Rates of severe neutropenia and infection risk in patients treated with deferiprone: 28 years of data

Patients treated with deferiprone for transfusional iron overload may experience idiosyncratic drug-induced neutropenia (IDIN) that may increase risk of infection. This analysis examined the rates of severe IDIN and risk of serious infections at different absolute neutrophil count (ANC) levels during deferiprone treatment. Events of severe IDIN (ANC <0.5 × 109/L) and associated serious infections from clinical trials and postmarketing setting were analyzed by discrete ANC levels: group 1, 0.2 × 109/L to 0.5 × 109/L; group 2, 0.1 × 109/L to 0.199 × 109/L; group 3, <0.1 × 109/L. In clinical trials, 22 events of severe IDIN occurred (group 1, n = 9; group 2, n = 3; group 3, n = 10), and rates of severe IDIN per 100 patient-years were 0.45 in group 1; 0.15 in group 2; and 0.50 in group 3 (1990.26 patient-years deferiprone exposure). All serious infections were in group 3 (3/10 [30.0%]). In the postmarketing setting, 176 events of severe IDIN were reported (group 1, n = 65; group 2, n = 20; group 3, n = 91) and rates of severe IDIN per 100 patient-years were 0.06 in group 1; 0.02 in group 2; and 0.08 in group 3 (111 570.24 patient-years deferiprone exposure). Rates of serious infection were 7.7% (5/65) in group 1; 10% (2/20) in group 2; and 13.2% (12/91) in group 3. Our findings suggest a high risk of serious infections with ANC <0.2 × 109/L during deferiprone treatment, a level consistent with the recent neutropenia guidelines.