Iranian experience of deferasirox (Exjade(®)) in transfusion-dependent patients with iron overload: what is the most effective dose based on serum ferritin levels?

Characterisation of individual ferritin response in patients receiving chelation therapy

Aims

To develop a drug–disease model describing iron overload and its effect on ferritin response in patients affected by transfusion‐dependent haemoglobinopathies and investigate the contribution of interindividual differences in demographic and clinical factors on chelation therapy with deferiprone or deferasirox.

Methods

Individual and mean serum ferritin data were retrieved from 13 published studies in patients affected by haemoglobinopathies receiving deferiprone or deferasirox. A nonlinear mixed effects modelling approach was used to characterise iron homeostasis and serum ferritin production taking into account annual blood consumption, baseline demographic and clinical characteristics. The effect of chelation therapy was parameterised as an increase in the iron elimination rate. Internal and external validation procedures were used to assess model performance across different study populations.

Results

An indirect response model was identified, including baseline ferritin concentrations and annual blood consumption as covariates. The effect of chelation on iron elimination rate was characterised by a linear function, with different slopes for each drug (0.0109 [90% CI: 0.0079–0.0131] vs. 0.0013 [90% CI: 0.0008–0.0018] L/mg mo). In addition to drug‐specific differences in the magnitude of the ferritin response, simulation scenarios indicate that ferritin elimination rates depend on ferritin concentrations at baseline.

Conclusion

Modelling of serum ferritin following chronic blood transfusion enabled the evaluation of drug‐induced changes in iron elimination rate and ferritin production. The use of a semi‐mechanistic parameterisation allowed us to disentangle disease‐specific factors from drug‐specific properties. Despite comparable chelation mechanisms, deferiprone appears to have a significantly larger effect on the iron elimination rate than deferasirox.

The Zinc and Copper Levels in Thalassemia Major Patients, Receiving Iron Chelation Therapy

Essential trace elements deficiency including zinc and copper are frequently reported in the literature, but the results are controversial. The aim of this study was to evaluate zinc and copper levels in thalassemia major (TM) patients who were on regular transfusion and iron chelation therapy. In a case-control cross-sectional study 43 TM patients and 43 age-matched and sex-matched healthy controls were examined. Patients were selected by convenience sampling method from TM patients who were registered in Thalassemia Clinic during 6 months. Serum zinc and copper levels were evaluated in all subjects. Zinc and copper dietary intake were also assessed. The median zinc level in the participants was significantly lower than the control group (35 [6.3 to 298] vs. 173 [3.1 to 584] μg/dL; P<0.05), but the mean copper level was significantly higher in the patients in comparison with the control group (260±118 vs. 201±69 μg/dL; P<0.05). In contrast, the mean zinc and copper dietary intake in the patient's group were significantly lower than the control group. The mean serum zinc and copper levels in the patient's group were not different according to iron chelation therapy type. Also, zinc and copper levels in the patient's group were not statistically significant based on ferritin level, age, and duration of therapy. Essential trace elements level change and deficiency might occur in TM patients. Hence, routine assessment of these elements is recommended for better management.

Evaluation of Proteinuria in β-Thalassemia Major Patients With and Without Diabetes Mellitus Taking Deferasirox

BACKGROUND

β-thalassemia is the most common heredity disease in Iran. Regular blood transfusion is critical to sustain life and normal growth. Deferasirox is an oral chelator. One of the side effects of the deferasirox is proteinuria.

OBJECTIVES

This study aimed to investigate the safety of deferasirox on kidney function in diabetic and nondiabetic β-thalassemia major patients.

MATERIALS AND METHODS

In this cross-sectional study, 34 diabetic and 36 nondiabetic patients who take deferasirox (Exjade) 20 to 40 mg/kg/d were studied. Exclusion criteria included patient with renal failure, proteinuria, hepatitis B, hepatitis C, and the patients who refused to continue the study to the end. Subjects were divided into diabetic and nondiabetic groups. Spot urine protein/creatinine ratio, urinary analysis, alanine transaminase, aspartate transaminase, creatinine, fasting blood sugar, blood urea nitrogen, and serum ferritin were checked every 3 months. Patients were followed for a period of 1 year.

RESULTS

In the ninth month after therapy there was a significant relationship in mean change of spot urine protein/creatinine ratio between diabetic and nondiabetic (P=0.011). Spot urine protein/creatinine ratio in diabetic and nondiabetic group was 0.19±0.18 and 0.1±0.05, respectively, which showed no significant relationship between the 2 groups at the end of study (P=0.162).

CONCLUSION

The results of our study showed that consumption of deferasirox is safe, as there was no significant relationship between spot urine protein/creatinine ratio in diabetic and nondiabetic group. Deferasirox consumption is not associated with increased proteinuria in diabetic patients compared with nondiabetic group having only a transient proteinuria.

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.

Efficacy and safety of deferasirox in β-thalassemia major patients in Iran: a prospective study from a single referral center in Iran

INTRODUCTION

Herein, the results of a prospective study evaluating the efficacy and safety of treatment with deferasirox are studied in iron-overloaded patients with β-thalassemia major during an 18-month trial.

METHODS

Thirty patients who were previously chelated with deferoxamine with/without deferiprone, and fulfilled the inclusion criteria were recruited. Patients received an initial dose of 10-30 mg/kg/day. Liver and cardiac MRI T2* were evaluated before and after the trial. In addition, serum ferritin level was assessed every 3 months. Primary endpoint was regarded as significant improvement in the severity of liver and cardiac iron overload in severe and moderate cases, in addition to improvement or maintenance of the grade of severity in patients with mild iron overload or normal iron accumulation. Therapy was considered effective if primary endpoint was met in >50%.

RESULTS

Liver MRI values improved significantly (P = .002), achieving a 73.33% success rate. A successful outcome regarding myocardial iron overload was observed in 80%. Finally, an overall of 66.66% of patients met the success criteria. Secondary endpoint, regarded as safety and tolerability was reached by 93.33%. The most common adverse events were skin rash and gastrointestinal disturbance. A dose between 30 and 40 mg/kg/day, tailored to each patient was considered the optimal dose.

CONCLUSION

Deferasirox proved as an efficient and safe chelating agent in our patients, specifically in mild to moderate iron overloaded patients.