The Sydney Children's Hospital experience with the oral iron chelator deferiprone (L1)

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.

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.

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 transfusions of red blood cells. Repeated transfusions result in 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 for thalassaemia with desferrioxamine.

SEARCH STRATEGY

We searched the Group's Haemoglobinopathies Trials Register, MEDLINE, EMBASE, Biological Abstracts, ZETOC, Current Controlled Trials and bibliographies of relevant publications. We contacted the manufacturers of deferiprone and desferrioxamine. Most recent searches: June 2006.

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Missing data were requested from the original investigators.

MAIN RESULTS

Ten trials involving 398 people (range 10 to 144 people) were included. Nine trials compared deferiprone with desferrioxamine or a combination of deferiprone and desferrioxamine and one compared different schedules of deferiprone. There was little consistency between outcomes and little information to fully assess the methodological quality of most of the included trials. No trial reported long-term outcomes (mortality and end organ damage). There was no consistent effect on reduction of iron overload between all treatment comparisons, with the exception of urinary iron excretion in comparisons of deferiprone with desferrioxamine. An increase in iron excretion levels favoured deferiprone in one trial and desferrioxamine in three trials, even though measurement of urinary iron excretion underestimates total iron excretion by desferrioxamine.Adverse events were recorded in trials comparing deferiprone with desferrioxamine. There was evidence of adverse events in all treatment groups. Adverse events in one trial were significantly more likely with deferiprone than desferrioxamine, relative risk 2.24 (95% confidence interval 1.19 to 4.23).

AUTHORS' CONCLUSIONS

We found no reason to change current treatment recommendations, namely deferiprone is indicated for treating iron overload in people with thalassaemia major when desferrioxamine is contraindicated or inadequate. However, there is an urgent need for adequately-powered, high quality trials comparing the overall clinical efficacy and long-term outcome of deferiprone with desferrioxamine.

Commentary: Science scandal or ethics scandal? Olivieri redux

Dr. Nancy Olivieri has become an icon of research integrity for her insistence on publishing adverse data about a drug she was investigating. She has been celebrated world-wide as a hero of biomedical ethics for her bravery in disclosing potential dangers to research subjects, in the face of both drug company threats and coercive pressures from her hospital and university. Like so many other 'whistle-blowers' however, she now faces both personal vilification and disturbing accusations of scientific error. The case against Olivieri is assessed and found to be baseless.

Deferiprone: New Insight

Recent results from independent studies suggest that deferiprone is more cardioprotective than deferoxamine. Patients on long-term treatment with deferiprone have a better myocardial magnetic resonance imaging pattern and less chance to develop a new cardiac disease or worsen an existing one. Most of these observations are retrospective and require confirmation from randomized controlled trials. Other new observations regard the effects of combining the two chelators. Most results indicate an additional effect on iron excretion and a significant reduction of the time required to mitigate severe iron overload and to reverse clinical heart disease. Again, these data require confirmation, as they were mostly obtained on individual cases or small groups of patients treated with a wide range of combinations of the two chelators, but the univocity of results is impressive. After many years of controversy, deferiprone is emerging as a useful oral iron chelator that enhances the chances for the patient to have optimal treatment. Well-designed and -conducted studies will help in answering the questions still open.

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 transfusions of red blood cells. Repeated transfusions results in excessive accumulation of iron in the body (iron overload), removal of which is achieved through iron chelation therapy. Desferrioxamine is the most widely used iron chelator. Substantial data have shown the beneficial effects of desferrioxamine. However, important questions exist about whether desferrioxamine is the best schedule for iron chelation therapy.

OBJECTIVES

To determine the effectiveness (dose and method of administration) of desferrioxamine in people with transfusion-dependent thalassaemia.

SEARCH STRATEGY

We searched the Cochrane Haemoglobinopathies Trials Register, MEDLINE, EMBASE, ZETOC, Current Controlled Trials and bibliographies of relevant publications. We also contacted the manufacturers of desferrioxamine and other iron chelators. Date of last searches: April 2004.

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

Four authors working independently, were involved in trial quality assessment and data extraction. Missing data were requested from the original investigators.

MAIN RESULTS

Eight trials involving 334 people (range 20 to 144 people) were included. One trial compared desferrioxamine with placebo, five compared desferrioxamine with another iron chelator (deferiprone) and two compared different schedules of desferrioxamine. Overall, few trials measured the same outcomes.Compared to placebo, desferrioxamine significantly reduced iron overload. The number of deaths at 12 years follow up and evidence of reduced end-organ damage was less for desferrioxamine than placebo. When desferrioxamine was compared to deferiprone or a different desferrioxamine schedule there were no statistically significant differences in measures of iron overload. Compliance was recorded by two trials. Compliance was less for desferrioxamine than deferiprone in one trial and of no difference in comparison with desferrioxamine and deferiprone combined with a second trial. Adverse events were recorded in trials comparing desferrioxamine with other iron chelators. There was evidence of adverse events in all treatment groups. In one trial, adverse events were significantly less likely with desferrioxamine than deferiprone, relative risk 0.45 (95% confidence interval 0.24 to 0.84). Assessment of the methodological quality of included trials was not possible, given the general absence of these data in the trials.

AUTHORS' CONCLUSIONS

We found no reason to change current treatment recommendations. However, considerable uncertainty continues to exist about the optimal schedule for desferrioxamine in people with transfusion-dependent thalassaemia.

Pharmacotherapy of iron overload in thalassaemic patients

The recommended treatment for thalassaemia major is regular blood transfusions, although these lead to the harmful accumulation of iron in the body. If untreated, iron overload is responsible for heart, liver and endocrine diseases. The only two iron chelating agents available for the treatment of iron overload are deferoxamine and deferiprone. The standard iron chelation therapy is based on the use of deferoxamine. Although this drug was introduced in the 1970s, it still remains the treatment of choice. Recently, another iron chelator, deferiprone, became available for clinical use in the European Community. Deferiprone is indicated as second-line treatment in patients with thalassaemia major, for whom deferoxamine therapy is contraindicated or in patients who present with serious toxicity to deferoxamine therapy. This paper examines this chelating agent and compares it with deferoxamine in order to ascertain the current and potential contribution of deferiprone to the treatment of thalassaemic patients.

Benefits and risks of deferiprone in iron overload in Thalassaemia and other conditions: comparison of epidemiological and therapeutic aspects with deferoxamine

Deferiprone is the only orally active iron-chelating drug to be used therapeutically in conditions of transfusional iron overload. It is an orphan drug designed and developed primarily by academic initiatives for the treatment of iron overload in thalassaemia, which is endemic in the Mediterranean, Middle East and South East Asia and is considered an orphan disease in the European Union and North America. Deferiprone has been used in several other iron or other metal imbalance conditions and has prospects of wider clinical applications. Deferiprone has high affinity for iron and interacts with almost all the iron pools at the molecular, cellular, tissue and organ levels. Doses of 50-120 mg/kg/day appear to be effective in bringing patients to negative iron balance. It increases urinary iron excretion, which mainly depends on the iron load of patients and the dose of the drug. It decreases serum ferritin levels and reduces the liver and heart iron content in the majority of chronically transfused iron loaded patients at doses >80 mg/kg/day. It is metabolised to a glucuronide conjugate and cleared through the urine in the metabolised and a non-metabolised form, usually of a 3 deferiprone: 1 iron complex, which gives the characteristic red colour urine. Peak serum levels of deferiprone are observed within 1 hour of its oral administration and clearance from blood is within 6 hours. There is variation among patients in iron excretion, the metabolism and pharmacokinetics of deferiprone. Deferiprone has been used in more than 7500 patients aged from 2-85 years in >50 countries, in some cases daily for >14 years. All the adverse effects of deferiprone are considered reversible, controllable and manageable. These include agranulocytosis with frequency of about 0.6%, neutropenia 6%, musculoskeletal and joint pains 15%, gastrointestinal complains 6% and zinc deficiency 1%. Discontinuation of the drug is recommended for patients developing agranulocytosis. Deferiprone is of similar therapeutic index to subcutaneous deferoxamine but is more effective in iron removal from the heart, which is the target organ of iron toxicity and mortality in iron-loaded thalassaemia patients. Deferiprone is much less expensive to produce than deferoxamine. Combination therapy of deferoxamine and deferiprone has been used in patients not complying with subcutaneous deferoxamine or experiencing toxicity or not excreting sufficient amounts of iron with use of either drug alone. New oral iron-chelating drugs are being developed, but even if successful these are likely to be more expensive than deferiprone and are not likely to become available in the next 5-8 years. About 25% of treated thalassaemia patients in Europe and more than 50% in India are using deferiprone. For most thalassaemia patients worldwide who are not at present receiving any form of chelation therapy the choice is between deferiprone and fatal iron toxicity.

The safety and effectiveness of deferiprone in a large-scale, 3-year study in Italian patients

In 1997, the Italian Ministry of Health created a special programme for the controlled distribution of deferiprone to collect data and to evaluate its safety and effectiveness in long-term use. Five hundred and thirty-two thalassaemia patients from 86 treatment centres were enrolled in this programme. One hundred and eighty-seven patients (32%) experienced a total of 269 events that led to a temporary interruption or, in some cases, to a discontinuation of treatment. The incidence of agranulocytosis and milder neutropenias were 0.4/100 and 2.1/100 patient-years respectively. Neutropenia occurred predominantly in younger and non-splenectomized patients. Transient alanine transaminase increase, gastrointestinal discomfort and arthralgia were the other most commonly reported events. Ferritin levels showed a significant decrease in time after 3 years of therapy. This is the largest number of deferiprone-treated patients to have been reported to date. These data show that the drug was effective in reducing serum ferritin levels and the incidence of adverse events was not greater than the frequency reported in clinical trials.

Orally active iron chelators

In patients with transfusion-dependent anemias, iron accumulation is fatal in the absence of chelating therapy. Extended survival, free of most complications of iron overload is observed in patients treated with early, adequate parenteral deferoxamine. Despite its success in prevention and treatment of iron toxicity, the expense and inconvenience of this therapy have stimulated a continued quest for an effective chelating agent that is orally active. Unfortunately, studies emerging over the last five years have confirmed that the most widely administered orally active agent, deferiprone (L1; 1,2-dimethyl-3-hydropyrid-4-one) may be harmfully ineffective in many patients: 18-65% of patients in six studies which obtained hepatic irons after long term deferiprone treatment had body iron exceeding the threshold for cardiac disease and premature death. The impact of deferiprone on cardiac and liver disease must be evaluated further, while the association between deferiprone and accelerated hepatic fibrosis still awaits refutation in large prospective trials. In view of the striking therapeutic successes of deferoxamine over the past 20 years, administration of deferiprone outside the setting of prospective clinical trials may need to be reconsidered. Meanwhile, an orally active iron chelator of demonstrated safety and effectiveness remains an objective for development for transfused patients.

Secondary iron overload

Transfusion therapy for inherited anemias and acquired refractory anemias both improves the quality of life and prolongs survival. A consequence of chronic transfusion therapy is secondary iron overload, which adversely affects the function of the heart, the liver and other organs. This session will review the use of iron chelating agents in the management of transfusion-induced secondary iron overload. In Section I Dr. John Porter describes techniques for the administration of deferoxamine that exploit the pharmacokinetic properties of the drug and minimize potential toxic side effects. The experience with chelation therapy in patients with thalassemia and sickle cell disease will be reviewed and guidelines will be suggested for chelation therapy of chronically transfused adults with refractory anemias. In Section II Dr. Nancy Olivieri examines the clinical consequences of transfusion-induced secondary iron overload and suggests criteria useful in determining the optimal timing of the initiation of chelation therapy. Finally, Dr. Olivieri discusses the clinical trials evaluating orally administered iron chelators.