LAUSR

INTRODUCTION Cancer-related fatigue (CRF) is one of the most distressing and persistent symptoms reported during pediatric acute lymphoblastic leukemia (ALL) therapy; however, information on the pathways underlying CRF severity is limited. Therefore, we conducted global metabolomics profiling of cerebrospinal fluid (CSF) samples to provide insight into the underlying mechanisms of CRF. METHODS Fatigue in pediatric ALL patients (2012-2017) was assessed during post-induction therapy approximately 6-months post-diagnosis. Post-induction CSF was collected on 171 participants, comprising discovery (n=86) and replication (n=85) cohorts. We also conducted secondary validation using diagnostic CSF from 48 replication cohort participants. CSF metabolomic profiling was performed using gas chromatography-mass spectrometry (MS) and liquid chromatography-MS/MS. Kendall's rank correlation was used to evaluate associations between metabolite abundance and CRF. False discovery rate (FDR) was used to account for multiple comparisons. RESULTS Participants were 56% male and 59% Hispanic with a mean age at diagnosis of 8.5 years. A total of 274 CSF-derived metabolites were common to the discovery and replication cohorts. Eight metabolites were significantly associated with fatigue in the discovery cohort (p<0.05), of which three were significant in the replication cohort, including FDR-corrected associations with gamma-glutamylglutamine (pcombined = 6.2E-6) and asparagine (pcombined = 3.5E-4). Notably, the abundance of gamma-glutamylglutamine in diagnostic CSF samples was also significantly associated with fatigue (p=0.0062). CONCLUSION The metabolites identified in our assessment have been implicated in neurotransmitter transportation and glutathione recycling, suggesting glutamatergic pathways or oxidative stress may contribute to ALL-associated CRF. This information could inform targeted therapies for reducing CRF in at-risk individuals.