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NCT Number: NCT07406594

Gut Microbiome Changes During Abemaciclib Therapy in Breast Cancer

Abemaciclib (Verzenio) is a commonly used treatment for hormone receptor-positive breast cancer, but it can cause gastrointestinal side effects such as diarrhea, which may affect quality of life and treatment tolerance. The gut microbiome, which is the collection of bacteria living in the digestive tract, may play a role in these symptoms.

The purpose of this study is to examine how the gut microbiome changes during the early phase of abemaciclib treatment and how these changes relate to gastrointestinal symptoms experienced by patients. Participants will provide stool samples at multiple time points using mailed collection kits and will complete questionnaires about gastrointestinal symptoms while receiving standard-of-care abemaciclib therapy. All study procedures will be conducted remotely.

Information gained from this study may help inform future supportive care strategies for breast cancer patients receiving abemaciclib.

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Key information

Conditions

Breast Cancer Breast Diseases Breast Neoplasms HER-2 Positive Breast Cancer Neoplasms Neoplasms by Site Skin Diseases Skin and Connective Tissue Diseases

Age range

18 year and older

Sex eligibility

Female

Study type

Interventional

Phase

Not applicable

Primary location

University of Vermont

Burlington, Vermont, 05401, United States

Location contact

Tracy Smith, PhD

CONTACT

1 (802) 656-2021

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age ≥ 18 years.
  • Histologically confirmed hormone receptor-positive, HER2-negative breast cancer.
  • Planned initiation of adjuvant abemaciclib (Verzenio) as part of standard clinical care, with enrollment occurring prior to or within 7 days of starting abemaciclib.
  • Eastern Cooperative Oncology Group (ECOG) performance status of 0-2.
  • Women of child-bearing potential must agree to use contraception prior to study entry, for the duration of study participation, and for 90 days following completion of study participation. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately.

A female of child-bearing potential is any woman (regardless of sexual orientation, having undergone a tubal ligation, or remaining celibate by choice) who meets the following criteria:

  • Has not undergone a hysterectomy or bilateral oophorectomy; or
  • Has not been naturally postmenopausal for at least 12 consecutive months (i.e., has had menses at any time in the preceding 12 consecutive months).
  • Ability to understand and the willingness to sign a written informed consent.

Exclusion criteria

  • Concurrent participation in another interventional clinical trial that, in the opinion of the investigator, would interfere with study participation or interpretation of results.
  • Known gastrointestinal conditions that would significantly interfere with study procedures or interpretation of results, including but not limited to inflammatory bowel disease, short bowel syndrome, or chronic diarrheal disorders.
  • Known allergy or intolerance to resistant starch or any component of the study supplement.
  • Pregnant or breastfeeding individuals.
  • Any medical, psychiatric, or social condition that, in the judgment of the investigator, would limit the participant's ability to comply with study procedures.

Treatment and study plan

Resistant Potato Starch

Dietary Supplement

Participants randomized to the resistant starch intervention will receive a resistant starch dietary supplement administered orally. The supplement will be taken during early abemaciclib therapy according to study instructions. Abemaciclib is administered as standard of care and is not altered by study participation.

Placebo Control

Dietary Supplement

Participants randomized to the placebo intervention will receive a placebo dietary supplement administered orally as a powder mixed with a beverage. The supplement will be taken during early abemaciclib therapy according to study instructions. Abemaciclib is administered as standard of care and is not altered by study participation.

Primary outcomes

  1. Recruitment rate

    Time frame: From study opening through completion of enrollment (approximately 12 months)

    Feasibility will be assessed by the proportion of eligible participants who enroll in the study out of those approached for participation.

  2. Participant retention

    Time frame: Through end of intervention (6 weeks)

    Feasibility and acceptability will be assessed by the proportion of enrolled participants who complete the intervention period and final study assessments.

  3. Supplement adherence

    Time frame: During the 6-week intervention

    Feasibility will be assessed by participant adherence to the assigned supplement, measured as the proportion of prescribed doses taken during the intervention period.

  4. Completion of study procedures

    Time frame: Baseline through end of intervention (6 weeks)

    Feasibility will be assessed by the proportion of participants who complete protocol-specified stool sample collections and questionnaires.

Secondary outcomes

  1. Change in Gut Microbial Community Composition During Early Abemaciclib Therapy

    Time frame: Baseline through Week 6 of abemaciclib therapy

    Changes in gut microbial community composition will be assessed using stool samples collected at baseline and during early abemaciclib therapy. Microbiome profiles will be compared over time and between intervention groups to characterize longitudinal changes associated with treatment.

  2. Correlation between gut microbiome diversity and gastrointestinal symptom severity

    Time frame: Baseline through Week 6 of abemaciclib therapy

    Correlation between gut microbiome alpha diversity measured from stool samples using 16S rRNA gene sequencing (Shannon diversity index, unitless) and gastrointestinal symptom severity measured using the Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE) gastrointestinal symptom items (score range 0-4 per item). Correlation coefficients will be calculated to assess the relationship between microbiome diversity and symptom severity during early abemaciclib therapy.

  3. Differences in Gut Microbial Community Composition Between Resistant Starch and Placebo Groups

    Time frame: Baseline through Week 6 of abemaciclib therapy

    Differences in gut microbial community composition and temporal patterns will be explored between participants randomized to resistant starch supplementation and those receiving placebo using stool samples collected at multiple time points during early abemaciclib therapy.

Study contacts

Contact information is provided by the study sponsor or research team.

Tracy Smith, PhD

CONTACT

[email protected]

1 (802) 656-2021

Sponsors and collaborators

Lead sponsor

University of Vermont Medical Center

Other

Registry information

Official study title

MICRO-VERZ: MICRObiome Changes During VERZenio Therapy

Acronym: MICRO-VERZ

Important dates

Study start
2027
Primary completion
2031
Study completion
2031
First posted
Feb 12, 2026
Registry last updated
Feb 12, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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