Infectious Complications During Reinduction in Children with Relapsed Acute Lymphoblastic Leukemia: A Descriptive Analysis.

Children with relapsed acute lymphoblastic leukemia (ALL) face higher rates of infection and treatment-related mortality than at initial diagnosis. Although immunotherapy is increasingly used in the relapsed setting, combination intensive chemotherapy remains the standard approach for reinduction. Serious infections during this phase can delay or preclude curative therapy. We aimed to describe the incidence and pattern of infections during reinduction in this high-risk population. In this single-center retrospective study, we reviewed charts of patients with relapsed ALL treated with combination chemotherapy reinduction at British Columbia Children's Hospital between 2006 and 2022. Forty-three patients were included (median age 10.2 years at relapse). Most (90%) received a standard four-drug reinduction. Median duration of severe neutropenia was 20.8 days. About half (51%) experienced at least one infection, including 16% with confirmed or probable fungal infection. Infection was associated with significantly longer hospitalization (median 17 vs. 7 days; p = 0.006). While no predictors reached statistical significance, hyperglycemia and neutropenia ≥ 21 days were associated with higher odds of infection. Overall survival did not differ significantly by infection status (log-rank p = 0.43). Infectious complications remain common during reinduction chemotherapy for relapsed ALL despite advances in supportive care. While pharmacologic and clinical strategies may reduce risk, safer and more targeted reinduction approaches are urgently needed to optimize outcomes in this vulnerable group.