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NCT Number: NCT07264985

Gut Microbiota and Diarrhea in Breast Cancer Patients Receiving Pyrotinib

Background:

Pyrotinib is an effective targeted drug for HER2-positive breast cancer, but it very frequently causes diarrhea, which can be severe enough to disrupt treatment and reduce patients' quality of life. The reason why some patients develop diarrhea while others do not is not well understood. Recent research suggests that the community of bacteria in the gut (gut microbiota) may play a key role in this side effect.

What is the purpose of this study? This is an observational study (Phase 1) that aims to understand the relationship between pyrotinib treatment, changes in gut bacteria, and the occurrence of diarrhea. The main goal is to compare the gut bacteria of patients who develop diarrhea while taking pyrotinib with those who do not. Researchers hope to identify specific bacteria that might protect against diarrhea, which could lead to new ways to prevent or treat this side effect in the future.

What will happen in the study? Patients with HER2-positive breast cancer who are being treated with pyrotinib will be invited to participate. They will be divided into two groups: those who experience diarrhea and those who do not. Participants will provide stool samples at specific time points (e.g., 2 and 4 weeks after starting pyrotinib). They will also allow researchers to collect information from their medical records about their clinical condition and diarrhea symptoms. No experimental intervention will be administered in this phase of the study; all patients will receive standard medical care.

Potential Benefits:

Participants will not receive any direct benefit from this observational phase of the study. However, the information gathered may help scientists better understand pyrotinib-induced diarrhea and develop future strategies to help other breast cancer patients manage this side effect more effectively.

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Key information

Conditions

Breast Cancer Breast Diseases Breast Neoplasms Chemically-Induced Disorders Diarrhea Drug-Related Side Effects Drug-Related Side Effects and Adverse Reactions Neoplasms Neoplasms by Site Pathological Conditions, Signs and Symptoms Signs and Symptoms Signs and Symptoms, Digestive Skin Diseases Skin and Connective Tissue Diseases

Age range

18 year–75 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • Patients aged 18-75 years, regardless of gender.
  • Diagnosed with HER2-positive breast cancer and currently receiving pyrotinib treatment (either as monotherapy or in combination with endocrine therapy), with a treatment duration of ≥ 2 weeks.
  • Voluntarily agree to participate in this study and provide written informed consent.

Exclusion criteria

  • History of significant gastrointestinal diseases (e.g., inflammatory bowel disease, Crohn's disease, ulcerative colitis, intestinal obstruction) or previous major gastrointestinal surgery.
  • Recent use (within 1 month) of antibiotics, probiotics, or traditional Chinese medicine intended to alter intestinal function.
  • Pregnant or lactating women.
  • Patients who refuse to provide informed consent or explicitly express unwillingness to participate. Patients found not meeting the inclusion criteria after enrollment will be discontinued from the study.

Treatment and study plan

Primary outcomes

  1. Difference in gut microbiota β-diversity between the Diarrhea group and the Non-diarrhea group.

    Time frame: Through study completion, an average of 6 months.

    Beta diversity (e.g., using UniFrac distance) of the gut microbiota will be compared between the two groups based on metagenomic sequencing data. A statistically significant difference (P < 0.05) is expected.

  2. Identification of specific bacterial species enriched in the Non-diarrhea group.

    Time frame: Through study completion, an average of 6 months.

    Metagenomic sequencing data will be analyzed to identify bacterial species that are significantly more abundant in the Non-diarrhea group compared to the Diarrhea group, using statistical methods such as LEfSe (Linear Discriminant Analysis Effect Size) with a threshold of LDA Score > 2 and P < 0.05.

Secondary outcomes

  1. Difference in gut microbiota α-diversity between groups.

    Time frame: Through study completion, an average of 6 months.

    Alpha diversity indices (e.g., Shannon index, Chao1 index) of the gut microbiota will be compared between the Diarrhea and Non-diarrhea groups.

  2. Differences in metagenomic functional pathways between groups.

    Time frame: Through study completion, an average of 6 months.

    Metagenomic sequencing data will be annotated using databases like KEGG. The abundance of functional pathways (e.g., KEGG Level 2 or 3) will be compared between the two groups to identify differentially abundant metabolic or functional modules.

  3. Differences in serum inflammatory cytokine levels between groups.

    Time frame: Through study completion, an average of 6 months.

    Levels of systemic inflammatory cytokines (e.g., IL-6, TNF-α, CRP) measured in serum samples by ELISA or other assays will be compared between the Diarrhea and Non-diarrhea groups.

  4. Differences in serum metabolomic profiles between groups.

    Time frame: Through study completion, an average of 6 months.

    Metabolomic profiling of serum samples will be performed (e.g., by mass spectrometry). The metabolic profiles will be compared between the two groups to identify differentially abundant metabolites.

Other outcomes

  1. Predictive potential of baseline gut microbiota for pyrotinib-induced diarrhea risk.

    Time frame: Through study completion, an average of 6 months.

    An exploratory analysis to assess whether the composition and features of the gut microbiota before starting pyrotinib treatment (baseline) can predict the subsequent risk of developing diarrhea during treatment. Metagenomic sequencing data from baseline stool samples will be used to build predictive models.

Study contacts

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

Xinhong Wu Wu, Principal Investigator

CONTACT

[email protected]

18602726300

Sponsors and collaborators

Lead sponsor

Hubei Cancer Hospital

Other

Registry information

Official study title

Gut Microbiota Changes in Breast Cancer Patients Treated With Pyrotinib and Correlation With Drug-Induced Diarrhea: An Observational Cohort Study

Important dates

Study start
2025
Primary completion
2027
Study completion
2027
First posted
Dec 4, 2025
Registry last updated
Jul 16, 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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