Randomized Phase II Study Evaluating the Efficacy and Safety of Deferasirox in Non-Transfusion-Dependent Thalassemia Patients with Iron Overload.

Clinically mild forms of thalassemia exist that, unlike β-thalassemia major, require no or only infrequent transfusions (eg. β-thalassemia intermedia, HbH disease). However, due to increased gastrointestinal iron absorption secondary to ineffective erythropoiesis these patients may still develop iron overload. For example, thalassemia intermedia patients (n=74) within a cross-sectional study had a mean serum ferritin (SF) of 1023 ng/mL (range 15–4140) and a mean liver iron concentration (LIC) of 9 mg Fe/g dw (range 0.5–32.1) at baseline despite most being transfusion-naïve (n=20) or rarely transfused (n=45), and only nine receiving regular transfusions (2–4 times/yr) (Taher et al. ITIFPaP: 13th International TIF Conference for Thalassaemia Patients & Parents, October 8–11 2008, Singapore, poster number MON04). Non-transfusional iron overload leads to the same serious clinical sequelae as transfusional iron overload, including liver, cardiac and endocrine dysfunctions. As patients with non-transfusional iron overload are not candidates for phlebotomy due to their underlying anemia, chelation therapy is the only available option for decreasing their iron burden. However, there is currently limited data available on the use of chelation in this population. The once-daily oral iron chelator deferasirox (Exjade^®) is currently approved for the treatment of iron overload in patients with transfusion-dependent anemia. This prospective, randomized, double-blind, placebo-controlled Phase II ‘THALASSA’ study will evaluate the efficacy and safety of deferasirox in patients with non-transfusion-dependent thalassemia.

Non-transfusion-dependent thalassemia patients aged ≥10 yrs will be randomized 2:1:2:1 to starting doses of deferasirox/placebo 5 mg/kg/day/ deferasirox/placebo 10 mg/kg/day over a planned 12-month treatment period. Doses can be doubled after 6 months should patients require a higher dose, which will be determined after 6 months of treatment. All patients are required to have a baseline LIC of ≥5 mg Fe/g dw, as measured by R2 magnetic resonance imaging, and SF levels of >300 ng/mL. Patients will be excluded if they have: anticipated regular transfusions during the study (sporadic transfusions, such as in cases of infection, are allowed); any transfusion within 6 months prior to study start, chelation within 1 month prior to study start; HbS variants of thalassemia; impaired renal and liver function. Primary efficacy endpoint is absolute change from baseline in LIC at 12 months; secondary efficacy endpoints include change from baseline in LIC after 6 months and in SF after 6 and 12 months, as well as change in hematological and iron metabolism parameters (eg hemoglobin, transferrin saturation). Safety assessments include adverse event and laboratory parameter monitoring. 156 patients are planned for inclusion.

As of 3 August 2009, 18 sites had been activated. Sites currently activated are in Thailand (n=5), Turkey (n=4), Italy (n=3), Malaysia (n=2), UK (n=2) Lebanon (n=1). Fifty-seven patients have been randomized to either deferasirox or placebo and their demographic data are shown in Table 1.

Table 1

Baseline characteristics

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Similar to transfusion-dependent thalassemia patients, non- transfusion-dependent thalassemia patients also develop iron overload. This ongoing study will generate prospective efficacy and safety data for the use of deferasirox in non-transfusion-dependent thalassemia patients with iron overload. To prevent long term complications due to iron overload, it is important to assess iron chelation in this patient population as they are not candidates for phlebotomy due to the underlying anemia.

Taher:Novartis: Honoraria, Research Funding. Porter:Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Vifor International: Membership on an entity's Board of Directors or advisory committees. Kattamis:Novartis: Consultancy, Honoraria, Speakers Bureau. Viprakasit:Thai Government: Employment; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Government Pharmaceutical Organization of Thailand: Honoraria, Research Funding. Lawniczek:Novartis Pharma AG: Employment. Pereno:Novartis Pharma AG: Employment. Schoenborn-Kellenberger:Novartis Pharma AG: Employment. Cappellini:Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Genzyme: Membership on an entity's Board of Directors or advisory committees.