*Purpose: Data on the role of DD-cfDNA after pancreas transplantation is lacking. Herein we report on our center experience with DD-cfDNA in 10 unique SPK recipients and eight pancreas alone transplants.

*Methods: We retrospectively reviewed all DD-cfDNA (Prospera^TM) testing in simultaneous-pancreas-kidney (SPK) and solitary pancreas transplant recipients performed in 10 unique SPK recipients (11 tests) and 8 unique solitary-pancreas recipients (10 tests) between January and June of 2020 at our institution. All patients with suspected rejection underwent DD-cfDNA testing. Patients with a positive test underwent a biopsy, except for one subject with known chronic rejection. Among those with a negative test, a biopsy was performed selectively in those with a high degree of suspicion for rejection.

*Results: 10 SPK recipients were tested 11 times. 8 tests were negative, and 3 tests were positive. Of the recipients with negative tests, 2 underwent kidney and 2 others underwent pancreas biopsies for results confirmation. Of the kidney biopsies, 1 biopsy showed pyelonephritis and CNI changes, and the other biopsy was negative. Of the pancreas biopsies, 1 was indeterminate for rejection, and the other was negative for cellular rejection but showed some c4d positivity without circulating DSA. Of the positive tests, 2 tests were performed on the same recipient before the biopsy, which showed moderate cellular rejection. The other positive test was confirmed with a kidney biopsy showing acute cellular rejection grade Banff IA (Table 1).8 unique solitary pancreas were tested 10 times. 2 tests were positive. Of the recipients with a positive test, 1 was not biopsied due to known chronic rejection and evidence of several DSAs at high MFI levels. The other recipient had a biopsy-proven mixed rejection that was successfully treated with subsequently negative tests (Table 2). Of the recipients with a negative test, 2 subjects had confirmatory biopsies: 1 was pancreas biopsy, and the other was kidney biopsy. Both biopsies were negative for acute rejection. All subjects with a negative test result who did not undergo a biopsy had no evidence of clinical rejection on follow up.

*Conclusions: In this early report on DD-cfDNA in pancreas recipients, DD-cfDNA correlated with negative and positive biopsy results in all subjects with confirmatory biopsy. The accuracy of the test was not altered by the presence of more than one organ. While these early results are encouraging, further prospective studies are needed to confirm our results.

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