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

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University of Washington

Status and phase

Enrolling
Phase 2

Conditions

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

Treatments

Drug: Cyclin-Dependent Kinase 6 Inhibitor
Biological: CD105/Yb-1/SOX2/CDH3/MDM2-polyepitope Plasmid DNA Vaccine
Procedure: Biopsy Procedure
Drug: Capecitabine
Procedure: Positron Emission Tomography
Drug: Cyclin-Dependent Kinase 4 Inhibitor
Drug: Hormone Therapy
Procedure: Computed Tomography
Procedure: Biospecimen Collection
Procedure: Ultrasound Imaging
Drug: F-18 16 Alpha-Fluoroestradiol

Study type

Interventional

Funder types

Other

Identifiers

NCT07112053
0020922 (Other Identifier)
RG1125521
NCI-2025-04692 (Registry Identifier)

Details and patient eligibility

About

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.

Full 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, 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.

Enrollment

40 estimated patients

Sex

All

Ages

18+ years old

Volunteers

No Healthy Volunteers

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

Trial design

Primary purpose

Treatment

Allocation

Non-Randomized

Interventional model

Parallel Assignment

Masking

None (Open label)

40 participants in 2 patient groups

Cohort 1 (STEMVAC, ET + CDK4/6i)
Experimental group
Description:
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.
Treatment:
Procedure: Ultrasound Imaging
Procedure: Biospecimen Collection
Procedure: Computed Tomography
Drug: Hormone Therapy
Drug: Cyclin-Dependent Kinase 4 Inhibitor
Procedure: Positron Emission Tomography
Procedure: Biopsy Procedure
Biological: CD105/Yb-1/SOX2/CDH3/MDM2-polyepitope Plasmid DNA Vaccine
Drug: Cyclin-Dependent Kinase 6 Inhibitor
Cohort 2 (STEMVAC, capecitabine)
Experimental group
Description:
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.
Treatment:
Drug: F-18 16 Alpha-Fluoroestradiol
Procedure: Ultrasound Imaging
Procedure: Biospecimen Collection
Procedure: Computed Tomography
Procedure: Positron Emission Tomography
Drug: Capecitabine
Procedure: Biopsy Procedure
Biological: CD105/Yb-1/SOX2/CDH3/MDM2-polyepitope Plasmid DNA Vaccine

Trial contacts and locations

1

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Central trial contact

Research Coordinator(s)

Data sourced from clinicaltrials.gov

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