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In vitro blood distribution and plasma protein binding of the iron chelator deferasirox (ICL670) and its iron complex Fe-[ICL670]2 for rat, marmoset, rabbit, mouse, dog, and human.

Deferasirox (Exjade, ICL670) is an orally active iron chelator. Two molecules of deferasirox can form a complex with ferric iron (Fe-[ICL670]2) that can be excreted, reducing body iron overload. The blood binding parameters across species and the interaction with human serum albumin were analyzed for deferasirox and its iron complex. Both molecules were very highly bound to plasma proteins in all the tested species with unbound fractions in plasma in the range of 0.4 to 1.8% and 0.2 to 1.2% for deferasirox and Fe-[ICL670]2, respectively; binding of the iron complex was either similar or higher in all the species. The high plasma protein binding was in line with a distribution mainly into the plasma fraction of blood; the fraction in plasma was around 100% for Fe-[ICL670]2 in all the species and 65 to 95% for deferasirox depending on the species. Investigations with isolated proteins pointed to serum albumin as the principal binding protein for deferasirox and its iron complex in human plasma. Competition binding experiments indicated that deferasirox at high concentrations displaced markers from the two main drug binding sites of human albumin, whereas Fe-[ICL670]2 displaced only warfarin. In the context of the pharmacokinetic properties of deferasirox and Fe-[ICL670]2, the data indicate the importance of plasma protein binding for their disposition and support a comparison of the pharmacokinetics of deferasirox and its iron complex across species. The low likelihood of clinically relevant drug displacement by deferasirox in plasma is discussed.

Animals↗

Deferasirox--an oral agent for chronic iron overload.

OBJECTIVE: To review the available literature on the pharmacology, pharmacokinetics, efficacy, toxicology, adverse effects, drug interactions, and dosage guidelines for deferasirox, an oral iron chelator, in Phase III trials. DATA SOURCES: Reviewers searched the following databases for English-language studies: MEDLINE (1966-April 2006), International Pharmaceutical Abstracts (1970-April 2006), and the Cochrane Library Database. Key search terms included iron chelation, chelation, iron overload, deferasirox, and ICL670. STUDY SELECTION AND DATA EXTRACTION: Data on efficacy, toxicology, adverse effects, and pharmacokinetics for deferasirox were obtained from randomized, open-label, blinded clinical trials. Other information was obtained from the manufacturer, including unpublished studies in abstract form as well as available data on deferasirox. DATA SYNTHESIS: Deferasirox is an orally active iron chelator. In clinical trials, deferasirox demonstrated efficacy at dosages of 20 and 30 mg/kg/day in treating iron overload in patients with beta-thalassemia. Deferasirox has been studied in patients older than 2 years and appears to be safe, with the most common adverse effects reported being mild, transient nausea, gastrointestinal disturbances, and rash. There were no reports of serious adverse effects in trials to date. CONCLUSIONS: Deferasirox represents a new approach to the management of chronic iron overload in patients with chronic anemias who require blood transfusions. The available literature suggests that deferasirox is safe and as effective as the current standard of therapy at dosages of 20-30 mg/kg/day for beta-thalassemia. Further studies are needed to confirm its efficacy in other chronic transfusion-requiring diseases.

Benzoates↗

Randomized phase II trial of deferasirox (Exjade, ICL670), a once-daily, orally-administered iron chelator, in comparison to deferoxamine in thalassemia patients with transfusional iron overload.

BACKGROUND AND OBJECTIVES: Iron accumulation is an inevitable consequence of chronic blood transfusions and results in serious complications in the absence of chelation treatment to remove excess iron. Deferoxamine (Desferal, DFO) reduces morbidity and mortality although the administration schedule of slow, parenteral infusions several days each week limits compliance and negatively affects long-term outcome. Deferasirox (Exjade, ICL670) is an oral chelator with high iron-binding potency and selectivity. In a phase II study, the tolerability and efficacy of deferasirox were compared with those of DFO in 71 adults with transfusional hemosiderosis. DESIGN AND METHODS: Patients were randomized to receive once-daily deferasirox (10 or 20 mg/kg; n=24 in both groups) or DFO (40 mg/kg, 5 days/week; n=23) for 48 weeks. Results. Both treatments were well tolerated and no patient discontinued deferasirox due to drug-related adverse events. The reported frequency of transient, mild to moderate gastrointestinal disturbances was higher in the deferasirox group than in the DFO group, but these disturbances settled spontaneously without dose interruption in all patients. Decreases in liver iron concentration (LIC) were comparable in the deferasirox 20 mg/kg/day and DFO groups; baseline values of 8.5 and 7.9 mg Fe/g dw fell to 6.6 and 5.9 mg Fe/g dw, respectively, by week 48. Deferasirox showed a plasma elimination half-life of 8-16 hours, supporting its once-daily administration. INTERPRETATION AND CONCLUSIONS: Deferasirox at daily doses of 10 or 20 mg/kg was well tolerated and, at 20 mg/kg, showed similar efficacy to DFO 40 mg/kg in terms of decreases in LIC.

Adolescent↗

Phase II clinical evaluation of deferasirox, a once-daily oral chelating agent, in pediatric patients with beta-thalassemia major.

BACKGROUND AND OBJECTIVES: Deferasirox (ICL670) is a novel once-daily oral iron chelator developed for the treatment of chronic iron overload from blood transfusions. This study evaluated the safety and tolerability of deferasirox in pediatric patients with transfusion-dependent beta-thalassemia major. Efficacy and pharmacokinetic assessments were secondary objectives. DESIGN AND METHODS: Forty patients equally stratified into two age groups--children (2 to <12 years) and adolescents (12-17 years)--were treated with deferasirox for 48 weeks. All received once-daily deferasirox 10 mg/kg/day with modifications allowed after 12 weeks' treatment. Safety, liver iron concentration (LIC), serum ferritin and pharmacokinetics were assessed. RESULTS: Thirty-nine patients completed the study. One withdrew due to a skin rash. Adverse events were typical of this population, but only four were considered related to the study drug: mild nausea (two adolescents) and moderate skin rash (two children). There were no serious adverse events related to the study drug. Five patients briefly interrupted treatment due to elevated transaminases with no recurrences when treatment resumed. The mean deferasirox dose was 11.3 mg/kg/day. Overall LIC increased gradually from week 12 as mean daily iron intake was higher than excretion. Steady-state plasma levels of deferasirox and its iron complex, Fe-[deferasirox]2, were comparable between children and adolescents. INTERPRETATION AND CONCLUSIONS: Deferasirox was well tolerated by this pediatric population. Toxicities known to be associated with other commercially available iron chelators were not observed. The dose employed was too low to induce a net negative iron balance in this regularly transfused population. Pharmacokinetic data support a once-daily dosing regimen based on body weight.

Administration, Oral↗

Deferasirox and deferiprone remove cardiac iron in the iron-overloaded gerbil.

INTRODUCTION: Deferasirox effectively controls liver iron concentration; however, little is known regarding its ability to remove stored cardiac iron. Deferiprone seems to have increased cardiac efficacy compared with traditional deferoxamine therapy. Therefore, the relative efficacy of deferasirox and deferiprone were compared in removing cardiac iron from iron-loaded gerbils. METHODS: Twenty-nine 8- to 10-week-old female gerbils underwent 10 weekly iron dextran injections of 200 mg/kg/week. Prechelation iron levels were assessed in 5 animals, and the remainder received deferasirox 100 mg/kg/D po QD (n = 8), deferiprone 375 mg/kg/D po divided TID (n = 8), or sham chelation (n = 8), 5 days/week for 12 weeks. RESULTS: Deferasirox reduced cardiac iron content 20.5%. No changes occurred in cardiac weight, myocyte hypertrophy, fibrosis, or weight-to-dry weight ratio. Deferasirox treatment reduced liver iron content 51%. Deferiprone produced comparable reductions in cardiac iron content (18.6% reduction). Deferiprone-treated hearts had greater mass (16.5% increase) and increased myocyte hypertrophy. Deferiprone decreased liver iron content 24.9% but was associated with an increase in liver weight and water content. CONCLUSION: Deferasirox and deferiprone were equally effective in removing stored cardiac iron in a gerbil animal model, but deferasirox removed more hepatic iron for a given cardiac iron burden.

Animals↗

A phase 3 study of deferasirox (ICL670), a once-daily oral iron chelator, in patients with beta-thalassemia.

Deferasirox (ICL670) is a once-daily oral iron chelator developed for the treatment of chronic iron overload from blood transfusions. A comparative phase 3 trial was conducted to demonstrate the efficacy of deferasirox in regularly transfused patients with beta-thalassemia aged 2 years or older. Patients were randomized and received treatment with deferasirox (n = 296) or deferoxamine (n = 290), with dosing of each according to baseline liver iron concentration (LIC). The primary endpoint was maintenance or reduction of LIC; secondary endpoints included safety and tolerability, change in serum ferritin level, and net body iron balance. In both arms, patients with LIC values of 7 mg Fe/g dry weight (dw) or higher had significant and similar dose-dependent reductions in LIC and serum ferritin, and effects on net body iron balance. However, the primary endpoint was not met in the overall population, possibly due to the fact that proportionally lower doses of deferasirox relative to deferoxamine were administered to patients with LIC values less than 7 mg Fe/g dw. The most common adverse events included rash, gastrointestinal disturbances, and mild nonprogressive increases in serum creatinine. No agranulocytosis, arthropathy, or growth failure was associated with deferasirox administration. Deferasirox is a promising once-daily oral therapy for the treatment of transfusional iron overload.

Administration, Oral↗

Deferasirox: An effective once-daily orally active iron chelator.

Deferasirox (ICL670) in an orally absorbed tridentate chelator of iron (III), intended as a once-daily monotherapy for transfusional iron overload. Deferasirox was identified by Novartis from over 700 molecular entities in preclinical screening, comparing favorably with parenteral desferrioxamine or oral deferiprone. Clinical phase I and II studies demonstrated an exclusively fecal route of iron excretion, with a long plasma half-life, suitable for once-daily dosing and 24-hour protection from labile iron. Systematic large-scale prospective clinical trials have been completed in thalassemia major, sickle cell disease, and other transfusionally dependent anemias, such as myelodysplastic syndrome. These show dose-dependent reduction in body iron and have identified doses necessary either to stabilize or to decrease iron loading according to transfusion requirements. Tolerability after more than two years in phase III studies is good, with a low trial dropout rate and no drug-related arthropathy or agranulocytosis. An early, nonprogressive serum creatinine increase, remaining within normal ranges, was seen in about one-third of patients. Preliminary clinical findings using T2* as well as preclinical models suggest good drug access to myocardial iron. Deferasirox is currently registered as monotherapy for transfusional iron overload in more than 65 countries worldwide, including the United States and in the European Union.

Administration, Oral↗

Oral chelators deferasirox and deferiprone for transfusional iron overload in thalassemia major: new data, new questions.

For nearly 30 years, patients with transfusional iron overload have depended on nightly deferoxamine infusions for iron chelation. Despite dramatic gains in life expectancy in the deferoxamine era for patients with transfusion-dependent anemias, the leading cause of death for young adults with thalassemia major and related disorders has been cardiac disease from myocardial iron deposition. Strategies to reduce cardiac disease by improving chelation regimens have been of the highest priority. These strategies have included development of novel oral iron chelators to improve compliance, improved assessment of cardiac iron status, and careful epidemiologic assessment of European outcomes with deferiprone, an oral alternative chelator available for about a decade. Each of these strategies is now bearing fruit. The novel oral chelator deferasirox was recently approved by the Food and Drug Administration (FDA); a randomized clinical trial demonstrates that deferasirox at 20 to 30 mg/kg/d can maintain or improve hepatic iron in thalassemia as well as deferoxamine. A randomized trial based on cardiac T2* magnetic resonance imaging (MRI) suggests that deferiprone can unload myocardial iron faster than deferoxamine. Retrospective epidemiologic data suggest dramatic reductions in cardiac events and mortality in Italian subjects exposed to deferiprone compared with deferoxamine. These developments herald a new era for iron chelation, but many unanswered questions remain.

Administration, Oral↗

The oral iron chelator ICL670A (deferasirox) does not protect myocytes against doxorubicin.

The oral iron chelating agent ICL670A (deferasirox) and the clinically approved cardioprotective agent dexrazoxane (ICRF-187) were compared for their ability to protect neonatal rat cardiac myocytes from doxorubicin-induced damage. Doxorubicin is thought to induce oxidative stress on the heart muscle through iron-mediated oxygen radical damage. While dexrazoxane was able to protect myocytes from doxorubicin-induced lactate dehydrogenase release, ICL670A, in contrast, depending upon the concentration, synergistically increased or did not affect the cytotoxicity of doxorubicin. This occurred in spite of the fact that ICL670A quickly and efficiently removed iron(III) from its complex with doxorubicin, and rapidly entered myocytes and displaced iron from a fluorescence-quenched trapped intracellular iron-calcein complex. Continuous exposure of ICL670A to either myocytes or Chinese hamster ovary (CHO) cells resulted in cytotoxicity while treatment of CHO cells with the ferric complex of ICL670A did not. These results suggest that ICL670A was cytotoxic either by removing or withholding iron from critical iron-containing proteins. Electron paramagnetic resonance spectroscopy was used to show that neither ICL670A nor its ferric complex were able to generate free radicals in either oxidizing or reducing systems suggesting that its cytotoxicity is not due to radical generation.

Administration, Oral↗

Deferasirox Novartis.

Novartis is developing a chelating agent, deferasirox, as a once-daily oral therapy for the potential treatment of chronic iron overload in patients needing blood transfusions. By December 2004, data from a phase III trial for iron overload had been released, and filing is expected in the US and EU in the first half of 2005.

Administration, Oral↗

Action of chelators in iron-loaded cardiac cells: Accessibility to intracellular labile iron and functional consequences.

Labile iron in hemosiderotic plasma and tissue are sources of iron toxicity. We compared the iron chelators deferoxamine, deferiprone, and deferasirox as scavengers of labile iron in plasma and cardiomyocytes at therapeutic concentrations. This comprised chelation of labile plasma iron (LPI) in samples from thalassemia patients; extraction of total cellular iron; accessing labile iron accumulated in organelles and preventing formation of reactive-oxidant species; and restoring impaired cardiac contractility. Neonatal rat cardiomyocytes were used for monitoring chelator extraction of LCI (labile cell iron) as 59Fe; assessing in situ cell iron chelation by epifluorescence microscope imaging using novel fluorescent sensors for iron and reactive oxygen species (ROS) selectively targeted to organelles, and monitoring contractility by time-lapse microscopy. At plasma concentrations attained therapeutically, all 3 chelators eliminated LPI but the orally active chelators rapidly gained access to the LCI pools of cardiomyocytes, bound labile iron, attenuated ROS formation, extracted accumulated iron, and restored contractility impaired by iron overload. The effect of deferoxamine at therapeutically relevant concentrations was primarily by elimination of LPI. The rapid accessibility of the oral chelators deferasirox and deferiprone to intracellular labile iron compartments renders them potentially efficacious for protection from and possibly reversal of cardiac damage induced by iron overload.

Animals↗