- HERIZON-GEA-01 study is now open and enrolling patients to evaluate zanidatamab and chemotherapy with or without tislelizumab, versus standard of care
- Phase 2 data demonstrate potential benefit of zanidatamab in first-line GEA, with response rates and durability that compare favorably to both current standard of care and emerging treatments
- Study design enables a potential supplemental biologics license application (BLA) for zanidatamab in first-line HER2-positive GEA as early as 2024
- Zymeworks will host a conference call and webcast at 4:15pm ET today to discuss the HERIZON‑GEA‑01 Phase 3 trial design as well as the commercial strategy in HER2‑positive gastrointestinal cancers
VANCOUVER, British Columbia–Nov. 9, 2021– Zymeworks Inc. (NYSE: ZYME), a clinical-stage biopharmaceutical company developing multifunctional biotherapeutics, today announced, together with its partner BeiGene, the launch of HERIZON‑GEA‑01. This is a randomized, global Phase 3 study evaluating Zymeworks’ investigational HER2‑targeted bispecific antibody, zanidatamab, plus chemotherapy, with or without BeiGene’s anti-PD‑1‑targeted antibody tislelizumab, versus standard of care (trastuzumab plus chemotherapy), for the first-line treatment of metastatic HER2‑postive GEA.
“We are incredibly excited to launch our second pivotal, and first Phase 3 clinical trial for zanidatamab, HERIZON‑GEA‑01,” said Ali Tehrani, Ph.D., Zymeworks’ President & CEO. “Gastrointestinal cancers have significant unmet patient need and we have the opportunity to help a large and growing patient population. With two potential Biologics License Applications over the next 3 years, we believe zanidatamab has the potential to achieve blockbuster status and position Zymeworks as the leader in the treatment of HER2‑positive GI cancers.”
The primary objective of the HERIZON‑GEA‑01 study is to evaluate the efficacy and safety of zanidatamab in combination with physician’s choice chemotherapy [CAPOX (capecitabine/oxaliplatin) or FP (5FU/cisplatin)] with or without tislelizumab compared to trastuzumab plus physician’s choice chemotherapy in subjects with advanced or metastatic HER2-positive GEA. Primary endpoints are progression-free survival by RECIST 1.1, assessed by blinded independent central review, and overall survival.
The HERIZON-GEA-01 study seeks to enroll approximately 700 patients at approximately 300 sites across 38 countries. BeiGene will oversee trial sites in Asia (excluding Japan), Australia and New Zealand, and Zymeworks will oversee trial sites in the rest of the world, including North and South America, Japan, Europe, Middle East, and Africa.
“We are pleased the HERIZON‑GEA‑01 study has begun enrollment and our aim is to establish zanidatamab as the foundational agent of a new standard of care with tislelizumab for the first‑line treatment of HER2‑positive GEA,” said Neil Josephson, M.D., Zymeworks’ Interim Chief Medical Officer. “Based on the study design, we expect to have progression-free survival data as soon as 2024, which could enable submission of a supplemental Biologics License Application that same year.”
GEA is the fifth most common cancer worldwide and approximately 20 percent of patients diagnosed with this form of cancer are HER2‑positive. HER2‑positive GEA has high morbidity and mortality and patients are urgently in need of new treatment options.
“The encouraging zanidatamab Phase 2 data support its further investigation with tislelizumab in this Phase 3 HERIZON-GEA-01 trial in first-line HER2-positive gastroesophageal adenocarcinomas,” said Yong (Ben) Ben, M.D., Chief Medical Officer, Solid Tumors, at BeiGene. “We are excited to continue our collaboration with Zymeworks as we strive to address the unmet medical needs in this patient population by accelerating the development of zanidatamab.”
Phase 2 Study Results
In September, Zymeworks presented data at the European Society for Medical Oncology Annual Meeting from a Phase 2 clinical study of 36 patients with HER2‑expressing GEA who received zanidatamab in combination with either CAPOX (n=14), FP (n=2), or mFOLFOX6 (5FU/leucovorin/oxaliplatin; n=20). None of the patients had received prior HER2‑targeted therapies.
In 28 response-evaluable patients with metastatic HER2‑positive GEA, zanidatamab plus chemotherapy resulted in a confirmed objective response rate (cORR) of 75% and disease control rate (DCR) of 89% overall, with a cORR of 93% and DCR of 100% in the proposed Phase 3 regimen of zanidatamab and CAPOX/FP. All patients except one experienced a decrease in their tumor size. Across all treatment regimens, the median duration of response is 16.4 months and the median progression-free survival is 12.0 months, with 61% of patients still on study at the time of data cutoff.
In addition, the data demonstrate that zanidatamab plus chemotherapy is generally well tolerated, with the majority of treatment-related adverse events (TRAEs) considered mild to moderate in severity (Grade 1 or 2). The most common grade ≥ 3 TRAE was diarrhea, which was manageable in the outpatient setting; introduction of prophylactic loperamide reduced the incidence in cycle 1 from 44% to 18%. No severe (grade ≥ 3) infusion-related reactions or cardiac events were observed.
