An evaluation of deferiprone as twice-a-day tablets or in combination therapy for the treatment of transfusional iron overload in thalassemia syndromes

INTRODUCTION

Regular blood transfusions in patients with thalassemia syndromes can cause iron overload resulting in complications including cirrhosis, heart problems, or endocrine abnormalities. To prevent iron overload toxicity in these patients, three iron chelators are currently FDA-approved for use: deferoxamine, deferasirox, and deferiprone. In the United States, deferiprone has been approved for three times daily dosing since 2011 and has recently gained approval for twice-daily administration.

AREAS COVERED

A PubMed literature search was performed with the keywords 'deferiprone' and 'thalassemia.' Relevant original research studying deferiprone's effects on transfusional iron overload in patients with thalassemia syndromes was included. Exclusion criteria included case reports and review papers. Deferiprone is effective at reducing serum ferritin levels in patients with iron overload. Twice-daily administration provides a similar level of iron chelation as three times daily dosing with a comparable side effect profile and increased patient acceptability.

EXPERT OPINION

New studies are highlighting deferiprone's potential for combination therapy with either deferoxamine or deferasirox to improve iron chelation. Deferiprone's ability to significantly decrease cardiac and liver iron content can be utilized in other transfusion-dependent hematologic conditions, as evidenced by its recent approval for use in the United States for sickle cell disease or other anemias.

Single-center retrospective study of the effectiveness and toxicity of the oral iron chelating drugs deferiprone and deferasirox

BACKGROUND

Iron overload, resulting from blood transfusions in patients with chronic anemias, has historically been controlled with regular deferoxamine, but its parenteral requirement encouraged studies of orally-active agents, including deferasirox and deferiprone. Deferasirox, licensed by the US Food and Drug Administration in 2005 based upon the results of randomized controlled trials, is now first-line therapy worldwide. In contrast, early investigator-initiated trials of deferiprone were prematurely terminated after investigators raised safety concerns. The FDA declined market approval of deferiprone; years later, it licensed the drug as "last resort" therapy, to be prescribed only if first-line drugs had failed. We undertook to evaluate the long-term effectiveness and toxicities of deferiprone and deferasirox in one transfusion clinic.

METHODS AND FINDINGS

Under an IRB-approved study, we retrospectively inspected the electronic medical records of consented iron-loaded patients managed between 2009 and 2015 at The University Health Network (UHN), Toronto. We compared changes in liver and heart iron, adverse effects and other outcomes, in patients treated with deferiprone or deferasirox.

RESULTS

Although deferiprone was unlicensed in Canada, one-third (n = 41) of locally-transfused patients had been switched from first-line, licensed therapies (deferoxamine or deferasirox) to regimens of unlicensed deferiprone. The primary endpoint of monitoring in iron overload, hepatic iron concentration (HIC), increased (worsened) during deferiprone monotherapy (mean 10±2-18±2 mg/g; p < 0.0003), exceeding the threshold for life-threatening complications (15 mg iron/g liver) in 50% patients. During deferasirox monotherapy, mean HIC decreased (improved) (11±1-6±1 mg/g; p < 0.0001). Follow-up HICs were significantly different following deferiprone and deferasirox monotherapies (p < 0.0000002). Addition of low-dose deferoxamine (<40 mg/kg/day) to deferiprone did not result in reductions of HIC to <15 mg/g (baseline 20±4 mg/g; follow-up, 18±4 mg/g; p < 0.2) or in reduction in the proportion of patients with HIC exceeding 15 mg/g (p < 0.2). During deferiprone exposure, new diabetes mellitus, a recognized consequence of inadequate iron control, was diagnosed in 17% patients, most of whom had sustained HICs exceeding 15 mg/g for years; one woman died after 13 months of a regimen of deferiprone and low-dose deferasirox. During deferiprone exposure, serum ALT increased over baseline in 65% patients. Mean serum ALT increased 6.6-fold (p < 0.001) often persisting for years. During deferasirox exposure, mean ALT was unchanged (p < 0.84). No significant differences between treatment groups were observed in the proportions of patients estimated to have elevated cardiac iron.

CONCLUSIONS

Deferiprone showed ineffectiveness and significant toxicity in most patients. Combination with low doses of first-line therapies did not improve the effectiveness of deferiprone. Exposure to deferiprone, over six years while the drug was unlicensed, in the face of ineffectiveness and serious toxicities, demands review of the standards of local medical practice. The limited scope of regulatory approval of deferiprone, worldwide, should restrict its exposure to the few patients genuinely unable to tolerate the two effective, first-line therapies.

Efficacy and safety of iron chelators in thalassemia and sickle cell disease: a multiple treatment comparison network meta-analysis and trial sequential analysis

BACKGROUND

To compare the efficacy and safety of desferrioxamine (DFO), deferiprone (DFP), deferasirox (DFX) and silymarin in patients with either thalassemia or sickle cell disorder through network meta-analysis.

METHODS

Electronic databases were searched for appropriate randomized clinical trials comparing iron chelators in patients with iron overload. Random effects model was used to generate direct, indirect and mixed treatment comparison pooled estimates for the following outcomes: serum ferritin, liver iron concentration (LIC), changes in serum ferritin, mortality, urine iron excretion, adverse events, neutropenia, agranulocytosis and number of patients withdrawing the chelating therapy.

RESULTS

Thirty-two clinical trials were included in the meta-analysis. DFX/DFO was associated with better serum ferritin levels compared to DFO, DFX, DFO/Silymarin and DFP/DFO. DFX/DFO also lower LIC significantly compared to DFO. DFP/DFO was associated with higher LVEF, low risk of adverse events and reduced end of serum ferritin compared to DFO. Combination of silymarin with either DFP or DFX was observed with reduced end of treatment serum ferritin compared to using either of the drugs alone. DFP was observed with better effects in sickle cell disease. The strength of evidence was very low for most of the comparisons.

CONCLUSION

Relative estimates between the individual iron chelators have been established. However, this evidence should be considered preliminary and may change with the results of future head-to-head clinical trials.

Combined chelation therapy with daily oral deferiprone and twice-weekly subcutaneous infusion of desferrioxamine in children with β-thalassemia: 3-year experience

OBJECTIVE

To study the efficacy of combined treatment with oral and subcutaneous iron chelators.

MATERIAL AND METHODS

50-100 mg/kg/day of oral deferiprone (DFP) combined with 40 mg/kg/dose s.c. desferrioxamine (DFO) twice weekly were given to transfusion-dependent β-thalassemia children.

RESULTS

Enrolled patients (9 with β-thalassemia major and 33 with β-thalassemia hemoglobin E), ranging from 3 to 18 years in age, were divided into 3 groups; group 1 ferritin ≥1,000-2,500 ng/ml (n = 10), group 2 ferritin >2,500-4,000 ng/ml (n = 23) and group 3 ferritin >4,000 ng/ml (n = 9). Of the 42 patients, 28 reached the 36-month follow-up. Ten patients whose ferritin declined <15% while receiving 100 mg/kg/day of DFP were considered nonresponders. The median age and previous transfusion duration before enrollment were significantly higher in nonresponders than responders (p = 0.04 and 0.003, respectively). The responders exhibited a significant fall in median ferritin levels from 2,954.6 to 936.6 ng/ml (p < 0.001). Time to a significant decrease in serum ferritin among responders was 6 months. In 13 patients, 16 episodes of adverse events occurred: hemophagocytosis with cytopenia (n = 1), neutropenia (n = 2), thrombocytopenia (n = 2), elevated alanine aminotransferase (n = 5), elevated serum creatinine (n = 1), proteinuria (n = 1) and gastrointestinal discomfort (n = 4).

CONCLUSION

Combination therapy with daily oral DFP and subcutaneous DFO twice weekly is a safe and effective alternative to chelation monotherapy in β-thalassemia children.

Oral deferiprone for iron chelation in people with thalassaemia

BACKGROUND

Thalassaemia major is a genetic disease characterised by a reduced ability to produce haemoglobin. Management of the resulting anaemia is through red blood cell transfusions.Repeated transfusions result in an excessive accumulation of iron in the body (iron overload), removal of which is achieved through iron chelation therapy. A commonly used iron chelator, deferiprone, has been found to be pharmacologically efficacious. However, important questions exist about the efficacy and safety of deferiprone compared to another iron chelator, desferrioxamine.

OBJECTIVES

To summarise data from trials on the clinical efficacy and safety of deferiprone and to compare the clinical efficacy and safety of deferiprone with desferrioxamine for thalassaemia.

SEARCH METHODS

We searched the Cochrane Cystic fibrosis and Genetic Disorders Group's Haemoglobinopathies trials Register and MEDLINE, EMBASE, CENTRAL (The Cochrane Library), LILACS and other international medical databases, plus registers of ongoing trials and the Transfusion Evidence Library (www.transfusionevidencelibrary.com). We also contacted the manufacturers of deferiprone and desferrioxamine.All searches were updated to 05 March 2013.

SELECTION CRITERIA

Randomised controlled trials comparing deferiprone with another iron chelator; or comparing two schedules or doses of deferiprone, in people with transfusion-dependent thalassaemia.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trials for risk of bias and extracted data. Missing data were requested from the original investigators.

MAIN RESULTS

A total of 17 trials involving 1061 participants (range 13 to 213 participants per trial) were included. Of these, 16 trials compared either deferiprone alone with desferrioxamine alone, or a combined therapy of deferiprone and desferrioxamine with either deferiprone alone or desferrioxamine alone; one compared different schedules of deferiprone. There was little consistency between outcomes and limited information to fully assess the risk of bias of most of the included trials.Four trials reported mortality; each reported the death of one individual receiving deferiprone with or without desferrioxamine. One trial reported five further deaths in patients who withdrew from randomised treatment (deferiprone with or without desferrioxamine) and switched to desferrioxamine alone. Seven trials reported cardiac function or liver fibrosis as measures of end organ damage.Earlier trials measuring the cardiac iron load indirectly by magnetic resonance imaging (MRI) T2* signal had suggested deferiprone may reduce cardiac iron more quickly than desferrioxamine. However, a meta-analysis of two trials suggested that left ventricular ejection fraction was significantly reduced in patients who received desferrioxamine alone compared with combination therapy.  One trial, which planned five years of follow up, was stopped early due to the beneficial effects of combined treatment compared with deferiprone alone in terms of serum ferritin levels reduction.The results of this and three other trials suggest an advantage of combined therapy over monotherapy to reduce iron stores as measured by serum ferritin. There is, however, no conclusive or consistent evidence for the improved efficacy of combined deferiprone and desferrioxamine therapy over monotherapy from direct or indirect measures of liver iron. Both deferiprone and desferrioxamine produce a significant reduction in iron stores in transfusion-dependent, iron-overloaded people. There is no evidence from randomised controlled trials to suggest that either has a greater reduction of clinically significant end organ damage.Evidence of adverse events were observed in all treatment groups. Occurrence of any adverse event was significantly more likely with deferiprone than desferrioxamine in one trial, RR 2.24 (95% CI 1.19 to 4.23). Meta-analysis of a further two trials showed a significant increased risk of adverse events associated with combined deferiprone and desferrioxamine compared with desferrioxamine alone, RR 3.04 (95% CI 1.18 to 7.83). The most commonly reported adverse event was joint pain, which occurred significantly more frequently in patients receiving deferiprone than desferrioxamine, RR 2.64 (95% CI 1.21 to 5.77). Other common adverse events included gastrointestinal disturbances as well as neutropenia or leucopenia, or both.

AUTHORS' CONCLUSIONS

In the absence of data from randomised controlled trials, there is no evidence to suggest the need for a change in current treatment recommendations; namely that deferiprone is indicated for treating iron overload in people with thalassaemia major when desferrioxamine is contraindicated or inadequate. Intensified desferrioxamine treatment (by either subcutaneous or intravenous route) or use of other oral iron chelators, or both, remains the established treatment to reverse cardiac dysfunction due to iron overload. Indeed, the US Food and Drug Administration (FDA) recently only gave support for deferiprone to be used as a last resort for treating iron overload in thalassaemia, myelodysplasia and sickle cell disease. However, there is evidence that adverse events are increased in patients treated with deferiprone compared with desferrioxamine and in patients treated with combined deferiprone and desferrioxamine compared with desferrioxamine alone. There is an urgent need for adequately-powered, high-quality trials comparing the overall clinical efficacy and long-term outcome of deferiprone with desferrioxamine.

Desferrioxamine mesylate for managing transfusional iron overload in people with transfusion-dependent thalassaemia

BACKGROUND

Thalassaemia major is a genetic disease characterised by a reduced ability to produce haemoglobin. Management of the resulting anaemia is through red blood cell transfusions.Repeated transfusions result in an excessive accumulation of iron in the body (iron overload), removal of which is achieved through iron chelation therapy. Desferrioxamine mesylate (desferrioxamine) is one of the most widely used iron chelators. Substantial data have shown the beneficial effects of desferrioxamine, although adherence to desferrioxamine therapy is a challenge. Alternative oral iron chelators, deferiprone and deferasirox, are now commonly used. Important questions exist about whether desferrioxamine, as monotherapy or in combination with an oral iron chelator, is the best treatment for iron chelation therapy.

OBJECTIVES

To determine the effectiveness (dose and method of administration) of desferrioxamine in people with transfusion-dependent thalassaemia.To summarise data from trials on the clinical efficacy and safety of desferrioxamine for thalassaemia and to compare these with deferiprone and deferasirox.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register. We also searched MEDLINE, EMBASE, CENTRAL (The Cochrane Library), LILACS and other international medical databases, plus ongoing trials registers and the Transfusion Evidence Library (www.transfusionevidencelibrary.com). All searches were updated to 5 March 2013.

SELECTION CRITERIA

Randomised controlled trials comparing desferrioxamine with placebo, with another iron chelator, or comparing two schedules or doses of desferrioxamine, in people with transfusion-dependent thalassaemia.

DATA COLLECTION AND ANALYSIS

Six authors working independently were involved in trial quality assessment and data extraction. For one trial, investigators supplied additional data upon request.

MAIN RESULTS

A total of 22 trials involving 2187 participants (range 11 to 586 people) were included. These trials included eight comparisons between desferrioxamine alone and deferiprone alone; five comparisons between desferrioxamine combined with deferiprone and deferiprone alone; eight comparisons between desferrioxamine alone and desferrioxamine combined with deferiprone; two comparisons of desferrioxamine with deferasirox; and two comparisons of different routes of desferrioxamine administration (bolus versus continuous infusion). Overall, few trials measured the same or long-term outcomes. Seven trials reported cardiac function or liver fibrosis as measures of end organ damage; none of these included a comparison with deferasirox.Five trials reported a total of seven deaths; three in patients who received desferrioxamine alone, two in patients who received desferrioxamine and deferiprone. A further death occurred in a patient who received deferiprone in another who received deferasirox alone. One trial reported five further deaths in patients who withdrew from randomised treatment (deferiprone with or without desferrioxamine) and switched to desferrioxamine alone.One trial planned five years of follow up but was stopped early due to the beneficial effects of a reduction in serum ferritin levels in those receiving combined desferrioxamine and deferiprone treatment compared with deferiprone alone. The results of this and three other trials suggest an advantage of combined therapy with desferrioxamine and deferiprone over monotherapy to reduce iron stores as measured by serum ferritin. There is, however, no evidence for the improved efficacy of combined desferrioxamine and deferiprone therapy against monotherapy from direct or indirect measures of liver iron.Earlier trials measuring the cardiac iron load indirectly by measurement of the magnetic resonance imaging T2* signal had suggested deferiprone may reduce cardiac iron more quickly than desferrioxamine. However, meta-analysis of two trials showed a significantly lower left ventricular ejection fraction in patients who received desferrioxamine alone compared with those who received combination therapy using desferrioxamine with deferiprone.Adverse events were recorded by 18 trials. These occurred with all treatments, but were significantly less likely with desferrioxamine than deferiprone in one trial, relative risk 0.45 (95% confidence interval 0.24 to 0.84) and significantly less likely with desferrioxamine alone than desferrioxamine combined with deferiprone in two other trials, relative risk 0.33 (95% confidence interval 0.13 to 0.84). In particular, four studies reported permanent treatment withdrawal due to adverse events from deferiprone; only one of these reported permanent withdrawals associated with desferrioxamine. Adverse events also occurred at a higher frequency in patients who received deferasirox than desferrioxamine in one trial. Eight trials reported local adverse reactions at the site of desferrioxamine infusion including pain and swelling. Adverse events associated with deferiprone included joint pain, gastrointestinal disturbance, increases in liver enzymes and neutropenia; adverse events associated with deferasirox comprised increases in liver enzymes and renal impairment. Regular monitoring of white cell counts has been recommended for deferiprone and monitoring of liver and renal function for deferasirox.In summary, desferrioxamine and the oral iron chelators deferiprone and deferasirox produce significant reductions in iron stores in transfusion-dependent, iron-overloaded people. There is no evidence from randomised clinical trials to suggest that any one of these has a greater reduction of clinically significant end organ damage, although in two trials, combination therapy with desferrioxamine and deferiprone showed a greater improvement in left ventricular ejection fraction than desferrioxamine used alone.

AUTHORS' CONCLUSIONS

Desferrioxamine is the recommended first-line therapy for iron overload in people with thalassaemia major and deferiprone or deferasirox are indicated for treating iron overload when desferrioxamine is contraindicated or inadequate. Oral deferasirox has been licensed for use in children aged over six years who receive frequent blood transfusions and in children aged two to five years who receive infrequent blood transfusions. In the absence of randomised controlled trials with long-term follow up, there is no compelling evidence to change this conclusion.Worsening iron deposition in the myocardium in patients receiving desferrioxamine alone would suggest a change of therapy by intensification of desferrioxamine treatment or the use of desferrioxamine and deferiprone combination therapy.Adverse events are increased in patients treated with deferiprone compared with desferrioxamine and in patients treated with combined deferiprone and desferrioxamine compared with desferrioxamine alone. People treated with all chelators must be kept under close medical supervision and treatment with deferiprone or deferasirox requires regular monitoring of neutrophil counts or renal function respectively. There is an urgent need for adequately-powered, high-quality trials comparing the overall clinical efficacy and long-term outcomes of deferiprone, deferasirox and desferrioxamine.