A new therapy has been shown to significantly reduce proteinuria (protein in the urine) — a key sign of kidney damage — in people living with immunoglobulin A nephropathy (IgAN). In a large clinical trial, the drug sibeprenlimab lowered proteinuria levels by 51.2 percent after nine months of treatment, compared with a placebo (inactive treatment).

Sibeprenlimab works by targeting a protein called APRIL, which plays a role in the immune system’s overactivity in IgAN. Blocking APRIL helps reduce the production of harmful forms of IgA that can damage the kidneys.

What Are IgA Nephropathy and Proteinuria?

IgA nephropathy (also called Berger’s disease) is a chronic kidney condition caused by a buildup of immunoglobulin A, a type of protein, in the kidneys. Over time, this can lead to inflammation, scarring, and kidney failure.

One of the most common signs of IgAN is proteinuria — high levels of protein in the urine. Lowering proteinuria is a key treatment goal because it’s linked to slower kidney damage and better long-term outcomes.

What the Study Found

The study included more than 500 adults already receiving standard care. People who received sibeprenlimab injections every four weeks saw their proteinuria levels drop by more than half after nine months, compared with those who got a placebo.

The drug also showed a favorable safety profile. Fewer people taking sibeprenlimab had serious side effects than those on placebo.

Why This Matters for People With IgAN

IgA nephropathy can progress slowly but steadily, and current treatment options are limited. Many people rely on blood pressure medications and other supportive care to slow the disease, but these approaches don’t work for everyone.

This study offers hope for a new targeted therapy that could be used along with existing treatments — and may help delay kidney failure for many people.

Sibeprenlimab is now under priority review by the U.S. Food and Drug Administration (FDA), with a decision expected by late November 2025. If approved, the drug could be available as a once-a-month injection, offering a convenient option for home use.

Talk with your kidney specialist about whether new treatments like sibeprenlimab may be an option for you in the future.

Learn six facts about different rare kidney diseases, including IgAN.

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