Delayed-Release Budesonide in a Patient With Progressive IgA Nephropathy and Stage 4 Chronic Kidney Disease: A Case Report.

Delayed-release (DR) budesonide received expedited approval from the US Food and Drug Administration (FDA) as a treatment for reducing proteinuria in individuals with primary IgA nephropathy (IgAN) who are at significant risk of disease progression. The approval was based on clinical trials primarily involving patients with an estimated glomerular filtration rate (eGFR) greater than 30 mL/min/1.73 m 2 . However, the efficacy of DR budesonide in reducing kidney function decline, especially in patients with an eGFR less than 30 mL/min/1.73 m 2 and proteinuria less than 1 g/d, remains unclear. We report the case of a 43-year-old man with a long-term history of hypertension and biopsy-proven IgAN who experienced a progressive increase in proteinuria and serum creatinine, along with a decline in eGFR to 28 mL/min/1.73 m 2 despite maximal supportive management. Following therapy with DR budesonide, a decreasing trend in proteinuria and a stabilization of eGFR were observed in the recent measurements. While initial data suggested the effectiveness of DR budesonide primarily in patients with an eGFR over 30 mL/min/1.73 m 2 , our case demonstrates the potential of DR budesonide for use in scenarios beyond its currently approved indications. This underscores the need for additional research on patients with advanced stages of chronic kidney disease.