Elevated total iron-binding capacity as a predictor of response to deferasirox therapy in the setting of chronic iron overload.

It is difficult to predict the efficacy of deferasirox (DFX) as its pharmacokinetics varies among patients. The area under the curve (AUC) is reportedly useful for determining adequate DFX dosage; however, serum concentration measurements are often challenging. Effective DFX dosage is thus defined by assessing the efficacy of this agent in clinical practice. To analyze a predictive response marker to DFX therapy for use in adjusting the effective dosage during the early treatment phase, we retrospectively evaluated 39 DFX-treated patients. We defined response as a >40 % decrease in serum ferritin concentration from the pretreatment level. A maximum elevation of the total iron-binding capacity (TIBC) correlated with response in a multivariate analysis of iron metabolic markers (R (2) = 0.37, p < 0.001). A receiver operating characteristic curve analysis revealed that TIBC elevation had an AUC of 0.85 (p < 0.001) and the optimal cut-off value of TIBC elevation was 150 µg/dl. TIBC elevation of >150 µg/dl is a favorable predictor of effective ferritin reduction in DFX therapy (hazard ratio 29.6, 95 % confidence interval 4.8-183.6; p < 0.001). DFX therapy with TIBC monitoring may enable the determination of the minimum effective DFX dosage.