A Multi-Center, Open Label Study Evaluating the Efficacy of Iron Chelation Therapy with Deferasirox in Transfusional Iron Overload Patients with Myelodysplastic Syndromes or Aplastic Anemia Using Quantitative R₂ MRI

Transfusion-related iron overload and its consequences are emerging challenges in chronically transfused patients with myelodysplastic syndromes (MDS) or aplastic anemia (AA). Measurement of liver iron concentration (LIC) is used as a surrogate for total iron burden to guide chelation therapy in transfusion-dependent patients. Although deferasirox (Exjade®, ICL670) is an oral iron chelation agent that is now widely available for the treatment of transfusional hemosiderosis, the clinical data on its specific benefits of iron chelation, including reduction of LIC, in transfusion-related iron overload patients with MDS or AA has been limited. We have prospectively investigated the efficacy of deferasirox for iron chelation by serial measurement of serum ferritin level and LIC, which is measured in vivo using quantitative tissue proton transverse relaxation rates (R2) magnetic resonance imaging (MRI), in transfusional iron overload patients with MDS or AA. Here we report the interim analysis data. A total of 79 patients with de novo MDS (n = 29) or idiopathic AA (n = 50) showing serum ferritin level over 1,000ng/ml were enrolled from 23 institutes. All patients were regularly transfused and received a median of 30 red blood cells (RBC) units in the year prior to the start of the study. Among MDS cases, 3 (10.3%), 20 (69.0%), and 4 cases (13.8%) were categorized as IPSS low-risk, intermediate-1-risk, and intermediate-2-risk group, respectively. In AA cases, 34 (64%) were severe form. Mean value of serum ferritin level in enrolled patients was 4,417 ± 3,378 (4,788 ± 3,996 in MDS, 4,185 ± 2,962 in AA) ng/ml at the time of deferasirox initiation. LIC value was measured using quantitative R₂ MRI and FerriScan (Resonance Health, Australia) analysis. Mean value of LIC was 23.9 ± 13.8 (26.1 ± 15.0 in MDS, 22.8 ± 13.2 in AA) mg Fe/g dry weight. Linear regression analysis indicated a close correlation between serum ferritin level and LIC (r=0.55, p<0.001). Deferasirox was given orally at a dose of 20 mg/kg/day for at least 6 months to all patients. If the serum ferritin falls below 500 ng/ml, treatment was withheld. A consistent decrease in the serum ferritin level was demonstrated during the first 6 months in vast majority of patients despite of continued transfusion (209.7 ± 159.9 ng/ml and 324.0 ± 289.4 ng/ml per month in MDS and AA, respectively). Over the study period, patients with MDS or AA received a mean of 3.7 and 2.7 units RBC per month, respectively. After 6 months of medication, a slower decrease in the serum ferritin level was observed in MDS patients. In 30 cases, one-year medication of deferasirox was completed. At the end of study (EOS), the serum ferritin levels were significantly decreased to 3,085 ± 2,150 ng/ml (64.4% of baseline level) and 2,913 ± 2,232 ng/ml (69.6% of baseline level, p<0.01) in MDS and AA, respectively. One-year follow-up R₂ MRI could be evaluated in 24 cases, and LIC was significantly decreased to the level of 19.3 ± 13.6 mg Fe/g dry weight (67.4% of baseline value, p=0.01). Decrease in the level of LIC at EOS in MDS (64.3% of baseline) was comparable to that in AA cases (68.5% of baseline). The most common drug-related adverse events (AE) were gastrointestinal disturbances, non-progressive increase in serum creatinine, and skin rash. However, AE were transient and mild-to-moderate in severity. Deferasirox was discontinued in 28 (35.4%) cases because of death (7 in MDS and 6 in AA), patient refusal (11 cases), and decrease in the serum ferritin level below 500ng/ml (4 cases). All death was ascribed to disease-related causes including cytopenia in nine (11.4%) and disease progression in one (1.3%). This study clearly shows that deferasirox is effective in reducing LIC and serum ferritin level in transfusional iron overload patients with MDS or AA, even with ongoing transfusion requirement, and well tolerated. Careful assessment of patient’s transfusion requirement will be important in making dose adjustment according to purpose of iron chelation. Data from extension phase of this clinical trial may expand our knowledge about the beneficial effects of deferasirox on prolonging survival and improving quality of life in these patients.