Zymeworks Announces Presentations for Ziihera (zanidatamab-hrii) at 2026 AACR Annual Meeting

The company’s partner, Jazz Pharmaceuticals, will present four abstracts featuring data from clinical trials evaluating Ziiher (zanidatamab-hrii) at the American Association for Cancer Research (AACR) Annual Meeting, being held April 17-22, 2026 in San Diego, CA.

“We are pleased to see the continued clinical progress of zanidatamab reflected in multiple presentations at AACR,” said Ken Galbraith, Chair, Chief Executive Officer, and Interim Chief Financial Officer of Zymeworks. “These studies highlight emerging data evaluating zanidatamab across tumor types beyond biliary tract cancer and gastroesophageal adenocarcinoma, and contribute to the growing body of evidence supporting its potential across HER2-expressing cancers.”

Highlights at the AACR Annual Meeting include:

• An oral presentation with results from the Phase 2 single-arm, open-label NeoZanHER trial (NCT05035836) evaluating zanidatamab for the investigational use as neoadjuvant monotherapy in patients with early-stage HER2+ breast cancer. At six weeks, zanidatamab treatment resulted in a statistically significant decrease in tumor size and volume from baseline, and 30% of patients (n=6) achieved pathologic complete response (pCR). Treatment with zanidatamab was manageable with no new safety signals.
• A poster presentation detailing mechanistic and multi-omics analyses characterizing zanidatamab’s differentiated HER2 biology, including dual, domain-specific binding and downstream effects on key cellular signaling pathways, with insights into activity in models following progression on trastuzumab deruxtecan (T-DXd).

Additional presentations further explore zanidatamab’s utility across HER2-expressing solid tumors and within innovative biomarker-driven clinical trial designs, including adaptive organ-preservation strategies in gastroesophageal adenocarcinoma.

Oral Presentation

Title: A Phase 2 Single-Arm Open-Label Trial Evaluating Zanidatamab in Patients with Early Stage HER2 positive Breast Cancer: The NeoZanHER Study
Presentation Number: CT012
Session: Clinical Trials Minisymposium: Aiming for Cure: Perioperative Clinical Trials
Date/Time: Saturday, April 18, 2026 at 12:30 – 2:30 pm Pacific Standard Time (PST)

Poster Presentations

Title: Zanidatamab Modulates Multiple Pathways Involved in Tumor Growth and Survival is Efficacious Post-T-DXd
Abstract: 4542
Session: Experimental and Molecular Therapeutics: Next-Generation Targeted Therapies Directed Against Tumor Surface Antigens
Date/Time: Tuesday, April 21, 2026 at 9:00 am – 12:00 pm PST

Title: DiscovHER PAN-206: Phase 2 Tumor-Agnostic Study of Zanidatamab in Patients With Previously Treated Human Epidermal Growth Factor Receptor 2–Overexpressing Solid Tumors
Abstract: CT209
Session: Phase II and Phase III Clinical Trials in Progress
Date/Time: Tuesday, April 21, 2026 at 9:00 am – 12:00 pm PST

Title: AACR Adaptive Biomarker-Driven Organ Preservation Trial in GE Adenocarcinomas (AACR-ADOPT-GEA)
Abstract: CT223
Session: Phase II and Phase III Clinical Trials in Progress
Date/Time: Tuesday, April 21, 2026 at 9:00 am – 12:00 pm PST

The AACR abstracts are available at https://www.abstractsonline.com/pp8/#!/21436.