Fanconi Syndrome Due to Deferasirox

The pathophysiology of hypophosphatemia

After identification of fibroblast growth factor (FGF) 23 as the pivotal regulator of chronic serum inorganic phosphate (Pi) levels, the etiology of disorders causing hypophosphatemic rickets/osteomalacia has been clarified, and measurement of intact FGF23 serves as a potent tool for differential diagnosis of chronic hypophosphatemia. Additionally, measurement of bone-specific alkaline phosphatase (BAP) is recommended to differentiate acute and subacute hypophosphatemia from chronic hypophosphatemia. This article divides the etiology of chronic hypophosphatemia into 4 groups: A. FGF23 related, B. primary tubular dysfunction, C. disturbance of vitamin D metabolism, and D. parathyroid hormone 1 receptor (PTH1R) mediated. Each group is further divided into its inherited form and acquired form. Topics for each group are described, including "ectopic FGF23 syndrome," "alcohol consumption-induced FGF23-related hypophosphatemia," "anti-mitochondrial antibody associated hypophosphatemia," and "vitamin D-dependent rickets type 3." Finally, a flowchart for differential diagnosis of chronic hypophosphatemia is introduced.

Efficacy and Safety of a Dispersible Tablet of GPO-Deferasirox Monotherapy among Children with Transfusion-Dependent Thalassemia and Iron Overload

The study aimed to determine efficacy and safety of generic deferasirox monotherapy. Deferasirox was administered in transfusion-induced iron overloaded thalassemia. Efficacy was defined as responders and nonresponders by ≤ 15 reduced serum ferritin from baseline. Adverse events were also monitored. Fifty-two patients with mainly Hb E/β-thalassemia at the mean (SD) age of 8.7 (4.1) years, were enrolled. The mean (SD) daily transfusion iron load was 0.47 (0.1) mg/kg and maximum daily deferasirox was 35.0 (6.2) mg/kg. Altogether, 52, 40 and 18 patients completed the first, second and third years of study, respectively. The median baseline serum ferritin 2,383 ng/mL decreased to 1,478, 1,038 and 1,268 ng/mL at the end of first, second and third years, respectively, with overall response rate at 73.1% (38/52). Patients with baseline serum ferritin >2,500 ng/mL showed a change in serum ferritin higher than those ≤2,500 ng/mL starting from the 9th month of chelation. Adverse events were found in 5 of 52 patients (9.6%) including transaminitis (n = 2), one each of proteinuria, rash and proximal tubular dysfunction which resolved after transient stopping or decreasing the chelation dose. Generic deferasirox was effective and safe among pediatric patients with transfusion-induced iron overloaded thalassemia.

Iron Chelators in Treatment of Iron Overload

Patients suffering from iron overload can experience serious complications. In such patients, various organs, such as endocrine glands and liver, can be damaged. Although iron is a crucial element for life, iron overload can be potentially toxic for human cells due to its role in generating free radicals. In the past few decades, there has been a major improvement in the survival of patients who suffer from iron overload due to the application of iron chelation therapy in clinical practice. In clinical use, deferoxamine, deferiprone, and deferasirox are the three United States Food and Drug Administration-approved iron chelators. Each of these iron chelators is well known for the treatment of iron overload in various clinical conditions. Based on several up-to-date studies, this study explained iron overload and its clinical symptoms, introduced each of the above-mentioned iron chelators, and evaluated their advantages and disadvantages with an emphasis on combination therapy, which in recent studies seems a promising approach. In numerous clinical conditions, due to the lack of accurate indicators, choosing a standard approach for iron chelation therapy can be difficult; therefore, further studies on the issue are still required. This study aimed to introduce each of these iron chelators, combination therapy, usage doses, specific clinical applications, and their advantages, toxicity, and side effects.

The Impact of Iron Chelators on the Biology of Cancer Stem Cells

Neoplastic diseases are still a major medical challenge, requiring a constant search for new therapeutic options. A serious problem of many cancers is resistance to anticancer drugs and disease progression in metastases or local recurrence. These characteristics of cancer cells may be related to the specific properties of cancer stem cells (CSC). CSCs are involved in inhibiting cells’ maturation, which is essential for maintaining their self-renewal capacity and pluripotency. They show increased expression of transcription factor proteins, which were defined as stemness-related markers. This group of proteins includes OCT4, SOX2, KLF4, Nanog, and SALL4. It has been noticed that the metabolism of cancer cells is changed, and the demand for iron is significantly increased. Iron chelators have been proven to have antitumor activity and influence the expression of stemness-related markers, thus reducing chemoresistance and the risk of tumor cell progression. This prompts further investigation of these agents as promising anticancer novel drugs. The article presents the characteristics of stemness markers and their influence on the development and course of neoplastic disease. Available iron chelators were also described, and their effects on cancer cells and expression of stemness-related markers were analyzed.

Kidney Tubular Damage Secondary to Deferasirox: Systematic Literature Review

Deferasirox is a first-line therapy for iron overload that can sometimes cause kidney damage. To better define the pattern of tubular damage, a systematic literature review was conducted on the United States National Library of Medicine, Excerpta Medica, and Web of Science databases. Twenty-three reports describing 57 individual cases could be included. The majority (n = 35) of the 57 patients were ≤18 years of age and affected by thalassemia (n = 46). Abnormal urinary findings were noted in 54, electrolyte or acid–base abnormalities in 46, and acute kidney injury in 9 patients. Latent tubular damage was diagnosed in 11 (19%), overt kidney tubular damage in 37 (65%), and an acute kidney injury in the remaining nine (16%) patients. Out of the 117 acid–base and electrolyte disorders reported in 48 patients, normal-gap metabolic acidosis and hypophosphatemia were the most frequent. Further abnormalities were, in decreasing order of frequency, hypokalemia, hypouricemia, hypocalcemia, and hyponatremia. Out of the 81 abnormal urinary findings, renal glucosuria was the most frequent, followed by tubular proteinuria, total proteinuria, and aminoaciduria. In conclusion, a proximal tubulopathy pattern may be observed on treatment with deferasirox. Since deferasirox-associated kidney damage is dose-dependent, physicians should prescribe the lowest efficacious dose.

Pharmacological and clinical evaluation of deferasirox formulations for treatment tailoring

Deferasirox (DFX) is the newest among three different chelators available to treat iron overload in iron-loading anaemias, firstly released as Dispersible Tablets (DT) and more recently replaced by Film-Coated Tablets (FCT). In this retrospective observational study, pharmacokinetics, pharmacodynamics, and safety features of DFX treatment were analyzed in 74 patients that took both formulations subsequently under clinical practice conditions. Bioavailability of DFX FCT compared to DT resulted higher than expected [C_max: 99.5 (FCT) and 69.7 (DT) μMol/L; AUC: 1278 (FCT) and 846 (DT), P < 0.0001]. DFX FCT was also superior in scalability among doses. After one year of treatment for each formulation, no differences were observed between the treatments in the overall iron overload levels; however, DFX FCT but not DT showed a significant dose–response correlation [Spearman r (dose-serum ferritin variation): − 0.54, P < 0.0001]. Despite being administered at different dosages, the long-term safety profile was not different between formulations: a significant increase in renal impairment risk was observed for both treatments and it was reversible under strict monitoring (P < 0.002). Altogether, these data constitute a comprehensive comparison of DFX formulations in thalassaemia and other iron-loading anaemias, confirming the effectiveness and safety characteristics of DFX and its applicability for treatment tailoring.

Deferasirox-associated Fanconi syndrome in adult patients with transfusional iron overload

BACKGROUND AND OBJECTIVES

Deferasirox is an oral chelator approved for iron overload, which has a potential side effect of renal Fanconi syndrome, with proximal tubular dysfunction and tubular acidosis. Monitoring of renal function is recommended, though no standard for monitoring exists. We aim to describe cases of deferasirox-associated Fanconi syndrome in adults and the renal monitoring required to detect these findings.

MATERIALS AND METHODS

We present a review of the literature and six cases from our institution of deferasirox-associated partial Fanconi syndrome in adult patients with transfusional iron overload secondary to β-thalassemia or Diamond Blackfan Anaemia.

RESULTS

While prior cases in the literature occurred at high doses of deferasirox, our series included patients on doses as low as deferasirox 10 mg/kg who had been aggressively chelated. All patients had resolution of laboratory abnormalities with drug interruption.

CONCLUSION

Rather than chelating to normal iron levels, this series supports prior suggestions that deferasirox dose be reduced if ferritin <500-1000 ng/ml, and also supports dose reduction if liver iron content <3 mg iron per g dry weight or for those undergoing aggressive chelation with rapid decrease in iron. Monitoring with metabolic panel and urinalysis were sufficient to detect clinically significant proximal tubular dysfunction, but should be followed up with additional studies to confirm the diagnosis while deferasirox dose is decreased or held.

Hypophosphataemia, fibroblast growth factor 23 and third-generation intravenous iron compounds: a narrative review

Third-generation intravenous (i.v.) iron preparations are safe and efficacious and are increasingly used in the treatment of iron-deficiency anaemia. Hypophosphataemia is emerging as an established side-effect following the administration of certain compounds. Symptoms of hypophosphataemia can be masked by their similarity to those of iron-deficiency anaemia and both acute and chronic hypophosphataemia can be detrimental. Hypophosphataemia appears to be linked to imbalances in the metabolism of the phosphatonin fibroblast growth factor 23. In this narrative review, we discuss the possible pathophysiology behind this phenomenon, the studies comparing third-generation i.v. iron compounds, and the potential implications of the changes in fibroblast growth factor 23 and hypophosphataemia. We also present an algorithm of how to approach such patients requiring i.v. iron in anticipation of hypophosphataemia and how the impact related to it can be minimized.

Management of Iron Overload in Beta-Thalassemia Patients: Clinical Practice Update Based on Case Series

Thalassemia syndromes are characterized by the inability to produce normal hemoglobin. Ineffective erythropoiesis and red cell transfusions are sources of excess iron that the human organism is unable to remove. Iron that is not saturated by transferrin is a toxic agent that, in transfusion-dependent patients, leads to death from iron-induced cardiomyopathy in the second decade of life. The availability of effective iron chelators, advances in the understanding of the mechanism of iron toxicity and overloading, and the availability of noninvasive methods to monitor iron loading and unloading in the liver, heart, and pancreas have all significantly increased the survival of patients with thalassemia. Prolonged exposure to iron toxicity is involved in the development of endocrinopathy, osteoporosis, cirrhosis, renal failure, and malignant transformation. Now that survival has been dramatically improved, the challenge of iron chelation therapy is to prevent complications. The time has come to consider that the primary goal of chelation therapy is to avoid 24-h exposure to toxic iron and maintain body iron levels within the normal range, avoiding possible chelation-related damage. It is very important to minimize irreversible organ damage to prevent malignant transformation before complications set in and make patients ineligible for current and future curative therapies. In this clinical case-based review, we highlight particular aspects of the management of iron overload in patients with beta-thalassemia syndromes, focusing on our own experience in treating such patients. We review the pathophysiology of iron overload and the different ways to assess, quantify, and monitor it. We also discuss chelation strategies that can be used with currently available chelators, balancing the need to keep non-transferrin-bound iron levels to a minimum (zero) 24 h a day, 7 days a week and the risk of over-chelation.

β2-Microglobulin, Neutrophil Gelatinase-Associated Lipocalin, and Endocan Values in Evaluating Renal Functions in Patients with β-Thalassemia Major

Chronic anemia, transfusion-associated iron deposition, and chelating agents lead to renal impairment in β-thalassemia (β-thal) patients. The present study aimed to determine the most reliable and practical method in assessing and predicting renal injury in β-thal major (β-TM) patients. Therefore, we assessed the predictive values of urine β2-microglobulin (β2-MG) and neutrophil gelatinase-associated lipocalin (NGAL) levels, their ratios to urine creatinine, and serum endocan level. Sixty β-TM patients and 30 healthy controls were included. Renal functions of the patients and controls were evaluated by means of urine protein/creatinine ratio, urine β2-MG, urine NGAL, and serum endocan level. The β-TM and control groups were comparable in terms of the demographic characteristics. Of the β-TM patients, 26.7% had glomerular hyperfiltration and 41.7% had proteinuria. Compared with the control group, the β-TM group had significantly higher levels of urine protein/creatinine, urine β2-MG, urine β2-MG/creatinine, urine NGAL, urine NGAL/creatinine, and serum endocan. These parameters did not differ between the chelating agent subgroups in the patient group. Urine β2-MG/creatinine and NGAL/creatinine ratios were the parameters with high specificity in predicting proteinuria. There were significant correlations of urine β2-MG, urine NGAL, and serum endocan levels with serum ferritin concentration. Urine β2-MG/creatinine, NGAL/creatinine, and protein/creatinine ratios were correlated with each other in the patient group. Positive correlations of urine β2-MG, urine NGAL, and serum endocan levels with serum ferritin concentration indicated that iron deposition was associated with endothelial damage and renal injury.

The iron chelator Deferasirox causes severe mitochondrial swelling without depolarization due to a specific effect on inner membrane permeability

The iron chelator Deferasirox (DFX) causes severe toxicity in patients for reasons that were previously unexplained. Here, using the kidney as a clinically relevant in vivo model for toxicity together with a broad range of experimental techniques, including live cell imaging and in vitro biophysical models, we show that DFX causes partial uncoupling and dramatic swelling of mitochondria, but without depolarization or opening of the mitochondrial permeability transition pore. This effect is explained by an increase in inner mitochondrial membrane (IMM) permeability to protons, but not small molecules. The movement of water into mitochondria is prevented by altering intracellular osmotic gradients. Other clinically used iron chelators do not produce mitochondrial swelling. Thus, DFX causes organ toxicity due to an off-target effect on the IMM, which has major adverse consequences for mitochondrial volume regulation.

Proximal renal tubular acidosis with and without Fanconi syndrome

Proximal renal tubular acidosis (RTA) is caused by a defect in bicarbonate (HCO₃⁻) reabsorption in the kidney proximal convoluted tubule. It usually manifests as normal anion-gap metabolic acidosis due to HCO₃⁻ wastage. In a normal kidney, the thick ascending limb of Henle’s loop and more distal nephron segments reclaim all of the HCO₃⁻ not absorbed by the proximal tubule. Bicarbonate wastage seen in type II RTA indicates that the proximal tubular defect is severe enough to overwhelm the capacity for HCO₃⁻ reabsorption beyond the proximal tubule. Proximal RTA can occur as an isolated syndrome or with other impairments in proximal tubular functions under the spectrum of Fanconi syndrome. Fanconi syndrome, which is characterized by a defect in proximal tubular reabsorption of glucose, amino acids, uric acid, phosphate, and HCO₃⁻, can occur due to inherited or acquired causes. Primary inherited Fanconi syndrome is caused by a mutation in the sodium-phosphate cotransporter (NaP_i-II) in the proximal tubule. Recent studies have identified new causes of Fanconi syndrome due to mutations in the EHHADH and the HNF4A genes. Fanconi syndrome can also be one of many manifestations of various inherited systemic diseases, such as cystinosis. Many of the acquired causes of Fanconi syndrome with or without proximal RTA are drug-induced, with the list of causative agents increasing as newer drugs are introduced for clinical use, mainly in the oncology field.

Deferasirox - a rarer cause of Fanconi syndrome

Deferasirox is a recently approved iron chelator and is widely used to treat iron overload in transfusion-dependent patients. Its once-daily dosing and oral route of administration have made it an appealing alternative to deferoxamine. Recent case studies have brought to light its potential to cause damage to the proximal convoluted tubule resulting in Fanconi syndrome (FS). FS is a proximal tubular dysfunction that leads to glycosuria, phosphaturia, aminoaciduria, and normal anion gap metabolic acidosis. Herein, we discuss a case of a young male on chronic blood transfusions requiring deferasirox therapy, who was found to have FS from its use. We discuss the possible mechanism of drug toxicity and the need for regular monitoring of serum electrolytes andurinalysis along with renal function tests to avoid this consequence.

The footprints of mitochondrial impairment and cellular energy crisis in the pathogenesis of xenobiotics-induced nephrotoxicity, serum electrolytes imbalance, and Fanconi's syndrome: A comprehensive review

Fanconi's Syndrome (FS) is a disorder characterized by impaired renal proximal tubule function. FS is associated with a vast defect in the renal reabsorption of several chemicals. Inherited and/or acquired conditions seem to be connected with FS. Several xenobiotics including many pharmaceuticals are capable of inducing FS and nephrotoxicity. Although the pathological state of FS is well described, the exact underlying etiology and cellular mechanism(s) of xenobiotics-induced nephrotoxicity, serum electrolytes imbalance, and FS are not elucidated. Constant and high dependence of the renal reabsorption process to energy (ATP) makes mitochondrial dysfunction as a pivotal mechanism which could be involved in the pathogenesis of FS. The current review focuses on the footprints of mitochondrial impairment in the etiology of xenobiotics-induced FS. Moreover, the importance of mitochondria protecting agents and their preventive/therapeutic capability against FS is highlighted. The information collected in this review may provide significant clues to new therapeutic interventions aimed at minimizing xenobiotics-induced renal injury, serum electrolytes imbalance, and FS.

Beta-thalassemia: renal complications and mechanisms: a narrative review

OBJECTIVES

Beta-thalassemias are a group of recessively autosomal inherited disorders of hemoglobin synthesis, which, due to mutations of the beta-globin gene, lead to various degrees of defective beta-chain production, an imbalance in alpha/beta-globin chain synthesis, ineffective erythropoiesis, and anemia. Improved survival in thalassemic patients has led to the emergence of previously unrecognized complications, such as renal disease.

METHODS

A comprehensive literature review through PubMed was undertaken to summarize the published evidence on the epidemiology and pathophysiology of renal disease in thalassemia. Literature sources published in English since 1990 were searched, using the terms beta-thalassemia, renal disease.

RESULTS

Renal disease is considered to be the 4th cause of morbidity among patients with transfusion dependent thalassemia. Chronic anemia, hypoxia and iron overload are the main mechanisms implicated in development of renal injury, whereas several studies also suggested a contributive role of iron chelators.

DISCUSSION AND CONCLUSION

Kidney disease may develop through progressive renal tubular and glomerular damage; thus, its early recognition is important in order to prevent and/or reverse deterioration. This review will provide an insight on the involved mechanisms implicated in kidney disease in thalassemic patients and will discuss the updates on diagnosis and prevention of renal complications in thalassemia.

Acute kidney injury due to thin basement membrane disease mimicking Deferasirox nephrotoxicity: a case report

BACKGROUND

Although the renal toxicity of Deferasirox, an oral iron chelator, has been reported to be mild, there have been reports of acute interstitial nephritis or Fanconi syndrome due to this agent. Thin basement membrane disease (TBMD) is a hereditary disease characterized primarily by hematuria, with gross hematuria also observed in about 7% of cases. We herein report a case of TBMD that presented with acute kidney injury and gross hematuria during treatment with Deferasirox.

CASE PRESENTATION

The patient was a 63-year-old man who had been diagnosed with myelodysplastic syndrome 6 years ago. He had started taking Deferasirox at 125 mg due to post-transfusion iron overload 6 months ago. Deferasirox was then increased to 1000 mg three months ago. When the serum creatinine level increased, Deferasirox was reduced to 500 mg three weeks before hospitalization. Although the serum creatinine level decreased once, he developed a fever and macroscopic hematuria one week before hospitalization. The serum creatinine level increased again, and Deferasirox was stopped four days before hospitalization. He was admitted for the evaluation of acute kidney injury and gross hematuria. Treatment with temporary hemodialysis was required, and a kidney biopsy was performed on the eighth day of admission. Although there was no major abnormality in the glomeruli, the leakage of red blood cells into the Bowman's space was observed. Erythrocyte cast formation was observed in the tubular lumen, which was associated with acute tubular necrosis. The results of an electron microscopic study were compatible with TBMD.

CONCLUSION

Although Deferasirox is known to be nephrotoxic, gross hematuria is relatively rare. When we encounter a case of acute kidney injury with gross hematuria during treatment with Deferasirox, TBMD should be considered as a possible cause of gross hematuria.

Deferasirox: Over a Decade of Experience in Thalassemia

Thalassemia incorporates a broad clinical spectrum characterized by decreased or absent production of normal hemoglobin leading to decreased red blood cell survival and ineffective erythropoiesis. Chronic iron overload remains an inevitable complication resulting from regular blood transfusions (transfusion-dependent) and/or increased iron absorption (mainly non-transfusion-dependent thalassemia), requiring adequate treatment to prevent the significant associated morbidity and mortality. Iron chelation therapy has become a cornerstone in the management of thalassemia patients, leading to improvements in their outcome and quality of life. Deferasirox (DFX), an oral iron chelating agent, is approved for use in transfusion dependent and non-transfusion-dependent thalassemia and has shown excellent efficacy in this setting. We herein present an updated review of the role of deferasirox in thalassemia, exploring over a decade of experience, which has documented its effectiveness and convenience; in addition to its manageable safety profile.

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.

Transfusion-dependent thalassaemic patients with renal Fanconi syndrome due to deferasirox use

AIM

Deferasirox is a new oral iron chelating agent with several cases reporting renal adverse events in recent years. Our aim was to identify the incidence of deferasirox-related Fanconi syndrome (FS) and its risk factors.

METHODS

All transfusion-dependent thalassaemic patients who received deferasirox at the outpatient department of the National Taiwan University Hospital (NTUH) from January 2006 to February 2014 were evaluated.

RESULTS

This cohort study included 57 patients, and mean age of deferasirox initiation was 18.2 ± 7.7 years. After 6.9 ± 1.8 years of follow-up, 5 in 57 (8.8%) thalassaemic patients had FS. Age of starting deferasirox negatively correlated with incidence of FS (correlation coefficient -0.892, P = 0.008). Other factors were not significantly associated with FS. Serum creatinine level at the start of deferasirox compared to at the end of study or onset of FS did not show significant change (P = 0.277). All the deferasirox-related FS manifested with proximal renal tubular acidosis and hypophosphataemia, which needed specific treatment or withdrawal of deferasirox use.

CONCLUSIONS

We recommend that children, especially of young age, who regularly use deferasirox should undergo routine urinalysis and blood testing for early detection of FS.

Fanconi Syndrome Secondary to Deferasirox in Diamond-Blackfan Anemia: Case Series and Recommendations for Early Diagnosis

Deferasirox is an oral iron chelator used to treat patients with transfusion-related iron overload. We report, from two institutions, two children with Diamond-Blackfan anemia who developed Fanconi syndrome secondary to deferasirox administration, along with a review of the literature. The current recommendation for the laboratory monitoring of patients receiving deferasirox does not include serum electrolytes or urine analysis. Thus, despite routine clinic visits and bloodwork, these two patients presented with life-threatening electrolyte abnormalities requiring hospitalization. Hence, we propose the inclusion of serum electrolytes and urine analysis as part of routine monitoring to facilitate the early diagnosis of Fanconi syndrome in the context of high doses of deferasirox therapy.

Drug-Induced Metabolic Acidosis

Metabolic acidosis could emerge from diseases disrupting acid-base equilibrium or from drugs that induce similar derangements. Occurrences are usually accompanied by comorbid conditions of drug-induced metabolic acidosis, and clinical outcomes may range from mild to fatal. It is imperative that clinicians not only are fully aware of the list of drugs that may lead to metabolic acidosis but also understand the underlying pathogenic mechanisms. In this review, we categorized drug-induced metabolic acidosis in terms of pathophysiological mechanisms, as well as individual drugs’ characteristics.

Transfusional iron overload and iron chelation therapy in thalassemia major and sickle cell disease

Iron overload is an inevitable consequence of blood transfusions and is often accompanied by increased iron absorption from the gut. Chelation therapy is necessary to prevent the consequences of hemosiderosis. Three chelators, deferoxamine, deferiprone, and deferasirox, are presently available and a fourth is undergoing clinical trials. The efficacy of all 3 available chelators has been demonstrated. Also, many studies have shown the efficacy of the combination of deferoxamine plus deferiprone as an intensive treatment of severe iron overload. Alternating chelators can reduce adverse effects and improve compliance. Adherence to therapy is crucial for good results.

Deferasirox nephrotoxicity-the knowns and unknowns

In 2005, the oral iron chelator deferasirox was approved by the FDA for clinical use as a first-line therapy for blood-transfusion-related iron overload. Nephrotoxicity is the most serious and frequent adverse effect of deferasirox treatment. This nephrotoxicity can present as an acute or chronic decrease in glomerular filtration rate (GFR). Features of proximal tubular dysfunction might also be present. In clinical trials and observational studies, GFR is decreased in 30-100% of patients treated with deferasirox, depending on dose, method of assessment and population studied. Nephrotoxicity is usually nonprogressive and/or reversible and rapid iron depletion is one of several risk factors. Scarce data are available on the molecular mechanisms of nephrotoxicity and the reasons for the specific proximal tubular sensitivity to the drug. Although deferasirox promotes apoptosis of cultured proximal tubular cells, the trigger has not been well characterized. Observational studies are required to track current trends in deferasirox prescription, assess the epidemiology of deferasirox nephrotoxicity in routine clinical practice, explore the effect on outcomes of various monitoring and dose-adjustment protocols and elucidate the long-term consequences of the different features of nephrotoxicity. Deferasirox nephrotoxicity can be more common in the elderly; thus, specific efforts should be dedicated to investigate the effect of deferasirox use in this group of patients.

Safety of deferasirox: a retrospective cohort study on the risks of gastrointestinal, liver and renal events

BACKGROUND

Deferasirox (DFX) is an effective and well-tolerated oral iron chelator elevating the adherence to iron chelating therapy among patients with iron overload. However, the US Food and Drug Administration issued a warning about the potential adverse events associated with DFX in 2010.

METHODS

To examine the risks of gastrointestinal (GI) bleeding, acute liver necrosis, and acute renal failure among DFX users compared with desferrioxamine (DFO) users in a real-world setting, first-time users of DFX or DFO between 2005 and 2008 in Taiwan's National Health Insurance database were observed in this population-based retrospective cohort study. The risks of different adverse events were individually analyzed by Cox proportional hazards models and adjusted by age, sex, concomitant medications, and prior medical conditions.

RESULTS

Deferasirox users had the highest incidence rates of GI bleeding (2.03 per 10 000 patient-days), acute liver necrosis (0.26 per 10 000 patient-days) and acute renal failure (1.45 per 10 000 patient-days) compared with other iron chelator users. Compared with DFO users, DFX users were not associated with the risk of GI bleeding (adjusted HR 1.03, 95% CI 0.61-1.74, p = 0.90) and the risk of acute liver necrosis (adjusted HR 2.13, 95% CI 0.49-9.33, p = 0.32). The association between DFX use and acute renal failure was found to be statistically significant (HR 2.18, 95% CI 1.18-4.02, p = 0.01; adjusted HR 2.41, 95% CI 1.27-4.58, p = 0.01).

CONCLUSION

In this study, we found statistically significant higher risk of acute renal failure and non-statistically significant higher risk of GI bleeding and acute liver necrosis associated with DFX use. More researches are warranted to evaluate the association between DFX use and potential adverse events.

A prospective study of tubular dysfunction in pediatric patients with Beta thalassemia major receiving deferasirox

BACKGROUND

Beta thalassemia major is a lifelong transfusion-dependent disorder. Transfusion-dependent thalassemia patients are prone to develop renal dysfunction due to iron overload, chronic anemia, and/or chelation therapy.

METHODS

In this prospective study, thalassemia patients who fitted inclusion and exclusion criteria received Deferasirox 20 mg/kg/day. A complete biochemistry analysis of serum and 24-hour-urine specimens was performed before and after treatment. Estimated glomerular filtration rate (eGFR), Fractional excretion of sodium (FENA), potassium (FEK), uric acid (FEUA), and the maximum ratio of tubular reabsorption of phosphorus to eGFR (TmP/GFR) at baseline and after treatment was calculated and compared.

RESULTS

A total of 30 patients with mean age of 4.9 ± 3.2 years were recruited. The mean serum creatinine increased significantly after 6 months of treatment (0.54 ± 0.08 vs. 0.67 ± 0.16, P < .001) while eGFR was decreased (104.36 ± 19.62 vs. 86.00 ± 16.92, P < .001). Mean potassium level in serum was increased after treatment, while serum calcium, magnesium, and uric acid levels decreased significantly (P > .05). A significant increase was confirmed for mean urinary β2-microglobulin (β2-MG), protein, uric acid, calcium, and magnesium (P > .05).

CONCLUSION

Our findings highlighted tubular nephropathy induced by Deferasirox in patients with beta thalassemia, and confirmed the necessity for diligent monitoring of renal function in thalassemia patients receiving Deferasirox.

Potential clinical applications of chelating drugs in diseases targeting transferrin-bound iron and other metals

INTRODUCTION

Iron is essential for normal, neoplasmic and microbial cells. Transferrin (Tf) is responsible for iron transport and its interactions with chelators are of physiological and toxicological importance and could lead to new therapeutic applications.

AREAS COVERED

Differential interactions of Tf with chelators such as deferiprone (L1) could be used to modify toxicity and disease pathways in relation to iron and other metal metabolism. Iron mobilization by L1 could achieve normal body iron stores in thalassemia patients. Iron mobilization from the reticuloendothelial system by L1 and exchange with Tf could be used to increase the production of hemoglobin in the anemia of chronic disease. Iron accumulation is pathogenic in neurodegenerative, acute kidney and other diseases and could be removed by L1 with therapeutic implications. Deprivation of iron from neoplasmic and microbial cells by chelators could increase the prospect of improved treatments in cancer and infectious diseases. Other applications include metal detoxification and inhibition of oxidative stress-related conditions.

EXPERT OPINION

Specific mechanisms apply in the interactions of chelators with Tf, which could be used in the design of targeted therapeutic strategies in many conditions. In each case specific chelator protocols have to be designed for achieving optimum therapeutic activity.

Cost-utility analysis of deferiprone for the treatment of β-thalassaemia patients with chronic iron overload: a UK perspective

BACKGROUND

Patients with β-thalassaemia major experience chronic iron overload due to regular blood transfusions. Chronic iron overload can be treated using iron-chelating therapies such as desferrioxamine (DFO), deferiprone (DFP) and deferasirox (DFX) monotherapy, or DFO-DFP combination therapy.

OBJECTIVES

This study evaluated the relative cost effectiveness of these regimens over a 5-year timeframe from a UK National Health Service (NHS) perspective, including personal and social services.

METHODS

A Markov model was constructed to evaluate the cost effectiveness of the treatment regimens over 5 years. Based on published randomized controlled trial evidence, it was assumed that all four treatment regimens had a comparable effect on serum ferritin concentration (SFC) and liver iron concentration (LIC), and that DFP was more effective for reducing cardiac morbidity and mortality. Published utility scores for route of administration were used, with subcutaneously administered DFO assumed to incur a greater quality of life (QoL) burden than the oral chelators DFP and DFX. Healthcare resource use, drug costs (2010/2011 costs), and utilities associated with adverse events were also considered, with the effect of varying all parameters assessed in sensitivity analysis. Incremental costs and quality-adjusted life-years (QALYs) were calculated for each treatment, with cost effectiveness expressed as incremental cost per QALY. Assumptions that DFP conferred no cardiac morbidity, mortality, or morbidity and mortality benefit were also explored in scenario analysis.

RESULTS

DFP was the dominant strategy in all scenarios modelled, providing greater QALY gains at a lower cost. Sensitivity analysis showed that DFP dominated all other treatments unless the QoL burden associated with the route of administration was greater for DFP than for DFO, which is unlikely to be the case. DFP had >99 % likelihood of being cost effective against all comparators at a willingness-to-pay threshold of £20,000 per QALY.

CONCLUSIONS

In this analysis, DFP appeared to be the most cost-effective treatment available for managing chronic iron overload in β-thalassaemia patients. Use of DFP in these patients could therefore result in substantial cost savings.

Iron: effect of overload and deficiency

Iron is a redox active metal which is abundant in the Earth's crust. It has played a key role in the evolution of living systems and as such is an essential element in a wide range of biological phenomena, being critical for the function of an enormous array of enzymes, energy transduction mechanisms, and oxygen carriers. The redox nature of iron renders the metal toxic in excess and consequently all biological organisms carefully control iron levels. In this overview the mechanisms adopted by man to control body iron levels are described.Low body iron levels are related to anemia which can be treated by various forms of iron fortification and supplementation. Elevated iron levels can occur systemically or locally, each giving rise to specific symptoms. Systemic iron overload results from either the hyperabsorption of iron or regular blood transfusion and can be treated by the use of a selection of iron chelating molecules. The symptoms of many forms of neurodegeneration are associated with elevated levels of iron in certain regions of the brain and iron chelation therapy is beginning to find an application in the treatment of such diseases. Iron chelators have also been widely investigated for the treatment of cancer, tuberculosis, and malaria. In these latter studies, selective removal of iron from key enzymes or iron binding proteins is sought. Sufficient selectivity between the invading organism and the host has yet to be established for such chelators to find application in the clinic.Iron chelation for systemic iron overload and iron supplementation therapy for the treatment of various forms of anemia are now established procedures in clinical medicine. Chelation therapy may find an important role in the treatment of various neurodegenerative diseases in the near future.

Deferasirox-induced renal impairment in children: an increasing concern for pediatricians

BACKGROUND

Deferasirox (DFX) is an oral iron chelator with an established dose-dependent efficacy in transfusion-related iron overload. Whereas emerging long-term data confirm the safety of the drug, with transient moderate elevation of serum creatinine level, several authors have reported renal tubular dysfunction. The aim of this study was to evaluate tubular and glomerular function before and after the initiation of DFX therapy in a pediatric patient population.

METHODS

Ten children (4 girls, mean age 12.4 ± 3.9 years) enrolled in a routine blood transfusion program were treated with 24.8 ± 9.6 mg/kg per day of DFX, and renal function was assessed before and 17.2 ± 8.9 months after the initiation of DFX therapy.

RESULTS

Prior to treatment with DFX, all patients had a normal glomerular function rate (GFR) (125 ± 15 ml/min per 1.73 m(2)) and normal tubular function. Following the initiation of DFX therapy, the GFR decreased by approximately 20 % with one patient with a GFR of <80 mL/min per 1.73 m(2) and seven patients with a GFR of <100 mL/min per 1.73 m(2). Two patients experienced a generalized proximal tubular dysfunction whereas nine patients presented at least one sign of proximal tubular dysfunction.

CONCLUSIONS

Renal toxicity is a frequent adverse event of DFX treatment, presenting as both glomerular and proximal dysfunction. A routine renal assessment is therefore required to prevent chronic kidney disease that may result from prolonged tubular injury.

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.

A case of hypophosphatemic osteomalacia secondary to deferasirox therapy

Patients with β-thalassemia major require iron-chelation therapy to avoid the complication of iron overload. Until recently, deferoxamine (DFO) was the major iron chelator used in patients requiring chronic hypertransfusion therapy, but DFO required continuous subcutaneous therapy. The availability of deferasirox (Exjade®), an orally active iron chelator, over the past 4 years represented a necessary alternative for patients requiring chelation therapy. However, there have been increasing reports of proximal renal tubular dysfunction and Fanconi syndrome associated with deferasirox in the literature. We report a case of hypophosphataemic osteomalacia secondary to deferasirox therapy.

Fok-I polymorphism of vitamin D receptor gene and the presence of renal dysfunction in patients with β-thalassemia major

Recent evidence supports the presence of renal dysfunction even among young patients with β-thalassemia major. However, the possible genetic contribution has never been investigated. The aim of this study was to correlate the presence of Fok-I polymorphism of the vitamin D receptor gene with abnormal levels of early markers of renal impairment in children and young adults with thalassemia. Thirty-four patients (19 male and 15 female) with β-thalassemia major on conventional treatment, with a mean decimal age of 14.62 ± 5.47 years (range: 5-22 years), were included in the study. Markers of renal function were determined in serum and in urine and patients were genotyped for Fok-I gene polymorphism. Genotype frequencies were similar to those previously reported for other populations: 47.06% of the patients were homozygous for the F allele, 41.18% were heterozygous, and 11.76% were homozygous for the f allele. A considerable number of patients demonstrated impaired renal function with increased serum cystatin C levels (29.41%), glomerular dysfunction with proteinuria (68%), as well as significant tubulopathy with hypercalciuria (73.08%), and increased levels of urinary β(2)-microglobulin (29.41%). When patients were stratified according to Fok-I polymorphism, a significantly higher prevalence of abnormally increased serum levels of cystatin C was observed in patients being homozygous for the f allele (75%) compared with those being heterozygous (Ff) or homozygous for the F allele (14.29% and 31.25%, respectively, P = .02). Further studies are needed to confirm these preliminary results and elucidate the possible mechanisms involved.

Novel nephrotoxins

Drug and xenobiotic toxicity is an important cause of kidney injury, especially in vulnerable patients. Nephrotoxic syndromes include functional disorders; vascular injury, such as thrombotic microangiopathy; glomerular injury resulting in nephrotic syndrome or glomerulonephritis; acute tubular necrosis; acute interstitial nephritis; and crystalopathy/nephrolithiasis. Recently reported nephrotoxins are reviewed in the context of these syndromes of kidney injury.

The effects of deferasirox on renal, cardiac and hepatic iron load in patients with β-thalassemia major: preliminary results

The iron loading related to erythrocyte transfusions is the major cause of morbidities and mortalities in patients with β-thalassemia major (β-TM). Deferasirox, an orally active iron chelator, has been reported to cause serum creatinine increases in addition to acute renal failures in elderly patients with comorbidities. The nefrotoxicities in patients using deferasirox, despite the facts that the drug is minimally excreted from kidneys and its effective chelation of iron from liver and heart, may rise the question of decomparmentalization of iron from these organs to kidneys. Thirteen patients with β-TM were included in the study (mean age 18.5 ± 7.5 years [9-33 years]). The patients received deferasirox in a dose of 34.3 ± 6.5 mg/kg [17-37 mg/kg]. Four patients (31%) exhibited consecutive increases in serum creatinine greater than 33% above baseline twice during the follow-up period. The results indicated that the earliest iron chelation starts in liver in patients receiving deferasirox. Additionally, by the 6th month of deferasirox, the status of cardiac and renal iron in chronically transfused patients with β-TM were preserved. This may indicate that the serum creatinine increases may not be attributed to iron decompartmantalization from other organs to kidneys.

Reversible Fanconi syndrome in a pediatric patient on deferasirox

Deferasirox (Exjade®, Novartis) is a widely used oral iron chelator for the treatment of patients with iron overload due to chronic transfusion therapy for diseases such as β-thalassemia and sickle cell disease. Renal side effects of deferasirox are common and include non-progressive increases in serum creatinine, however, the effect of deferasirox on proximal tubule function is unclear. We report one pediatric patient with reversible Fanconi syndrome associated with long-term deferasirox therapy and one patient with mild proximal tubular dysfunction. Kidney and proximal tubular function should be periodically monitored in patients receiving deferasirox throughout their course of therapy.

Acquired proximal renal tubular dysfunction in β-thalassemia patients treated with deferasirox

Deferasirox is a recently approved oral iron chelator for treatment of patients with transfusion-related iron overload. Although renal function disturbances were recognized, proximal renal tubulopathy was not addressed in published safety reports for deferasirox. Although subclinical proximal tubulopathy was described in β-thalassemia homozygotes, overt Fanconi kidney is not an established disease complication. We describe 4 cases out of 50 children and adults with transfusion-dependent β-thalassemia, treated with deferasirox for iron overload, who developed clinically significant Fanconi syndrome. Three had concomitant infectious events; the fourth case was entirely spontaneous. In addition, all 4 patients were moderately to well chelated. Cessation of deferasirox resulted in prompt recovery. We propose the necessity for diligent monitoring for proximal tubule nephropathy, possibly related to infectious events, during treatment with deferasirox.

Introduction of higher doses of deferasirox: better efficacy but not effective iron removal from the heart and increased risks of serious toxicities

IMPORTANCE OF THE FIELD

Thousands of iron loaded patients are using deferasirox, who are not aware of the new, fatal and irreversible serious toxic side effects, the need for prophylaxis and the availability of more effective and less toxic chelation therapies.

AREAS COVERED IN THIS REVIEW

Updating on efficacy issues in relation to the introduction of higher deferasirox doses and comparison to existing chelation therapies. A new maximum dose of 40 mg/kg/day has been introduced for deferasirox in an attempt to achieve negative iron balance in thalassemia and other transfused iron loaded patients. A marginal increase in cardiac iron removal using doses of 30 - 40 mg/kg/day suggests that the rate of iron removal by deferasirox is insufficient by comparison to the deferiprone/deferoxamine combination, where total and rapid clearance of excess cardiac iron and normalization of the body iron stores could be achieved.

WHAT THE READER WILL GAIN

Identification of drug interactions and new fatal and permanent toxic side effects of deferasirox and implications on efficacy, toxicity and cost of using higher doses. Deferasirox has been identified to cause fatal gastrointestinal hemorrhages, renal tubulopathy, hepatic and renal failure, alopecia and anaphylactic reactions in addition to previously reported fatal or serious toxic side effects such as agranulocytosis, renal and hepatic toxicity, skin rash and gastric intolerance. Interactions with UDP-glucuronosyl transferase inducers, CYP2C8 and CYP3A4 substrates and drugs affecting enterohepatic recycling are likely to affect deferasirox's efficacy and toxicity. Increased toxicity is expected from the use of higher doses of deferasirox and regular prophylactic monitoring is required to avoid fatal and permanent toxicity incidences. The increased costs from higher doses of deferasirox will mostly affect patients living in the developing countries.

TAKE HOME MESSAGE

Only few patients may benefit from the introduction of higher doses of deferasirox. There is a need for introducing more effective prophylactic measures. Safer, more effective and less costly chelation treatments are available using deferiprone, deferoxamine and their combination.