Ferriprox

Pharmacotherapeutic group: All other therapeutic products, iron chelating agents, ATC code: V03AC03 Mechanism of action Deferasirox is an orally active chelator that is highly selective for iron (III). It is a tridentate ligand that binds iron with high affinity in a 2:1 ratio. Deferasirox promotes excretion of iron, primarily in the faeces. Deferasirox has low affinity for zinc and copper, and does not cause constant low serum levels of these metals. Pharmacodynamic effects In an iron-balance metabolic study in iron-overloaded adult thalassaemic patients, deferasirox at daily doses of 10, 20 and 40 mg/kg (dispersible tablet formulation) induced the mean net excretion of 0.119, 0.329 and 0.445 mg Fe/kg body weight/day, respectively. Clinical efficacy and safety Clinical efficacy studies were conducted with deferasirox dispersible tablets. Deferasirox has been investigated in 411 adult (age ≥16 years) and 292 paediatric patients (aged 2 to <16 years) with chronic iron overload due to blood transfusions. Of the paediatric patients 52 were aged 2 to 5 years. The underlying conditions requiring transfusion included beta-thalassaemia, sickle cell disease and other congenital and acquired anaemias (myelodysplastic syndromes [MDS], Diamond-Blackfan syndrome, aplastic anaemia and other very rare anaemias). Daily treatment with the deferasirox dispersible tablet formulation at doses of 20 and 30 mg/kg for one year in frequently transfused adult and paediatric patients with beta-thalassaemia led to reductions in indicators of total body iron; liver iron concentration was reduced by about -0.4 and -8.9 mg Fe/g liver (biopsy dry weight (dw)) on average, respectively, and serum ferritin was reduced by about -36 and -926 µg/l on average, respectively. At these same doses the ratios of iron excretion: iron intake were 1.02 (indicating net iron balance) and 1.67 (indicating net iron removal), respectively. Deferasirox induced similar responses in iron-overloaded patients with other anaemias. Daily doses of 10 mg/kg (dispersible tablet formulation) for one year could maintain liver iron and serum ferritin levels and induce net iron balance in patients receiving infrequent transfusions or exchange transfusions. Serum ferritin assessed by monthly monitoring reflected changes in liver iron concentration indicating that trends in serum ferritin can be used to monitor response to therapy. Limited clinical data (29 patients with normal cardiac function at baseline) using MRI indicate that treatment with deferasirox 10-30 mg/kg/day (dispersible tablet formulation) for 1 year may also reduce levels of iron in the heart (on average, MRI T2* increased from 18.3 to 23.0 milliseconds). The principal analysis of the pivotal comparative study in 586 patients suffering from beta-thalassaemia and transfusional iron overload did not demonstrate non-inferiority of deferasirox dispersible tablets to deferoxamine in the analysis of the total patient population. It appeared from a post-hoc analysis of this study that, in the subgroup of patients with liver iron concentration ≥7 mg Fe/g dw treated with deferasirox dispersible tablets (20 and 30 mg/kg) or deferoxamine (35 to ≥50 mg/kg), the non-inferiority criteria were achieved. However, in patients with liver iron concentration <7 mg Fe/g dw treated with deferasirox dispersible tablets (5 and 10 mg/kg) or deferoxamine (20 to 35 mg/kg), non-inferiority was not established due to imbalance in the dosing of the two chelators. This imbalance occurred because patients on deferoxamine were allowed to remain on their pre-study dose even if it was higher than the protocol specified dose. Fifty-six patients under the age of 6 years participated in this pivotal study, 28 of them receiving deferasirox dispersible tablets. It appeared from preclinical and clinical studies that deferasirox dispersible tablets could be as active as deferoxamine when used in a dose ratio of 2:1 (i.e. a dose of deferasirox dispersible tablets that is numerically half of the deferoxamine dose). For deferasirox film-coated tablets, a dose ratio of 3:1 can be considered (i.e. a dose of deferasirox film-coated tablets that is numerically one third of the deferoxamine dose). However, this dosing recommendation was not prospectively assessed in the clinical studies. In addition, in patients with liver iron concentration ≥7 mg Fe/g dw with various rare anaemias or sickle cell disease, deferasirox dispersible tablets up to 20 and 30 mg/kg produced a decrease in liver iron concentration and serum ferritin comparable to that obtained in patients with beta-thalassaemia. A placebo-controlled randomised study was performed in 225 patients with MDS (Low/Int-1 risk) and transfusional iron overload. The results of this study suggest that there is a positive impact of deferasirox on event-free survival (EFS, a composite endpoint including non-fatal cardiac or liver events) and serum ferritin levels. The safety profile was consistent with previous studies in adult MDS patients. In a 5-year observational study in which 267 children aged 2 to <6 years (at enrollment) with transfusional haemosiderosis received deferasirox, there were no clinically meaningful differences in the safety and tolerability profile of deferasirox in paediatric patients aged 2 to <6 years compared to the overall adult and older paediatric population, including increases in serum creatinine of >33% and above the upper limit of normal on ≥2 consecutive occasions (3.1%), and elevation of alanine aminotransferase (ALT) greater than 5 times the upper limit of normal (4.3%). Single events of increase in ALT and aspartate aminotransferase were reported in 20.0% and 8.3%, respectively, of the 145 patients who completed the study. In a study to assess the safety of deferasirox film-coated and dispersible tablets, 173 adult and paediatric patients with transfusion dependent thalassaemia or myelodysplastic syndrome were treated for 24 weeks. A comparable safety profile for film-coated and dispersible tablets was observed. In patients with non-transfusion-dependent thalassaemia syndromes and iron overload, treatment with deferasirox dispersible tablets was assessed in a 1-year, randomised, double-blind, placebo-controlled study. The study compared the efficacy of two different deferasirox dispersible tablet regimens (starting doses of 5 and 10 mg/kg/day, 55 patients in each arm) and of matching placebo (56 patients). The study enrolled 145 adult and 21 paediatric patients. The primary efficacy parameter was the change in liver iron concentration (LIC) from baseline after 12 months of treatment. One of the secondary efficacy parameters was the change in serum ferritin between baseline and fourth quarter. At a starting dose of 10 mg/kg/day, deferasirox dispersible tablets led to reductions in indicators of total body iron. On average, liver iron concentration decreased by 3.80 mg Fe/g dw in patients treated with deferasirox dispersible tablets (starting dose 10 mg/kg/day) and increased by 0.38 mg Fe/g dw in patients treated with placebo (p<0.001). On average, serum ferritin decreased by 222.0 µg/l in patients treated with deferasirox dispersible tablets (starting dose 10 mg/kg/day) and increased by 115 µg/l in patients treated with placebo (p<0.001).