Zymeworks Drug Zanidatamab Shows Major Survival Benefit in Stomach Cancer
Positive Phase 3 data for its HER2-targeted therapy, developed with partner Jazz Pharmaceuticals, positions it as a potential new standard of care in gastroesophageal adenocarcinoma.
Zymeworks Inc. (NASDAQ: ZYME) and its partner Jazz Pharmaceuticals have unveiled compelling data from a pivotal late-stage trial for their cancer therapeutic, zanidatamab, marking a significant milestone that could reshape the treatment landscape for a specific type of stomach cancer.
The positive topline results from the Phase 3 HERIZON-GEA-01 study, announced in late November, showed that zanidatamab achieved its primary endpoints, demonstrating statistically significant and clinically meaningful improvements in progression-free survival (PFS) for patients with HER2-positive gastroesophageal adenocarcinoma (GEA). The treatment, a bispecific antibody, also showed a notable improvement in the key secondary endpoint of overall survival (OS).
The study data revealed an impressive median overall survival of 26.4 months for the patient group receiving zanidatamab in combination with chemotherapy. This result is a potential step forward from the current standard-of-care regimens for this aggressive form of cancer.
"These results are unprecedented and represent a potential paradigm shift in how we treat HER2-positive GEA," a sentiment echoed in company statements and subsequent analyst reports. The successful trial outcome is a major validation for Zymeworks' proprietary Azymetric™ platform and its lead clinical asset.
The market has reacted favorably since the news broke. While shares traded around $23.17 on Friday, the stock has climbed significantly from its 52-week low of $9.03, reaching a high of $28.49 in the weeks following the announcement. The company currently holds a market capitalization of approximately $1.75 billion. Wall Street has taken a Kelley Wrightstive stance, with data showing a consensus of 14 'Buy' or 'Strong Buy' ratings from analysts and an average price target of $35.62, suggesting considerable upside potential.
The development and potential commercialization of zanidatamab are part of a major strategic partnership. In a deal valued at up to $1.76 billion, Jazz Pharmaceuticals acquired exclusive development and commercialization rights to zanidatamab in key global markets, including the U.S., Europe, and Japan. This arrangement provides Zymeworks with significant non-dilutive funding through milestone payments and royalties, while leveraging Jazz’s commercial expertise in the oncology space.
Looking ahead, the path to market is becoming clearer. Jazz Pharmaceuticals is preparing to submit a supplemental Biologics License Application (sBLA) to the U.S. Food and Drug Administration (FDA) in the first half of 2026. Further detailed results from the HERIZON-GEA-01 study were presented at the ASCO Gastrointestinal Cancers Symposium in January, offering the medical community a deeper look at the data that has generated significant optimism. Success in this indication is expected to drive peak annual sales of over $2 billion, according to analyst projections, positioning zanidatamab as a future blockbuster and a cornerstone therapy for Zymeworks and Jazz.