This document summarizes interim results from a randomized multicenter trial evaluating a novel blood transcriptional assay called kSORT for its accuracy in diagnosing and predicting biopsy-confirmed acute rejection in 222 renal transplant recipients. The kSORT assay analyzes expression of 17 genes and provides high or low immune risk scores. Of 18 biopsy-confirmed acute rejection episodes, 15 had definite high-risk kSORT scores and 3 were intermediate. The kSORT assay demonstrated 93.3% sensitivity, 90% specificity, and 98.6% negative predictive value for diagnosing acute rejection. The assay also identified 73% of acute rejection cases days to months before diagnosis through serum creatinine levels alone. These interim results support using kSORT for serial monitoring of rejection