Breast CancerGEMMANCT07553234
Study to Understand Relationship Between Gut Health and Toxicities of Hormonal Breast Cancer Treatment
A study testing Stool Sampling and Chia Seeds in people with Breast Cancer, run by University of Chicago at 1 site in United States.
Trial summary
This study will be conducted in 2 sequential parts. The first part will be a prospective, observational study. This will be followed by a small interventional, pilot study involving use of fiber supplement (chia seeds). Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Breast Cancer
- What is being tested?
- Stool Sampling and Chia Seeds
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 20 participants
- Where
- 1 siteUnited States
- Study dates
- 21 Sep 2026to 3 May 2030
- Phase
- Interventional
- 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
- Be willing and able to provide written informed consent for the trial
- Be a male or female subject 18 years of age on day of signing informed consent.
- Histologically proven infiltrating carcinoma of the breast on core needle biopsy that is:
- HER2 negative in primary tumour pre-treatment by local pathology assessed according current American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines: In situ hybridization non-amplified (ratio of HER2 to CEP17 < 2.0 or single probe average HER2 gene copy number < 4 signals/cell), OR Immunohistochemistry (IHC) 0 or IHC 1+.
- Estrogen receptor (ER) and progesterone receptors (PR) positive in primary tumour pre-treatment defined as >1% of cells expressing hormonal receptors via IHC analysis by local laboratory assessment.
- Planned to undergo standard of care therapy with abemaciclib and endocrine therapy, in the adjuvant or metastatic setting (Part 1) or the adjuvant setting (Part 2).
- Be willing to provide mandatory stool samples at baseline and on treatment.
- The Eastern Cooperative Oncology Group (ECOG) 0-2
Who cannot join
- Patients who are pregnant or breast-feeding
- Current use of any investigational agents
- Uncontrolled Ulcerative Colitis, Crohn's Disease, Malabsorption syndrome or any disease significantly affecting gastrointestinal function
- History or current evidence of any condition, therapy, lab abnormality or other circumstance that in the opinion of the investigator might expose the subject to risk by participating in the trial, confound the results of the trial, or interfere with the subject's participation for the full duration of the trial.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Rita Nanda contact
United States1 site, 1 recruiting
- Recruiting
The University of Chicago Medicine Comprehensive Cancer Center
Chicago, Illinois, 60637
Clinical Trials Intake, 855-702-8222, cancerclinicaltrials@bsd.uchicago.edu
Rita Nanda
About this study
Official title: Prospective Evaluation of the Gut Microbiome and a Pilot Dietary Intervention in Patients With HR+/HER2- Breast Cancer Receiving Abemaciclib (GEMMA)
This study will be conducted in 2 sequential parts. The first part will be a prospective, observational study. This will be followed by a small interventional, pilot study involving use of fiber supplement (chia seeds). The study aims to evaluate the relationship between the gut microbiome (a diverse ecosystem of microorganisms that affects your health and well-being) and treatment-related gastrointestinal toxicities in patients with HR+/HER2- breast cancer receiving abemaciclib plus endocrine therapy.
- Conditions
- Breast Cancer
- Being tested
- Stool Sampling, Chia Seeds
- Medical subject headings
- Breast Neoplasms
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Stool SamplingOther
Stool samples will be collected continuously (during as many bowel movements as possible) using the GutLab device (BiomeSense, Inc.).
Chia SeedsOther
In the Fiber Study cohort (Part 2), participants will be advised to consume a standardized daily serving of chia seeds (25g/day) and provided with guidance on how to integrate this into their usual diet.
| Study group | Role | What they receive |
|---|---|---|
| Observational Cohort | Experimental | Enrolled patients with early or advanced HR+/HER2- breast cancer starting abemaciclib as per standard of care to characterize the baseline composition and longitudinal dynamics of the gut microbiome before and during treatment. Stool samples will be collected continuously using the GutLab platform, alongside clinical toxicity assessments, with a focus on identifying microbial signatures associated with the development and severity of diarrhea. No intervention will be administered. Receives: Other: Stool Sampling |
| Dietary Intervention Cohort | Experimental | Enrolled patients with early-stage HR+/HER2- breast cancer. A 2-week chia seed intervention will be administered prior to initiation of abemaciclib. The goal of this high fiber intervention is to favorably modulate the gut microbiome by supporting a more diverse microbiome and reducing the risk of inflammation and dysbiosis. Receives: Other: Stool Sampling; Other: Chia Seeds |
What is being measured
The primary outcome is the main question the study is designed to answer.
Stool Sampling Feasibility
Proportion of enrolled participants who provide serial stool samples during the baseline and on-treatment periods, as recorded by device data and study records.
Measured: 2 years
Secondary outcomes (2)
Baseline Microbiome-Diarrhea Associations
Correlation between baseline gut microbiome composition and incidence of grade ≥2 diarrhea during abemaciclib therapy, as defined by CTCAE v6.0.
Measured: 2 years
Microbiome Dynamics and Diarrhea
Correlation between longitudinal changes in gut microbiome composition during abemaciclib therapy and incidence and severity of grade ≥2 diarrhea, as defined by CTCAE v6.0.
Measured: 2 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted27 Apr 2026
- Study start21 Sep 2026
- Primary completion3 May 2030 (estimated)
- Study completion3 May 2030 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Breast CancerStudies of the same condition, open and under way.
- More trials run by University of ChicagoThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
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 N/A
- Primary purpose
- Supportive care
- Allocation
- Non-randomised
- Intervention model
- Sequential
- Masking
- None (open label)
- Enrolment
- 20 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Chicago
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Rita Nanda, Principal investigator, University of Chicago
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07553234
- Sponsor's protocol ID
- IRB25-2098
- Acronym
- GEMMA
- Status last verified
- Sep 2026
- First submitted
- 2 Mar 2026
- Last updated
- 28 Sep 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 28 Sep 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Prospective Evaluation of the Gut Microbiome and a Pilot Dietary Intervention in Patients With HR+/HER2- Breast Cancer Receiving Abemaciclib (GEMMA)
- ClinicalTrials.gov ID
- NCT07553234
- Acronym / sponsor ID
- GEMMA / IRB25-2098
- Conditions
- Breast Cancer
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 20 participants (estimated)
- Lead sponsor
- University of ChicagoUniversity, hospital or other
- Study start
- 21 Sep 2026 (actual)
- Primary completion
- 3 May 2030 (estimated)
- Study completion
- 3 May 2030 (estimated)
- First posted
- 27 Apr 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study will be conducted in 2 sequential parts. The first part will be a prospective, observational study. This will be followed by a small interventional, pilot study involving use of fiber supplement (chia seeds). The study aims to evaluate the relationship between the gut microbiome (a diverse ecosystem of microorganisms that affects your health and well-being) and treatment-related gastrointestinal toxicities in patients with HR+/HER2- breast cancer receiving abemaciclib plus endocrine therapy.
Study design
- Primary purpose
- Supportive care
- Allocation
- Non-randomised
- Intervention model
- Sequential
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Observational Cohort | Experimental | Other: Stool SamplingEnrolled patients with early or advanced HR+/HER2- breast cancer starting abemaciclib as per standard of care to characterize the baseline composition and longitudinal dynamics of the gut microbiome before and during treatment. Stool samples will be collected continuously using the GutLab platform, alongside clinical toxicity assessments, with a focus on identifying microbial signatures associated with the development and severity of diarrhea. No intervention will be administered. |
| Dietary Intervention Cohort | Experimental | Other: Stool Sampling, Other: Chia SeedsEnrolled patients with early-stage HR+/HER2- breast cancer. A 2-week chia seed intervention will be administered prior to initiation of abemaciclib. The goal of this high fiber intervention is to favorably modulate the gut microbiome by supporting a more diverse microbiome and reducing the risk of inflammation and dysbiosis. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (8 listed)
- Be willing and able to provide written informed consent for the trial
- Be a male or female subject 18 years of age on day of signing informed consent.
- Histologically proven infiltrating carcinoma of the breast on core needle biopsy that is:
- HER2 negative in primary tumour pre-treatment by local pathology assessed according current American Society of Clinical Oncology (ASCO)/College of American Pathologists (CAP) guidelines: In situ hybridization non-amplified (ratio of HER2 to CEP17 < 2.0 or single probe average HER2 gene copy number < 4 signals/cell), OR Immunohistochemistry (IHC) 0 or IHC 1+.
- Estrogen receptor (ER) and progesterone receptors (PR) positive in primary tumour pre-treatment defined as >1% of cells expressing hormonal receptors via IHC analysis by local laboratory assessment.
Key exclusion criteria (4 listed)
- Patients who are pregnant or breast-feeding
- Current use of any investigational agents
- Uncontrolled Ulcerative Colitis, Crohn's Disease, Malabsorption syndrome or any disease significantly affecting gastrointestinal function
- History or current evidence of any condition, therapy, lab abnormality or other circumstance that in the opinion of the investigator might expose the subject to risk by participating in the trial, confound the results of the trial, or interfere with the subject's participation for the full duration of the trial.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Stool SamplingStool samples will be collected continuously (during as many bowel movements as possible) using the GutLab device (BiomeSense, Inc.). | Other | Dietary Intervention Cohort, Observational Cohort |
| Chia SeedsIn the Fiber Study cohort (Part 2), participants will be advised to consume a standardized daily serving of chia seeds (25g/day) and provided with guidance on how to integrate this into their usual diet. | Other | Dietary Intervention Cohort |
Primary outcome
Stool Sampling Feasibility
Time frame: 2 years
Proportion of enrolled participants who provide serial stool samples during the baseline and on-treatment periods, as recorded by device data and study records.
2 secondary outcomes
Baseline Microbiome-Diarrhea Associations
Time frame: 2 years
Microbiome Dynamics and Diarrhea
Time frame: 2 years
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 28 Sep 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Rita Nanda contact
Rita Nanda principal investigator
University of Chicago
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Stool Sampling and Chia Seeds in people with Breast Cancer, run by University of Chicago 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 8 inclusion and 4 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: looking for participants now, as of the sponsor's last update on 28 Sep 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.
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?
Contact Clinical Trials Intake (855-702-8222, cancerclinicaltrials@bsd.uchicago.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Stool Sampling Feasibility (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 28 Sep 2026.