The ESMO Congress 2026 is set to bring several potentially important readouts across gastric, gastroesophageal junction, and esophageal cancers. From HER2- and CLDN18.2-directed therapies to immunotherapy combined with definitive chemoradiotherapy, adjuvant treatment de-escalation, biomarker-guided strategies, and nonoperative management, the gastroesophageal cancer program includes studies addressing multiple stages of disease.
This overview highlights 10 gastroesophageal cancer trials to watch at ESMO 2026, including several phase III studies that could inform future treatment strategies.
HERIZON-GEA-01: Zanidatamab + Chemotherapy ± Tislelizumab in 1L HER2-Positive Advanced GEA
Abstract: LBA79
Presenter: Kohei Shitara (Kashiwa, Japan)
Trial Type: Phase III, Randomized, Open-Label
Session: Rapid Oral Session
HERIZON-GEA-01 (NCT05152147) is a global phase III trial evaluating zanidatamab plus chemotherapy with or without tislelizumab compared with trastuzumab plus chemotherapy as first-line treatment for HER2-positive advanced or metastatic gastroesophageal adenocarcinoma.
The primary analysis was published on May 27, 2026, in The New England Journal of Medicine in the article “Zanidatamab with and without Tislelizumab in HER2-Positive Gastroesophageal Cancer.” In the previously reported first interim analysis, median PFS by blinded independent central review was 12.4 months in both zanidatamab-containing arms versus 8.1 months with trastuzumab plus chemotherapy. Median OS was 26.4 months with zanidatamab plus tislelizumab plus chemotherapy and 24.4 months with zanidatamab plus chemotherapy, versus 19.2 months with trastuzumab plus chemotherapy.
The OS benefit was statistically significant for zanidatamab plus tislelizumab plus chemotherapy, while the comparison of zanidatamab plus chemotherapy versus trastuzumab plus chemotherapy did not meet the prespecified criteria for statistical significance at that interim analysis.
At ESMO GI 2026, HRQoL results showed that physical functioning and Global Health Status/QoL were generally maintained across treatment arms, with no substantive changes in Global Health Status/QoL from baseline over time.
ESMO 2026 will present the second interim analysis from HERIZON-GEA-01.
KC-WISE: Anbenitamab + Chemotherapy in Previously Treated HER2-Positive Gastric or GEJ Cancer
Abstract: LBA80
Presenter: Ruixing Zhang (Shijiazhuang, China, Hebei)
Trial Type: Phase III, Randomized, Double-Blind
Session: Rapid Oral Session
KC-WISE (NCT05427383) is a randomized, double-blind phase III trial evaluating anbenitamab plus chemotherapy versus chemotherapy alone in patients with HER2-positive gastric or gastroesophageal junction adenocarcinoma whose previous trastuzumab-containing therapy had failed.
The prespecified interim analysis was presented at ESMO 2025 and subsequently published in Annals of Oncology. Among 188 patients, median PFS was 7.1 months with anbenitamab plus chemotherapy versus 2.7 months with chemotherapy alone, while median OS was 19.6 versus 11.5 months, respectively.
ESMO 2026 will present the updated overall survival analysis from KC-WISE.
LOMAC: Four Months vs Six Months of Adjuvant XELOX in Stage II–IIIB Gastric Cancer
Abstract: LBA81
Presenter: Dazhi Xu (Shanghai, China)
Trial Type: Phase III, Randomized, Noninferiority
Session: Rapid Oral Session
LOMAC (NCT03399110) is a phase III randomized trial comparing four months versus six months of adjuvant capecitabine plus oxaliplatin after D2 gastrectomy in patients with stage II–IIIB gastric cancer. The study was designed to determine whether four months of XELOX is noninferior to six months with respect to disease-free survival and is associated with lower treatment-related toxicity.
ESMO 2026 will present the LOMAC results comparing four versus six months of adjuvant XELOX after D2 gastrectomy in stage II–IIIB gastric cancer.
G-HOPE-001: Arcotatug Tavatecan vs Physician’s Choice in Previously Treated CLDN18.2-Positive Gastric/GEJ Cancer
Abstract: LBA77
Presenter: Kohei Shitara (Kashiwa, Japan)
Trial Type: Phase III, Randomized, Open-Label
Session: Proffered Paper Session
G-HOPE-001 (NCT06238843) is a multiregional, randomized phase III trial evaluating arcotatug tavatecan (IBI343/TAK-921) versus treatment of investigator’s choice in patients with previously treated, CLDN18.2-positive, HER2-negative advanced gastric or gastroesophageal junction adenocarcinoma. Patients had received and progressed on 2–4 prior systemic treatment regimens. Arcotatug tavatecan is a CLDN18.2-directed antibody-drug conjugate composed of an anti-CLDN18.2 antibody conjugated to exatecan, a topoisomerase I inhibitor. Progression-free survival and overall survival are primary endpoints.
ESMO 2026 will present the first interim analysis of G-HOPE-001.
KEYNOTE-975: Pembrolizumab + Definitive Chemoradiotherapy in Esophageal and GEJ Cancer
Abstract: 2875O
Presenter: Manish A. Shah (New York, United States)
Trial Type: Phase III, Randomized, Double-Blind, Placebo-Controlled
Session: Proffered Paper Session
KEYNOTE-975 (NCT04210115) is a randomized phase III trial evaluating pembrolizumab versus placebo in combination with concurrent definitive chemoradiotherapy in patients with locally advanced esophageal or gastroesophageal junction cancer. The study includes esophageal squamous cell carcinoma, esophageal adenocarcinoma, and GEJ carcinoma. Concurrent chemotherapy consists of either 5-FU plus cisplatin or FOLFOX with radiotherapy. Overall survival and event-free survival are the primary efficacy endpoints, assessed in the overall population and predefined subgroups.
ESMO 2026 will present the phase III results comparing pembrolizumab with placebo plus concurrent definitive chemoradiotherapy.
TQB2102 + Bemotrizumab ± Capecitabine in First-Line HER2-Positive Advanced Gastric/GEJ Cancer
Abstract: 2876RO
Presenter: Miaozhen Qiu (Guangzhou, China)
Trial Type: Phase II
Session: Rapid Oral Session
This phase II study evaluates TQB2102 combined with bemotrizumab, with or without capecitabine, as first-line treatment for HER2-positive advanced gastric or gastroesophageal junction cancer. TQB2102 is a biparatopic HER2-directed antibody-drug conjugate targeting HER2 extracellular domains 2 and 4 and carrying a topoisomerase I inhibitor payload. Its preclinical characterization and phase I results in advanced solid tumors were published in Annals of Oncology in 2026.
ESMO 2026 will present phase II results of this first-line combination strategy.
GERCOR-GONO DEWI: Dostarlimab With a Watch-and-Wait Strategy in Localized dMMR/MSI-H GEA
Abstract: 2877RO
Presenter: Thierry André (Paris, France, CEDEX 12)
Trial Type: Phase II
Session: Rapid Oral Session
The GERCOR-GONO DEWI phase II study evaluates dostarlimab followed by a watch-and-wait strategy in patients with localized dMMR/MSI-H gastric or gastroesophageal junction adenocarcinoma. The primary objective is to assess this nonoperative strategy in patients with localized dMMR/MSI-H disease. A separate cohort evaluates dostarlimab in patients older than 70 years with localized dMMR/MSI-H gastric or GEJ adenocarcinoma who are considered unfit for surgery.
ESMO 2026 will present the first interim analysis of the DEWI phase II study.
CLARITY-Gastric 01: Sonesitatug Vedotin in CLDN18.2-Positive Previously Treated Gastroesophageal Cancer
Abstract: LBA7
Presenter: Rui-Hua Xu (Guangzhou, China)
Trial Type: Phase III, Randomized, Open-Label
Session: Proffered Paper Session
CLARITY-Gastric 01 (NCT06346392) is a global phase III trial evaluating sonesitatug vedotin versus investigator’s choice of therapy in patients with CLDN18.2-positive advanced gastric, gastroesophageal junction, or esophageal adenocarcinoma after at least one prior systemic treatment. The trial used a CLDN18.2 positivity threshold of expression in at least 25% of tumor cells at any staining intensity.
On July 27, 2026, AstraZeneca announced topline results showing that the trial met its primary overall survival endpoint in the third-line-or-later population. A statistically significant improvement in overall survival was also reported in the overall second-line-or-later population, while progression-free survival showed a favorable trend but did not reach statistical significance.
ESMO 2026 will present the phase III results from CLARITY-Gastric 01.
FORTITUDE-101 and FORTITUDE-102: Bemarituzumab Efficacy by FGFR2 Amplification Status
Abstract: 2883RO
Presenter: Zev A. Wainberg (Los Angeles, United States of America)
Trial Type: Exploratory Biomarker Analysis
Session: Rapid Oral Session
This exploratory analysis will evaluate the efficacy of bemarituzumab according to FGFR2 amplification status using data from FORTITUDE-101 and FORTITUDE-102.
FORTITUDE-101 (NCT05052801) is a randomized phase III trial comparing bemarituzumab plus mFOLFOX6 with placebo plus mFOLFOX6 in previously untreated FGFR2b-overexpressing advanced gastric or gastroesophageal junction cancer. FORTITUDE-102 (NCT05111626) is a phase 1b/3 study evaluating bemarituzumab plus chemotherapy and nivolumab versus placebo plus chemotherapy and nivolumab in previously untreated FGFR2b-overexpressing advanced gastric or GEJ cancer.
ESMO 2026 will present an exploratory biomarker analysis of treatment outcomes according to FGFR2 amplification status.
IKFs602/AIO RAMIRIS: FOLFIRI + Ramucirumab vs Paclitaxel + Ramucirumab After Prior Taxane Therapy
Abstract: 2878RO
Presenter: Sylvie Lorenzen (Munich, Germany)
Trial Type: Phase III, Randomized
Session: Rapid Oral Session
The phase III IKFs602/AIO RAMIRIS study compares FOLFIRI plus ramucirumab with paclitaxel plus ramucirumab as second-line treatment for patients with advanced or metastatic gastroesophageal adenocarcinoma previously treated with a taxane.
The earlier randomized phase II RAMIRIS study, presented at ESMO 2020 and subsequently published, enrolled 111 patients. The study did not meet its primary endpoint, but among patients previously treated with docetaxel, median PFS was 4.6 months with FOLFIRI plus ramucirumab versus 2.1 months with paclitaxel plus ramucirumab, supporting further phase III evaluation.
ESMO 2026 will present the final results of the phase III RAMIRIS study.
The Bottom Line
The ESMO 2026 gastroesophageal cancer programme reflects several major areas of ongoing treatment development. HERIZON-GEA-01, KC-WISE, and TQB2102 continue to expand HER2-directed strategies across first-line and previously treated disease, while G-HOPE-001 and CLARITY-Gastric 01 evaluate CLDN18.2-directed ADCs.
LOMAC addresses the duration of adjuvant XELOX after D2 gastrectomy, KEYNOTE-975 evaluates pembrolizumab with definitive chemoradiotherapy, and DEWI explores a watch-and-wait approach after dostarlimab in localized dMMR/MSI-H disease. FORTITUDE-101/102 examines FGFR2 amplification as a biomarker for bemarituzumab efficacy, while RAMIRIS compares two ramucirumab-based second-line strategies after prior taxane exposure. Together, these studies will provide new data across localized, adjuvant, and advanced gastroesophageal cancer settings.
Full abstract details are available in the official ESMO programme.
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