Influence of Nitrosative Stress on Fatigue During Childhood Leukemia Treatment

The focus on a cure for childhood leukemia over the last three decades has resulted in survival rates of more than 80%. However, efforts to manage leukemia-treatment symptoms have not kept pace with new therapies. Symptom toxicity during treatment can result in complications, treatment delays, and therapy dose reductions. Compromise in therapy can negatively influence the quality of life and, even more notably, jeopardize chances for long-term survival. This study examined biologic mechanisms that influence fatigue caused by increased reactive oxidative species (ROS) or actual failure of the antioxidant defense system due to genetic variation by investigating reactive nitrosative species, a "downstream" consequence of ROS. The specific aims of this study were to characterize the trajectory of nitrosative stress during acute lymphoblastic leukemia treatment and evaluate the influence of nitrosative stress on fatigue. A repeated measures design was used to evaluate the fatigue experienced by 186 children and adolescents, 3-18 years of age, with a diagnosis of leukemia during the most intense phase of treatment. An established biomarker of nitrosative stress, protein 3-nitrotyrosine (3NT) residues in the cerebral spinal fluid, was evaluated at diagnosis, postinduction, and consolidation phases of treatment. Higher fatigue was associated with higher 3NT levels at the beginning of treatment. Two distinct groups of children experienced either consistently high or consistently low 3NT levels across the treatment trajectory, from diagnosis to 12 months postinduction. Findings from this study support continued exploration into the phenotypic biochemical mechanisms that influence a reactive response to childhood cancer treatment.