Otsuka Shares New Phase 3 Data Showing Voyxact Slows Kidney Function Decline in IgA Nephropathy

New Two-Year Phase 3 Results Highlight Long-Term Benefits of Voyxact

Otsuka Pharmaceutical Development & Commercialization, Inc. and Otsuka Pharmaceutical Co., Ltd. have announced new Phase 3 clinical trial results showing that Voyxact (sibeprenlimab-szsi) helped stabilize kidney function in adults living with primary IgA nephropathy (IgAN).

The latest findings come from the Phase 3 VISIONARY study and were presented during a late-breaking oral session at the GlomCon Hawaii 2026 conference.

According to the company, the treatment slowed kidney function decline to a level that closely matches the normal age-related decline seen in healthy adults over a two-year period.

Study Meets Key Secondary Endpoint

The VISIONARY trial successfully achieved its key secondary endpoint by measuring the annual rate of change in estimated glomerular filtration rate (eGFR), an important indicator of kidney function.

After 24 months of treatment:

• Patients receiving Voyxact showed an annualized eGFR slope of +0.3 mL/min/1.73 m²/year.
• Patients receiving placebo experienced an annualized decline of -4.2 mL/min/1.73 m²/year.

The treatment difference between the two groups was +4.5 mL/min/1.73 m²/year, which was statistically significant.

According to Otsuka, Voyxact became the first treatment for IgA nephropathy to reach the Kidney Disease: Improving Global Outcomes (KDIGO) therapeutic goal of slowing kidney function decline to less than 1 mL/min/1.73 m² per year.

Kidney Function Remained Stable After Two Years

Researchers also looked at the overall change in kidney function from the beginning of the study to the two-year mark.

The results showed:

• Patients treated with Voyxact experienced an average increase of 1.3 mL/min/1.73 m² in eGFR.
• Patients in the placebo group experienced an average decline of 7.9 mL/min/1.73 m².

This resulted in an overall treatment difference of 9.2 mL/min/1.73 m² in favor of Voyxact.

These findings suggest the medicine not only reduced protein leakage into the urine but also helped preserve kidney function over time.

Safety Profile Remained Consistent

The company reported that the overall safety profile of Voyxact remained stable throughout the two-year study period.

Rates of adverse events were similar between the treatment and placebo groups.

Researchers also reported:

• Similar rates of infections in both groups.
• Comparable rates of injection site reactions.
• No new safety concerns.
• Lower rates of serious infections in the Voyxact group compared with placebo.
• Lower rates of serious adverse events and treatment discontinuations among patients receiving Voyxact.

These results support the long-term tolerability of the treatment.

Doctors See the Findings as an Important Step

Dr. Dana Rizk, Professor of Medicine in the Division of Nephrology at the University of Alabama at Birmingham and a principal investigator in the VISIONARY study, said stabilizing kidney function represents a major advancement for patients with IgA nephropathy.

She explained that reaching the KDIGO treatment target changes the course of the disease rather than simply slowing symptoms.

According to Dr. Rizk, the consistent benefits seen across different patient groups, together with the favorable safety profile, offer encouraging news for people living with this progressive kidney disease.

Otsuka Highlights Potential to Change IgAN Treatment

Dr. John Kraus, Executive Vice President and Chief Medical Officer at Otsuka, said the VISIONARY study is the largest Phase 3 trial conducted in IgA nephropathy with two years of patient follow-up.

He noted that the study included a broad patient population that closely reflects real-world clinical practice.

According to Otsuka, the trial produced the largest treatment effect reported so far in a Phase 3 IgAN study and supports selective APRIL inhibition as a durable, disease-modifying treatment approach.

About the VISIONARY Trial

VISIONARY is a global Phase 3, randomized, double-blind, placebo-controlled clinical study evaluating the safety and effectiveness of Voyxact in adults with primary IgA nephropathy who are at risk of disease progression.

The study evaluated several important outcomes, including:

• Reduction in proteinuria after nine months.
• Long-term changes in kidney function over 24 months.
• Overall safety and tolerability.

The clinical program also includes an ongoing open-label extension study that will continue collecting long-term data.

What Is IgA Nephropathy?

IgA nephropathy is a chronic autoimmune kidney disease that usually develops in adults between 20 and 40 years of age.

The disease occurs when abnormal IgA antibodies build up inside the kidneys, causing inflammation and gradual damage.

Over time, many patients experience a steady decline in kidney function that can eventually lead to kidney failure.

Although supportive care has improved over the years, there is still a need for treatments that target the underlying disease process rather than only managing symptoms.

How Voyxact Works

Voyxact is a humanized monoclonal antibody that blocks A Proliferation-Inducing Ligand (APRIL), an immune protein involved in the development and progression of IgA nephropathy.

APRIL contributes to the production of galactose-deficient IgA1 (Gd-IgA1), which plays a central role in kidney damage.

By blocking APRIL, Voyxact lowers Gd-IgA1 levels and targets one of the root causes of the disease.

The medicine is given as a self-administered injection under the skin once every four weeks.

Voyxact received accelerated approval from the US Food and Drug Administration in November 2025 for reducing proteinuria in adults with primary IgA nephropathy who are at risk for disease progression.

Otsuka has now submitted additional data, including the two-year kidney function results, as part of its rolling supplemental Biologics License Application seeking traditional FDA approval.

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