IgA nephropathy (IgAN) is a chronic autoimmune kidney disease in which the body’s immune system mistakenly produces abnormal IgA1 proteins that accumulate in the kidneys, leading to inflammation and progressive damage. A relatively new therapy called Tarpeyo® addresses the disease at its suspected source—the gut. Here, Dr. Sahar Nouri, a clinical nephrologist and assistant professor of medicine at Loma Linda University Medical Center, shares key insights into how this medication works.*

Understanding IgAN: Pathology and Diagnostic Process

IgAN is a progressive autoimmune kidney disease in which the immune system mistakenly attacks, instead of protects, healthy tissues. This process begins with the overproduction of abnormal IgA1 proteins in the gut, leading to the production of immune complexes (particles formed when antibodies bind to antigens). These particles build up in the kidneys, causing chronic inflammation and eventual damage. 

Though many patients present with symptoms like hematuria (blood in urine), foamy urine, or leg swelling, these indicators can be subtle. “We usually diagnose a patient with IgA nephropathy with only one kidney biopsy,” Nouri notes, “… and then we monitor kidney function and proteinuria through lab tests.”

With an accurate diagnosis, you and your care team can begin to create a customized treatment plan. Your treatment plan may incorporate diet and lifestyle changes, as well as medications and/or dialysis, depending at what stage of the disease you’re diagnosed. Many medications prescribed for people with kidney disease are intended to address other conditions that strain and damage the kidneys, such as:

• High blood pressure, 
• High blood sugar, and
• High cholesterol.

Tarpeyo takes a different therapeutic approach.

Tarpeyo: A Targeted Approach to Gut-Kidney Interaction

Tarpeyo is a delayed-release corticosteroid called budesonide, designed to reduce inflammation directly where the faulty IgA1 protein originates. “This capsule doesn’t get released until it gets to that point on your gut,” Nouri explains, making the treatment more targeted and reducing systemic side effects.

Clinical trials involving 364 patients showed that:

• Those who took Tarpeyo experienced a 50% lower decline in kidney function compared to those on placebo over two years, and
• Proteinuria dropped by 34% in the treatment group compared to just 4% in the placebo group.

“The medication makes sense pathophysiologically,” Nouri says. “It addresses the source of the disease, not just the symptoms.” 

Practical Guidance

As with any medication, Tarpeyo does carry potential side effects and risks such as:

• Allergic reactions (hives, swollen tongue or lips, difficulty breathing)
• Easier bruising
• Facial rounding
• Fatigue
• Nausea and vomiting
• Weakened immune system

For those interested in exploring Tarpeyo, Dr. Nouri suggests broaching the subject with your doctor by asking, “Could Tarpeyo be an option for me based on my lab results?” 

She also stresses the importance of patient self-advocacy: “Sometimes your primary care doctor might not be updated on IgAN…The more you know, the more you can advocate for yourself.” 

*IgAN Foundation [iganfoundation]. (2024, March 16). Learn about an FDA-approved treatment for IgA Nephropathy- Tarpeyo [Video file]. Retrieved from https://www.youtube.com/watch?v=kp6sB4PwWxM 

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