Circulating serum microRNAs in kidney transplant recipients with post-transplant malignancies

Post-transplant malignancies are a major cause of long-term morbidity and mortality in kidney transplant recipients. Reliable non-invasive biomarkers may improve post-transplant oncological surveillance. Circulating microRNAs have emerged as promising candidate biomarkers in several malignancies, but their role in kidney transplant recipients remains poorly characterized.

To compare circulating serum microRNA concentrations between kidney transplant recipients with and without post-transplant malignancies and to identify candidate microRNAs associated with the presence of malignancy.

This exploratory pilot study included 40 kidney transplant recipients (27 with post-transplant malignancies and 13 cancer-free controls). Serum concentrations of five preselected microRNAs (miR-21, miR-146a, miR-196a, miR-203a, and miR-221) were quantified using droplet digital PCR. Group comparisons were performed using the Mann-Whitney U test, and receiver operating characteristic (ROC) curve analysis was used to evaluate discriminatory performance.

Serum concentrations of miR-21 and miR-196a were significantly higher in recipients with post-transplant malignancies than in cancer-free controls (both p = 0.003). Serum miR-221 concentrations were also significantly elevated (p = 0.020), whereas no significant differences were observed for miR-146a or miR-203a. ROC analysis demonstrated acceptable discriminatory performance for miR-21 (AUC 0.742, 95%CI 0.601-0.883) and miR-196a (AUC 0.771, 95%CI 0.619-0.922).

Circulating serum miR-21 and miR-196a were significantly associated with the presence of post-transplant malignancy in kidney transplant recipients, while miR-221 showed an additional exploratory association. These findings support further investigation of circulating microRNAs as candidate non-invasive biomarkers in transplant oncology. Larger prospective studies are required to validate these observations.