Oral Aromatase Inhibitors Modify the Gut Microbiome

June 11, 2026 updated by: Wake Forest University Health Sciences

Oral Aromatase Inhibitors Modify the Gut Microbiome Effecting Estrogen Bioavailability

The purpose of this research is to study the bacteria in participants' gut before receiving a medicine called an aromatase inhibitor for breast cancer and after participants receive medicine for breast cancer.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Primary Objective: To describe the microbiome shift of gut microbiome from baseline after 4-weeks and 12-weeks of oral aromatase inhibitor treatment.

Secondary Objective

  • To correlate gut microbiome populations with circulating sex hormone metabolite concentrations at baseline and 12 weeks.
  • To describe the correlation of change in the microbiome populations with change in circulating sex hormone metabolite concentrations from baseline to 12 weeks.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
24

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • North Carolina
      • Winston-Salem, North Carolina, United States, 27157
        • Wake Forest Baptist Health Sciences

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

14 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Sampling Method

Probability Sample

Study Population

Women of all races and ethnicity who meet the eligibility criteria are eligible for this trial.

Description

Inclusion Criteria:

  • Pathologic diagnosis in situ or invasive breast cancer for which initiating aromatase inhibitors therapy is recommended or initiating aromatase inhibitors for risk reduction.
  • ECOG performance status 0,1, 2, 3.
  • Age ≥ 18 years
  • HER2+ breast cancer is allowed if patients are on a monoclonal antibody therapy for which a change is not anticipated while on study (12 weeks) and they have been on the monoclonal antibody therapy for at least 4 weeks.
  • Ability to read, understand and evaluate study materials and willingness to sign a written informed consent document.

Exclusion Criteria:

  • Have been on antibiotics within 4 weeks of enrollment.
  • Administered chemotherapy less than 4 weeks prior to enrollment.
  • Hormone replacement (defined as only estrogen and/or progesterone replacement) or anti-estrogen therapy within 4 weeks of starting aromatase inhibitors
  • Use of antibody drug conjugate (HER2+ breast cancer)
  • Male breast cancer
  • Any serious and/or unstable pre-existing medical, psychiatric, or other existing condition that would prevent compliance with the trial or consent process

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Observational Models: Cohort
  • Time Perspectives: Prospective

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Aromatase inhibitor for breast cancer treatment
Participants will receive their standard of care for breast cancer treatment which includes an aromatase inhibitor. Pre-study assessments will be done at baseline as well as stool and blood samples at baseline, then again at 4 weeks and at 12 weeks during the course of the trial.
Biological: Fecal swab collection
Participants will collect fecal sample at home and either mail in the sample, or drop it off at the lab
Biological: Blood samples
Participants will have approximately 1 teaspoon of blood withdrawn from a vein, for research, on 2 different occasions. The total amount of blood withdrawn during the study will be approximately 2 teaspoons.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change in Gut Microbial Levels - Fecal Swab
Time Frame: At baseline, 4 weeks and 12 weeks
To describe the microbiome shift of gut microbiome from baseline after 4-weeks and 12-weeks of oral aromatase inhibitor treatment Investigators will calculate the change in gut microbial levels using paired t-tests.
At baseline, 4 weeks and 12 weeks

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change in Gut Microbial Levels - Blood Samples
Time Frame: At baseline and at 12 weeks
Investigators will calculate Pearson or Spearman correlation coefficients between diversity and gut microbial levels and circulating sex hormone metabolite concentrations at baseline and at 12 weeks. Bacterial derived bioactive compounds, bile acids, and glucuronidated sex hormones will be compared by metabolomics conducted on plasma.
At baseline and at 12 weeks
Change in Sex Hormone Concentrations - Blood Samples
Time Frame: At baseline and at 12 weeks

Investigators will fit a model with independent variables of the value (baseline or 12 weeks), and a second variable that represents the change from baseline (will be 0 or the change at 12 weeks).

Estrone, estrone-3-glucuronide, and estrone-3-sulfate concentrations will be measured using an ELISA assay conducted on plasma.
At baseline and at 12 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Wake Forest University Health Sciences

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
National Cancer Institute (NCI)

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Katherine Ansley, MD, Wake Forest Baptist Health Sciences

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
March 29, 2022

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
July 28, 2025

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
July 28, 2025

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
August 25, 2021

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 25, 2021

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
September 1, 2021

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
June 15, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
June 11, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • IRB00076577
  • P30CA012197 (U.S. NIH Grant/Contract)
  • WFBCCC 74121 (Other Identifier: Wake Forest Baptist Comprehensive Cancer Center)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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