Pharmacokinetic assessments. (A) Mean systemic exposure levels (DSX-AUC) of each group over the 24-hour time course after administration. Error bars represent standard error. (Adequate responders [●]; inadequate responders [▵].) (B) Free DSX concentrations in individual study participants over the 24-hour time course after administration. The actual average dose per kilogram was 34.7 plus or minus 1.12 mg (SD). (Adequate responders [●]; inadequate responders [▵].). One inadequate responder has documented outpatient noncompliance but good exposure in observed therapy setting. (2): The youngest inadequate responder has very rapid clearance and low exposure. Total DSX (free DSX +Fe [ICL670]₂) yielded similar results (not shown). (C) Box and whisker plots of exposure (area under the curve) of free DSX levels in responders versus inadequate responders (P < .001). Box represents median interquartile range and whiskers are minimum to maximum range. Generated with the Mann-Whitney test.