Oral Aromatase Inhibitors Modify the Gut Microbiome

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: Recruiting
• Conditions: Breast Cancer
• Intervention / Treatment: Biological: Fecal swab collection; Biological: Blood samples

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: Observational
• Enrollment (Estimated): 25

Contacts and Locations

• Study Contact: Name: Study Coordinator; Phone Number: 336-713-5435; Email: jriley@wakehealth.edu

Study Locations

• United States
  • North Carolina
    • Winston-Salem, North Carolina, United States, 27157
      • Recruiting
      • Wake Forest Baptist Health Sciences
      • Contact: Study Coordinator; Phone Number: 336-713-5435; Email: jriley@wakehealth.edu
      • Principal Investigator: Katherine Ansley, MD

Participation Criteria

Eligibility Criteria

• 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

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Prospective

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
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

Outcome Measure	Measure Description	Time Frame
Change in Gut Microbial Levels - Fecal Swab	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

Outcome Measure	Measure Description	Time Frame
Change in Gut Microbial Levels - Blood Samples	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	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

• Sponsor: Wake Forest University Health Sciences
• Collaborators: National Cancer Institute (NCI)
• Investigators: Principal Investigator: Katherine Ansley, MD, Wake Forest Baptist Health Sciences

Study record dates

Study Major Dates

• Study Start (Actual): March 29, 2022
• Primary Completion (Estimated): July 1, 2026
• Study Completion (Estimated): July 1, 2026

Study Registration Dates

• First Submitted: August 25, 2021
• First Submitted That Met QC Criteria: August 25, 2021
• First Posted (Actual): September 1, 2021

Study Record Updates

• Last Update Posted (Actual): April 13, 2026
• Last Update Submitted That Met QC Criteria: April 9, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Gut microbiome; Circulating sex hormone metabolite concentrations
• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Skin Diseases; Breast Diseases; Skin and Connective Tissue Diseases; Breast Neoplasms; Investigative Techniques; Specimen Handling; Clinical Laboratory Techniques; Diagnostic Techniques and Procedures; Diagnosis; Punctures; Surgical Procedures, Operative; Blood Specimen Collection
• Other Study ID 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