Efficacy and Safety of Finerenone in Biopsy-Proven CKD Associated with Type 2 Diabetes: A Single-Center, Single-Arm Real-World Study

Background: Finerenone, a nonsteroidal mineralocorticoid receptor antagonist, has shown renoprotective effects in type 2 diabetes (T2DM) with chronic kidney disease (CKD). However, its efficacy and safety in biopsy-confirmed CKD subtypes remain unclear. Optimal dosing in diabetic nephropathy (DN) also requires clarification. This study evaluated the efficacy and safety of Finerenone in patients with biopsy-confirmed T2DM-CKD. Methods: This single-center, single-arm retrospective study enrolled 22 T2DM patients who underwent renal biopsy from March 2018 to April 2023. Participants were stratified into DN (n=14), non-diabetic renal disease (NDRD, n=4), and DN+NDRD (n=4). All patients received guideline-directed standard therapy for at least 12 weeks. Finerenone began at 10 mg/day, with titration up to 20 mg/day based on serum potassium and estimated glomerular filtration rate (eGFR). The median follow-up was 26 weeks (IQR 10-40). Outcomes included percentage changes in urinary albumin-to-creatinine ratio (UACR), eGFR, serum potassium, and adverse events. Results: The cohort enrolled 14 DN patients, 4 NDRD patients (focal segmental glomerulosclerosis=3, IgA nephropathy=1), and 4 DN+NDRD patients (DN+IgA nephropathy=3, DN+hypertensive nephropathy=1). In DN, median UACR declined from 1005.5 to 541.8 mg/g (–46.1%, p=0.0295) with stable eGFR(p=0.15) and serum potassium(p=0.94). In NDRD, UACR dropped from 838.2 to 383.8 mg/g (–54.2%, p=0.049) with no notable eGFR change (p=0.57). DN+NDRD patients showed no significant UACR (p=0.562) or eGFR changes (p=0.837). One patient discontinued treatment due to hyperkalemia and serum creatinine elevation >30%. In three patients titrated to 20 mg/day, mean UACR was 1345.68±861.69 mg/g at baseline, decreased to 1223.72±968.77 mg/g (-9.06%) after 12 weeks at 10 mg/day, and further to 586.68±693.08 mg/g (-56.4%) after 24 weeks at 20 mg/day. All showed UACR reductions at 20 mg/day (range -26.9% to -85.7%), with stable renal function and no adverse events. Conclusion: In biopsy-confirmed T2DM-associated CKD, finerenone significantly reduced proteinuria in both DN and NDRD while preserving renal function and normokalemia. Benefits in DN+NDRD remain inconclusive and require further study. Dose escalation to 20 mg/day may confer additional antiproteinuric effects, supporting personalized strategies. Funding: Government Support – Non-U.S.