A Phase 3 Trial of Atacicept in Patients with IgA Nephropathy

BACKGROUND: IgA nephropathy, the most common primary glomerulopathy worldwide, is a kidney disorder of B-cell origin characterized by mesangial accumulation of IgA-containing immune complexes. In at least 50% of patients, IgA nephropathy leads to kidney failure or death within 10 to 20 years after diagnosis. Atacicept is a native human transmembrane activator and calcium-modulator and cyclophilin-ligand interactor (TACI)-Fc fusion protein that inhibits two key immunoregulatory cytokines - B-cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL) - that are thought to be central to the pathophysiology of IgA nephropathy. METHODS: In this ongoing, phase 3, multicenter, double-blind, randomized, placebo-controlled trial, we assigned patients with IgA nephropathy in a 1:1 ratio to receive atacicept at a dose of 150 mg once weekly, administered subcutaneously by patients at home, or matching placebo. The primary end point was the percentage change from baseline in the 24-hour urinary protein-to-creatinine ratio at week 36. Safety was also evaluated. RESULTS: A total of 203 patients were included in the prespecified interim analysis: 106 patients in the atacicept group and 97 in the placebo group. At week 36, the percentage reduction from baseline in the urinary protein-to-creatinine ratio was 45.7% in the atacicept group and 6.8% in the placebo group, with a geometric mean between-group difference of 41.8 percentage points (95% confidence interval, 28.9 to 52.3; P<0.001). Adverse events were observed in 59.3% of the patients in the atacicept group and in 50.0% in the placebo group; most were mild or moderate in severity. CONCLUSIONS: In this prespecified interim analysis, treatment with atacicept resulted in a significantly greater reduction in proteinuria than placebo at week 36 in patients with IgA nephropathy. (Funded by Vera Therapeutics; ORIGIN 3 ClinicalTrials.gov number, NCT04716231.).