319 Optimizing Urinary cell mRNA profiling of kidney allograft recipients: Development of a home processing protocol for noninvasive diagnosis of T cell mediated rejection and BK virus nephropathy

Abstract

OBJECTIVES/GOALS: Development of a user friendly home kit that enables kidney transplant recipients to process urine at home and post the lysate containing RNA to a Core Laboratory would simplify urinary cell mRNA profiling and facilitate longitudinal monitoring. We report our home processing protocol and investigation of its diagnostic performance characteristics. METHODS/STUDY POPULATION: We developed a home processing protocol (HPP) consisting of urine filtration and lysis of urinary cells, both performed at home by the kidney transplant recipients (KTR) themselves, followed by isolation of total RNA from the lysate and mRNA enrichment using a silica-membrane-based cartridge, both performed at the Core Laboratory. Using the HPP, total RNA was isolated from kidney allograft biopsy-matched urines and absolute copy numbers of CD3εmRNA, CXCL10 mRNA, and 18S rRNA, components of the Clinical Trials in Organ Transplantation 04 (CTOT-04) three-gene TCMR diagnostic signature, and urinary cell BKV VP1 mRNA copy number, were measured using customized RT-qPCR assays. RESULTS/ANTICIPATED RESULTS: CTOT-04 three-gene TCMR diagnostic signature scores in urine processed using HPP discriminated KTR with TCMR (12 TCMR biopsies from 11 KTR) from KTR with no TCMR/BKVN (29 No TCMR/No BKVN biopsies from 29 KTR) (P=0.0005, Mann-Whitney test), and AUROC was 0.84 (95% CI, 0.69 to 0.98). TCMR was diagnosed with sensitivity of 67% (95% CI, 35 to 89) at a specificity of 86% (95% CI, 67 to 95) using the CTOT-04 validated cutpoint of -1.213 (P=0.0016,Fisher exact test). BKV VP1 mRNA copy number in urine processed with HPP discriminated KTR with BKVN (n=7) from KTR with no TCMR/BKVN (n=29) and AUROC was 1.0 (95% CI, 1.00 to 1.00). BKVN was diagnosed with a sensitivity of 86% (95% CI, 42 to 99) at specificity of 100% (95% CI, 85 to 100) with the previously validated cutpoint of 6.5x10^8 BKV VP1 mRNA copies/μg of RNA (P DISCUSSION/SIGNIFICANCE: Urine processed using the HPP predicted TCMR and BKVN in KTR. The HPP represents not only a significant advance towards portability of urinary cell mRNA profiling but also should improve patient management by minimizing visits for urine collection.