Effects of Chelation Therapy on Cardiac Function Improvement in Thalassemia Patients: Literature Review and the Taiwanese Experience

The Vital Role Played by Deferiprone in the Transition of Thalassaemia from a Fatal to a Chronic Disease and Challenges in Its Repurposing for Use in Non-Iron-Loaded Diseases

The iron chelating orphan drug deferiprone (L1), discovered over 40 years ago, has been used daily by patients across the world at high doses (75-100 mg/kg) for more than 30 years with no serious toxicity. The level of safety and the simple, inexpensive synthesis are some of the many unique properties of L1, which played a major role in the contribution of the drug in the transition of thalassaemia from a fatal to a chronic disease. Other unique and valuable clinical properties of L1 in relation to pharmacology and metabolism include: oral effectiveness, which improved compliance compared to the prototype therapy with subcutaneous deferoxamine; highly effective iron removal from all iron-loaded organs, particularly the heart, which is the major target organ of iron toxicity and the cause of mortality in thalassaemic patients; an ability to achieve negative iron balance, completely remove all excess iron, and maintain normal iron stores in thalassaemic patients; rapid absorption from the stomach and rapid clearance from the body, allowing a greater frequency of repeated administration and overall increased efficacy of iron excretion, which is dependent on the dose used and also the concentration achieved at the site of drug action; and its ability to cross the blood-brain barrier and treat malignant, neurological, and microbial diseases affecting the brain. Some differential pharmacological activity by L1 among patients has been generally shown in relation to the absorption, distribution, metabolism, elimination, and toxicity (ADMET) of the drug. Unique properties exhibited by L1 in comparison to other drugs include specific protein interactions and antioxidant effects, such as iron removal from transferrin and lactoferrin; inhibition of iron and copper catalytic production of free radicals, ferroptosis, and cuproptosis; and inhibition of iron-containing proteins associated with different pathological conditions. The unique properties of L1 have attracted the interest of many investigators for drug repurposing and use in many pathological conditions, including cancer, neurodegenerative conditions, microbial conditions, renal conditions, free radical pathology, metal intoxication in relation to Fe, Cu, Al, Zn, Ga, In, U, and Pu, and other diseases. Similarly, the properties of L1 increase the prospects of its wider use in optimizing therapeutic efforts in many other fields of medicine, including synergies with other drugs.

Deferasirox for managing iron overload in people with thalassaemia

BACKGROUND

Thalassaemia is a hereditary anaemia due to ineffective erythropoiesis. In particular, people with thalassaemia major develop secondary iron overload resulting from regular red blood cell transfusions. Iron chelation therapy is needed to prevent long-term complications.Both deferoxamine and deferiprone are effective; however, a review of the effectiveness and safety of the newer oral chelator deferasirox in people with thalassaemia is needed.

OBJECTIVES

To assess the effectiveness and safety of oral deferasirox in people with thalassaemia and iron overload.

SEARCH METHODS

We searched the Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register: 12 August 2016.We also searched MEDLINE, Embase, the Cochrane Library, Biosis Previews, Web of Science Core Collection and three trial registries: ClinicalTrials.gov; the WHO International Clinical Trials Registry Platform; and the Internet Portal of the German Clinical Trials Register: 06 and 07 August 2015.

SELECTION CRITERIA

Randomised controlled studies comparing deferasirox with no therapy or placebo or with another iron-chelating treatment.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed risk of bias and extracted data. We contacted study authors for additional information.

MAIN RESULTS

Sixteen studies involving 1807 randomised participants (range 23 to 586 participants) were included. Twelve two-arm studies compared deferasirox to placebo (two studies) or deferoxamine (seven studies) or deferiprone (one study) or the combination of deferasirox and deferoxamine to deferoxamine alone (one study). One study compared the combination of deferasirox and deferiprone to deferiprone in combination with deferoxamine. Three three-arm studies compared deferasirox to deferoxamine and deferiprone (two studies) or the combination of deferasirox and deferiprone to deferiprone and deferasirox monotherapy respectively (one study). One four-arm study compared two different doses of deferasirox to matching placebo groups.The two studies (a pharmacokinetic and a dose-escalation study) comparing deferasirox to placebo (n = 47) in people with transfusion-dependent thalassaemia showed that deferasirox leads to net iron excretion. In these studies, safety was acceptable and further investigation in phase II and phase III studies was warranted.Nine studies (1251 participants) provided data for deferasirox versus standard treatment with deferoxamine. Data suggest that a similar efficacy can be achieved depending on the ratio of doses of deferoxamine and deferasirox being compared. In the phase III study, similar or superior efficacy for the intermediate markers ferritin and liver iron concentration (LIC) could only be achieved in the highly iron-overloaded subgroup at a mean ratio of 1 mg of deferasirox to 1.8 mg of deferoxamine corresponding to a mean dose of 28.2 mg per day and 51.6 mg per day respectively. The pooled effects across the different dosing ratios are: serum ferritin, mean difference (MD) 454.42 ng/mL (95% confidence interval (CI) 337.13 to 571.71) (moderate quality evidence); LIC evaluated by biopsy or SQUID, MD 2.37 mg Fe/g dry weight (95% CI 1.68 to 3.07) (moderate quality evidence) and responder analysis, LIC 1 to < 7 mg Fe/g dry weight, risk ratio (RR) 0.80 (95% CI 0.69 to 0.92) (moderate quality evidence). The substantial heterogeneity observed could be explained by the different dosing ratios. Data on mortality (low quality evidence) and on safety at the presumably required doses for effective chelation therapy are limited. Patient satisfaction was better with deferasirox among those who had previously received deferoxamine treatment, RR 2.20 (95% CI 1.89 to 2.57) (moderate quality evidence). The rate of discontinuations was similar for both drugs (low quality evidence).For the remaining comparisons in people with transfusion-dependent thalassaemia, the quality of the evidence for outcomes assessed was low to very low, mainly due to the very small number of participants included. Four studies (205 participants) compared deferasirox to deferiprone; one of which (41 participants) revealed a higher number of participants experiencing arthralgia in the deferiprone group, but due to the large number of different types of adverse events reported and compared this result is uncertain. One study (96 participants) compared deferasirox combined with deferiprone to deferiprone with deferoxamine. Participants treated with the combination of the oral iron chelators had a higher adherence compared to those treated with deferiprone and deferoxamine, but no participants discontinued the study. In the comparisons of deferasirox versus combined deferasirox and deferiprone and that of deferiprone versus combined deferasirox and deferiprone (one study, 40 participants), and deferasirox and deferoxamine versus deferoxamine alone (one study, 94 participants), only a few patient-relevant outcomes were reported and no significant differences were observed.One study (166 participants) included people with non-transfusion dependent thalassaemia and compared two different doses of deferasirox to placebo. Deferasirox treatment reduced serum ferritin, MD -306.74 ng/mL (95% CI -398.23 to -215.24) (moderate quality evidence) and LIC, MD -3.27 mg Fe/g dry weight (95% CI -4.44 to -2.09) (moderate quality evidence), while the number of participants experiencing adverse events and rate of discontinuations (low quality evidence) was similar in both groups. No participant died, but data on mortality were limited due to a follow-up period of only one year (moderate quality evidence).

AUTHORS' CONCLUSIONS

Deferasirox offers an important treatment option for people with thalassaemia and secondary iron overload. Based on the available data, deferasirox does not seem to be superior to deferoxamine at the usually recommended ratio of 1 mg of deferasirox to 2 mg of deferoxamine. However, similar efficacy seems to be achievable depending on the dose and ratio of deferasirox compared to deferoxamine. Whether this will result in similar efficacy and will translate to similar benefits in the long term, as has been shown for deferoxamine, needs to be confirmed. Data from randomised controlled trials on rare toxicities and long-term safety are still limited. However, after a detailed discussion of the potential benefits and risks, deferasirox could be offered as the first-line option to individuals who show a strong preference for deferasirox, and may be a reasonable treatment option for people showing an intolerance or poor adherence to deferoxamine.

Survival and complication rates in patients with thalassemia major in Taiwan

BACKGROUND

While transfusion and iron chelation therapy for thalassemia major (TM) has improved dramatically in recent years, the consequences of this improvement (current rates of survival and TM-related complications) remain unknown.

METHODS

This nationwide population-based cohort study analyzed 2007-2011 data obtained from the Taiwanese National Health Insurance Research Database.

RESULTS

After excluding those patients receiving hematopoietic stem cell transplantation, we enrolled 454 patients with TM who received transfusion and chelation therapy (median age, 17.2 years). Among these patients, the mortality rate was 2.9% in 2007, 2.3% in 2008, 2.9% in 2009, 2.6% in 2010, and 0.7% in 2011. Heart was the most common target organ of TM-related complications. There were 80 patients (17.6%) with arrhythmia and 86 patients (18.9%) with congestive heart failure. Dysfunction of endocrine organs was common, and the most common endocrinopathy was hypogonadism (23.1%), followed by diabetes (21.2%). There were 75 patients (16.5%) with liver cirrhosis and 79 patients (17.4%) with osteoporosis.

CONCLUSIONS

Adequate red blood cell transfusion and iron chelation is available to all patients with TM in Taiwan under the universal health insurance system, and has resulted in reduction of TM-related mortality to very low levels. As these patients get older, early detection of complications and adequate intervention are important to quality-of-life improvement.

Deferasirox for managing iron overload in people with myelodysplastic syndrome

BACKGROUND

The myelodysplastic syndrome (MDS) comprises a diverse group of haematopoietic stem cell disorders. Due to symptomatic anaemia, most people with MDS require supportive therapy including repeated red blood cell (RBC) transfusions. In combination with increased iron absorption, this contributes to the accumulation of iron resulting in secondary iron overload and the risk of organ dysfunction and reduced life expectancy. Since the human body has no natural means of removing excess iron, iron chelation therapy, i.e. the pharmacological treatment of iron overload, is usually recommended. However, it is unclear whether or not the newer oral chelator deferasirox leads to relevant benefit.

OBJECTIVES

To evaluate the effectiveness and safety of oral deferasirox for managing iron overload in people with myelodysplastic syndrome (MDS).

SEARCH METHODS

We searched the following databases up to 03 April 2014: MEDLINE, EMBASE, The Cochrane Library, Biosis Previews, Web of Science, Derwent Drug File and four trial registries: Current Controlled Trials (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov), ICTRP (www.who.int./ictrp/en/), and German Clinical Trial Register (www.drks.de).

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing deferasirox with no therapy, placebo or with another iron-chelating treatment schedule.

DATA COLLECTION AND ANALYSIS

We did not identify any trials eligible for inclusion in this review.

MAIN RESULTS

No trials met our inclusion criteria. However, we identified three ongoing and one completed trial (published as an abstract only and in insufficient detail to permit us to decide on inclusion) comparing deferasirox with deferoxamine, placebo or no treatment.

AUTHORS' CONCLUSIONS

We planned to report evidence from RCTs that evaluated the effectiveness of deferasirox compared to either placebo, no treatment or other chelating regimens, such as deferoxamine, in people with MDS. However, we did not identify any completed RCTs addressing this question.We found three ongoing and one completed RCT (published as an abstract only and in insufficient detail) comparing deferasirox with deferoxamine, placebo or no treatment and data will hopefully be available soon. These results will be important to inform physicians and patients on the advantages and disadvantages of this treatment option.

Deferasirox for managing transfusional iron overload in people with sickle cell disease

BACKGROUND

Sickle cell disease (SCD) is a group of genetic haemoglobin disorders, that occurs in about 2.2 per 1000 births worldwide. Increasingly, some people with SCD develop secondary iron overload due to occasional red blood cell transfusions or are on long-term transfusion programmes for e.g. secondary stroke prevention. Iron chelation therapy can prevent long-term complications.Deferoxamine and deferiprone have been found to be efficacious. However, questions exist about the effectiveness and safety of the newer oral chelator deferasirox.

OBJECTIVES

To assess the effectiveness and safety of oral deferasirox in people with SCD and secondary iron overload.

SEARCH METHODS

We searched the Cystic Fibrosis &amp; Genetic Disorders Group's Haemoglobinopathies Trials Register: date of most recent search:13 March 2014.We searched MEDLINE, Embase, Biosis Previews, Web of Science, Derwent Drug File, XTOXLINE, EBMR and The Cochrane Library, respectively; date of most recent searches: 02 August 2013.We searched four trial registries: www.controlled-trials.com; www.clinicaltrials.gov; www.who.int./ictrp/en/; www.drks.de; date of most recent searches: 03 June 2013.

SELECTION CRITERIA

Randomised controlled trials comparing deferasirox with no therapy or placebo or with another iron chelating treatment schedule.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed risk of bias and extracted data. We contacted the corresponding study authors for additional information.

MAIN RESULTS

Two studies (with 203 and 212 people) comparing the efficacy and safety of deferasirox and deferoxamine after 12 months and 24 weeks, respectively, were included. The overall quality, according to GRADE, for the main outcomes was moderate to low. Only limited data were available on mortality and end-organ damage, although one study did assess mortality, relative risk 1.26 (95% confidence interval 0.05 to 30.41), the 24-week follow up was too short to allow us to draw firm conclusions. One study reported a relative risk of 1.26 for the incidence of type 2 diabetes mellitus (95% confidence interval 0.05 to 30.41). Serum ferritin reduction was significantly greater with deferoxamine, mean difference of change of 440.69 µg/l (95% confidence interval 11.73 to 869.64). Liver iron concentration (reported in one study) measured by superconduction quantum interference device showed no significant difference for the overall group of patients adjusted for transfusion category, mean difference -0.20 mg Fe/g dry weight (95% confidence interval -3.15 to 2.75).The occurrence of serious adverse events did not differ between drugs. Nausea, diarrhoea and rash occurred significantly more often in people treated with deferasirox, while adverse events of any kind were more often reported for patients treated with deferoxamine (one study). The mean increase of creatinine was also significantly higher with deferasirox, mean difference 3.24 (95% confidence interval 0.45 to 6.03). Long-term adverse events could not be measured in the included studies (follow up 52 weeks and 24 weeks). Patient satisfaction and the likelihood of continuing treatment, were significantly better with deferasirox.

AUTHORS' CONCLUSIONS

Deferasirox appears to be of similar efficacy to deferoxamine depending on depending on the appropriate ratio of doses of deferoxamine and deferasirox being compared. However, only limited evidence is available assessing the efficacy regarding patient-important outcomes. The short-term safety of deferasirox seems to be acceptable, however, follow up in the available studies was too short to assess long-term side effects. Long-term safety and efficacy data are available from a non-controlled extension phase not included in our review; however, no valid comparative conclusions can be drawn and future studies should assess comparatively long-term outcomes both for safety and efficacy.

Deferasirox for the treatment of iron overload in non-transfusion-dependent thalassemia

Non-transfusion-dependent thalassemia (NTDT) defines a group of patients who do not require regular transfusions for survival, but are at significant risk of iron accumulation from underlying disease-related mechanisms distinct from transfusional iron overload. Management of iron overload in NTDT has received little attention compared with that of β-thalassemia major, despite evidence of significant iron-induced complications with advancing age. The efficacy and safety of the iron chelator deferasirox in NTDT has been evaluated in two pilot studies and the first prospective, randomized, placebo-controlled study (THALASSA) of any chelator in NTDT. Treatment with deferasirox for up to 2 years yielded a sustained reduction in iron burden, with a clinically manageable safety profile. Following these trial data, deferasirox is the first iron chelator approved for use in NTDT patients, and with NTDT guidelines now available, physicians are better equipped to achieve effective monitoring and management of iron burden in NTDT.

Deferasirox for managing iron overload in people with thalassaemia

BACKGROUND

Thalassemia is a hereditary anaemia due to ineffective erythropoiesis. In particular, people with thalassaemia major develop secondary iron overload resulting from regular red blood cell transfusion. Iron chelation therapy is needed to prevent long-term complications.Both deferoxamine and deferiprone have been found to be efficacious. However, a systematic review of the effectiveness and safety of the new oral chelator deferasirox in people with thalassaemia is needed.

OBJECTIVES

To assess the effectiveness and safety of oral deferasirox in people with thalassaemia and secondary iron overload.

SEARCH METHODS

We searched the Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register. We also searched MEDLINE, EMBASE, EBMR, Biosis Previews, Web of Science, Derwent Drug File, XTOXLINE and three trial registries: www.controlled-trials.com; www.clinicaltrials.gov; www.who.int./ictrp/en/. Date of the most recent searches of these databases: 24 June 2010.Date of the most recent search of the Group's Haemoglobinopathies Trials Register: 03 November 2011.

SELECTION CRITERIA

Randomised controlled trials comparing deferasirox with no therapy or placebo or with another iron chelating treatment.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed risk of bias and extracted data. We contacted study authors for additional information.

MAIN RESULTS

Four studies met the inclusion criteria.Two studies compared deferasirox to placebo or standard therapy of deferoxamine (n = 47). The placebo-controlled studies, a pharmacokinetic and a dose escalation study, showed that deferasirox leads to net iron excretion in transfusion-dependent thalassaemia patients. In these studies, safety was acceptable and further investigation in phase II and phase III trials was warranted.Two studies, one phase II study (n = 71) and one phase III study (n = 586) compared deferasirox to standard treatment with deferoxamine. Data suggest that a similar efficacy can be achieved depending on the ratio of doses of deferoxamine and deferasirox being compared; in the phase III trial, similar or superior efficacy for surrogate parameters of ferritin and liver iron concentration could only be achieved in the highly iron-overloaded subgroup at a mean ratio of 1 mg of deferasirox to 1.8 mg of deferoxamine corresponding to a mean dose of 28.2 mg/d and 51.6 mg/d respectively. Data on safety at the presumably required doses for effective chelation therapy are limited. Patient satisfaction was significantly better with deferasirox, while rate of discontinuations was similar for both drugs.

AUTHORS' CONCLUSIONS

Deferasirox offers an important alternative line of treatment for people with thalassaemia and secondary iron overload. Based on the available data, deferasirox does not seem to be superior to deferoxamine at the usually recommended ratio of 1 mg of deferasirox to 2 mg of deferoxamine. However, similar efficacy seems to be achievable depending on the dose and ratio of deferasirox compared to deferoxamine. Whether this will result in similar efficacy in the long run and will translate to similar benefits as has been shown for deferoxamine, needs to be confirmed. Data on safety, particularly on rare toxicities and long-term safety, are still limited.Therefore, we think that deferasirox should be offered as an alternative to all patients with thalassaemia who either show intolerance to deferoxamine or poor compliance with deferoxamine. In our opinion, data are still too limited to support the general recommendation of deferasirox as first-line treatment instead of deferoxamine. If a strong preference for deferasirox is expressed, it could be offered as first-line option to individual patients after a detailed discussion of the potential benefits and risks.

Deferasirox for managing iron overload in people with myelodysplastic syndrome

BACKGROUND

The myelodysplastic syndrome (MDS) comprises a diverse group of haematopoietic stem cell disorders. Due to symptomatic anaemia most patients require supportive therapy including repeated red blood cell (RBC) transfusions. In combination with increased iron absorption, this contributes to the accumulation of iron resulting in secondary iron overload and the risk of organ dysfunction and reduced life expectancy. Since the human body has no natural means of getting rid of excess iron, iron chelation therapy is usually recommended. However, whether the new oral chelator deferasirox leads to relevant benefit is unclear.

OBJECTIVES

To assess the effectiveness and safety of oral deferasirox in people with myelodysplastic syndrome and iron overload.

SEARCH STRATEGY

We searched MEDLINE, EMBASE, The Cochrane Library, Biosis Previews, Web of Science, Derwent Drug File, XTOXLINE and three trial registries: Current Controlled Trials: www.controlled-trials.com, ClinicalTrials.gov: www.clinicaltrials.gov, ICTRP: www.who.int./ictrp/en/. Most recent searches of these databases: June 2010.

SELECTION CRITERIA

Randomised controlled trials comparing deferasirox with no therapy/placebo or with another iron chelating treatment schedule.

DATA COLLECTION AND ANALYSIS

No studies eligible for inclusion in this review were identified.

MAIN RESULTS

No studies were included in this review. However, we identified one ongoing study comparing deferasirox with deferoxamine.

AUTHORS' CONCLUSIONS

We planned to report evidence from randomised clinical trials evaluating the effectiveness of deferasirox compared to either placebo/no treatment or other chelating regimens such as deferoxamine in people with myelodysplastic syndrome. However, no completed randomised trials addressing this question could be identified.One ongoing randomised study comparing deferasirox with placebo was identified and preliminary data will hopefully be available soon. These results will be important to inform physicians and patients on the advantages and disadvantages of this treatment option.

Deferasirox for managing transfusional iron overload in people with sickle cell disease

BACKGROUND

Sickle cell disease (SCD) is a group of genetic haemoglobin disorders. Increasingly, some people with SCD develop secondary iron overload due to occasional red blood cell transfusions or are on long-term transfusion programmes for e.g. secondary stroke prevention. Iron chelation therapy can prevent long-term complications.Deferoxamine and deferiprone have been found to be efficacious. However, questions exist about the effectiveness and safety of the new oral chelator deferasirox.

OBJECTIVES

To assess the effectiveness and safety of oral deferasirox in people with SCD and secondary iron overload.

SEARCH STRATEGY

We searched the Cystic Fibrosis & Genetic Disorders Group's Haemoglobinopathies Trials Register (06 April 2010).We searched MEDLINE, EMBASE, EBMR, Biosis Previews, Web of Science, Derwent Drug File, XTOXLINE and three trial registries: www.controlled-trials.com; www.clinicaltrials.gov; www.who.int./ictrp/en/. Most recent searches: 22 June 2009.

SELECTION CRITERIA

Randomised controlled trials comparing deferasirox with no therapy or placebo or with another iron chelating treatment schedule.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study quality and extracted data. We contacted the study author for additional information.

MAIN RESULTS

One study (203 people) was included comparing the efficacy and safety of deferasirox and deferoxamine after 12 months. Data were not available on mortality or end-organ damage. Using a pre-specified dosing algorithm serum ferritin reduction was similar in both groups, mean difference (MD) 375.00 microg/l in favour of deferoxamine; (95% confidence interval (CI) -106.08 to 856.08). Liver iron concentration measured by superconduction quantum interference device showed no difference for the overall group of patients adjusted for transfusion category, MD -0.20 mg Fe/g dry weight (95% CI -3.15 to 2.75).Mild stable increases in creatine were observed more often in people treated with deferasirox, risk ratio 1.64 (95% CI 0.98 to 2.74). Abdominal pain and diarrhoea occurred significantly more often in people treated with deferasirox. Rare adverse events (less than 5% increase) were not reported; long-term adverse events could not be measured in the included study (follow-up 52 weeks). Patient satisfaction with, and convenience of treatment were significantly better with deferasirox.

AUTHORS' CONCLUSIONS

Deferasirox appears to be as effective as deferoxamine. However, only limited evidence is available assessing the efficacy regarding patient-important outcomes. The short-term safety of deferasirox seems to be acceptable, however, follow-up was too short to exclude long-term side effects and thus treatment with deferasirox cannot be judged completely safe. Future studies should assess long-term outcomes for safety and efficacy, and also evaluate rarer adverse effects.

Update on thalassemia treatment in Taiwan, including bone marrow transplantation, chelation therapy, and cardiomyopathy treatment effects

Over the past few decades, Taiwan has seen striking improvements in the life expectancy of its 400 registered beta-thalassemia major (beta-TM) patients due mainly to adequate transfusion regimens and effective iron chelation therapy. Since 1995, Taiwanese citizens have enjoyed universal health care through National Health Insurance (NIH), receiving comprehensive treatment at minimal cost. In 1984, a national program for thalassemia prevention, control, and hematopoietic stem cell transplantation (HSCT) was initiated. Recent data show 1- and 2-year event-free survival rates of 85 and 78%, respectively. Chelation agents like deferoxamine (DFO), deferiprone (L1) and deferasirox (DFRA) are available in Taiwan, and therapy is tailored to individuals based on drug availability and tissue distribution of iron load. Intensive chelation regimens combining L1 and DFO are recommended in patients with cardiac complications, while DFRA has been found to be effective in reducing serum ferritin, with acceptable side effects. Here, we report advances in thalassemia treatment in Taiwan and suggest treatment guidelines.