*Purpose: Non-invasive validated rejection biomarkers are now available to monitor kidney transplant patients (KTRs). Two such biomarkers are; TruGraf^TM (TG) gene expression profile validated to rule out subclinical acute rejection(subAR) and TRAC^TM (donor derived cell free DNA ) as a marker of allograft injury in KTRs. The purpose of this study is to describe the initial single center experience of TruGraf GEP and TRAC dd-cfDNA surveillance for KTR within the first year post-txp and greater than one year post-txp. Our program has done 3 and 12 month protocol biopsies for many years. We have now replaced biopsies with biomarker surveillance.

*Methods: TG and TRAC was done in all KTRs at 3 and 12 months post-txp. Additionally, all patients being followed by this nephrology group (total n=170) are to be tested once post-txp to determine baseline status (immune quiescence). A positive TG and/or TRAC prompted further evaluation including focused lab review. Biopsies were done only in cases where there was equipoise. Donor specific antibodies (DSA) were done in all patients.

*Results: To date, 55 KTRs have been surveilled with TG and/or TRAC; total of 72 TG and 47 TRAC. 9 of 10 new transplants were spared 3 month biopsies, the one biopsy was for DGF; was normal and had a negative TG. An additional 14 were tested one year post tx and 11 of them avoided one year protocol biopsy. A total of 31 patients were tested at > one year post tx. Overall, a total of 2 episodes of subAR were identified. Table 1 and Table 2 showsresults of TG and TRAC testing in lieu of 3 month and 1 year protocol biopsy. Table 3 shows testing concordance. 49% (23/47) confirmed in immune quiescence (rule out subAR) with no allograft injury (GEP negative, dd-cfDNA negative). 5% had positive GEP and dd-cfDNA prompting biopsy and diagnosis (DX) and/or treatment of subAR. The remaining 46% had either GEP or dd-cfDNA positive, prompting further clinical evaluation and correlation with other findings such as DSA, proteinuria, and renal function.

*Conclusions: Non-invasive TruGraf GEP surveillance with synergy from TRAC dd-cfDNA ruling out allograft injury spared unnecessary protocol biopsies in KTR at 3 months and provided enhanced surveillance at 12 months and further post-txp, assuring adequacy of immunosuppression and ruling out subAR. Combined TruGraf GEP and TRAC dd-cfDNA is promising, warranting larger studies to determine the optimal synergy with serial testing, especially beyond the first year post-txp where KTR continue to be at risk for subAR

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