Iron Chelation Therapy in Transfusion Dependent Patients with Thalassemia and Minimal Liver Iron Load

Recent advances in the treatment of iron overload in patients with transfusion- dependent thalassemia have dramatically changed iron related morbidity and mortality. Intensive chelation therapy by using combination therapy or monotherapy at high doses had led to total clearing of the iron in many patients. The best approach for chelation treatment in patients with low levels of iron overload is debatable.

This study included all the patients with thalassemia major with minimal liver iron overload, followed in our unit. More precisely, to be eligible for this observational study, the patients needed to have liver iron concentration (LIC) <1.5 mg Fe/gram dry weight tissue, defined by MRI, and to have at least a subsequent MRI evaluation after this time. The mean observation time, which was the time between the two MRIs, was 16.9±5.2 months.

Fourty five patients (22 females, 30 non-splemectomized, 21 HCV seropositive, mean age: 31±5.6 years) have reached minimal levels of iron overload in any time point after 2004. Thirty one of them have been treated with combined therapy of desferrioxamine (DFO) and deferiprone (DFP) and 5, 6 and 3 with monotherapy of deferasirox (DFX), DFP and DFO, respectively. After reaching these levels, 42% of the patients changed therapy, with the most frequent change being from combined therapy to monotherapy (15 patients).

Baseline ferritin levels at the time of the first MRI range from 43 to 4336 ng/ml (median 230 ng/ml) and they were not affected by spleen, gender or HCV status. Baseline LIC (mean 1.2 ± 1.7 mgFe/g.d.w.) correlated well with ferritin levels (Spearman's rho = 0.47, p<0.005), as did ferritin changes to LIC changes (Spearman's rho = 0.67, p<0.005).

The results on the follow up evaluation, stratified according to the actual treatment, are shown in the table

Deferiprone was less efficacious in controlling both LIC and ferritin levels compared to combination therapy (p=0.016 and 0.031, respectively). Fifteen out of 17 patients treated with DFP showed an increase in LIC, despite using the recommended dose. Six out of 9 patients treated with DFX, most at a low dose, showed an increase in LIC. There were no differences in changes in the cardiac parameters (LVEF, cardiac T2*) in between treatment groups. The efficiency of DFP and DFX, which represents the ratio of iron excreted to the theoretical maximum of iron that could be bound by the chelators, was calculated at 1.8±0.9 % and 15.2 ± 3.6 %, respectively.

Current iron chelation therapy regimens are able to render iron load-free many patients with thalassemia major. As iron accumulation from transfusions continues, a fine balance needs to be found in which neither worsening of iron overload nor toxicity from excessive dose of iron chelators will occur. This study showed that at low levels of iron overload both combination therapy and DFX can control iron accumulation, whether monotherapy with DFP may be insufficient to achieve iron balance in many patients. The dose of the chelators needs to be adjusted according to the needs and the clinical course of the patients, which can be predicted by the trend of the ferritin levels. Furthermore, it should be kept in mind that at low levels of iron overload, the iron chelators' efficiency may be lower than previously described.

Kattamis:NOVARTIS ONCOLOGY: Honoraria, Research Funding, Speakers Bureau; APOPHARMA: Honoraria. Ladis:NOVARTIS ONCOLOGY: Honoraria, Research Funding; APOPHARMA: Honoraria, Research Funding.