Iohexol Clearance and Biomarker Analysis to Predict Toxicity in Patients With Acute Lymphoblastic Leukemia and Lymphoma Receiving High-Dose Methotrexate.

Background: High-dose methotrexate (HDMTX) remains integral to acute lymphoblastic leukemia/lymphoma (ALL) treatment. However, high MTX concentrations can lead to acute kidney injury (KI) and other toxicities. We investigated whether measured GFR (mGFR) by iohexol clearance better predicts delayed MTX excretion and/or toxicity compared with standard of care using an estimated GFR (eGFR). We also examined if KI biomarkers (urine KIM-1 and clusterin, serum cystatin C, and plasma FGF23) identify KI more frequently than serum creatinine (sCr) alone.

Procedure: ALL patients receive 4 doses of HDMTX with alkalinized IV fluids, leucovorin rescue, and MTX clearance per the standard of care. We obtained mGFRs before HDMTX doses 1 and 4. eGFR was calculated using the Schwartz formula and biomarkers of KI were collected around each HDMTX dose.

Results: Overall, there were some associations between the mGFR/biomarkers with KI and other toxicities, but mGFR was not found to be a better predictor of delayed MTX clearance or toxicity than eGFR. The biomarkers did not predict KI development more frequently than sCr alone.

Conclusions: On the basis of this study, there is no evidence that the current standard of care for determining the GFR in advance of HDMTX administration, nor postadministration management, should be adjusted.