A Vaccine (STEMVAC) With Standard Endocrine-Based Therapy or Chemotherapy for the Treatment of Metastatic Hormone Receptor Positive, HER2 Negative Breast Cancer

NCT ID: NCT07112053

Last Updated: 2025-12-15

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

RECRUITING

Clinical Phase

PHASE2

Total Enrollment

40 participants

Study Classification

INTERVENTIONAL

Study Start Date

2025-11-07

Study Completion Date

2028-12-31

Brief Summary

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This phase II trial studies how well a vaccine, STEMVAC, works in combination with standard endocrine-based therapy (ET) with a CDK4/6 targeted drug therapy, or with the chemotherapy drug capecitabine, in treating patients with hormone receptor (HR)-positive, HER2-negative breast cancer that has spread from where it first started (primary site) to other places in the body (metastatic). STEMVAC is designed to target proteins that cancer cells use when they become more aggressive and start to spread, and it is believed to work by boosting the immune system to recognize and destroy the invader tumor cells that are causing the disease. Standard ET is treatment that adds, blocks, or removes hormones in order to slow or stop the growth of cancer. Standard CDK4/6 inhibitors may stop the growth of tumor cells and may kill them by blocking some of the enzymes needed for cell growth. Capecitabine is in a class of medications called antimetabolites. It is taken up by tumor cells and breaks down into fluorouracil, a substance that kills tumor cells. Giving STEMVAC in combination with standard ET or chemotherapy may be an effective treatment for metastatic HR positive, HER2 negative breast cancer.

Detailed Description

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OUTLINE: Patients with ET-sensitive disease are assigned to Cohort 1, while patients with ET-resistant disease are assigned to Cohort 2.

COHORT 1: After completion of 2 cycles of standard of care (SOC) ET + CDK4/6 inhibitor (CDK4/6i) therapy, patients receive STEMVAC intradermally (ID) on the following schedule: 1) Three "priming" doses every 28 days; 2) Two "booster" doses at 6 and 9 months after "priming" dose #1; and 3) Additional "booster" doses every 6 months in the absence of disease progression or unacceptable toxicity. Patients also undergo computed tomography (CT) or ultrasound-guided biopsies for research purposes, as well as collection of blood samples and CT or positron emission tomography (PET) scans throughout the trial.

COHORT 2: After completion of 1 cycle of SOC capecitabine treatment, patients receive STEMVAC ID on the following schedule: 1) Three "priming" doses every 28 days; 2) Two "booster" doses at 6 and 9 months after "priming" dose #1; and 3) Additional "booster" doses every 6 months in the absence of disease progression or unacceptable toxicity. Patients also undergo CT or ultrasound-guided biopsies for research purposes, collection of blood samples, and fluoroestradiol (FES) positron emission tomography (PET) scans, as well as CT or PET scans throughout the trial.

After completion of study treatment, patients are followed every 6 months for 3 years.

Conditions

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Anatomic Stage IV Breast Cancer AJCC v8 Metastatic HER2-Negative Breast Carcinoma Metastatic Hormone Receptor-Positive Breast Carcinoma

Study Design

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Allocation Method

NON_RANDOMIZED

Intervention Model

PARALLEL

Primary Study Purpose

TREATMENT

Blinding Strategy

NONE

Study Groups

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Cohort 1 (STEMVAC, ET + CDK4/6i)

After completion of 2 cycles of SOC ET + CDK4/6i therapy, patients receive STEMVAC ID on the following schedule: 1) Three "priming" doses every 28 days; 2) Two "booster" doses at 6 and 9 months after "priming" dose #3; and 3) Additional "booster" doses every 6 months in the absence of disease progression or unacceptable toxicity. Patients also undergo CT or ultrasound-guided biopsies, as well as collection of blood samples and CT or PET scans throughout the trial.

Group Type EXPERIMENTAL

CD105/Yb-1/SOX2/CDH3/MDM2-polyepitope Plasmid DNA Vaccine

Intervention Type BIOLOGICAL

Given ID

Computed Tomography

Intervention Type PROCEDURE

Undergo CT or ultrasound-guided biopsies

Cyclin-Dependent Kinase 4 Inhibitor

Intervention Type DRUG

Given SOC CDK4/6i

Cyclin-Dependent Kinase 6 Inhibitor

Intervention Type DRUG

Given SOC CDK4/6i

Hormone Therapy

Intervention Type DRUG

Given SOC ET

Positron Emission Tomography

Intervention Type PROCEDURE

Undergo PET or FES PET

Ultrasound Imaging

Intervention Type PROCEDURE

Undergo CT or ultrasound-guided biopsies

Biopsy Procedure

Intervention Type PROCEDURE

Undergo CT or ultrasound-guided biopsies

Biospecimen Collection

Intervention Type PROCEDURE

Undergo collection of blood samples

Cohort 2 (STEMVAC, capecitabine)

After completion of 1 cycle of SOC capecitabine treatment, patients receive STEMVAC ID on the following schedule: 1) Three "priming" doses every 28 days; 2) Two "booster" doses at 6 and 9 months after "priming" dose #3; and 3) Additional "booster" doses every 6 months in the absence of disease progression or unacceptable toxicity. Patients also undergo CT or ultrasound-guided biopsies, collection of blood samples, and FES PET scans, as well as CT or PET scans throughout the trial.

Group Type EXPERIMENTAL

CD105/Yb-1/SOX2/CDH3/MDM2-polyepitope Plasmid DNA Vaccine

Intervention Type BIOLOGICAL

Given ID

Capecitabine

Intervention Type DRUG

Given SOC capecitabine

Computed Tomography

Intervention Type PROCEDURE

Undergo CT or ultrasound-guided biopsies

F-18 16 Alpha-Fluoroestradiol

Intervention Type DRUG

Undergo FES PET

Positron Emission Tomography

Intervention Type PROCEDURE

Undergo PET or FES PET

Ultrasound Imaging

Intervention Type PROCEDURE

Undergo CT or ultrasound-guided biopsies

Biopsy Procedure

Intervention Type PROCEDURE

Undergo CT or ultrasound-guided biopsies

Biospecimen Collection

Intervention Type PROCEDURE

Undergo collection of blood samples

Interventions

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CD105/Yb-1/SOX2/CDH3/MDM2-polyepitope Plasmid DNA Vaccine

Given ID

Intervention Type BIOLOGICAL

Capecitabine

Given SOC capecitabine

Intervention Type DRUG

Computed Tomography

Undergo CT or ultrasound-guided biopsies

Intervention Type PROCEDURE

Cyclin-Dependent Kinase 4 Inhibitor

Given SOC CDK4/6i

Intervention Type DRUG

Cyclin-Dependent Kinase 6 Inhibitor

Given SOC CDK4/6i

Intervention Type DRUG

F-18 16 Alpha-Fluoroestradiol

Undergo FES PET

Intervention Type DRUG

Hormone Therapy

Given SOC ET

Intervention Type DRUG

Positron Emission Tomography

Undergo PET or FES PET

Intervention Type PROCEDURE

Ultrasound Imaging

Undergo CT or ultrasound-guided biopsies

Intervention Type PROCEDURE

Biopsy Procedure

Undergo CT or ultrasound-guided biopsies

Intervention Type PROCEDURE

Biospecimen Collection

Undergo collection of blood samples

Intervention Type PROCEDURE

Other Intervention Names

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STEMVAC STEMVAC Th1 Polyepitope Plasmid-based Vaccine CD105/Yb-1/SOX2/CDH3/MDM2 Plasmid Vaccine Ro 09-1978/000 Xeloda CAT CAT Scan Computed Axial Tomography Computerized Axial Tomography Computerized axial tomography (procedure) Computerized Tomography Computerized Tomography (CT) scan CT CT Scan tomography CDK4 Inhibitor CDK6 Inhibitor 16 alpha-fluroestradiol-17 beta F-18 FES FES Fluorine-18 16 alpha-fluoroestradiol Fluoroestradiol F-18 Chemotherapy-Hormones/Steroids Endocrine Therapy Hormonal Hormonal Therapy hormone treatment Hormones Medical Imaging, Positron Emission Tomography PET PET Scan Positron emission tomography (procedure) Positron Emission Tomography Scan Positron-Emission Tomography PT 2-Dimensional Grayscale Ultrasound Imaging 2-Dimensional Ultrasound Imaging 2D-US Ultrasonography Ultrasound Ultrasound Test Ultrasound, Medical US Biopsy BIOPSY_TYPE Bx Biological Sample Collection

Eligibility Criteria

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Inclusion Criteria

* Patients must be at least ≥ 18 years of age
* Histologically confirmed hormone receptor positive metastatic breast cancer: Tumors that are positive for estrogen receptor (ER) and/or progesterone receptor (PR)
* HER2-negative or HER2-low will be included and defined as:

* 0-1+ HER2 expression by immunohistochemistry (IHC) OR
* Fluorescence in situ hybridization (FISH) negative OR
* HER2 2+ and FISH negative
* HER2 low per standard of care in breast cancer
* Patients should be receiving the following therapies to be eligible for the study:

* Cohort 1: First or second line of endocrine therapy in combination with a CDK4/6 inhibitor. Patients must have completed at least 2 cycles of CDK4/6 inhibitor
* Cohort 2: Progressed on endocrine-based therapies and after completion of at least 1 cycle of capecitabine
* Subjects with Eastern Cooperative Oncology Group (ECOG) Performance Status Score of 0 or 1
* Metastatic disease that is measurable based on Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 or PET Response Criteria in Solid Tumors (PERCIST). Target lesions situated in a previously irradiated area are considered measurable if progression has been demonstrated in such lesions
* Willing to undergo up to two serial biopsies while on study
* Have at least 1 site of disease confirmed by the treating oncologist that could be biopsied during treatment. Ideally the tumor biopsy should not be a site that is used for RECIST/PERCIST measurement and response to treatment; however, this site may have to be biopsied to adhere to protocol or for patient safety. Lesions that will be biopsied should not be in a previously irradiated area unless progression has been demonstrated in such lesions
* White blood cell (WBC) ≥ 2000/mm\^3 (within 28 days of receiving the study vaccine)
* Lymphocyte count ≥ 500/mm\^3 (within 28 days of receiving the study vaccine)
* Absolute neutrophil count (ANC) ≥ 800/µL (within 28 days of receiving the study vaccine)
* Platelets ≥ 75,000/µL (within 28 days of receiving the study vaccine)
* Total bilirubin ≤ 1.5 x institutional upper limit of normal (ULN), except patients with Gilbert's syndrome in whom total bilirubin must be ≤ 3.0 mg/dL (within 28 days of receiving the study vaccine)
* Aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ≤ 3 x institutional upper limit of normal (ULN) (within 28 days of receiving the study vaccine)
* Creatinine ≤ 2.0 mg/dL or creatinine clearance \> 30 mL/min (within 28 days of receiving the study vaccine)
* Patients of child-bearing potential must agree to use dual methods of contraception and have a negative urine pregnancy test at screening, and male patients must use an effective barrier method of contraception if sexually active with a female of child-bearing potential. Acceptable methods of contraception are condoms with contraceptive foam, oral, implantable or injectable contraceptives, contraceptive patch, intrauterine device, diaphragm with spermicidal gel, or a sexual partner who is surgically sterilized or postmenopausal. Effective methods of contraception must be used throughout the study and until the end of treatment on study
* Must have recovered from major infections and/or surgical procedures; and in the opinion of the investigator, not have any significant active concurrent medical illnesses or condition precluding protocol treatment

Exclusion Criteria

* Patients with any of the following cardiac conditions:

* Symptomatic restrictive cardiomyopathy
* Dilated cardiomyopathy
* Unstable angina within 4 months prior to enrollment
* New York Heart Association functional class III-IV heart failure on active treatment
* Symptomatic pericardial effusion
* Uncontrolled hypertension
* Uncontrolled cardiac arrhythmias
* Patients with any autoimmune disease or comorbidities that require chronic steroids or immunosuppressants
* A non-breast malignancy requiring radiation or systemic therapy within last 5 years
* Known hypersensitivity reaction to the granulocyte-macrophage colony-stimulating factor (GM-CSF) adjuvant; any known contra-indication to GM-CSF
* Pregnant or breast feeding
* Known history of human immunodeficiency virus (HIV) infection, hepatitis B (e.g., hepatitis B virus surface antigen \[HBsAg\] reactive), or hepatitis C (e.g., hepatitis C virus \[HCV\] ribonucleic acid \[RNA\] \[qualitative\] is detected)
* Major surgery within the 4 weeks prior to initiation of study vaccine
* Current use of immunosuppressive agents or systemic corticosteroids. Topical, ocular, intra-articular, intranasal, and inhalational corticosteroids (with minimal systemic absorption) are allowed. Patients who have received systemic corticosteroids ≤ 30 days prior to starting study drug will be excluded
* Patient is currently enrolled in any other clinical protocol or investigational trial that involves administration of experimental therapy and/or therapeutic devices, or investigational drug

* NOTE: Biomarker or tissue collection or any other non-interventional clinical trial enrollment is allowed
* Must be 14 days between a non-study vaccine and any STEMVAC vaccination

* NOTE: The minimum of 14 days does not apply to the tetanus and diphtheria (Td) vaccine
* Any condition that may interfere with the patient's participation in the study per treating physician
Minimum Eligible Age

18 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No

Sponsors

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University of Washington

OTHER

Sponsor Role lead

Responsible Party

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Responsibility Role SPONSOR

Principal Investigators

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Natasha Hunter, MD

Role: PRINCIPAL_INVESTIGATOR

Fred Hutch/University of Washington Cancer Consortium

Locations

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Fred Hutch/University of Washington Cancer Consortium

Seattle, Washington, United States

Site Status RECRUITING

Countries

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United States

Central Contacts

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Research Coordinator(s)

Role: CONTACT

1-866-932-8588

Facility Contacts

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Research Coordinator(s)

Role: primary

866-932-8588

Other Identifiers

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NCI-2025-04692

Identifier Type: REGISTRY

Identifier Source: secondary_id

0020922

Identifier Type: OTHER

Identifier Source: secondary_id

RG1125521

Identifier Type: -

Identifier Source: org_study_id

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