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A Phase 2 Single-Arm Open-Label Pilot Trial Evaluating Zanidatamab (ZW25) in Patients With Early Stage HER2/Neu Positive (HER2+) Breast Cancer (BC)

  • PhasePhase 2
  • StatusRecruiting
  • Planned enrollment20 people
  • Recruiting US sites1
  • SponsorM.D. Anderson Cancer Center
  • RegistryNCT05035836

Recruitment re-checked on ClinicalTrials.gov Oct 30, 2026. Public record; not medical advice.

A Phase 2 Single-Arm Open-Label Pilot Trial Evaluating Zanidatamab (ZW25) in Patients With Early Stage HER2/Neu Positive (HER2+) Breast Cancer (BC): a one-minute explainerNCT050358361 min

Eligibility

Who can join

The film gives the main points. The full list below is copied from the registry; the study team makes the final decision.

  • Age18 Years to no maximum
  • SexFemale
  • Healthy volunteersNo

You may be able to join if

  • Ability to give written informed consent
  • Age > 18 years at time of study entry.
  • Patient would be willing to undergo surgery is appropriate for surgery
  • Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 (Appendix 1).
  • Tumor size > 1 cm to ≤ 3 cm assessed by ultrasound and clinically and radiographically node negative with no known metastatic disease.
  • HER2+ BC as defined by American Society of Clinical Oncology-College of American Pathologists (ASCO-CAP) guidelines.31 Patients may have ER+ or ER- negative disease, as defined by ASCO-CAP guidelines.
  • Left ventricular ejection fraction (LVEF) must be within institutional limits of normal as assessed by echocardiogram (ECHO) or multigated acquisition (MUGA) scan, documented within 4 weeks prior to first dose of study drug.
  • Adequate normal organ and marrow function as defined below:
  • Hemoglobin ≥ 9.0 g/dL
  • Absolute neutrophil count (ANC) ≥ 1.5 x 109/L (≥ 1500 per mm3)
  • Platelet count ≥ 100 x 109/L (≥100,000 per mm3)
  • Serum bilirubin ≤ 1.5 x institutional upper limit of normal (ULN). The maximum allowable bilirubin is ≤ 2.5 x ULN for patients with Gilbert's disease.
  • Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 3 x institutional ULN
  • Calculated glomerular filtration rate >50 mL/min
  • Patients must either be of non-reproductive potential or willing to undergo appropriate contraception. Male subjects must agree not to donate sperm and female subjects must agree not to donate oocytes starting at screening and throughout the study period, and for at least 12 months after treatment discontinuation.
  • Patient with reproductive potential must have a negative pregnancy test ≤3 days prior to the first dose of zanidatamab.

You cannot join if

  • An individual who meets any of the following criteria will be excluded from participation in this study:
  • Involvement in the planning and/or conduct of the study.
  • Prior or concurrent malignancy whose natural history or treatment has the potential to interfere with the safety or efficacy assessment of the investigational regimen
  • Has received therapy for this current diagnosis of BC including investigational therapy, endocrine therapy, targeted therapy, or chemotherapy, surgery or radiation.
  • Mean QT interval corrected for heart rate (QTc) ≥ 470 ms.
  • Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, active peptic ulcer disease or gastritis, active bleeding diatheses, , or psychiatric illness/social situations that would limit compliance with study requirements or compromise the ability of the patient to give written informed consent.
  • Female patients who are pregnant, breast-feeding, or of reproductive potential who are not employing an effective method of birth control.
  • Patients with uncontrolled seizures.
  • Any major surgery for any reason, within 4 weeks of the enrollment. Portacath placement will be allowed.
  • Clinically significant cardiac disease such as ventricular arrhythmia requiring therapy, , myocardial infarction, unstable angina (within 6 months prior to first dose of study drug), any history of cardiac failure, and uncontrolled hypertension (defined as systolic blood pressure > 150 mmHg and/or diastolic blood pressure > 100 mmHg on antihypertensive medications).
  • Known active Hepatitis B and/or Hepatitis C. Hepatitis testing is not required unless the patient has a history of Hepatitis B or C.
  • Known to be HIV positive. HIV testing is not required for those patients who are not known to be positive.
  • Total lifetime anthracycline load exceeding 360 mg/m2 doxorubicin or equivalent
  • Any condition that requires systemic treatment with either corticosteroids (>10 mg daily of prednisone or equivalent) or other immunosuppressive medication ≤14 days prior to randomization. Note: Subjects who are currently or have previously been on any of the following steroid regimens are not excluded:
  • Adrenal replacement steroid (dose ≤10 mg daily of prednisone or equivalent)
  • Topical, ocular, intra-articular, intranasal, or inhaled corticosteroid with minimal systemic absorption\
  • Short course (≤7 days) of corticosteroid prescribed prophylactically (e.g., for contrast dye allergy) or for the treatment of a non-autoimmune condition (e.g., delayed-type hypersensitivity reaction caused by contact allergen)
  • History of life-threatening hypersensitivity to monoclonal antibodies or to recombinant proteins or excipients in the drug formulation
  • Known distant metastatic disease including (CNS) metastases, symptomatic CNS metastases, and leptomeningeal disease (LMD).
  • Acute or chronic uncontrolled renal disease, pancreatitis, or liver disease (with exception of subjects with Gilbert's Syndrome, asymptomatic gall stones, liver metastases, or stable chronic liver disease per investigator assessment)
  • Symptomatic pulmonary embolism ≤28 days
  • Administered a live vaccine ≤4 weeks prior to randomization. Patients can get COVID vaccine that are not alive before ot during the study period, with 48 hours between vaccine administration and investigation agent administration.

The treatment

How it is intended to work

This is how the treatment is meant to work. Whether it helps, and how safe it is, is what this trial is testing.

zanidatamab-hrii. A humanized, immunoglobulin G1 (IgG1) bispecific monoclonal antibody that targets two different non-overlapping epitopes of the human tumor-associated antigen (TAA) epidermal growth factor receptor 2 (HER2), ECD2 and ECD4, with potential immunomodulating and antineoplastic activities. Upon administration, zanidatamab-hrii targets and binds to the two distinct HER2 domains on the tumor cell surface. This results in dual HER2 signal blockade, HER2 clustering, receptor internalization and downregulation. This inhibits HER2 activation, HER2-mediated signaling and HER2-mediated tumor cell growth. The specific binding of zanidatamab to tumor cells and HER2 aggregation also activates various immune-mediated responses, and induces complement-dependent cytotoxicity (CDC), antibody-dependent cellular cytotoxicity (ADCC), and antibody-dependent cellular phagocytosis (ADCP) against tumor cells that overexpress HER2. HER2, a tyrosine kinase receptor, is overexpressed by many cancer cell types. NCI Drug Dictionary

Treatments listed in the registry

  • Zanidatamab (Drug): Given IV
  • Letrozole (Drug): Given by PO
  • Tamoxifen (Drug): Given by PO

The study

Treatment groups

Na · Single Group · masking: None

Zanidatamab (Experimental)

zanidatamab by vein every 2 weeks (+/- 3 days) for up to 6 doses (3 study cycles

What it involves

Procedures

As the registry describes them. Requirements to join, such as a tissue sample, are in the eligibility list above even when on-study procedures are optional. Ask the study team which steps apply to you.

  • MRI: Part of the study plan

Goals

What the study measures

Main goals

  • To determine the efficacy of zanidatamab for patients with early stage HER2/neu positive (HER2+) breast cancer (BC) as determined by pathologic complete response (pCR (through study completion, an average of 1 year)

Planned enrollment: 20 (estimated).

Where

Recruiting US sites

  • M D Anderson Cancer Center, Houston, Texas

Site status as of Oct 30, 2026. Check the live record before contacting a site.

Background research

Papers linked by the registry

These papers are listed in the registry record. Unless a paper is marked as about this trial, it is background research on the treatment or disease, not results from this study.

Sources

Where this comes from

Registry record reviewed as fetched Oct 30, 2026, last updated by the sponsor Aug 23, 2026. Public record; not medical advice.

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