Trifecta-Lung cfDNA-MMDx Study

The current standard for assessment of rejection in lung transplants is a transbronchial biopsy (TBB) interpreted by histology according to International Society of Heart and Lung Transplantation (ISHLT) guidelines. This has considerable error rates, many due to the high disagreement among pathologists. There is a need for new methods of assessing TBBs. Furthermore, by analyzing different types of biopsies (TBBs and endobronchial - 3BMBs), we hope to improve the safety of the biopsy procedure, while maintaining its accuracy. The emergence of blood donor-derived cell-free DNA (dd-cfDNA) measurement offers a new opportunity for screening for rejection. To address the unmet need for precision and accuracy, the Alberta Transplant Applied Genomics Centre (ATAGC, University of Alberta) has developed a new diagnostic system - the Molecular Microscope® Diagnostic System (MMDx), which uses microarrays to define the genome-wide gene expression and interpret lung transplant rejection and injury ((chronic lung allograft dysfunction (CLAD) related changes)). Now a new screening test is being introduced: the monitoring of dd-cfDNA released in the blood by the heart during rejection. The Natera Inc dd-cfDNA Prospera® test is based on the massively multiplex polymerase chain reaction that targets 13,392 single nucleotide polymorphisms and targeted sequences are quantified by Next Generation Sequencing. The Prospera® test has been done on kidney transplant recipients and detected "active rejection" and differentiated it from borderline rejection and no rejection. However, Prospera® test was not examined (the dd-cfDNA results) in lung transplant recipients. dd-cf-DNA test for lung transplants must now be calibrated against MMDx that is based on global gene expression, the new standard for biopsy interpretation. The present study will calibrate centrally measured (Natera Inc) dd-cfDNA levels obtained at the time of an indication or protocol biopsy against the MMDx measurements of T cell-mediated rejection (TCMR), antibody-mediated rejection (ABMR-like) and tissue injury. The present study will compare dd-cfDNA and MMDx in 600 prospectively collected TBBs and 3BMBs for clinical indications and protocol, and accompanying 1800 blood samples, to calibrate the dd-cfDNA (Natera Inc.) levels against the MMDx biopsy diagnoses of TCMR, ABMR-like (and its stages), and injury, as well as central assessment of Human Leukocyte Antibody (HLA) antibody (One Lambda), interpreted centrally as donor specific antibody (DSA) based on the tissue typing results. This study is an extension of the INTERLUNG ClinicalTrials.gov identifier: NCT02812290.

Currently the study accrued 141 paired TBBs and 3BMBs, 182 TBBs, 267 corresponding blood samples for dd-cfDNA test and 159 for DSA test.

• Assessment of donor-specific antibody status [Time frame: 6 months]
• .Estimate the false positive rate of dd-cfDNA for MMDx and histology in indication and protocol biopsies [Time frame: 6 months]
• Determine whether calibrated dd-cfDNA blood test will replace biopsies [Time frame: 6 months]
• Determine whether calibrated dd-cfDNA blood test predicts the effect of treatment [Time frame: 6 months]