B-214 Serial Changes of Donor-derived Cell-free DNA in Pancreas Transplant Recipients

Abstract

Abstract Background Pancreatic transplant patients need invasive pancreatic biopsies to diagnose graft rejection. Organ damage following organ donation yields circulating tissue-isolated donor-derived cell-free DNA (ddcf-DNA). Based on the ddcf-DNA ratio or quantity in several transplantations, graft rejection is predicted. Thus, we examined a 2-week ddcf-DNA monitoring study after pancreatic transplantation at this medical institution. Methods The current prospective observational study examined five pancreas transplant recipients who were sampled on postoperative days (PODs) 4, 7, 14, 30, 60, 90, 120, and 180 following the study protocol. Serum levels were determined for the following: amylase, lipase, and tacrolimus. Cell-free DNA (cf-DNA) was isolated from the plasma using a NucleoSnap cf-DNA extraction kit. The QX200 Droplet Digital PCR System was used to measure ddcf-DNA. To analyze transplant rejection and differentiate between donor and recipient, all selected single nucleotide polymorphisms (SNPs) met the following criteria: known and validated minor allele frequency of 43% in Koreans and reported ethnicities from global populations. Results The median patient age was 35 years. All recipients achieved euglycemia without exogenous insulin immediately after the surgery. All 6-month postoperative hemoglobin A1c levels were within the normal range (4%–6%). One (20%) of the five patients with pancreas transplant had a T cell-mediated rejection event on POD 531. For PODs 4, 7, 14, 30, 60, 90, and 180, the percentage (median, range) of ddcf-DNA was 2.7 (0.4–5.5), 0.6 (0.2–4.4), 3.7 (0.4–12.7), 7.1 (0.4–7.9), 2.1 (0.1–5.4), 2.0 (0.3–8.5), and 0.3 (0.2–7.6), respectively; and amylase (median, range) was 68.0 (30.0–80.0), 82.0 (57.0–151.0), 74.0 (66.0–157.0), 81.0 (50.0–137.0), 74.0 (39.0–111.0), and 80.0 (27.0–98.0). (43.0–105.0), respectively. The ddcf-DNA value of POD 14 was greater than 10% in individuals who had TCMR on POD 530. Conclusion In our study, patients with high ddcf-DNA on POD 14 after transplantation respond poorly to immunosuppressive agents, and rejection was later confirmed.