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Anatomic Stage IV Breast Cancer AJCC v8Phase 2NCT07112053

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

A Phase 2 study testing CD105/Yb-1/SOX2/CDH3/MDM2-polyepitope Plasmid DNA Vaccine, Capecitabine and Computed Tomography in people with Anatomic Stage IV Breast Cancer AJCC v8 and Metastatic HER2-Negative Breast Carcinoma, run by University of Washington at 1 site in United States.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
Search all trials

Trial summary

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… Read more about this study

Who is it for?
Ages 18 years and older
What is being tested?
CD105/Yb-1/SOX2/CDH3/MDM2-polyepitope Plasmid DNA Vaccine, Capecitabine and Computed Tomography
Type of treatment
Vaccines, Surgery or procedure
Could I receive a placebo?
No, everyone receives an active treatment
How many people
40 participants
Where
1 siteUnited States
Study dates
17 Nov 2025to 31 Dec 2028
Phase
Phase 2
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • 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
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  • 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 the metastatic setting, in combination with a CDK4/6 inhibitor. Patients must have completed at least 2 cycles of CDK4/6 inhibitor. Patients who have stopped endocrine therapy for intolerance but remain on abemaciclib monotherapy will be considered for enrollment at the PI's discretion
  • 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
  • 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
  • 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

Who cannot join

  • 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
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  • Uncontrolled hypertension
  • Uncontrolled cardiac arrhythmias
  • Patients with any autoimmune disease/comorbidity 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 oncologist

Trial locations and contacts

1 site in 1 country. Contact the study team or a site near you to ask about taking part.

Research Coordinator(s) contact

1-866-932-8588

cvitrial@uw.edu

United States1 site, 1 recruiting

  • Fred Hutch/University of Washington Cancer Consortium

    Seattle, Washington, 98109

    Research Coordinator(s), 866-932-8588, cvitrial@uw.edu

    Natasha Hunter, MD

    Recruiting

Other trials in United States

About this study

Official title: A Phase II Study of STEMVAC Vaccine Therapy for Patients With Hormone Receptor Positive Metastatic Breast Cancer

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, including abemaciclib, 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.

Read the detailed description

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 or abemaciclib alone, 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 image-guided biopsies for research purposes, as well as collection of blood samples and computed tomography (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 image-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.

Being tested
CD105/Yb-1/SOX2/CDH3/MDM2-polyepitope Plasmid DNA Vaccine, Capecitabine, Computed Tomography, Cyclin-Dependent Kinase 4 Inhibitor, Cyclin-Dependent Kinase 6 Inhibitor

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • CD105/Yb-1/SOX2/CDH3/MDM2-polyepitope Plasmid DNA VaccineBiological

    Also called STEMVAC, STEMVAC Th1 Polyepitope Plasmid-based Vaccine, CD105/Yb-1/SOX2/CDH3/MDM2 Plasmid Vaccine

    Given ID

  • CapecitabineDrug

    Also called Ro 09-1978/000, Xeloda

    Given SOC capecitabine

  • Computed TomographyProcedure or surgery

    Also called CAT, CAT Scan, Computed Axial Tomography, Computerized Axial Tomography

    Undergo CT or ultrasound-guided biopsies

  • Cyclin-Dependent Kinase 4 InhibitorDrug

    Also called CDK4 Inhibitor

    Given SOC CDK4/6i

  • Cyclin-Dependent Kinase 6 InhibitorDrug

    Also called CDK6 Inhibitor

    Given SOC CDK4/6i

  • F-18 16 Alpha-FluoroestradiolDrug

    Also called 16 alpha-fluroestradiol-17 beta, F-18 FES, FES, Fluorine-18 16 alpha-fluoroestradiol

    Undergo FES PET

  • Hormone TherapyDrug

    Also called Chemotherapy-Hormones/Steroids, Endocrine Therapy, Hormonal, Hormonal Therapy

    Given SOC ET

  • Positron Emission TomographyProcedure or surgery

    Also called Medical Imaging, Positron Emission Tomography, PET, PET Scan, Positron emission tomography (procedure)

    Undergo PET or FES PET

  • Biopsy ProcedureProcedure or surgery

    Also called Biopsy, BIOPSY_TYPE, Bx

    Undergo image-guided biopsies

  • Biospecimen CollectionProcedure or surgery

    Also called Biological Sample Collection

    Undergo collection of blood samples

  • AbemaciclibDrug

    Also called LY 2835219, LY-2835219, LY2835219, Verzenio

    Given SOC abemaciclib

Study groups in NCT07112053
Study groupRoleWhat they receive
Cohort 1 (STEMVAC, ET + CDK4/6i)ExperimentalAfter completion of 2 cycles of SOC ET + CDK4/6i therapy or abemaciclib alone, 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 image-guided biopsies, as well as collection of blood samples and CT or PET scans throughout the trial.
Receives: Biological: CD105/Yb-1/SOX2/CDH3/MDM2-polyepitope Plasmid DNA Vaccine; Procedure: Computed Tomography; Drug: Cyclin-Dependent Kinase 4 Inhibitor; Drug: Cyclin-Dependent Kinase 6 Inhibitor; Drug: Hormone Therapy; Procedure: Positron Emission Tomography; Procedure: Biopsy Procedure; Procedure: Biospecimen Collection; Drug: Abemaciclib
Cohort 2 (STEMVAC, capecitabine)ExperimentalAfter 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 image-guided biopsies, collection of blood samples, and FES PET scans, as well as CT or PET scans throughout the trial.
Receives: Biological: CD105/Yb-1/SOX2/CDH3/MDM2-polyepitope Plasmid DNA Vaccine; Drug: Capecitabine; Procedure: Computed Tomography; Drug: F-18 16 Alpha-Fluoroestradiol; Procedure: Positron Emission Tomography; Procedure: Biopsy Procedure; Procedure: Biospecimen Collection

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Incidence of adverse events (AEs)

    Safety and systemic toxicity will be determined by chemical and clinical parameters evaluated at various time points. Toxicity grading will be evaluated according to the National Cancer Institute (NCI) Common Terminology Criteria for Adverse Events version 6.0 and monitoring of AEs will be done per Food and Drug Administration and NCI guidelines. The type and grade of toxicities noted during the immunization regimen will be summarized. The duration of toxicities will also be summarized using descriptive statistics such as mean and standard deviation. All AEs noted by the investigator will be tabulated according to the affected body system. The frequency and severity of adverse events will be summarized with a proportion and a 95% confidence interval (CI).

    Measured: Up to 3 years after completion of study treatment

  2. Incidence of immunogenicity

    Will be defined as the sum of the interferon gamma enzyme-linked immunosorbent spot of all STEMVAC antigens on blood samples collected pre-vaccine as compared to 1-month post dose #3 of the STEMVAC vaccine and again after 2 booster doses of STEMVAC vaccine. Both incidence and magnitude will be assessed. Immune responses will be summarized with mean and standard deviation or median and range (if skewness is observed) over time, the change over time will be summarized with graphs, and also analyzed using linear mixed-effects regression models with normalizing transformation if necessary.

    Measured: Pre-vaccine up to after 2 booster doses of STEMVAC vaccine (Up to 40 weeks)

Secondary outcomes (3)

  1. Progression-free survival (PFS)

    Will be analyzed using the Kaplan-Meier method. Kaplan-Meier estimates of the survival function with 95% CIs at specific time points (using Greenwood's formula for the standard error) will be computed.

    Measured: From the start of treatment to the worsening of cancer as determined by primary treating oncologist or death whichever occurs first, assessed up to 3 years after completion of study treatment

  2. Circulating tumor DNA (ctDNA)

    Will evaluate persistence and level of ctDNA over time in peripheral blood with addition of STEMVAC at baseline, after completion of priming monthly doses, at booster vaccines, and at progression (end of study). Linear mixed-effects regression models with normalizing transformation (if necessary) will be employed to evaluate changes in ctDNA levels over time. Paired t test or Wilcoxon signed rank tests will be applied for pairwise comparisons (depending on the distribution) between time points.

    Measured: Up to 3 years after completion of study treatment

  3. Elimination of cancer cells associated with epithelial to mesenchymal transformation (EMT)

    Will determine whether STEMVAC immunization in addition to either endocrine therapy plus a CDK4/6 inhibitor or capecitabine results in elimination of cancer cells associated with EMT, as EMT proteins are targeted by this vaccine. Will determine EMT signature by gene expression profiling in baseline tumor (previously collected tumor biopsy) and compare with post-STEMVAC tumor biopsy. Gene expression profiles from biopsies before and after vaccination will be compared using paired t test or Wilcoxon signed-rank test (depending on the distribution) to determine if vaccination modulates the EMT gene signature in the tumor. Differential gene expression analysis or linear models will be used to analyze individual EMT gene expression levels.

    Measured: Up to 3 years after completion of study treatment

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted8 Aug 2025
  2. Study start17 Nov 2025
  3. Primary completion31 Jul 2028 (estimated)
  4. Study completion31 Dec 2028 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 2
Primary purpose
Treatment
Allocation
Non-randomised
Intervention model
Parallel groups
Masking
None (open label)
Enrolment
40 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07112053
Sponsor's protocol ID
RG1125521
Other IDs
NCI-2025-04692, 0020922
Status last verified
Oct 2026
First submitted
18 Jul 2025
Last updated
2 Nov 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
No

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing CD105/Yb-1/SOX2/CDH3/MDM2-polyepitope Plasmid DNA Vaccine, Capecitabine and Computed Tomography in people with Anatomic Stage IV Breast Cancer AJCC v8 and Metastatic HER2-Negative Breast Carcinoma, run by University of Washington at 1 site in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 22 inclusion and 20 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: looking for participants now, as of the sponsor's last update on 2 Nov 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Research Coordinator(s) (1-866-932-8588, cvitrial@uw.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Incidence of adverse events (AEs) (time frame: Up to 3 years after completion of study treatment). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT07112053.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 2 Nov 2026.

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