*Purpose: Non-invasive rejection biomarkers continue to evolve with recent data supporting the use of combined gene expression and donor derived cell-free DNA (dd-cfDNA) in kidney transplant recipients (KTRs) with stable renal function. OmniGraf® is a novel peripheral blood biomarker panel combining TruGraf® (TG) gene expression and TRAC® dd-cfDNA (TRAC) into one testing kit and one blood draw to provide a comprehensive view of subclinical rejection. Previously, at this center, it was reported that 3- and 12-month protocol biopsies (BX) were replaced with the TG and TRAC testing. This is the initial real-world experience utilizing OmniGraf biomarker surveillance in KTRs previously monitored with TG and TRAC separately.

*Methods: Standard immunosuppression (IS) is alemtuzumab with tacrolimus maintenance, mycophenolate mofetil added in high risk. TG/TRAC surveillance is done at 3, 12 months post-txp, and after IS changes. Additionally, all KTR to be tested at least once to determine baseline status (immune quiescence). In September 2021, OmniGraf monitoring was implemented at the same time points, providing TG and TRAC results in a single panel. A double negative (neg) TG (Tx) and TRAC (<0.7%) result rules out subclinical rejection (NPV 94%), whereas double positive (pos) TG (not-tx) and TRAC (≥0.7%) prompt further evaluation (PPV 89%), which may include BX. Discordant results prompt further evaluation, including repeating OmniGraf and reviewing other clinical data. Donor specific antibodies (DSA) tested in all patients.

*Results: To date, 35 KTRs have been surveilled with 36 OmniGrafs. 25 OmniGraf results were double neg (neg TG and TRAC) confirming adequacy of immunosuppression. 10 were discordant (6 pos TG/neg TRAC; 4 neg TG/pos TRAC) and 1 patient had double pos results (pos TG and TRAC) prompting further evaluation. KTR were an average 6.5 ± 8.2 years post-txp at testing. Mean serum creatinine at testing was 2.1 ± 1.6 mg/dl. 14 KTRs were less than 1-year post-txp at testing, the earliest being 36 days post-op. 8 KTRs were 1-5 years post-txp, 6 KTRs were 5-10 years post-txp, and 5 were 10-20 years post-txp, and 3 were > 25 years post-txp. 13 KTRs were tested serially with TG and/or TRAC prior to OmniGraf. Discordant results prompted further evaluation/correlation: 3 of 4 pos TRAC/neg TG correlated with presence of DSA, and only 50% of discordant results correlated with proteinuria. 6 of 8 KTRs were spared 3-month BX based on OmniGraf.

*Conclusions: The early experience with OmniGraf® testing is promising as it consistently spares protocol BX in KTRs at 3 and 12 months, rules out subclinical acute rejection, confirms adequacy of IS, and provides synergistic information to be considered in concert with other clinical data, such as DSA. Larger studies are warranted to determine optimal testing frequency and approach for patient’s further post-txp.

« Back to 2022 American Transplant Congress