Early Experience Using Donor-derived Cell-free DNA for Surveillance of Rejection Following Simultaneous Pancreas and Kidney Transplantation

Background. Allograft biopsy is the gold standard for diagnosing graft rejection following simultaneous pancreas and kidney (SPK) transplant. Intraperitoneal biopsies are technically challenging and can be burdensome to patients and the healthcare system. Donor-derived cell-free DNA (dd-cfDNA) is well-studied in kidney transplant recipients; however, it has not yet been studied in the SPK population. Methods. We hypothesized that dd-cfDNA could be utilized for rejection surveillance following SPK transplant. We prospectively collected dd-cfDNA in 46 SPK patients at a single institution. Results. There were 10 rejection events, 5 of which were confirmed with biopsy. The other 5 were treated based on ddcfDNA and clinical data alone with favorable outcomes. Among all patients who did not have rejection, 97% had dd-cfDNA <0.5%. Dd-cfDNA may also help differentiate rejection from graft injury (ie, pancreatitis) with median values in rejection 2.25%, injury 0.36%, and quiescence 0.18% (P=0.0006). Conclusions. Similar to kidneys, dd-cfDNA shows promise for rejection surveillance in SPK transplant recipients.