Infectious complications in Philadelphia-Negative adolescent and young adult acute lymphoblastic leukemia patients in the era of pediatric-inspired regimen.

INTRODUCTION: Pediatric acute lymphoblastic leukemia (ALL) has a cure rate above 90%, but outcomes in adult remain poor, with 3-year survival around 40%. Adolescents and young adults (AYAs) fall between these groups, often facing worse disease features and treatment-related risks. While pediatric-inspired regimens improve survival in AYAs, they also raise the issue of infection due to treatment intensity. METHODS: A retrospective analysis was conducted on AYA-ALL patients treated at Chiang Mai University Hospital from 1 January 2007 to 31 December 2023. Data were accessed for research purpose from 10 January 2024 to 31 December 2024. Patients received either pediatric-inspired (TPOG) or adult regimens (Hyper-CVAD or GMALL). Infections were classified as clinically (CDI) or microbiologically documented (MDI). Logistic regression identified infection risk factors. RESULTS: Among 94 patients (62.8% male; median age 22.9 years), 56.4% received TPOG and 43.6% adult regimens. Infections occurred in 79.8%, higher with adult regimens (90.2% vs. 71.7%, p = 0.03). CDI was more frequent in adult regimens (73.4% vs. 52.8%, p = 0.04), while fungal infections predominated in TPOG (26.4% vs. 9.8%, p = 0.04). Adult regimens independently increased infection risk (OR 3.55; 95% CI 1.02-12.36, p = 0.04). Infection peaks occurred during induction (47.8%) and consolidation (51.8%). Gram-negative bacteria were most common (85%), mainly Escherichia coli (27%) and Salmonella spp. (21%). The invasive pulmonary aspergillosis was 11.7%. CONCLUSION: AYA-ALL patients are highly susceptible to infections, particularly with adult regimens. Fungal infections were more frequent with TPOG. Strengthening infection prevention and providing early treatment are vital.