---
schema_version: "secwatch.filing_event.v1"
accession: "0001104659-26-115151"
form_type: "8-K"
ticker: "ZBIO"
cik: "0001953926"
company_name: "Zenas BioPharma, Inc."
filed_at: "2026-10-13T10:01:28+00:00"
generated_at: "2026-10-13T10:05:54.629493+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.62
calibrated_materiality_score: 0.62
confidence: "high"
source: SEC EDGAR
---

# Zenas BioPharma reports Phase 3 INDIGO open-label extension obexelimab data in IgG4-RD

## Summary
- 12-month probability of remaining flare-free: 0.93 for adjudication committee-confirmed flares, 0.87 for investigator-determined; median cumulative glucocorticoid rescue dose 0 mg (mean 105 mg)
- Obexelimab significantly reduced cumulative glucocorticoid toxicity versus placebo at week 52 (GTI Cumulative Worsening Score difference -11.4; p=0.021)
- Vaccine sub-study: seroimmunity to influenza in 6 of 7 (86%) and COVID-19 in 4 of 4 (100%) during a treatment-free window averaging 34.6 days, with no disease flares
- Participants (n=7) maintained pre-existing immunity markers after long-term obexelimab treatment: 71% for influenza and 50% for COVID-19
- Data presented at the 6th International Symposium on IgG4-Related Disease, held October 8-10, 2026 in Cambridge, Massachusetts

## SEC filing metadata
- accession: 0001104659-26-115151
- form_type: 8-K
- ticker: ZBIO
- cik: 0001953926
- company_name: Zenas BioPharma, Inc.
- filed_at: 2026-10-13T10:01:28+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.62
- calibrated_materiality_score: 0.62
- confidence: high
- sec_items: 7.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1953926/000110465926115151/0001104659-26-115151-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1953926/000110465926115151/tm2627406d1_8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001104659-26-115151
- JSON: https://secwatch.observer/filing/0001104659-26-115151.json
- Plain text: https://secwatch.observer/filing/0001104659-26-115151.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.