- Arm II: Participants receive placebo PO QD on days 1-42. Participants complete a semi-automated, computerized cognitive-testing system (CogState) designed to assess psychomotor, attention/vigilance, memory, and other components of executive function by presenting different tasks, each with its own set of rules, at baseline and after completion of study therapy. Participants also complete the PedsQL Multidimensional Fatigue Scale (Peds QL-MFS).