*Purpose: We explore the viability of urinary biomarker-based monitoring for rejection in early days following renal transplantation.

*Methods: Patients are from the Erasmus MC and received basiliximab induction therapy followed by triple maintenance immunosuppression consisting of tacrolimus mycophenolate mofetil (MMF) and steriods. 18 adult renal transplant patients with BPAR and 9 with stable allografts had urine samples bio-banked from the first 2 weeks post-transplantation, at 6 month and during for-cause biopsies before M2. All samples were assayed by the urine-biomarker based QSant[Yang, STM 2020]. A ML-based allograft rejection model with a scaled QScore (0-100) – incorporating clinico-demographics with 6 urinary biomarkers – was applied. The QSant derived classes are[Sarwal, sub., 2021]: i)immunequiescence(IQ): QScore <32,ii)dynamic alloimmune injury spectrum: 32≥QScore≤55,; iii)acute rejection(AR) highly concordant with histological instability: QScore >55. The analyses comprised of:(i)Cross-sectional correlation between QScore, SCr and biopsy;(ii)Longitudinal IS treatment response-correlation with QSant.

*Results: 60% of samples enriched for early transplant outcome(<2weeks post). Given QScore had not been trained on early transplant, the assessed accuracy against early BPAR/DGF was significant at 86.8%; Spearman’s correlation against SCr was 41.2%. In this early period the estimated prevalence for: AR was 41% - perhaps explained by the absence of T cell depletion induction therapy[Hellemans, AJT, 2017]. IQ was 35% and dynamic alloimmune injury was 25%. It’s conceivable to optimize the IS regimen further and monitor AR by correlating with QScore trajectory. The longitudinal analysis highlights: In 42% of the BPAR cohort, QSant™ prognosticated AR pre-biopsy. We observed that QSant registers a continuous gradient in response to IS modulation or lack thereof; the directionality of change potentially underscores regimen efficacy.

*Conclusions: QSant trajectory tracking by serial urine analysis early post-transplant, can potentially obviate or trigger for-cause biopsies. Despite the sampling size, urinary QSant-based AR diagnosis is not confounded by early ischemia reperfusion injury and very early time post-transplant and underscores the potential to augment clinician decision-making during the early weeks post-transplant, to diagnose AR, irrespective of IRI or DGF status. 

« Back to 2022 American Transplant Congress