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Zymeworks (ZYME) Is Down 5.6% After Positive Phase 3 Ziihera Data Unlocks US$440 Million Milestones

Simply Wall St · 3d ago
  • Zymeworks Inc. recently reported positive Phase 3 HERIZON-GEA-01 results showing that Ziihera (zanidatamab-hrii) plus chemotherapy, with or without Tevimbra (tislelizumab), improved progression-free and overall survival versus trastuzumab plus chemotherapy in adults with HER2-positive metastatic gastroesophageal adenocarcinoma, with data presented as a late-breaking oral session at the 2026 ASCO-GI symposium.
  • The trial’s efficacy and manageable safety profile could support Ziihera’s use as a new first-line HER2-targeted option and unlock up to US$440.00 million in regulatory milestones and future royalty streams across major markets.
  • We’ll now examine how Ziihera’s Phase 3 survival benefit and associated US$440.00 million milestone potential affect Zymeworks’ royalty-focused investment narrative.

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Zymeworks Investment Narrative Recap

To own Zymeworks today, you need to believe its partner-led, royalty-first model can turn irregular milestone payments into a more predictable cash engine, while the early-stage internal pipeline matures without overstraining the balance sheet. The HERIZON-GEA-01 readout sharpens that story by tying Ziihera’s Phase 3 survival benefit directly to up to US$440.0 million in potential milestones, making regulatory progress on Ziihera the key near-term catalyst and any approval delay the most immediate risk.

Among recent announcements, the US$125.0 million share repurchase program stands out beside the Ziihera data, as it sits on top of a business still reliant on partner execution and milestone timing rather than recurring product revenue. For investors, the combination of a buyback and a maturing royalty stream may feel appealing, but the durability of those milestone and royalty inflows remains the central question.

Yet behind the strong Phase 3 headlines, investors should also be aware of the risk that milestone-dependent cash flows can...

Read the full narrative on Zymeworks (it's free!)

Zymeworks' narrative projects $150.9 million revenue and $24.2 million earnings by 2028. This requires 7.1% yearly revenue growth and a $97.9 million earnings increase from $-73.7 million today.

Uncover how Zymeworks' forecasts yield a $34.50 fair value, a 39% upside to its current price.

Exploring Other Perspectives

ZYME 1-Year Stock Price Chart
ZYME 1-Year Stock Price Chart

Simply Wall St Community members have only two fair value estimates for Zymeworks, ranging from US$1.43 to US$34.50, underscoring sharply different expectations. Before factoring in the new Ziihera data, these retail views sit against a business still heavily reliant on partner-driven milestones and royalties, so you may want to compare several viewpoints before deciding how that risk fits your own expectations.

Explore 2 other fair value estimates on Zymeworks - why the stock might be worth less than half the current price!

Build Your Own Zymeworks Narrative

Disagree with existing narratives? Create your own in under 3 minutes - extraordinary investment returns rarely come from following the herd.

  • A great starting point for your Zymeworks research is our analysis highlighting 4 key rewards that could impact your investment decision.
  • Our free Zymeworks research report provides a comprehensive fundamental analysis summarized in a single visual - the Snowflake - making it easy to evaluate Zymeworks' overall financial health at a glance.

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This article by Simply Wall St is general in nature. We provide commentary based on historical data and analyst forecasts only using an unbiased methodology and our articles are not intended to be financial advice. It does not constitute a recommendation to buy or sell any stock, and does not take account of your objectives, or your financial situation. We aim to bring you long-term focused analysis driven by fundamental data. Note that our analysis may not factor in the latest price-sensitive company announcements or qualitative material. Simply Wall St has no position in any stocks mentioned.