HEARTBIT: A Novel Biosignature for Detection of Acute Cellular Rejection of Heart Allografts
Casey P Shannon4, Zsuzsanna Hollander4, Sara Assadian4, Karen Lam4,17, Virginia Chen4, LiYing Dai4, Marek Zarzycki1, YoungWoong Kim1, Ji-Young Kim1,2,4, Robert Balshaw4,5, Ihdina S Dewi6, Olof Gidlöf6, Jenny Öhman6, Gustav Smith 6, Mustafa Toma7, Ross Davies8, Diego Delgado9, Haissam Haddad10, Andrew Ignaszewski7, Debra Isaac 11, Daniel Kim11, Alice Mui12, Miroslav Rajda13, Lori West14, Michel White15, Shelley Zieroth16, Scott J Tebbutt1,4, Paul Keown1, Robert McMaster1,2,4, Raymond T Ng1,3,4, Bruce M McManus4,17.
1Medicine, University of British Columbia, Vancouver, BC, Canada; 2Medical Genetics, University of British Columbia, Vancouver, BC, Canada; 3Computer Science, University of British Columbia, Vancouver, BC, Canada; 4Prevention of Organ Failure (PROOF) Centre of Excellence, Vancouver, BC, Canada; 5Statistics, University of British Columbia, Vancouver, BC, Canada; 6Cardiology, Skåne University Hospital, Lund University, Lund, Sweden; 7Cardiology, University of British Columbia, Vancouver, BC, Canada; 8Medicine, University of Ottawa, Ottawa, ON, Canada; 9University Health Network/Mount Sinai Hospital, Toronto, ON, Canada; 10Medicine, University of Saskatchewan, Saskatchewan, SK, Canada; 11Medicine, University of Alberta, Calgery, BC, Canada; 12Surgery, University of British Columbia, Vancouver, BC, Canada; 13Medicine, Dalhousie University, Halifax, NS, Canada; 14Pediatrics, University of Alberta, Edmonton, AB, Canada; 15Institut de Cardiologie de Montréal, Montréal, QC, Canada; 16Medicine, University of Manitoba, Winnipeg, MB, Canada; 17Pathology, University of British Columbia, Vancouver, BC, Canada
Background: Acute cellular allograft rejection remains a major cause of limited long-term graft survival in cardiac transplantation. A critical challenge in trying to reduce the incidence of acute cellular rejection arises from the difficulty of accurately and efficiently making diagnoses. The primary approach requires taking small pieces of heart muscle tissue, which is highly invasive and costly, and suffers from sampling error and inter-observer grading variability. Replacing the biopsy with a simple blood test would be of great value to patients and substantially reduce healthcare costs.
Approach and Methods: We previously used high-throughput, untargeted transcriptomic profiling in blood samples of heart transplant patients to identify 9 mRNAs and 5 proteins whose combined expression discriminated patients undergoing acute cellular rejection from those who were not. We now validated the mRNA targets on a clinically-amenable NanoString nCounter platform. The performance of the novel assay, HEARTBIT, as well as that of a proteogenomic ensemble including 5 proteins, was assessed by cross-validation.
Results: In cross-validation the area under the receiver operating characteristic curve (AUC) of the transcriptomic signature was 0.81, with 47% specificity at ≥ 90% sensitivity. Addition of 5 proteins to the mRNA panel using ensembling resulted in an enhanced performance (AUC of 0.86, with 65% specificity at ≥ 90% sensitivity, in cross-validation).
Summary and Conclusion: Here, we demonstrate 1) successful translation of biomarker signatures from untargeted high-throughput screening onto a compact, clinically-amenable technological platform, and 2) promising utility of our novel assay, HEARTBIT, for improved detection of acute cellular rejection.
