---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-25-283873"
form_type: "8-K"
ticker: "ZYME"
cik: "0001937653"
company_name: "Zymeworks Inc."
filed_at: "2025-11-17T23:59:59+00:00"
generated_at: "2026-05-16T19:24:18.860649+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# Zymeworks announces positive Phase 3 results for Ziihera in first-line HER2+ GEA

## Summary
- Ziihera + chemo showed statistically significant PFS improvement vs trastuzumab + chemo; OS trend with further analysis expected mid-2026.
- Ziihera + Tevimbra (tislelizumab) + chemo showed statistically significant improvements in both OS and PFS vs control.
- PFS and OS benefit observed across PD-L1 positive and negative subgroups in the triple combo arm.
- Jazz plans to submit supplemental BLA in 1H-2026; Zymeworks eligible for milestones and royalties.
- Safety profile consistent with known safety of each agent; no new signals observed.

## SEC filing metadata
- accession: 0001193125-25-283873
- form_type: 8-K
- ticker: ZYME
- cik: 0001937653
- company_name: Zymeworks Inc.
- filed_at: 2025-11-17T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1937653/000119312525283873/0001193125-25-283873-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1937653/000119312525283873/d17392d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-25-283873
- JSON: https://secwatch.observer/filing/0001193125-25-283873.json
- Plain text: https://secwatch.observer/filing/0001193125-25-283873.txt

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