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HERIZON-GEA-01

About the HERIZON-GEA-01 Trial



Table of Contents

Major Presentations and Milestones

HERIZON-GEA-01 Trial design, results, and conclusions

HERIZON-GEA-01 Sentiments and Criticisms

HERIZON-GEA-01 Temporal Sentiment Arc

Professional Resources : Interactive Tweet History, Influence Diagram, Sentiment Table, AI Chatbot

HERIZON-GEA-01 Trial: Major Presentations and Milestones

Primary speakers driving the story

At ASCO GI 2026 (#GI26), HERIZON-GEA-01 emerged as one of the key HER2-positive gastroesophageal adenocarcinoma readouts, driven by clinician amplification around the potential to reset first-line HER2 standards. Sharlene Gill, MD, MPH, MBA, FASCO (University of British Columbia) explicitly congratulated Dr Elimova (UHN) in the context of the presentation and summarized the three-arm phase III design evaluating zanidatamab-based regimens against trastuzumab-based chemotherapy in 1L HER2+ disease.

Arndt Vogel, MD added a high-level “off the press” signal prior to the full meeting discussion, flagging HERIZON-GEA-01 as phase III positive and explicitly positioning the key question as comparative context versus KEYNOTE-811.

HERIZON-GEA-01 Trial Design, Results, and Conclusions

Trial Design:

HERIZON-GEA-01 is a phase III, first-line trial in HER2-positive locally advanced unresectable or metastatic gastric/GEJ adenocarcinoma. As summarized by multiple KOLs, it randomized patients (N≈914 per Gill) to:

Control: trastuzumab + chemotherapy (CAPOX or cisplatin/5-FU)

Experimental arm: zanidatamab + chemotherapy

Experimental arm: zanidatamab + chemotherapy + tislelizumab (PD-1)

Primary Results:

Across independent tweet summaries, zanidatamab-based therapy improved PFS compared with trastuzumab + chemotherapy, and the triplet (zanidatamab + chemotherapy + tislelizumab) demonstrated an OS benefit in reported analyses.

Safety:

KOL summaries characterized safety as manageable, with specific AEs noted in one thread summary: “AEs: Diarrhea & Infusion related reactions” (Oncology Brothers). https://x.com/OncBrothers/status/2010147852496863260

Key Conclusions:

Based on the meeting-cycle tweets captured here, HERIZON-GEA-01 was interpreted as establishing zanidatamab-based therapy as a plausible new first-line HER2 backbone in metastatic gastroesophageal adenocarcinoma, with clear PFS improvement versus trastuzumab + chemotherapy and a reported OS benefit for the zanidatamab + chemotherapy + tislelizumab triplet. Multiple commentators emphasized the need to contextualize these results against existing HER2/IO standards (notably KEYNOTE-811).

HERIZON-GEA-01 Sentiments and Criticisms

Positive Reception:

Arndt Vogel, MD: “Could be practice changing, but let's see how it compares to KEYNOTE-811” https://x.com/ArndtVogel/status/1993368511138172964

Oncology Brothers (context: first-line HER2+ mGEA): “Zanidatamab, a new anti-Her2 treatment in 1L metastatic Her2+ GEJ/Gastric Adenocarcinoma!” https://x.com/OncBrothers/status/2010009808007790738

Critical Perspectives (trial design / control arm):

Erman Akkus questioned whether the control arm remained optimal given the timing of pembrolizumab + trastuzumab + chemotherapy accelerated approval (May 2021) relative to study start (Dec 2021): “Herizon-01 has control arms "trastuzumab plus ChT" and "zanidatamab plus ChT".” https://x.com/Erman_Akkus/status/2009357331939709106

Yakup Ergün raised the same core question succinctly: “Let’s also look at the HERIZON-GEA-01 trial from a design perspective. Was the control arm optimal?” https://x.com/dr_yakupergun/status/2009360719377256452

Nuanced implementation framing:

Cathy Eng, MD highlighted an “early trend” framing and tolerability: “Early trend for OS: 26.4 vs. 19.2M (HR = 0.80) … PFS 12.4 vs. 8.1M with good tolerance” https://x.com/CathyEngMD/status/2009310789442953408

HERIZON-GEA-01 Temporal Sentiment Arc

Late 2025 (Pre-meeting signal: “phase 3 positive”)

Primary/KOL tweets:

January 2026 (ASCO GI 2026: data-driven adoption vs design debate)

Primary/KOL tweets:

In aggregate, the HERIZON-GEA-01 conversation progressed from high-level excitement (late 2025) to a more mature #GI26 debate: strong efficacy and manageable safety signals on one hand, and a rigorous control-arm/standard-of-care critique on the other—both of which will influence how quickly and in whom zanidatamab-based therapy is adopted.

HERIZON-GEA-01 Professional Resources