Zenas reports new obexelimab data in IgG4-related disease

what happened

GlobeNewswire reported on October 12, 2026, that Zenas BioPharma had presented new findings for obexelimab in immunoglobulin G4-related disease, or IgG4-RD. The material covered the Phase 3 INDIGO open-label extension, an analysis of glucocorticoid-related toxicity and an ongoing vaccine-response sub-study. The presentations were made at the 6th International Symposium on IgG4-Related Disease, held October 8–10, 2026, in Cambridge, Massachusetts.

Patients completing the 52-week randomized, controlled portion of INDIGO could continue on 250 mg of subcutaneous obexelimab once a week. The estimated 12-month probability of avoiding a flare that required rescue treatment was 0.93 when based on investigator and adjudication committee confirmation, and 0.87 under investigator assessment; five cases were awaiting adjudication at the data cutoff. Median cumulative rescue glucocorticoid use was 0 mg, while the mean was 105 mg. Adverse-event rates were similar to, or below, those recorded during the controlled phase.

A separate analysis found that obexelimab reduced cumulative glucocorticoid toxicity versus placebo at week 52. The difference in GTI Cumulative Worsening Score was -11.4, with p=0.021, and fewer treated patients crossed clinically meaningful toxicity thresholds. During a planned treatment-free interval, influenza vaccination produced seroimmunity in 6 of 7 participants and COVID-19 vaccination did so in 4 of 4. No flares occurred during the interval, which averaged 34.6 days. Among seven participants, pre-existing immunity markers were retained for influenza in 71% and for COVID-19 in 50%. Obexelimab is an investigational bifunctional antibody targeting CD19 and FcγRIIb to inhibit implicated B-cell activity without depleting the cells. It has been assessed in nine trials involving 667 subjects, while topline Phase 2 SunStone results in systemic lupus erythematosus are expected in 4Q 2026.

why it matters

The update adds clinical evidence for Zenas’ lead candidate in a rare, chronic and relapsing immune-mediated disease. The findings address long-term flare control, steroid exposure and vaccination during a treatment pause, while the upcoming SunStone readout remains a scheduled development event.

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