Correlation of Longitudinal Gene-Expression Profiling (GEP) Score to Cytomegalovirus (CMV): Infection: Results From the Outcomes AlloMap® Registry (OAR)

s S115 additional serial samples were obtained from each pt (82 samples total). 21 pts were treated for the rejection event, with 17 having consecutive samples available from both the treatment and post-treatment visits required to determine the change in dd-cfDNA following treatment for rejection. Results: For these 17 cases, dd-cfDNA increased more than 2-fold in 3 cases, decreased more than 2-fold in 6 cases, and changed modestly (less than a 2-fold increase or decrease) in 8 cases. In 5 cases where the post-treatment biopsy was graded 0R, suggesting the pt responded favorably to treatment, dd-cfDNA decreased by more than 1.8-fold in 3 cases. Of the 11 samples that did not decrease by at least 2-fold, 6 cases experienced a subsequent 1R or 2R grade rejection event within 30 days of the post-treatment visit, suggesting that the initial treatment may not have been sufficient. Two samples with relatively large (1.9and 3.6-fold) increases in dd-cfDNA following treatment did not show any clinical signs of rejection. Conclusion: Consistent with previously observed rapid-clearance of ddcfDNA from peripheral blood, dd-cfDNA is a quantitative indicator of allograft health. Preliminary data suggest that levels of dd-cfDNA immediately following treatment of a rejection event often decrease when the rejection resolves, but may stay elevated or increase if signs of rejection persist. ddcfDNA may be a useful, non-invasive biomarker to ascertain clinical response to rejection treatment. (Study sponsored by CareDx, Inc.)