ORLANDO – The oral iron chelator deferiprone showed noninferiority to deferoxamine for treating iron overload in patients with sickle cell disease and other rare anemias in a randomized open-label trial.
The least squares mean change from baseline in liver iron concentration (LIC) – the primary study endpoint – was –4.04 mg/g dry weight (dw) in 152 patients randomized to receive deferiprone, and –4.45 mg/g dw in 76 who received deferoxamine,, of the Children’s Hospital of Philadelphia reported at the annual meeting of the American Society of Hematology.
The upper limit of the stringent 96.01% confidence interval used for the evaluation of noninferiority in the study was 1.57, thus the findings demonstrated noninferiority of deferiprone, Dr. Kwiatkowski said.
Deferiprone also showed noninferiority for the secondary endpoints of change in cardiac iron (about –0.02 ms on T2* MRI, log-transformed for both groups) and serum ferritin levels (–415 vs. –750 mcg/L for deferiprone vs. deferoxamine) at 12 months. The difference between the groups was not statistically significant for either endpoint.
Study participants, who had a mean age of 16.9 years, were aged 2 years and older with LIC between 7 and 30 mg/g dw. They were recruited from 33 sites in nine countries and randomized 2:1 to receive deferiprone or deferoxamine for up to 12 months; in patients with lower transfusional iron input and/or less severe iron load, deferiprone was dosed at 75 mg/kg daily and deferoxamine was dosed at 20 mg/kg for children and 40 mg/kg for adults. In those with higher iron input and/or more severe iron load, the deferiprone dose was 99 mg/kg daily and the deferoxamine doses were up to 40 mg/kg in children and up to 50 mg/kg for adults.
“Over the course of the treatment period, the dosage could be adjusted downward if there were side effects, or upward if there was no improvement in iron burden,” Dr Kwiatkowski said, adding that after 12 months, patients had the option of continuing on to a 2-year extension trial in which everyone received deferiprone.
No significant demographic differences were noted between the groups; 84% in both groups had sickle cell disease, and the remaining patients had other, rarer forms of transfusion-dependent anemia. Baseline iron burden was similar in the groups.
The rates of acceptable compliance over the course of the study were also similar at 69% and 79% in the deferiprone and deferoxamine arms, respectively, she noted.
No statistically significant difference between the groups was seen in the overall rate of adverse events, treatment-related AEs, serious AEs, or withdrawals from the study due to AEs. Agranulocytosis occurred in one deferiprone patient and zero deferoxamine patients, and mild or moderate neutropenia occurred in four patients and one patient in the groups, respectively.
All episodes resolved, no difference was seen in the rates of any of the serious AEs, and no unexpected serious adverse events occurred, she said.
Patients with sickle cell disease or other rare anemias whose care includes chronic blood transfusions require iron chelation to prevent iron overload. Currently, only deferoxamine and deferasirox are approved chelators in these patient populations, she said, noting that in 2011 deferiprone received accelerated Food and Drug Administrationfor the treatment of thalassemia.
The current study was conducted because of an FDA requirement for postmarket assessment of deferiprone’s efficacy and safety in patients with sickle cell disease and other anemias who develop transfusional iron overload. It was initiated prior to the approval of deferasirox for the first-line treatment of SCD, therefore it was compared only with deferoxamine, she explained.
Dr. Kwiatkowski reported research funding from Apopharma, bluebird bio, Novartis, and Terumo, and consultancy for Agios, bluebird bio, Celgene, and Imara.