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AzTrials

Breast Cancer Metastatic Breast CancerPhase 1NCT06691035

Immunologic Targeting of ESR1 Receptor for Hormone Receptor Expressing Metastatic Breast Cancer

A Phase 1 study testing Elacestrant and DC1 native/mutated ESR1 in people with Breast Cancer Metastatic Breast Cancer and HER2-negative Breast Cancer, run by H. Lee Moffitt Cancer Center and Research Institute at 1 site in United States.

Active, not recruiting

Under way, not looking for participants. Everyone needed has enrolled. The study is still running.

Official record
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Trial summary

This is a pilot study to determine feasibility and safety of the combination of Dendritic Cell (DC1) vaccines and elacestrant in patients with hormone positive HER2 negative metastatic breast cancer. Read more about this study

Who is it for?
Ages 18 years and older
What is being tested?
Elacestrant and DC1 native/mutated ESR1
Could I receive a placebo?
No, everyone receives an active treatment
How many people
18 participants
Where
1 siteUnited States
Study dates
4 Nov 2024to Nov 2027
Phase
Phase 1
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

  • Participants must have histologically or cytologically confirmed diagnosis of hormone positive HER2 negative metastatic breast cancer per ASCO/CAP criteria, with diagnosis established through either a breast/axillary biopsy or biopsy of a metastatic lesion.
  • Estrogen Receptor (ER) or Progesterone Receptor (PR) are considered positive when expressed ≥1% on immunohistochemistry (IHC).
  • HER2 is considered negative by IHC when expression is 0 or 1+ and if equivocal 2+ then a reflex in situ hybridization should be not amplified (standard practice per ASCO/CAP criteria).
  • Participants must have Presence of an ESR1 mutation detected via tissue based or blood based (ctDNA) genomic profiling.
  • Participants must have been previously treated with at least 1 line of endocrine therapy and a CDK 4/6 inhibitor in the metastatic setting.
  • Participants must have measurable or nonmeasurable (evaluable) disease on imaging by RECIST v1.1.
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  • Participants must have an Eastern Cooperative Oncology Group (ECOG) performance status 0 to 2.
  • Participants must be adults 18 years or older.
  • Participants must have the ability to understand and the willingness to sign a written informed consent document.
  • Participants must be able to read and speak standard English or Spanish.
  • Participants must have adequate organ and marrow function as defined below:
  • absolute neutrophil count ≥1,000/mcL
  • platelets ≥75,000/mcL
  • AST(SGOT)/ALT(SGPT) ≤3 fold × institutional ULN e. creatinine 1.5 ≤ institutional ULN f. hemoglobin (Hb) ≥ 9 g/dL g. Total bilirubin < 1.5 x ULN or <3 x ULN in the presence of documented Gilbert's syndrome unconjugated hyperbilirubinemia)
  • Participants must have a negative pregnancy test for pre-menopausal women of childbearing potential.
  • Participants that are pre-menopausal women of childbearing potential who are sexually active with a male partner must agree to use adequate contraception prior to the study, for the duration of study participation.
  • Inclusion of minorities: patients of all races and ethnic groups who meet the above inclusion and below exclusion criteria are eligible for this trial.
  • Stated willingness to comply with all study procedures and availability for the duration of the study.
  • Participants must have the ability to understand and the willingness to sign a written informed consent document or have a legally authorized representative sign on the participant's behalf.
  • Participants with treated and stable brain metastases are eligible if brain imaging shows no evidence of progression within 2 months of trial enrollment.

Who cannot join

  • Pregnant women are excluded from this study because study treatment agent(s) used in this study may have the potential for teratogenic or abortifacient effects. Because there is an unknown, but potential risk for adverse events in nursing infants secondary to treatment of the mother with agents used in this study, breastfeeding should be discontinued if the mother is treated with study agents used in this study.
  • Previous treatment with Elacestrant.
  • History of allergic reactions attributed to the study drugs.
  • Active, progressing or newly diagnosed CNS metastases, including leptomeningeal carcinomatosis, because systemic treatment would need to be paused for these patients.
  • Treatment with any investigational compound within 21 days prior to the first dose of study drugs or during this study.
  • 14 day washout periods from previous anticancer therapy(ies) is required prior to enrollment including:
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  • Cytotoxic chemotherapy
  • Tamoxifen or aromatase inhibitors
  • Fulvestrant
  • Targeted agents such as CDK 4/6 inhibitors, PIK3CA inhibitors, MTOR inhibitors
  • Diagnosis or treatment for another systemic malignancy within 2 years before the first dose of study drugs, or previously diagnosed with another malignancy and have any evidence of residual disease. Patients with non-melanoma skin cancer or carcinoma in situ of any type are not excluded if they have undergone complete resection.
  • Uncontrolled intercurrent illness including-but not limited to-ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements.
  • Patients with advanced, symptomatic visceral spread, that are at risk of life-threatening complications in the short term, including massive uncontrolled effusions (peritoneal, pleural, pericardial), pulmonary lymphangitis.
  • Known history of testing positive for human immunodeficiency virus (HIV) or known acquired immunodeficiency syndrome.
  • Active infection including tuberculosis, hepatitis B (known positive HBV surface antigen [HbsAg]), or hepatitis C (HCV). Participants with a past or resolved HBV infection (defined as the presence of hepatitis B core antibody [anti-HBc] and absence of HbsAg) are eligible. Participants with positive Hepatitis C Virus (HCV) antibody are eligible if polymerase chain reaction is negative for HCV RNA.
  • Concurrent or prior use of immunosuppressive medication within 14 days before the first dose of study drugs, with the following exceptions: premedication with dexamethasone, intranasal, inhaled, topical or local steroid injections, systemic corticosteroids at physiologic doses not exceeding 10 mg/day of prednisone or its equivalent; steroids as premedication for hypersensitivity reactions (e.g., premedication for iodinated contrast allergy before CT scan).
  • Inability to comply with protocol requirements.

Trial locations and contacts

1 site in 1 country.

United States1 site

  • Moffitt Cancer Center

    Tampa, Florida, 33612

Other trials in United States

About this study

Official title: Immunologic Targeting of Native and Mutated ESR1 Receptor for Treatment of Hormone Receptor Expressing Metastatic Breast Cancer

This is a pilot study to determine feasibility and safety of the combination of Dendritic Cell (DC1) vaccines and elacestrant in patients with hormone positive HER2 negative metastatic breast cancer.

Being tested
Elacestrant, DC1 native/mutated ESR1
Keywords
HER-2 Negative Breast Cancer, Metastatic Breast Cancer
Medical subject headings
Breast Neoplasms

What participants receive

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

  • ElacestrantDrug

    Also called Oserdu

    345 mg (or 86 mg tablets) orally daily during vaccination and continued after until progression.

    Cycle Length 28 days (4 weeks)

  • DC1 native/mutated ESR1Biological

    2.0-5.0 x 10 (20-50 million) cells (Injections in groin nodes (or accessible breast tumor if available) weekly with DC1 for eight consecutive weeks, alternating between native ESR1 DC1s and mutated ESR1 DC1s.

    Mutated ESR1 DC1s on week 1 followed by native ESR1 DC1s on week 2, alternating during the initial vaccination series and the subsequent booster phase.

    Pulsed DC1 will be administered after initial induction every four weeks x 3 doses.

Study groups in NCT06691035
Study groupRoleWhat they receive
Elacestrant + DC1ExperimentalPatients will undergo apheresis of peripheral blood to collect and create DC1 vaccines. DC1 will be pulsed with ESR1 native or mutated peptides. After DC1 vaccines have undergone safety testing and are ready to be used, patients will be injected in groin nodes (or accessible breast tumor if available) weekly with these pulsed DC1 for eight consecutive weeks. They will alternate between native ESR1 DC1s and mutated ESR1 DC1s. Patients will receive combination of DC1 vaccinations and Elacestrant concurrently. Elacestrant is a novel oral selective estrogen downregulator, administered during vaccination and continued after. Elacestrant is considered standard of care for patients with ESR1 mutated HR+ HER2-metastatic breast cancer. Pulsed DC1 will be administered after initial induction every four weeks x 3 doses.
Receives: Drug: Elacestrant; Biological: DC1 native/mutated ESR1

What is being measured

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

  1. Rate of Successful Completion

    Feasibility: Defined as a patient's ability and willingness to complete the treatment regimen (8 weeks) to End of Treatment (EOT) (window of + 30 days from date of last study treatment).

    Data collection will include rate of successful completion.

    Measured: Up to 2 years

  2. Occurrence Rate

    Feasibility: Defined as a patient's ability and willingness to complete the treatment regimen (8 weeks) to End of Treatment (EOT) (window of + 30 days from date of last study treatment).

    Data collection will include occurrence rate for each reason stated for non-completion.

    Measured: Up to 2 years

  3. Occurrence of Treatment Related Adverse Events

    Number of participants with treatment related adverse events, per event category.

    Measured: Up to 2 years

Secondary outcomes (3)

  1. Progression Free Survival (PFS)

    Progression Free Survival (PFS) is measured from the start of treatment until disease progression or death from any cause.

    Measured: Up to 2 years

  2. Clinical Benefit Rate (CBR)

    Clinical Benefit Rate (CBR) is measured by Complete Response (CR) + Partial Response (PR) + Stable Disease.

    Measured: Up to 2 years

  3. Overall Response Rate (ORR)

    Overall Response Rate (ORR) is measured by Complete Response (CR) + Partial Response (PR).

    Measured: Up to 2 years

Timeline

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

  1. First posted15 Nov 2024
  2. Study start4 Nov 2024
  3. Primary completionNov 2026 (estimated)
  4. Study completionNov 2027 (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 1
Primary purpose
Treatment
Allocation
Not applicable
Intervention model
Single group
Masking
None (open label)
Enrolment
18 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT06691035
Sponsor's protocol ID
MCC-23161
Status last verified
Aug 2026
First submitted
14 Nov 2024
Last updated
18 Aug 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No

Questions about this trial

What is this clinical trial studying?

A Phase 1 study testing Elacestrant and DC1 native/mutated ESR1 in people with Breast Cancer Metastatic Breast Cancer and HER2-negative Breast Cancer, run by H. Lee Moffitt Cancer Center and Research Institute 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 20 inclusion and 17 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: under way, not looking for participants, as of the sponsor's last update on 18 Aug 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 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.

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?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Rate of Successful Completion (time frame: Up to 2 years). The study lists 3 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 NCT06691035.

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 18 Aug 2026.

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