Finerenone Use in Coenzyme Q8B-Related Focal Segmental Glomerulosclerosis

Genetic focal segmental glomerulosclerosis (FSGS) caused by mutations affecting coenzyme Q (CoQ) biosynthesis is a rare podocytopathy that is associated with poor response to immunosuppression. Finerenone is a nonsteroidal mineralocorticoid antagonist that reduces oxidative stress, glomerular inflammation, and fibrosis, features seen in CoQ deficiency. We report the first case of its use in COQ8B-related FSGS. A 35-year-old woman was evaluated for persistent postpartum proteinuria and underwent a kidney biopsy that showed features of FSGS. She had a strong family history of early-onset kidney failure. She had no response to corticosteroids, tacrolimus, and empgagliflozin. Genetic testing revealed a homozygous COQ8B mutation. CoQ10 supplementation was not tolerated. Finerenone was initiated in May 2024, with significant improvement in albuminuria from 6,460 mg/g to 1,430 mg/g after 12 months and a slowing of the decline in estimated glomerular filtration rate from -9.55 mL/min/1.73 m²/y to -6.77 mL/min/1.73 m²/y. There was only mild transient hyperkalaemia. It was stopped after 12 months owing to hypotension, and by 6 months, the proteinuria increased to 4,860 mg/g and creatinine increased from 1.56 mg/dL to 2.22 mg/dL. This case suggests a potential role for finerenone as adjunctive therapy in genetic FSGS.