Longitudinal Microbiome in Pediatric AML

Background: Pediatric acute myeloid leukemia (AML) is associated with prolonged hospitalization, high infection risk, and significant relapse rates. The gut microbiome has been implicated in cancer progression, complications, and infection susceptibility, yet its longitudinal changes in pediatric AML remain unexplored. Methods: Longitudinal stool samples were collected from 14 pediatric AML patients undergoing chemotherapy. The fecal microbiome, as assessed using 16S rRNA gene sequencing, was related to clinical data exploring relationships with relapse, overall survival (OS), Streptococcus mitis bacteremia (SMB), and Clostridioides difficile infections (CDI). Results: Microbiome diversity varied substantially across and within patients over time, but was not associated with relapse or OS. Fusobacterium abundance was significantly higher in patients who relapsed suggesting a potential role in disease progression. SMB was not directly linked to gut Streptococcus abundance; however, changes in Blautia, Marvinbryantia, Anaerococcus, Parabacteroides, and Dielma were important for predicting SMB using Mixed Effects Random Forest (MERF) models. Clostridioides abundance was not related to CDI development and, MERF analysis showed that decreases in Faith Phylogenetic Diversity and changes in the genera Anarofustis, Bilophila, Alistipes were related to CDI's. Conclusions: These findings suggest that specific gut microbiome changes may serve as biomarkers for AML relapse and infectious complications. Microbiome-based surveillance could provide early risk assessment and inform supportive care strategies for these patients. Further research is warranted to explore microbiome-targeted interventions to improve outcomes in this vulnerable population.