Why is this study being done? Many patients with a type of breast cancer (called HR-positive) take a medicine called Abemaciclib. While this medicine is effective, a very common side effect is diarrhea, which can be severe enough to disrupt treatment and reduce quality of life. The reason why some patients get diarrhea and others do not is not well understood. This study aims to investigate whether the natural bacteria living in the gut (known as the gut microbiome) play a role in this side effect. Researchers will compare the gut bacteria of patients who develop diarrhea with those who do not.
What will happen in the study? This is an observational study, which means that patients will receive their normal cancer treatment and will not be given any new or experimental drugs as part of this initial phase.
* Patients who are already being treated with Abemaciclib will be invited to join. * They will be placed into one of two groups: those who experience diarrhea and those who do not. * Participants will be asked to provide stool (feces) samples and may also provide optional blood samples at specific times during their treatment. * Researchers will analyze these samples in the lab to study the types and functions of the gut bacteria.
Who can participate?
* Adult women (aged 18-75) diagnosed with HR-positive breast cancer. * Currently receiving treatment with Abemaciclib for at least 2 weeks. * Must be willing to provide informed consent and follow the study procedures.
What are the potential benefits? Participants will not receive any direct medical benefit from taking part in this study. However, the information learned may help researchers better understand why diarrhea occurs and, in the future, could lead to new ways to prevent or treat this side effect for other cancer patients.
How is privacy protected? All personal information and samples collected will be de-identified using a unique code. This means that the data used for analysis cannot be directly linked back to the participant's identity. All data is stored securely according to strict ethical guidelines.
Aged 18 to 75 years.
Diagnosed with hormone receptor-positive (HR⁺) breast cancer.
Currently receiving treatment with Abemaciclib (either as monotherapy or in combination with endocrine therapy) for a duration of at least 2 weeks.
Willing and able to provide written informed consent for participation in the study.
History of major gastrointestinal diseases, such as inflammatory bowel disease, Crohn's disease, ulcerative colitis, or intestinal obstruction, or having undergone major gastrointestinal surgery.
Recent use (within 1 month) of antibiotics, probiotics, or traditional Chinese medicine that may alter gut function.
Pregnant or lactating women.
Unwilling to provide informed consent or considered by the investigator to be unsuitable for the study for any other reason.
This study will enroll a prospective cohort of female patients with hormone receptor-positive (HR⁺) breast cancer who are receiving treatment with Abemaciclib (as monotherapy or in combination) as part of their standard clinical care at Hubei Cancer Hospital. Participants will be prospectively assigned into two groups based on the presence or absence of drug-induced diarrhea, as defined by CTCAE v5.0 criteria: the Diarrhea Group and the Non-Diarrhea (Control) Group. The study involves the collection of clinical data, fecal samples, and optional blood samples for microbiome and biomarker analysis. No investigational intervention is administered in this phase of the study.
Cohort
Prospective
Not listed
Difference in gut microbiota beta diversity
Beta diversity of the gut microbiome (e.g., Weighted UniFrac distance) will be compared between the diarrhea group and the non-diarrhea group to assess overall microbial community structure differences.
Identification of specific bacterial species enriched in non-diarrhea group
Metagenomic sequencing data will be analyzed (e.g., using LEfSe) to identify bacterial species that are significantly enriched in the non-diarrhea group compared to the diarrhea group (LDA Score \> 2, p-value \< 0.05).
Difference in gut microbiota alpha diversity
Alpha diversity indices (Shannon, Chao1) of the gut microbiome will be compared between the diarrhea group and the non-diarrhea group.
Difference in metagenomic functional pathways
Differential abundance analysis of functional pathways (e.g., KEGG Level 2/3) derived from metagenomic sequencing data between the two groups.
Differential metabolites in serum
Differences in serum metabolomic profiles between the diarrhea and non-diarrhea groups.
Difference in systemic inflammatory cytokine levels
Levels of inflammatory cytokines (e.g., IL-6, TNF-α, CRP) in serum will be compared between the two groups.
Predictive potential of baseline gut microbiota
Exploratory analysis to assess the potential of baseline gut microbiota features for predicting the risk of developing Abemaciclib-induced diarrhea.
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