies compared ruxolitinib with either placebo or best available therapy (BAT). This analysis compares the efficacy outcomes between the placebo arm from COMFORT-I and the BAT arm from COMFORT-II. Methods: COMFORT-I is a randomized (1:1), double-blind, multicenter study comparing ruxolitinib 15 or 20 mg twice daily (bid) with placebo, and COMFORT-II is a randomized (2:1), open-label, multicenter study comparing ruxolitinib 15 or 20 mg bid with BAT (investigator-selected therapy, including no treatment). Both studies met their primary end points with statistical significance (ruxolitinib vs control): the percentage of patients achieving ≥35% reduction in spleen volume at week 24 (COMFORT-I, P Results: In the COMFORT-I and COMFORT-II studies, 154 patients received placebo (ruxolitinib, n=155) and 73 patients received BAT (ruxolitinib, n=146), respectively, and were included in the primary efficacy analyses. The demographic and baseline characteristics were similar between the control arms of the 2 studies, including spleen size below the costal margin (mean [standard deviation, SD] 16.4 [6.27] cm and 15.8 [6.71] cm in placebo and BAT, respectively). Only 1 patient (0.7%) who received placebo and no patients who received BAT had a ≥35% reduction in spleen volume from baseline at week 24. The median spleen volume increased from baseline at week 24 in both the placebo and BAT groups and was numerically similar (placebo, 8.5% [range, −46.4% to 48.8%]; BAT, 5.1% [range, −33.3% to 29.7%]). In contrast, patients who received ruxolitinib had median reductions in spleen volume from baseline at week 24 of −33.0% (COMFORT-I) and −27.5% (COMFORT-II). The QLQ-C30 provides a measurement of change in QoL and MF-related symptoms, including fatigue, pain, dyspnea, insomnia, and appetite loss. At 24 weeks, neither the placebo nor BAT arms had clinically meaningful changes from baseline (10 points [Osoba et al. J Clin Oncol. 1998]) in any of the QoL (decreases indicate worsening) or symptom scores (increases indicate worsening) (Table). Although differences existed between the placebo and BAT arms, the SDs are large, thus complicating comparisons between the 2 groups. Conclusions: In the COMFORT studies, ruxolitinib demonstrated significantly greater reductions in spleen size compared with placebo or BAT. This post hoc analysis of the 2 studies shows that patients who received BAT in the COMFORT-II study had similar symptom and QoL responses and numerically similar increases in spleen size as those who received placebo in the COMFORT-I study. No clinically meaningful improvements in QoL or symptoms were seen on either the placebo or BAT arms. These new data strongly suggest that current therapies for MF provide little improvement in spleen size, symptoms, or QoL as compared with placebo. Disclosures: Mesa: Incyte: Research Funding; Lilly: Research Funding; SBio: Research Funding; Astra Zeneca: Research Funding; NS Pharma: Research Funding; Celgene: Research Funding. Verstovsek:Incyte Corporation: Research Funding. Cervantes:Bristol-Myers-Squibb: Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Waltzman:Novartis: Employment. Mendelson:Novartis: Employment, Equity Ownership. Martin:Novartis Pharma AG: Employment. Sun:Incyte: Employment. Sandor:Incyte: Employment. Levy:Incyte Corporation: Employment, Equity Ownership. Harrison:Novartis: Honoraria; Incyte: Honoraria; S*Bio: Honoraria; Celgene: Honoraria; Sanofi Aventis: Honoraria.

Abstract 5170 Background: There are currently no approved, effective drug therapies for myelofibrosis (MF). Ruxolitinib (INC424), a potent and selective oral JAK1 and JAK2 inhibitor, has recently demonstrated rapid and durable reductions in splenomegaly and improved disease-related symptoms, role functioning, and quality of life in 2 phase 3 studies in patients with MF. Both studies met their primary endpoint of the proportion of patients with ≥35% reduction in spleen volume at 24 weeks (COMFORT-I) and at 48 weeks (COMFORT-II): 41.9% vs 0.7% (ruxolitinib vs placebo, P Methods: Patients with PMF, PPV-MF or PET-MF who are determined by their physicians to be in need of treatment are considered for eligibility, irrespective of JAK2 mutation status. As in the COMFORT studies, the starting dose of ruxolitinib is determined on the basis of baseline platelet count and can be adjusted for efficacy and safety. Dose changes during treatment are registered, and AEs and serious AEs (SAEs) are monitored throughout the study. Results: To date, 231 patients have been screened at more than 150 study sites in 28 countries, including Canada, Australia, and locations in Europe, Latin America, the Middle East, and Asia. The baseline characteristics for patients whose requests for access were approved/enrolled (n=200) and denied/pending (n=31) are shown below (Table). The patient characteristics are generally similar to those expected in the overall MF patient population. To date, the proportion of patients with the JAK2V617F mutation enrolled in this ISP (68.5%) is higher than that for the general MF population (50–60%) and may reflect the tendency of physicians to include more JAK2V617F-positive patients in the ISP, even though ruxolitinib has demonstrated comparable efficacy in both patient types (Verstovsek S, et al. N Engl J Med. 2010;363(12):1117–1127). Thrombocytopenia and herpes zoster were each reported as an AE in 1 patient, and no SAEs have been reported. Conclusions: Ruxolitinib is currently the only drug to have completed phase 3 studies for the treatment of MF and has garnered a substantial number of requests for access through the individual supply program. Disclosures: Barosi: Novartis: Consultancy. Cervantes:Bristol-Myers-Squibb: Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Panagiotidis:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Research Funding; Janssen: Research Funding; GSK: Honoraria. Perez:Novartis: Employment. Orlando-Harper:Novartis: Employment. Martin:Novartis Pharma AG: Employment. Willenbacher:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Roche: Honoraria, Research Funding; Sandoz: Membership on an entity's Board of Directors or advisory committees; Mundipharma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AESCA: Honoraria, Research Funding. Ojeda:Novartis: Consultancy. Gisslinger:Novartis: Speakers Bureau; Celgene Austria: Research Funding, Speakers Bureau; Aop-Orphan: Speakers Bureau. Knoops:Novartis: Consultancy.

Abstract 1214 The use of tyrosine kinase inhibitors (TKI) has dramatically changed the prognosis and the natural history of CML. However the occurrence of drug resistances, especially at the stem cell level, requires the identification of novel functional targets. The signal transducer and activator of transcription 5 (Stat5), constitutively phosphorylated by BCR-ABL, is thought to be involved in the pathophysiology of CML, especially by its contribution to the antiapoptotic phenotype observed in CML cells via activation of Bcl-xL. There is currently no data linking clearly the involvement of Stat5 activation to TKI resistance in CML. Moreover, it has not been established, if the two closely related Stat5 factors, Stat5A and Stat5B, fulfill the same or distinct roles in leukemic cells. In order to study these potentially differential functions, we have specifically inhibited Stat5A and Stat5B through lentivirus-mediated RNA interference in human Ph+ CML cell lines K562, LAMA84 and Meg01 and their Imatinib mesylate (IM)-resistant counterparts. We have also transduced with the same lentiviral vectors, primary human CML CD34+ cells and evaluated the effects of Stat5A or B invalidation in terms of hematopoietic stem cell self-renewal in long-term culture initiating cell (LTC-IC) assays. In preliminary experiments, the successful inhibition of Stat5A or B was demonstrated using Western blotting with specific inhibition of each factor with the corresponding shRNA. In CML cell lines, Stat5B inhibition led to a massive apoptosis with growth arrest in all three cell lines whereas Stat5A inhibition had no effect. Surprisingly, Stat5B was active in the absence of canonical tyrosine phosphorylation and its absence strongly enhanced the apoptosis-inducing effects of TKI (Imatinib and Nilotinib). We then evaluated the role of Stat5A or B in the context of CML cell lines resistant to IM, in which there was no detectable ABL-kinase domain mutations neither MDR amplification. In this context, the Stat5A and B protein levels were identical but there was a strong over-activation of Stat5, as detected by Tyr694/699 phosphorylation status. In the two resistant sublines LAMA84-R and Meg01-R, anti-Stat5A and anti Stat5B selective immunoprecipitation assays further revealed that only Stat5A, and not Stat5B, was Tyr-phosphorylated. Therefore, in two independent IM-resistant sublines, LAMA84-R and Meg01-R, resistance correlated with over-activation of Stat5A, in the absence of canonical activation of Stat5B. We next investigated the role of Stat5A or B in primary CML stem cell self-renewal, using CD34+ cells from CML patients in chronic phase (CP-CML) at diagnosis. CD34+ cells were transduced with control (luciferase)-, Stat5A- or Stat5B-shRNA encoding lentiviral vectors and Long Term Colony Initiating Cell (LTC-IC) assays were performed. In four out of five patient samples, Stat5B-shRNA induced a massive inhibition of the LTC-IC activity. Stat5A-shRNA, on the reverse, had highly variable impact depending on the patients, either enhancing or somehow decreasing LTC-IC activity. We also performed similar assays with CD34+ progenitor cells collected from healthy donors. Except for one sample, Stat5B knock down had rather weak consequences on LTC-IC activity. Finally, to extend the potential roles of Stat5A and B in Imatinib resistance, we have transduced CD34+ cells of an IM-resistant CML patient whose cells had also been shown to be resistant to IM in vitro. GFP+ Stat5A-shRNA transduced cells were cell-sorted by FACS and their IM-resistance was tested in clonogenic assays. As compared to the control Luciferase shRNA vector, Stat5A inactivation reduced the colony numbers by 75%, with development of small sized colonies. Thus, these data strongly suggest that Stat5b plays a major role in the survival of CML cells, especially in the primitive hematopoietic cells, extending the results obtained in CML cell lines. Our data further show for the first time that this effect takes place in the absence of Tyrosine phosphorylation of Stat5B. Conversely, CML cells express tyrosine-phosphorylated Stat5A, whose levels strongly increased in TKI-resistant cells and its inhibition by an shRNA strategy leads to the reversal of TKI resistance of phenotype. Thus, Stat5A and Stat5B exhibit entirely distinct - not interchangeable- oncogenic activities in CML pathophysiology and represent novel therapeutic targets. Disclosures: No relevant conflicts of interest to declare.