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.

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.

A candidate prostate cancer susceptibility gene at chromosome 17p

It is difficult to identify genes that predispose to prostate cancer due to late age at diagnosis, presence of phenocopies within high-risk pedigrees and genetic complexity. A genome-wide scan of large, high-risk pedigrees from Utah has provided evidence for linkage to a locus on chromosome 17p. We carried out positional cloning and mutation screening within the refined interval, identifying a gene, ELAC2, harboring mutations (including a frameshift and a nonconservative missense change) that segregate with prostate cancer in two pedigrees. In addition, two common missense variants in the gene are associated with the occurrence of prostate cancer. ELAC2 is a member of an uncharacterized gene family predicted to encode a metal-dependent hydrolase domain that is conserved among eukaryotes, archaebacteria and eubacteria. The gene product bears amino acid sequence similarity to two better understood protein families, namely the PSO2 (SNM1) DNA interstrand crosslink repair proteins and the 73-kD subunit of mRNA 3' end cleavage and polyadenylation specificity factor (CPSF73).

Strain-dependent productive infection of a unique eosinophilic cell line by human immunodeficiency virus type 1

Eosinophils are granulocytic leukocytes that function in both protective and pathological immune responses. They can be infected by HIV-1, but characterization of the infection has been hindered by lack of a productive cell culture model. In the present study, the unique eosinophilic cell line AML14.3D10 was used as a model to test the hypothesis that HIV-1 productively infects eosinophilic cells in a strain-dependent fashion. The AML14.3D10 cell line was cultured with one T cell-tropic (T-tropic) strain and two macrophage-tropic (M-tropic) strains of HIV-1 (HTLV-IIIB, HIV-1AdaM, and HIV-1Ba-L strains, respectively). Cytopathic effects were evident in living cultures and in stained slide preparations of AML14.3D10 cells infected with the T-tropic strain of HIV-1. Culture supernatants from infected AML14.3D10 cells contained high levels of HIV-1 p24 protein that peaked at approximately 7-10 days postinfection. A line of AML14.3D10 cells chronically infected with HTLV-IIIB and continuously producing high levels of virus was established. In contrast to the T-tropic strain, the M-tropic strains of HIV-1 did not productively infect the eosinophilic cell line. Thus, the AML14.3D10 eosinophilic cell line was permissive for a T-tropic strain but not for M-tropic strains of HIV-1. Flow cytometry revealed that uninfected AML14.3D10 cells were positive for the HIV-1 receptor CD4 and coreceptors CXCR4 and CCR5; the cell line was negative for CCR3. The lack of productive infection by M-tropic strains despite CCR5 expression indicates that strain-dependent infection may not be determined at the coreceptor level in AML14.3D10 cells.