Meta-analytic review of the clinical effectiveness of oral deferiprone (L1)

Abstract

Objective: To summarize efficacy and effectiveness in iron overloaded patients treated with the orally active iron chelator deferiprone also known as L₁ or, using meta-analysis of the literature.

Methods: We reviewed the literature, searching Medline and Embase databases, as well as reviews and other literature on the topic. Inclusion criteria were: original clinical trials reporting results for serum ferritin concentration (SF), hepatic iron concentration or urinary iron excretion (UIE). Efficacy data had to have been reported after ≥3 months of treatment. Data were combined using a random effects model (Cochrane) modified for use with single groups to produce a point estimate and a 95% confidence interval. To summarize the clinical effectiveness, overall proportion of patients where deferiprone was able to reduce serum ferritin was calculated. We also examined average (mg · l⁻¹) serum ferritin levels over the reported time (mean) and absolute decrease from the baseline after therapy. To summarize efficacy, success was defined as the proportion of patients who achieved UIE of 25 mg per day or 0.5 mg · kg⁻¹ · day⁻¹, which equals the average amount received from monthly blood transfusions. We also calculated the overall average level (mg per day) of UIE over the reported time of therapy (mean). As part of a sensitivity analysis, data were analyzed for two ranges of deferiprone dosage: ≤50 mg · kg⁻¹ · day⁻¹ and ≥75 mg · kg⁻¹ · day⁻¹.

Results: Of 83 identified references, nine clinical trials met our inclusion criteria, providing data for 129 iron overloaded patients. After a mean of 16 months of therapy (range 6.4–36 months) with 66.4 mg · kg⁻¹ · day⁻¹ (mean) of deferiprone, 75.5% of highly iron overloaded patients had a decrease in serum ferritin from baseline. The average drop in serum ferritin of 0.8 mg · l⁻¹ was 23.5% from baseline. The overall average UIE for therapy was 28.8 mg per day in patients receiving ≥75 mg · kg⁻¹ · day⁻¹ over 8.5 months of therapy. At the same dosage, more than half of the patients (51.8%) achieved negative iron balance. When studies with patients receiving lower dosage (≤50 mg · kg⁻¹ · day⁻¹) were included, the success rate was 45.1%.

Conclusion: Overall, deferiprone has clinical efficacy in achieving negative iron balance and reducing body iron burden in highly iron overloaded patients. After an average of 16 months of deferiprone in doses ≥75 mg · kg⁻¹ · day⁻¹, most patients had a decrease in ferritine concentration.