Supplementary Material for: Efficacy and safety of telitacicept in IgA nephropathy: A retrospective, multicenter study

Introduction
The efficacy of Telitacicept treatment in reducing proteinuria in patients with IgA nephropathy (IgAN) was indicated in a phase II clinical trial with small sample size. In this study, we conducted a large multicenter retrospective study to explore the efficacy and safety of Telitacicept in patients with IgAN.
Methods
This study recruited patients with IgAN from 19 sites from China who were treated with Telitacicept and had been followed up at least once or with side effect reported, since April 1, 2021 to April 1, 2023. The primary outcomes of the study were the changing in proteinuria and eGFR over time.
Results
A cohort of 97 patients with IgAN who were treated with Telitacicept were recruited, with a median follow-up duration of 3 months. The median baseline proteinuria was 2.3 [1.3, 3.9] g/day and eGFR was 45.0 [26.8, 73.7] ml/min/1.73m2. There was a significant reduction of proteinuria at 2,4,6 months when compared with baseline (2.3 [1.5, 4.1] vs. 1.5 [0.8, 2.3] g/day; 2.3 [1.1, 3.7] vs. 1.1 [0.6, 1.9] g/day; 2.1 [1.0, 2.7] vs. 0.9 [0.5,1.7] g/day, all P values < 0.01). The level of eGFR were comparable between at the baseline and 2, 4, 6 months of follow-up time (41.5 [29.7, 72.0] vs. 42.5 [28.8, 73.3] ml/min/1.73m2; 41.0 [26.8, 67.7] vs. 44.7 [31.0, 67.8] ml/min/1.73m2; 33.7 [24.0, 58.5] vs. 32.6 [27.8, 57.5] ml/min/1.73m2, all P values > 0.26). Telitacicept was well tolerated in the patients.
Conclusions
This study indicates that Telitacicept alone or on top of steroids therapy can significantly and safely reduce proteinuria in patients with IgAN. The long-term kidney protection still need to be confirmed in large Phase III trial.