Early, empiric high-dose leucovorin rescue in lymphoma patients treated with sequential doses of high-dose methotrexate.

BACKGROUND: In patients exposed to high-dose methotrexate (HDMTX; >1g/m2) with a history of elevated methotrexate (MTX) concentrations during previous doses, it is unclear whether prescribing high-dose leucovorin (HDLV) rescue limits future high levels or reduces the likelihood of acute kidney injury (AKI). METHODS: This retrospective, single-center study longitudinally followed adult lymphoma patients treated with HDMTX between 1/1/2011 and 10/31/2017 from diagnosis until 30 days after the last HDMTX dose. Endpoints included elevated MTX concentrations at 48 h (>1.0 µmol/L) and incident AKI after each HDMTX dose. RESULTS: The 321 included patients had a median (IQR) age of 65 (57, 72) years, 190 (59%) were male, and 293 (91%) were Caucasian. There were 1558 HDMTX doses [median (IQR) 3 (2, 6) doses per patient] prescribed with 265 (83%) patients receiving more than one MTX dose. Those receiving HDLV rescue were more likely to have an elevated MTX concentration after that dose (OR = 2.69, 95% CI: 1.75-4.11, p < 0.001). Receiving HDLV rescue was associated with a greater likelihood of AKI after MTX (OR = 2.18, 95% CI: 1.38-3.43, p < 0.001). Hospital LOS was longer in those prescribed empiric HDLV rescue after MTX than those prescribed standard leucovorin with an estimated difference of 1.1 days, (95% CI: 0.5-1.7, p < 0.001). CONCLUSION: Sequential HDMTX doses are associated with a significant incidence of elevated MTX levels and AKI during lymphoma management. HDLV rescue prescribed during subsequent MTX doses in patients with a previously elevated level was not associated with improved safety outcomes. The optimal supportive care strategy following HDMTX administration requires further investigation.

Ideal Body Weight-Based Dosing of Rabbit Antithymocyte Globulin for Cost Minimization in Kidney Transplantation.

INTRODUCTION: Contemporary dosing strategies for rabbit anti-thymocyte globulin (rATG) in kidney transplantation aim to reduce cumulative exposure, minimizing long-term adverse events. The use of ideal body weight-based dosing has been trialed, however concern for increased rejection post-transplant exists due to lower doses of rATG. Research Questions: The primary aim of this study was to compare rejection rates between rATG dosing protocols using actual body weight and ideal body weight and secondarily to evaluate cost savings following protocol implementation. DESIGN: This was a retrospective study surrounding implementation of an ideal body weight-based dosing protocol for rATG. We compared 75 kidney transplant recipients in whom rATG was dosed based on actual body weight (pre-protocol group) to 64 in whom dosing was based on ideal body weight (post-protocol group), following a nine-month washout. RESULTS: The mean cumulative rATG dose in the pre-protocol group was 6.3 mg/kg of actual body weight. When ideal body weight was used in the post-protocol group, the mean dose was 4.5 mg/kg of actual body weight. The rejection rate was 18.7% pre-protocol and 23.4% postprotocol, which did not represent a statistically significant difference (p = 0.491). The actual annual cost savings after protocol implementation exceeded $162,000, approximately $2,500 per patient. CONCLUSION: Results suggest ideal body weight-based dosing of rATG may reduce exposure and cost, without significantly impacting the risk of rejection in kidney transplant recipients. More studies are needed to confirm these findings.