Real Time Central Assessment of Kidney Transplant Indication Biopsies by Microarrays: The INTERCOMEX Study

Abstract

The authors conducted a prospective trial to assess the feasibility of real time central molecular assessment of kidney transplant biopsy samples from 10 North American or European centers. Biopsy samples taken 1 day to 34 years posttransplantation were stabilized in RNAlater, sent via courier overnight at ambient temperature to the central laboratory, and processed (29 h workflow) using microarrays to assess T cell- and antibody-mediated rejection (TCMR and ABMR, respectively). Of 538 biopsy samples submitted, 519 (96%) were sufficient for microarray analysis (average length, 3 mm). Automated reports were generated without knowledge of histology and HLA antibody, with diagnoses assigned based on Molecular Microscope Diagnostic System (MMDx) classifier algorithms and signed out by one observer. Agreement between MMDx and histology (balanced accuracy) was 77% for TCMR, 77% for ABMR, and 76% for no rejection. A classification tree derived to provide automated sign-outs predicted the observer sign-outs with >90% accuracy. In 451 biopsy samples where feedback was obtained, clinicians indicated that MMDx more frequently agreed with clinical judgment (87%) than did histology (80%) (p = 0.0042). In 81% of feedback forms, clinicians reported that MMDx increased confidence in management compared with conventional assessment alone. The authors conclude that real time central molecular assessment is feasible and offers a useful new dimension in biopsy interpretation. ClinicalTrials.gov NCT#01299168.

The Banff 2017 Kidney Meeting Report: Revised diagnostic criteria for chronic active T cell–mediated rejection, antibody-mediated rejection, and prospects for integrative endpoints for next-generation clinical trials

“…Key issues here concern the threshold values of individual histologic lesions needed to diagnose chronic active TCMR, whether the Banff i‐IFTA score or ti score is more predictive of graft outcomes, association with nonadherence and underimmunosuppression, and possibly response to newer immunosuppressive therapy. Response to increase immunosuppressive therapies should be studied, as well as whether molecular parameters associated with TCMR may be useful in diagnosis.…”

“…The latter specifically include situations where a combination of histologic, immunohistologic, and serologic data remain equivocal for diagnosis of ABMR, such as when the biopsy shows microvascular inflammation (g + ptc ≥ 2) but no C4d and there are no detectable DSAs; in biopsy specimens of ABO‐incompatible allografts showing (g + ptc ≥ 2) and where a positive C4d is not helpful diagnostically; and in biopsy specimens of ABO‐compatible grafts where there is C4d positivity and DSA but no histologic evidence of rejection. In addition, testing for transcript sets strongly associated with TCMR may also prove useful in differentiating borderline infiltrates likely to lead to development of overt TCMR and/or graft fibrosis from those that are not, as well as evaluating the thresholds values for chronic active TCMR introduced in this report (Table ).…”

Diagnosis of renal transplant rejection: Banff classification and beyond

“…Sellarés et al [32] reported that microarray assessment of endothelial cells or NK gene expression was helpful in the diagnosis of ABMR. O'Connell et al [33], Modena et al [34], and Halloran et al [35] also showed benefits of gene expression profiling in the diagnosis of ABMR and identification of patients at risk of chronic injury. In addition, Reeve et al [36] demonstrated better prediction of graft survival from molecular scores than from histologic diagnoses.…”

Anti-C1s monoclonal antibody BIVV009 in late antibody-mediated kidney allograft rejection—results from a first-in-patient phase 1 trial

“…We obtained 2 cores for light microscopy, electron microscopy, and RNA extraction and gene expression analysis were performed using PrimeView GeneChip arrays (Affymetrix, Santa Clara, CA), as previously described in detail. 20,21 Classifiers related to rejection (ABMR, TCMR, all rejection) or chronic kidney injury (atrophy/ fibrosis score) were generated on the basis of a reference set of 1208 biopsy specimens. 21 In addition, various pathogenesis-based transcripts (PBT) scores, which represent major biological events derived from experimental cell culture studies, mouse transplant studies, and human kidney transplants, and were shown to be involved in diverse annotated pathologic processes (eg cytotoxic T cell infiltration, γ-interferon effects, natural killer cell burden, and epithelial cell damage) were evaluated as earlier-described in detail.…”

“…For gene expression analysis, a 3-mm portion of a biopsy core was placed in RNAlater, stored at −20°C, and shipped at room temperature to the Alberta Transplant Applied Genomics Centre (ATAGC, University of Alberta, Edmonton, AB, Canada).RNA extraction and gene expression analysis were performed using PrimeView GeneChip arrays (Affymetrix, Santa Clara, CA), as previously described in detail 20,21. For immunohistochemical C4d staining (performed on paraffin sections) we applied a polyclonal anti-C4d antibody (BI-RC4D, Biomedica, Vienna, Austria).…”