- Strong findings support VOYXACT, the first and only U.S. FDA-approved selective APRIL inhibitor, as an early, targeted therapy that addresses key drivers of disease progression: preserving kidney function and reducing Gd-IgA1, proteinuria and hematuria -

- At 12 months, VOYXACT preserved kidney function by showing a mean eGFR change from baseline of +0.7 compared to a decline of -4.8 mL/min/1.73 m² in the placebo-treated arm, representing a treatment effect of 5.5 mL/min/1.73 m² -

- Otsuka has initiated a rolling submission of a supplemental Biologics License Application (sBLA) to the U.S. FDA for VOYXACT traditional approval, based on the 24-month eGFR endpoint data -

Otsuka Pharmaceutical Co., Ltd. (Otsuka) and Otsuka Pharmaceutical Development & Commercialization, Inc. today announced that VOYXACT^® (sibeprenlimab-szsi) preserved kidney function compared to placebo over 12 months in adults with primary IgA nephropathy (IgAN) at risk for disease progression. VOYXACT demonstrated an increase in mean change for the estimated glomerular filtration rate (eGFR) from baseline of +0.7 mL/min/1.73 m² compared to a decline of -4.8 mL/min/1.73 m² in the placebo-treated group, providing early evidence that sibeprenlimab may stabilize eGFR decline in patients with IgA nephropathy, which will be further validated in the ongoing Phase 3 VISIONARY trial. These results were presented at the European Renal Association (ERA) Congress 2026 in Glasgow as part of a pre-specified interim analysis of the VISIONARY Phase 3 trial. In the VISIONARY study, VOYXACT was well tolerated with a favorable safety profile in line with previously reported data¹. Full data from the VISIONARY study final analysis will be presented at a future medical conference. These findings provide clinical evidence linking upstream selective A-PRoliferation-Inducing Ligand (APRIL) inhibition to downstream preservation of kidney function, reinforcing VOYXACT's ability to improve long-term outcomes.

"For patients with IgA nephropathy, slowing the loss of kidney function is essential to improve long-term outcomes, including the likelihood of kidney failure and the need for dialysis or transplant," said Vlado Perkovic, MBBS, PhD, Provost at the University of New South Wales, Australia. "These data are very encouraging and suggest that selective inhibition of APRIL may slow eGFR decline, helping patients preserve kidney function and improve long-term outcomes."

In this pre-specified interim analysis of the global VISIONARY Phase 3 trial (n=320; sibeprenlimab, n=152; placebo, n=168), patients treated with sibeprenlimab showed an increase in the mean eGFR change from baseline of +0.7 (95% CI, -0.9 to 2.3) mL/min/1.73 m² compared to a decline of -4.8 (95% CI, -6.3 to -3.3) mL/min/1.73 m² in the placebo-treated arm, representing a treatment effect of 5.5 (95% CI, 3.4 to 7.6) mL/min/1.73 m². At 12 months, sibeprenlimab showed a mean eGFR change from baseline that meets the KDIGO treatment goal to reduce the annual kidney function decline to the normal physiological rate of (<1 mL/min/1.73 m²/year).

Supporting the preservation of kidney function observed in the change from baseline analysis, the annualized slope of eGFR showed -3.0 (95% CI, -4.6 to -1.4) mL/min/1.73 m²/year with sibeprenlimab compared to -7.6 (95% CI, -9.1 to -6.1) mL/min/1.73 m²/year with placebo over 12 months, showing a treatment effect of 4.6 (95% CI, 2.5 to 6.8) mL/min/1.73 m²/year. The overall safety profile of VOYXACT was comparable to placebo, with infections and injection site reactions as the most common adverse events. Sibeprenlimab was generally well tolerated, and the types and frequencies of treatment-emergent adverse events (TEAEs) were comparable to placebo¹.

"Together with previously observed reductions in Gd-IgA1, proteinuria, and hematuria, these new eGFR data show preserved kidney function over 12 months, which expand the growing body of evidence for VOYXACT demonstrating the potential to meaningfully improve clinical outcomes for adults with primary IgAN at risk for disease progression," said John Kraus, M.D., Ph.D., executive vice president and chief medical officer, Otsuka Pharmaceutical Development & Commercialization, Inc. "These findings strengthen the rationale for selective APRIL inhibition as a targeted approach that modulates B-cell activity to reduce pathogenic IgA production, without B-cell depletion, differentiating selective APRIL inhibition as a safe and effective option for improving outcomes for patients with IgA nephropathy."

About the VISIONARY Study

The VISIONARY Phase 3 trial is ongoing and will evaluate the long-term safety and efficacy of sibeprenlimab in preserving kidney function based on annualized slope of estimated glomerular filtration rate (key second efficacy endpoint), estimated glomerular filtration rate change from baseline (secondary efficacy endpoint) over a 24-month treatment period. Additional longer-term assessments are planned in the Phase 2/3 open-label extension study (NCT05248659).

About IgAN

IgA nephropathy (IgAN) is a progressive, immune-mediated, chronic kidney disease that typically manifests in adults aged 20-40 years and can lead to end-stage kidney disease (ESKD) over the lifetime of most patients^2-4. IgAN is characterized by the accumulation of Gd-IgA1 complexes in the kidneys³. IgAN can lead to progressive loss of kidney function and, eventually, ESKD, imposing a significant burden on patients³. Despite supportive care, there is an unmet need for treatments that address the root causes of the condition⁵. Continued research in IgAN remains crucial to uncovering opportunities for advancement in our understanding and treatment of patients⁵.

About VOYXACT^®

VOYXACT (sibeprenlimab-szsi) is a humanized monoclonal antibody that binds to and blocks APRIL, which plays a key role in the 4-hit process of IgAN pathogenesis and is an important initiating and sustaining factor in IgAN progression by promoting the production of pathogenic galactose-deficient IgA1 (Gd-IgA1)^5-8. Inhibition of APRIL results in reduced levels of serum galactose-deficient IgA1 (Gd-IgA1), which is implicated in the pathogenesis of IgAN. VOYXACT is a self-administered, subcutaneous injection dosed once every four weeks. VOYXACT is the first and only FDA-approved treatment for primary IgAN that selectively inhibits APRIL, a key immune driver of the disease¹. VOYXACT was granted accelerated approval by the U.S. FDA on November 25, 2025. Otsuka has initiated a rolling submission of a supplemental Biologics License Application (sBLA) to the U.S. FDA for VOYXACT traditional approval, including data from the 24-month eGFR endpoint.

About Otsuka

Otsuka Pharmaceutical Co., Ltd. is a total healthcare company that focuses on each individual's potential to enhance their well-being. Our medical-related business provides treatments and diagnostics for both physical and mental health. Our nutraceutical business supports daily health maintenance and improvement. Otsuka's unique products and services are based on scientific evidence, under the guidance of our corporate philosophy: Otsuka-people creating new products for better health worldwide. For further information, please visit www.otsuka.co.jp/en/.

References

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• 5. Cheung CK, Barratt J, Liew A, Zhang H, Tesar V, Lafayette R. The role of BAFF and April in IGA nephropathy: Pathogenic mechanisms and targeted therapies. Frontiers in nephrology. February 1, 2024.
• 6. Mathur M, Barratt J, Suzuki Y, et al. Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of VIS649 (Sibeprenlimab), an APRIL-Neutralizing IgG2 Monoclonal Antibody, in Healthy Volunteers. Kidney Int Rep. 2022;7(5):993-1003.
• 7. Chang S, Li XK. The Role of Immune Modulation in Pathogenesis of IgA Nephropathy (nih.gov)
• 8. Mathur M, Barratt J, Chacko B, et al. A Phase 2 Trial of Sibeprenlimab in Immunoglobulin A Nephropathy Patients. NEJM. 2023 https://www.nejm.org/doi/full/10.1056/NEJMoa2305635