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Breast CancerPhase 2NCT03439735

Determinants of Resistance to Endocrine Therapy and a Cyclin-dependent Kinases 4 and 6 (CDK4/6) Inhibitor for HR+ MBC

A Phase 2 study testing Endocrine Therapy and a CDK 4/6 inhibitor in people with Breast Cancer, run by Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins 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

The goal of this research study is to determine if the investigators can predict which participants will respond to endocrine therapy and a cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitor for metastatic breast cancer and which participants will not. Read more about this study

Who is it for?
Ages 18 to 100 years
Conditions the study is for
Breast Cancer
What is being tested?
Endocrine Therapy and a CDK 4/6 inhibitor
Could I receive a placebo?
No, everyone receives an active treatment
How many people
45 participants
Where
1 siteUnited States
Study dates
20 Jul 2018to 1 Nov 2027
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 to 100 years
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Male or Female
  • 18 years or older
  • Eastern Cooperative Oncology Group (ECOG) performance status of 0-2
  • Metastatic (stage IV) breast cancer or locally advanced breast cancer
  • Estrogen Receptor (ER) and/or Progesterone Receptor (PR) positive, HER2- negative
  • Treatment naïve in metastatic or locally advanced setting and planning to undergo treatment with endocrine therapy (ET) and palbociclib OR receiving first-line ET and palbociclib for metastatic or locally advanced disease.
Show all 10Show fewer
  • Premenopausal women and men must be treated with concurrent luteinizing hormone-releasing hormone (LHRH) agonist as would be standard-of-care.
  • Evaluable or measurable disease.
  • Tissue from a metastatic site must be available within past 6 months prior to therapy initiation.
  • Ability to give voluntary informed consent

Who cannot join

  • Any pregnant or nursing woman
  • No history of another primary malignancy within past 5 years. Patients with prior history of in situ cancer or basal or localized squamous cell skin cancer are eligible.

Trial locations and contacts

1 site in 1 country.

United States1 site
  • Johns Hopkins University

    Baltimore, Maryland, 21287

Other trials in United States

About this study

Official title: Prospective Evaluation of Determinants of Resistance to Endocrine Therapy and a Cyclin-dependent Kinases 4 and 6 (CDK4/6) Inhibitor in Hormone Receptor (HR) Positive Metastatic Breast Cancer (MBC)

The goal of this research study is to determine if the investigators can predict which participants will respond to endocrine therapy and a cyclin-dependent kinases 4 and 6 (CDK4/6) inhibitor for metastatic breast cancer and which participants will not. Investigators will use information from the tumor tissue and serial blood samples. Investigators hope that a deeper understanding of which participants will respond to this combination and how resistance emerges will allow the investigators to better tailor therapies for metastatic breast cancer.

Subjects will have archived tissue or new biopsy collected at study enrollment. This tissue will undergo special molecular testing. Subjects will also have blood collected at study enrollment and periodically thereafter. This blood will also undergo special molecular testing. Information from this testing will not be available to subjects or their treating physicians as the investigators do not know how this information should impact treatment.

Read more

The investigators will collect information about which treatment the subjects receive and how their cancer responds.

Any man or woman being seen at Johns Hopkins for treatment of newly diagnosed estrogen receptor positive (ER+) and/or progesterone receptor positive (PR+) metastatic breast cancer may be eligible.

Read the detailed description

Resistance to endocrine therapy (ET) invariably develops in patients with estrogen and/or progesterone receptor (ER/ PR) positive metastatic breast cancer (MBC). Data regarding primary resistance and patterns of emergence of acquired resistance in patients treated with endocrine therapy (ET) and cyclin dependent kinase 4 and 6 (CDK4/6) inhibitors are limited. Understanding these mechanisms could result in improved selection of treatment options and provide new targets for therapy development. In this study, we aim to identify and characterize determinants of intrinsic and acquired resistance to endocrine therapy in patients with hormone receptor (HR) positive, human epidermal growth factor receptor 2 (HER2) negative MBC treated with the combination of endocrine therapy (aromatase inhibitor or fulvestrant) and a CDK4/6 inhibitor.

Investigators will determine the prevalence of genomic alterations at baseline in the primary tumor, metastatic tissue and plasma tumor DNA (ptDNA), including in the gene encoding estrogen receptor- alpha (ESR1). The mutational tumor burden in the primary tumor, metastatic tumor and blood will be assessed. Blood samples will be collected at several time points, allowing the detection of changes in molecular markers over time. We will further characterize tissue markers associated with progression and duration of response by evaluating these markers in available tissue obtained at progression. Investigators goal is to evaluate the prevalence and role of known alterations determining endocrine resistance in patients with metastatic disease, as knowledge regarding this population remains limited.The investigators also hope to unveil novel markers of endocrine resistance.

Conditions
Breast Cancer
Being tested
Endocrine Therapy and a CDK 4/6 inhibitor
Keywords
Breast Cancer, Metastatic Breast Cancer, Aromatase Inhibitors, Palbociclib, Hormone Receptor Positive 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.

  • Endocrine Therapy and a CDK 4/6 inhibitorDrug

    Also called ET and CDK4/6i

    Participants with untreated metastatic disease receiving ET and a CDK 4/6 i as first line therapy.

  • Endocrine Therapy and a CDK 4/6 inhibitorDrug

    Also called ET and CDK4/6i

    Participants initiating a CDK 4/6 i after progression on ET.

Study groups in NCT03439735
Study groupRoleWhat they receive
Cohort A: Participants with untreated metastatic disease receiving ET and a CDK 4/6ExperimentalParticipants will undergo blood collection (intervention) at time of initiating treatment with endocrine therapy and palbociclib, at 4 weeks after initiating this treatment, and every 3-4 months while on treatment. If a participant progresses on this treatment, they will have a blood collection at that time.
Receives: Drug: Endocrine Therapy and a CDK 4/6 inhibitor
Cohort B: Participants initiating a CDK 4/6 i after progression on ET.ExperimentalParticipants will undergo blood collection (intervention) at time of initiating treatment with endocrine therapy and palbociclib, at 4 weeks after initiating this treatment, and every 3-4 months while on treatment. If a participant progresses on this treatment, they will have a blood collection at that time.
Receives: Drug: Endocrine Therapy and a CDK 4/6 inhibitor

What is being measured

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

  1. Genetic Mutation

    The number of participants who have an ESR1 mutation prior to receiving endocrine therapy and palbociclib.

    Measured: 2 years

Secondary outcomes (2)
  1. Genetic Mutation

    The amount of time from receiving palbociclib and endocrine therapy to the first detectable ESR1 mutation

    Measured: 4 years

  2. Genetic Mutation

    Percentage of participants with an ESR1 mutation at the time of progression for those who received treatment with endocrine therapy and palbociclib.

    Measured: 3 years

Timeline

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

  1. First posted20 Feb 2018
  2. Study start20 Jul 2018
  3. Primary completion1 Aug 2027 (estimated)
  4. Study completion1 Nov 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 2
Primary purpose
Treatment
Allocation
Non-randomised
Intervention model
Parallel groups
Masking
None (open label)
Enrolment
45 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT03439735
Sponsor's protocol ID
J17118
Other IDs
IRB00143030
Status last verified
Aug 2026
First submitted
8 Dec 2017
Last updated
7 Aug 2026
Results posted
No
Data monitoring committee
No
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 Endocrine Therapy and a CDK 4/6 inhibitor in people with Breast Cancer, run by Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins 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 10 inclusion and 2 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 7 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 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?

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?

Genetic Mutation (time frame: 2 years). It is what the study was designed to measure, not a finding.

Where can I read the original study information?
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 7 Aug 2026.

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