A Study to Learn More About the Effects and Safety of Felzartamab Infusions in Adults With Primary Membranous Nephropathy (PMN)

This study is for adults who have a kidney condition called Primary Membranous Nephropathy, or PMN. Normally, your kidneys have tiny filters called glomeruli that clean your blood and remove waste. In PMN, your immune system – which usually fights off germs – gets confused and creates special proteins called autoantibodies. These autoantibodies attack and damage the kidney filters. When these filters are damaged, too much protein and sometimes blood can leak into your urine. This can cause symptoms like swelling in your legs, feeling very tired, and high blood pressure. If not treated, PMN can unfortunately lead to serious kidney problems over time.

Researchers want to learn more about a new study drug called felzartamab. This drug is a 'monoclonal antibody,' which is a special type of protein made in a lab. It's designed to target and reduce the immune cells that produce those harmful autoantibodies, hopefully preventing further damage to your kidneys. The main purpose of this study is to compare how well felzartamab works against another common treatment for PMN called tacrolimus, which is already used to help people with this condition. They want to find out which treatment is better at bringing down the high levels of protein in your urine and keeping your kidneys healthy.

The main question they're trying to answer is how many people achieve a 'complete response' after about two years of treatment. A complete response means your urine protein levels become very low and your kidney function stays stable. They will also look at how quickly your disease might get worse, how long your urine protein levels stay low, if you develop antibodies against the study drug, how the drug moves through your body, and if it helps with tiredness and overall well-being. This information will help doctors understand if felzartamab could be a good new option for treating PMN.