NCT07553234 · University of Chicago
Study to Understand Relationship Between Gut Health and Toxicities of Hormonal Breast Cancer Treatment
(GEMMA)
What this study is about
This study will be conducted in 2 sequential parts. The first part will be a forward-looking, observational study. This will be followed by a small interventional, pilot study involving use of fiber supplement (chia seeds).
View original scientific description
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.
Interventions
OTHER
Stool Sampling
Stool samples will be collected continuously (during as many bowel movements as possible) using the GutLab device (BiomeSense, Inc.).
OTHER
Chia Seeds
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.
Primary outcome measures
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.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- 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
Exclusion criteria
- 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.
Where
- Chicago, Illinois
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Sep 28, 2026 · Source of record for eligibility and locations