Factors influencing early response of IgA nephropathy following targeted-release budesonide (TRB) treatment: preliminary results from a multicenter study

ABSTRACT Background Formation of galactose-deficient IgA1 (Gd-IgA1) immunoglobulin is the initial step in the immunological cascade leading to IgA nephropathy (IgAN). Targeted-release budesonide (TRB), an evidence-based regimen without major side-effects, has recently been approved for IgAN treatment; herein we present our preliminary real-world data regarding prompt response to TRB. Methods Patients with primary IgAN who remained with Uprot >1 g/24 h despite conventional treatment for 6 months were started on TRB, and re-evaluated at 3 (T3) and 6 (T6) months. Reduction of proteinuria by ≥30%, at T3 and T6 was regarded as very early (VER) and early response (ER), respectively. Kidney biopsies were evaluated according to Oxford classification (MEST-C) score. Results Thirty-seven IgAN patients, male/female 26/11, mean ± standard deviation age 50.38 ± 14.32 years and mean time since diagnosis 45.65 ± 56.67 months, were included. Seventeen (45.94%) patients demonstrated VER, increasing to 29 (78.3%) as ER (P = .004). Patients who demonstrated VER had a shorter time interval since diagnosis compared with non-VER, 29.41 ± 6.96 vs 65.37 ± 17.64 months (P = .05), and preserved estimated glomerular filtration rate at diagnosis and T0, while time since diagnosis was the main factor associated with ER, 38.36 ± 19.6 vs 78.67 ± 18.64 months, in ER and non-ER respectively (P = .05). Patients with M0, E0, S0 and T0 had no significant changes during T0–T6, while patients with M1, E1, S1 and even T1 had significantly reduced proteinuria (P = .006, P = .0011, P < .0001 and P < .0001, respectively). Conclusions Almost half of the patients showed proteinuria reduction after TRB treatment at 3 months, and the proportion increased significantly at 6 months. Patients likely to have a prompt proteinuria reduction were relatively close to diagnosis, retained kidney function and had active lesions in kidney biopsy.