Perioperative Zanidatamab and Chemotherapy for HER2 Positive Gastroesophageal Cancer (HER-OIC)

March 18, 2026 updated by: Universitaire Ziekenhuizen KU Leuven

Perioperative Zanidatamab Combined With Chemotherapy in Operable HER2 Positive Locally Advanced Operable Gastroesophageal Adenocarcinoma (GEA): A Phase 1b/2a Single-Arm Trial

The HER-OIC clinical trial is a Phase 1b/2a study investigating a new combination of treatments for patients with HER2-positive gastroesophageal cancer. Standard treatment for localized gastroesophageal cancer usually involves chemotherapy before and after surgery. This study aims to see if adding targeted therapy (zanidatamab) and immunotherapy (tislelizumab) to standard chemotherapy is safe and effectively eliminates the tumor. The goal is to improve the pathological complete response (pCR) rate, which is the percentage of patients who have no visible cancer cells remaining in the tissue removed during surgery.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
29

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 2
  • Phase 1

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Voluntary written informed consent from the participant or their legally authorized representative
  • At least 18 years of age at the time of signing the consent form
  • Agreement to use highly effective birth control methods for both male and female patients
  • WHO-ECOG performance status of 0 or 1
  • Histologically proven HER2-positive gastroesophageal, esophageal, or gastric adenocarcinoma
  • Localized, resectable disease that is fit for perioperative treatment, including surgery
  • Adequate hepatic function
  • Adequate renal function with an estimated Glomerular Filtration Rate (GFR) > 50 mL/min
  • Adequate hematologic function
  • Cardiac ejection fraction

Exclusion Criteria:

  • Prior neoadjuvant or definitive chemoradiation
  • Squamous cell cancer of the esophagus
  • Metastatic or unresectable gastroesophageal cancer
  • Active or relapsing autoimmune diseases, with exceptions for controlled Type 1 diabetes, hypothyroidism (hormone replacement only), controlled celiac disease, or certain skin diseases not requiring systemic treatment
  • Known hypersensitivity to zanidatamab, tislelizumab, or any of their excipients
  • Known Dihydropyrimidine Dehydrogenase (DPD) deficiency
  • Active infections requiring systemic treatment
  • History of significant cardiac disease
  • Previous malignancy within the last 5 years
  • Current participation in another interventional Trial involving an investigational medicinal product or device

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Perioperative Zanidatamab and Chemotherapy
This is a single-arm, open-label trial where participants are assigned to receive specific interventions (zanidatamab, chemotherapy, tislelizumab) based on the study protocol.
Drug: Zanidatamab Combined with Chemotherapy
This intervention combines perioperative zanidatamab with chemotherapy and the PD-1 inhibitor tislelizumab for HER2-positive gastroesophageal adenocarcinoma

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Pathological Complete Response (pCR) Rate (Total Population)
Time Frame: At the time of surgery, which occurs 4 to 12 weeks after the last dose of pre-operative treatment (approximately 12 to 20 weeks after the first dose)
The primary efficacy endpoint is the improvement of the pCR rate, defined as the percentage of patients with no residual invasive cancer in the completely resected tumor specimen and sampled regional lymph nodes. The study aims to detect an improvement from a historical 8% to a 30% pCR rate across the total 29-patient cohort.
At the time of surgery, which occurs 4 to 12 weeks after the last dose of pre-operative treatment (approximately 12 to 20 weeks after the first dose)
Incidence of Qualifying Safety Events (Phase 1b Safety Run-in)
Time Frame: During the neoadjuvant period, which start from the first treatment administration and continues until the end of the fourth preoperative 14-day cycle (8 weeks)
The primary safety endpoint is the incidence of "qualifying safety events," defined as Grade ≥3 diarrhea or any Grade ≥3 treatment-emergent toxicity that results in the inability to administer the planned neoadjuvant chemotherapy or zanidatamab.
During the neoadjuvant period, which start from the first treatment administration and continues until the end of the fourth preoperative 14-day cycle (8 weeks)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Universitaire Ziekenhuizen KU Leuven

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
June 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
June 1, 2028

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
June 1, 2033

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
March 12, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 12, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 17, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
March 20, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 18, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • S71017

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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