ATC Abstracts

American Transplant Congress abstracts

  • Home
  • Meetings Archive
    • 2022 American Transplant Congress
    • 2021 American Transplant Congress
    • 2020 American Transplant Congress
    • 2019 American Transplant Congress
    • 2018 American Transplant Congress
    • 2017 American Transplant Congress
    • 2016 American Transplant Congress
    • 2015 American Transplant Congress
    • 2013 American Transplant Congress
  • Keyword Index
  • Resources
    • 2021 Resources
    • 2016 Resources
      • 2016 Welcome Letter
      • ATC 2016 Program Planning Committees
      • ASTS Council 2015-2016
      • AST Board of Directors 2015-2016
    • 2015 Resources
      • 2015 Welcome Letter
      • ATC 2015 Program Planning Committees
      • ASTS Council 2014-2015
      • AST Board of Directors 2014-2015
      • 2015 Conference Schedule
  • Search

Analytical Evaluation and Comparison to STR of an Accurate and Sensitive Microchimerism Monitoring Tool for Liver Transplant Recipients

A. S. Kothari1, C. Egidio1, J. Miles2, N. Gulbahce1, S. Dholakia3, M. Grskovic4

1Clinical Development, CareDx, South San Francisco, CA, 2Medical Affairs, CareDx, Brooklyn, NY, 3Medical Affairs, CareDx, South San Francisco, CA, 4CareDx, Brisbane, CA

Meeting: 2022 American Transplant Congress

Abstract number: 1578

Keywords: Bone marrow transplantation, Graft-versus-host-disease, Liver transplantation, Tolerance

Topic: Basic Science » Basic Clinical Science » 17 - Biomarkers: Clinical Outcomes

Session Information

Session Name: Biomarkers: Clinical Outcomes

Session Type: Poster Abstract

Date: Tuesday, June 7, 2022

Session Time: 7:00pm-8:00pm

 Presentation Time: 7:00pm-8:00pm

Location: Hynes Halls C & D

*Purpose: Peripheral blood chimerism is associated with clinically relevant events post liver transplantation (LT). Accurate quantification of donor chimerism in LT recipients with ultra-sensitive chimerism test AlloHeme may provide a novel biomarker to assess the association of chimerism with graft and recipient outcomes such as GvHD, engraftment, and tolerance. The most common method for chimerism testing utilizes Short Tandem Repeats (STR). However, STR-based chimerism has low sensitivity and high variability. These limitations may inhibit consistent and accurate detection of chimerism, including micro chimerism (defined as <1% donor chimerism). We describe the validation of AlloHemeTM , an ultra-sensitive Next Generation Sequencing (NGS) based chimerism surveillance solution and compare it to the STR-based chimerism method.

*Methods: To evaluate the chimerism assays, reference samples were prepared by mixing DNA samples to mimic post-transplant DNA ratio in the range from 0.01% to 75%, using unrelated and related donors. AlloHeme testing was performed at CareDx’s central laboratory in Brisbane, CA, using NGS to genotype 405 Single Nucleotide Polymorphisms (SNPs) distributed across all 22 pairs of human autosomes. The STR test was performed in a CLIA-certified/CAP-accredited clinical laboratory, with an established Limit of Detection (LOD) of 1%.

*Results: For unrelated donors, AlloHeme LOD was 0.035% and 0.044% when 100ng or 8ng of DNA was used respectively. For haplo-identical donors, LOD was 0.043% and 0.067% when 100ng or 8ng of DNA was used respectively. The assay was highly precise with coefficients of variation of 1.35% and 1.39% for repeatability and reproducibility respectively, when tested at 1% chimerism across 6 replicates. Accuracy was analyzed and compared across AlloHeme and STR close to their respective LODs at 0.06% and 1% respectively, using bias calculation [(observed-expected)/expected]. At 0.06% chimerism, AlloHeme was highly accurate with no bias, while STR showed 75% bias at 1% chimerism.

*Conclusions: These results demonstrate the high accuracy and sensitivity, at low DNA inputs, of AlloHeme in detecting micro chimerism compared to the commonly used approach using STR. AlloHeme may be suited for LT recipient surveillance to identify early GvHD or longer term engraftment and tolerance acquisition, allowing precise clinical diagnosis and potential intervention for improved patient outcomes. AlloHeme as an ultra sensitive chimerism detection tool, along with a suite of other post-LT relevant biomarkers, is being evaluated for clinical validation in the prospective, multi-center Molecular Assessment and Profiling of Liver transplant rEcipients (MAPLE) study (NCT 04793360).

  • Tweet
  • Click to email a link to a friend (Opens in new window) Email
  • Click to print (Opens in new window) Print

To cite this abstract in AMA style:

Kothari AS, Egidio C, Miles J, Gulbahce N, Dholakia S, Grskovic M. Analytical Evaluation and Comparison to STR of an Accurate and Sensitive Microchimerism Monitoring Tool for Liver Transplant Recipients [abstract]. Am J Transplant. 2022; 22 (suppl 3). https://atcmeetingabstracts.com/abstract/analytical-evaluation-and-comparison-to-str-of-an-accurate-and-sensitive-microchimerism-monitoring-tool-for-liver-transplant-recipients/. Accessed May 28, 2025.

« Back to 2022 American Transplant Congress

Visit Our Partner Sites

American Transplant Congress (ATC)

Visit the official site for the American Transplant Congress »

American Journal of Transplantation

The official publication for the American Society of Transplantation (AST) and the American Society of Transplant Surgeons (ASTS) »

American Society of Transplantation (AST)

An organization of more than 3000 professionals dedicated to advancing the field of transplantation. »

American Society of Transplant Surgeons (ASTS)

The society represents approximately 1,800 professionals dedicated to excellence in transplantation surgery. »

Copyright © 2013-2025 by American Society of Transplantation and the American Society of Transplant Surgeons. All rights reserved.

Privacy Policy | Terms of Use | Cookie Preferences