October 28, 2025

Promising results for new IgA nephropathy treatment

A clinical trial of the drug felzartamab has shown that it can provide sustained benefits for people living with IgA nephropathy, even months after treatment has ended. 

IgA nephropathy is a kidney disease caused by an overactive immune system. Traditional treatments for kidney disease, such as RAS inhibitors, are often less effective for this condition. While steroids can help by reducing immune function, they come with numerous—and sometimes serious—side effects. 

To find a safer and more effective option, researchers led by Jürgen Floege conducted an international, randomized clinical trial testing felzartamab, a drug that specifically targets the immune cells involved in IgA nephropathy. The study included 54 participants with the condition. 

The results show that patients treated with felzartamab experienced significant and lasting reductions in protein levels in their urine—a key marker of kidney health—compared to those who did not receive the drug. Participants who received the highest dosage (nine doses over six months) had a 44 per cent reduction in urinary protein, compared to people who did not receive the treatment. Notably, the reduction of protein in the urine was sustained for up to two years, or 18 months after the final dose of felzartamab. 

Serious side effects were uncommon. The most frequently reported were COVID-19 infection, reactions during infusion of the medication, diarrhea, nasopharyngitis, and upper respiratory tract infections. 

These findings suggest that felzartamab could offer a promising new treatment option for patients with IgA nephropathy. The drug is now being further evaluated in a large international phase 3 clinical trial.