Diagnostic and Therapeutic Applications of Microarrays in Lung Transplantation

Objective: To evaluate the potential impact of molecular phenotyping of transbronchial biopsies in lung transplant recipients with allograft dysfunction, and the potential for developing a safer endobronchial mucosal biopsy format.

The current standard for biopsy-based diagnoses of dysfunction of lung transplants is the International Society of Heart and Lung Transplantation (ISHLT) classification applied to transbronchial biopsies, which represents an arbitrary international consensus. Recent data-driven approaches using molecular and conventional technologies indicate that this system produces frequently incorrect diagnoses with potential harm to patients due to inappropriate treatment. especially in relationship to the correct diagnosis of chronic lung allograft dysfunction is a pressing need. To address this unmet need and improve diagnostics in the area of organ transplantation, the Alberta Transplant Applied Genomics Centre (ATAGC, University of Alberta) has developed a new diagnostic system - the Molecular Microscope® Diagnostic System (MMDx) that interprets biopsies in terms of their molecular phenotype. The MMDx, developed first in kidney transplant biopsies with thoroughly established phenotypes, will now be adapted to lung transplant transbronchial biopsies (TBBs). Microarray analysis of lung allograft biopsy specimens will be compared to conventional allograft phenotyping, including clinical, physiologic, radiographic and histological assessment. The present study will use the MMDx™ system to assess and report TBBs, and validate and refine this system in 300 unselected prospectively collected lung TBBs. A subset of the study will examine the third bifurcation mucosal endobronchial biopsies (3BMBs) paired with TBBs from 50 patients to see if the safer 3BMBs can substitute for the TBB to be used by MMDx™. Due to a considerable interest and support from participating Centers, the study is further extended and collected 1032 TBBs and 602 3BMBs from 849 patients. This this is the extension of the INTERLUNG study - INTERLUNGEX.