Estimating duration of leucovorin rescue among patients with non-Hodgkin lymphoma receiving high dose methotrexate therapy

Abstract

Background: High dose methotrexate (HDMTX) regimen is used in lymphoma with central nervous system (CNS) involvement or as primary CNS prophylaxis. Serum MTX concentrations should be monitored by adjusting leucovorin rescue until reaching the target of < 0.05 μmol/L. However, monitoring MTX level is not feasible in many Thai hospitals. Objective: The study aimed to estimate the most appropriate duration of leucovorin rescue among patients with lymphoma receiving HDMTX. Methods: A retrospective chart review was conducted of patients with lymphoma receiving HDMTX regimen from January 2016 to December 2019. Baseline estimated glomerular filtration rate (eGFR) was categorized into 3 groups: (1) 30-59, (2) 60-89 and (3) ≥ 90 mL/min/1.73 m². Patients developing acute kidney injury after HDMTX were excluded. Primary outcome was number of days from HDMTX administration to the MTX level of under 0.05 μmol/L (ΔDay0.05). Results: Sixty-six patients (23 in each eGFR category; 36 men), with mean age of 60±12 years were included. Median dose of HDMTX was 4.0 g/m² (range 1.0-4.8). Factor significantly associated with ΔDays0.05 was baseline eGFR category (p < 0.001). Mean ΔDay0.05 in group 1 (eGFR 30-59 mL/min/1.73 m2) was 6.7±1.7 day (range 4-10), in group 2 (eGFR 60-89) was 4.6±1.3 day (range 3-7), and in group 3 (eGFR ≥ 90) was 3.5±0.5 days (range 3-4). Conclusion: Our result showed that the estimated duration of MTX level under 0.05 μmol/L after HDMTX administration correlated with eGFR value. Notably, physicians could use this data for predicting the stopping date of leucovorin rescue at hospitals where monitoring MTX level was not feasible.