#2042 Efficacy and safety of telitacicept in IgA nephropathy: a retrospective study

Abstract Background and Aims Telitacicept is a novel fusion protein composed of a recombinant transmembrane activator, calcium modulator, and cyclophilin ligand interactor (TACI) receptor fused with the fragment crystallizable (Fc) region of human immunoglobulin G (IgG). Telitacicept inhibits the differentiation of immature B cell and survival of long-lived plasma cells by neutralizing the activity of B Lymphocyte Stimulator (BlyS) and A Proliferation-Inducing Ligand (APRIL). It was approved for the treatment of patients with Systemic Lupus Erythematosus (SLE) in China in March 2021. Given that BlyS/APRIL overexpression has also been identified in IgA nephropathy (IgAN), telitacicept is in clinical trials for the treatment in IgAN. In this study, we aim to retrospectively evaluate the efficacy and safety of telitacicept in patients with IgAN. Method In this retrospective study, 27 patients with primary IgAN were enrolled from Nephrology Department of Renmin hospital of Wuhan university in China from February 2022 to March 2023. Patients were administered 160 mg telitacicept by subcutaneous injection based on the previous treatment once a week at least 4 weeks, and were followed up. Adults 20–75 years of age who met the following criteria were included: biopsy-proven primary IgAN and 24-hour proteinuria >0.75 g. Patients were excluded if they had secondary causes of IgAN, 24 h proteinuria <0.75 g or immunocompromised state. Changes in proteinuria, serum creatinine, estimated glomerular filtration rate (eGFR), serum immunoglobulins, complement protein (in blood serum), albumin, urine erythrocyte, blood leukocyte and hemoglobin were analyzed during treatment. Key assessment time points were at 2, 4, 8, 12, 16 and 24 weeks after the first administration. Results In this study, duration of telitacicept exposure ranged from 4 weeks to 32 weeks, the median of which was 16 weeks. After administration of telitacicept, baseline 24 h proteinuria of 3.37 g/d decreased to 1.05 g/d at the Week 24 (z = −4.46, p < 0.05), with reductions statistically significant by Week 4. During telitacicept treatment, the median eGFR showed stable trend without sudden decline. Compared to the baseline eGFR of 68.34 ml/(min 1.73 m2), the eGFR at Week 24 was 72 ml/(min 1.73 m2). Changes in immunoglobulin A (IgA), immunoglobulin G (IgG) and immunoglobulin M (IgM) all showed downward trend while complement protein 3 (C3) and complement protein 4 (C4) maintained stable trend. Specifically, IgA decreased from 2.51 g/L at baseline to 1.41 g/L at Week 24, there was a significant reduction by Week 4 (P = 0.001). The median of IgG decreased from 8.31 g/L at baseline to 6.71 g/L at Week 24, with reductions statistically significant by Week 4 (P = 0.008). IgM decreased significantly at Week 2 from baseline of 1.13 g/L to 1.05 g/L (P = 0.017) and was 0.64 g/L at Week 24. The median C3 was stable from baseline to Week 24 (0.92 g/L, 0.87 g/L, respectively), and C4 were 0.22 g/L and 0.23 g/L, in order. Patients had a significant increase in albumin from baseline to Week 2 (P = 0.009) and the Week 24. (36.7 g/L, 37.1 g/L and 41.8 g/L, respectively). Conversely, there was a continuous reduction in urine erythrocyte, from baseline of 62.46/μL to 7.68/μL at Week 24. There remained stable in blood leukocyte from baseline to Week 24 (8.48 × 109/L, 8.67 × 109/L, respectively), with no significant changes. By the end of the study, 10/27 patients was in complete remission (CR) and 8/27 patients had achieved partial remission (PR). The overall remission rate of primary IgAN with telitacicept treatment reached 67%. Telitacicept was generally well tolerated in patients with IgAN in this study. No treatment-emergent adverse events (AEs) occurred in all 27 patients, such as respiratory tract infection, urinary tract infections and injection site allergic. Conclusion In conclusion, based on the retrospective analysis with a small sample, telitacicept, a novel BLyS/APRIL dual inhibitor, effectively decreases proteinuria in IgAN with stable renal function. In addition, it demonstrates a favorable safety profile in patients. The data are supportive of further study with telitacicept in IgAN.