Atacicept is a drug tested in IgA nephropathy, the most common primary kidney disease of the glomerulopathy type. In a phase 3 study, 203 patients were randomized to receive atacicept or placebo. After 36 weeks, the rate of proteinuria (loss of protein in the urine) was reduced by 45.7% in the atacicept group, compared to just 6.8% in the placebo group. The difference was statistically significant. Atacicept also significantly reduced levels of galactose-poor IgA1, a key biomarker of the disease. The most frequent side effects were mild to moderate. The study continues to monitor the long-term effect of the drug on kidney function.