Zenas BioPharma Reports 93% Flare-Free Rate in Phase 3 INDIGO Extension Study

Key highlights

• Obexelimab achieved a 93 percent probability of remaining flare-free over 12 months in the open-label extension
• Clinical data showed a significant reduction in cumulative glucocorticoid toxicity compared to placebo at week 52
• Median and mean cumulative glucocorticoid rescue doses were reported at 0 mg and 105 mg respectively
• Safety findings remained consistent with or lower than adverse event rates seen in earlier controlled periods
• Initial sub-study findings suggest patients can maintain vaccine responses following a treatment-free window

Phase 3 INDIGO Clinical Outcomes

Zenas BioPharma presented updated findings from its Phase 3 INDIGO open-label extension evaluating obexelimab for the treatment of IgG4-related disease. The data, shared at the 6th International Symposium on IgG4-RD, indicated a 93 percent probability of patients remaining flare-free over a 12-month period based on investigator and adjudication committee confirmation. Furthermore, the trial demonstrated that obexelimab significantly lowered cumulative glucocorticoid toxicity versus placebo at week 52, with a Glucocorticoid Toxicity Index Cumulative Worsening Score difference of -11.4. These results support the investigational role of obexelimab as a reversible, B-cell inhibitor capable of reducing long-term steroid reliance.

Strategic Development and Pipeline Milestones

• Obexelimab is currently under U.S. FDA review with a Biologics License Application PDUFA date of May 27, 2027
• Pipeline expansion includes the ongoing Phase 2 SunStone trial for systemic lupus erythematosus with results expected in late 2026
• A Virtual R&D Event is scheduled for October 27, 2026, to discuss the broader clinical development program
• Vaccine response sub-study data indicates the potential for treatment-free windows to support immunization
• Safety profiles in the open-label extension were comparable to previous randomized controlled trial phases

Management Perspective on IgG4-RD Therapy

“Together, these new findings reinforce the potential role of obexelimab in long-term disease management, including helping patients remain flare-free, reducing steroid exposure, and potentially supporting vaccine responses following a treatment-free window.”

Operational and Financial Overview

As a clinical-stage biopharmaceutical company, Zenas BioPharma reported a cash position of approximately $673.9 million as of June 30, 2026. Management reaffirmed that current liquidity is sufficient to fund operating expenses and capital requirements into 2029. This stability follows a series of capital raises in early 2026, including a $250 million debt facility from Pharmakon and $300 million through concurrent public offerings of common stock and convertible senior notes. The company continues to focus on the commercialization path for obexelimab while advancing secondary indications in warm autoimmune hemolytic anemia and multiple sclerosis.

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Sector Context and Market Dynamics

• IgG4-RD is a chronic fibro-inflammatory condition that frequently requires ongoing management and acute flare control
• The biotechnology sector is increasingly prioritizing steroid-sparing agents to minimize long-term toxicity in autoimmune patients
• Zenas BioPharma operates within the specialized B-cell inhibitor market, focusing on CD19 and Fc-gamma-RIIb binding
• Biotech market sentiment remains sensitive to regulatory decision timelines and late-stage clinical data readouts

Management commentary

“Together, these new findings reinforce the potential role of obexelimab in long-term disease management, including helping patients remain flare-free, reducing steroid exposure, and potentially supporting vaccine responses following a treatment-free window.”

Zenas BioPharma, Inc. · financial snapshot

Share price	$26.40
Market cap	$1.7B
Revenue (annual)	$10M
1-month price change	-15.11%
Sector	HealthcareBiotechnology

Reference market data from a third-party provider, as of the story. Not a valuation or a recommendation.