42 - Allosure values in pediatric kidney transplant recipients

Sunday, April 30, 2023

3:30 PM – 6:00 PM ET

Poster Number: 42
Publication Number: 42.349

Arundhati S. Kale, UC Davis, Sacramento, CA, United States; Stephanie Nguyen, University of California, Davis, School of Medicine, Sacramento, CA, United States; Daniel J. Tancredi, University of California, Davis, School of Medicine, Sacramento, CA, United States

Presenting Author(s)

Arundhati S. Kale, MD (she/her/hers)

Professor of Pediatrics
UC Davis
Sacramento, California, United States

Background:

AlloSure is a laboratory-developed, clinically-validated, next generation sequencing assay that utilizes single-nucleotide polymorphisms to accurately differentiate and quantify the fraction of donor-derived cell-free DNA (dd-cfDNA) in the plasma of solid organ transplant (tx) recipients without separate genotyping of either the donor or the recipient¹. Detection of dd-cfDNA is a marker of tissue injury and may be a sensitive marker of graft injury secondary to rejection.

Objective: Adult data shows a correlation between Allosure (AS) titers and graft injury; few data exist in children. Our objective was to determine the overall AS values in children, determine if any patterns emerged with donor/recipient size mismatch and correlation with biopsy (bx) findings.

Design/Methods: We obtained paired AS samples at least 4 weeks apart on 38 pediatric tx patients (pts). Analysis done to determine:

AS values in small pts (< 20 kg at time of tx) with adult donors vs size matched donor/recipients

Correlate AS values with biopsy findings

Overall AS range in pediatric pts

whether AS values changed over time in the first year post-tx

Results: Age range of pts was 2-19 years (yr); 16 male and 22 female; post-tx range to first draw was 4 weeks-16 yr. There were 13 white, 5 Black, 10 Hispanic and 10 Asian/mixed ethnicities. All received thymoglobulin induction with tacrolimus and mycophenolate mofetil maintenance immunosuppression. 14 pts had surveillance biopsies with paired Allosure assays. 4 pts were < 20 kg at the time of tx and received adult size kidneys. The mean overall AS value in pts with stable renal function was 0.33. Pts with normal histology on surveillance bx had a mean value of 0.34 vs 0.45 in those that showed borderline changes. Mean AS value was 0.46 in pts with size matched kidneys vs 0.67 in those < 20 kg. AS decreased from 0.49 to 0.18 when measured serially in the 1st year post-tx.

Conclusion(s):

Data from pediatric pts matches that reported in prior studies (mean value 0.33)

There was no statistical difference between AS values and biopsies showing "no rejection" vs "borderline changes"

AS decreased from 0.49 to 0.18 in serial measurements in the 1st year post-tx

Data from 4 pts who were < 20 kg at the time of tx with adult kidneys showed no statistical difference compared to pts with size matched kidneys

Limitations of the study are mainly small numbers in each group, given it is from a single center.

1. Grskovic, M., et al., Validation of a Clinical-Grade Assay to Measure Donor-Derived Cell-Free DNA in Solid Organ Transplant Recipients. J Mol Diagn, 2016. 18(6)