Delayed Elimination After High-dose Methotrexate in Pediatric Patients with Acute Lymphoblastic Leukemia and Non-Hodgkin Lymphoma

ABSTRACT

BACKGROUND: High doses of methotrexate (MTX) are often used in various chemotherapy protocols to treat acute lymphoblastic leukemia (ALL) and non-Hodgkin's lymphoma (NHL) in children, but its delayed elimination increases the occurrence of adverse events, such as bone marrow suppression. The aim of this study was to investigate the elimination of MTX at 24 and 48 hours. METHODS: We retrospectively analyzed electronic medical records of ALL or NHL pediatric patients who received 5 g/m² MTX infusion over 24 hours (between June, 2012 and July, 2018) at the Yonsei University Health System, Korea. The delayed elimination of MTX concentrations was assessed with 100 or 150 µM MTX at 24 hours, and 2 or 5 µM at 48 hours. RESULTS: Among the 85 MTX cycles administered, 23 cycles were classified in delayed elimination group, and 62 cycles showed normal elimination. At 24 hours, the delayed elimination group with MTX concentration > 100 µM showed higher percentage than group with MTX concentration < 100 µM (45.8% vs. 19.7%, p = 0.015). However, no differences were observed at 150 µM MTX (p = 0.66). At 48 hours, the delayed elimination was higher than the normal elimination at both concentration baselines (p < 0.001 at 2 µM, p = 0.024 at 5 µM). CONCLUSIONS: MTX concentrations greater than 100 µM show high probability of delayed elimination at 24 hours. When MTX levels are above normal, leucovorin and hydration regimens should be continued to prevent delayed elimination.