Actively Recruiting
A Phase II Study of STEMVAC Vaccine Therapy for Patients With Hormone Receptor Positive Metastatic Breast Cancer
Led by University of Washington · Updated on 2026-04-06
40
Participants Needed
1
Research Sites
21 weeks
Total Duration
On this page
AI-Summary
What this Trial Is About
Researchers are evaluating how well the vaccine STEMVAC works when combined with standard hormone therapy or chemotherapy in treating patients with hormone receptor-positive, HER2-negative metastatic breast cancer. This phase II trial explores STEMVAC's potential to boost the immune system to target aggressive cancer cells that have spread from the original tumor site. The study includes patients with endocrine therapy-sensitive and endocrine therapy-resistant disease, aiming to understand how these combinations affect cancer progression and immune response. Participants are divided into two groups: Cohort 1 includes patients who have completed at least two cycles of standard endocrine therapy plus a CDK4/6 inhibitor or abemaciclib alone, and Cohort 2 includes patients who have completed at least one cycle of the chemotherapy drug capecitabine after progression on endocrine therapies. Both groups receive STEMVAC vaccine injections intradermally on a schedule of three priming doses every 28 days, followed by two booster doses at 6 and 9 months, and additional boosters every 6 months if the disease does not worsen or cause unacceptable side effects. Imaging biopsies, blood collections, and CT or PET scans are performed regularly during the trial. Throughout the study, participants undergo various assessments including image-guided biopsies, blood sample collections, and PET or CT scans to monitor safety and immune response. After completing the vaccine treatment, patients are followed every six months for three years to track adverse events, immune response, progression-free survival, circulating tumor DNA, and cancer cell elimination. This comprehensive monitoring helps researchers evaluate the vaccine's impact and safety over time.
CONDITIONS
Brief Title
A Vaccine (STEMVAC) With Standard Endocrine-Based Therapy or Chemotherapy for the Treatment of Metastatic Hormone Receptor Positive, HER2 Negative Breast Cancer
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Patients must be at least �3e�3d 18 years of age
- Histologically confirmed hormone receptor positive metastatic breast cancer (ER and/or PR positive)
- HER2-negative or HER2-low defined by specific testing criteria
- Cohort 1: Receiving first or second line endocrine therapy with CDK4/6 inhibitor and completed at least 2 cycles
- Cohort 2: Progressed on endocrine therapies and completed at least 1 cycle of capecitabine
- Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1
- Willing to undergo up to two serial biopsies during the study
- Have at least 1 disease site suitable for biopsy
- Adequate blood counts and organ function within 28 days prior to vaccine
- Agree to use effective contraception if of child-bearing potential
- Recovered from major infections or surgeries and no significant active medical conditions
You will not qualify if you...
- Symptomatic restrictive or dilated cardiomyopathy
- Unstable angina within 4 months prior to enrollment
- NYHA class III-IV heart failure on active treatment
- Symptomatic pericardial effusion
- Uncontrolled hypertension or cardiac arrhythmias
- Autoimmune diseases requiring chronic steroids or immunosuppressants
- Non-breast malignancy needing treatment within last 5 years
- Known hypersensitivity to GM-CSF or contraindications
- Pregnant or breastfeeding
- Known HIV, hepatitis B, or hepatitis C infection
- Major surgery within 4 weeks before vaccine start
- Current use of systemic immunosuppressive agents or corticosteroids
- Enrollment in other investigational therapy trials
- Less than 14 days since non-study vaccine (except Td vaccine)
- Any condition interfering with study participation as judged by oncologist
AI-Screening
AI-Powered Screening
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Your Study Journey
Duration - 2 to 4 weeks
Participants are screened for eligibility to participate in the trial.
1 visit (in-person)
Duration - Duration of 1 to 2 cycles of standard treatment (varies by cohort)
Participants complete standard of care therapy before starting the vaccine: Cohort 1 undergoes 2 cycles of endocrine therapy with CDK4/6 inhibitor or abemaciclib alone; Cohort 2 undergoes 1 cycle of capecitabine treatment.
Visits as per routine care for standard treatment
Duration - Up to 9 months for priming and initial booster doses, with additional boosters every 6 months thereafter until disease progression or unacceptable toxicity
Participants receive STEMVAC vaccine given intradermally on a schedule of three priming doses every 28 days, followed by two booster doses at 6 and 9 months after the first priming dose. Additional booster doses are given every 6 months if there is no disease progression or unacceptable toxicity. Participants also undergo image-guided biopsies, blood sample collection, and CT or PET scans throughout this period.
Approximately 5 vaccine visits during initial priming and booster phase; imaging and biopsy visits scheduled periodically throughout treatment
Duration - Up to 3 years
After completion of study treatment, participants are followed every 6 months for up to 3 years to monitor safety and disease status.
Visits every 6 months for follow-up assessments
Trial Site Locations
Total: 1 location
1
Fred Hutch/University of Washington Cancer Consortium
Seattle, Washington, United States, 98109
Actively Recruiting
Research Team
R
Research Coordinator(s)
How is the study designed?
Study Type
INTERVENTIONAL
Masking
NONE
Allocation
NON_RANDOMIZED
Model
PARALLEL
Primary Purpose
TREATMENT
Number of Arms
2
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