Effects of High-Fiber Diet on Gut Microbiota, Metabolism, and Immune Microenvironment in Solid Tumor Patients: A Clinical Study

NCT07477522 | Completed Phase 1 DMC

• 1 other identifier: Approval No. 1038 (2025)
• Study Type: interventional
• Target: 17
• Locations: 1 country
• Sites: 2

Brief Summary

Cancer remains a major global public-health challenge and a central focus of medical research. According to the International Agency for Research on Cancer (IARC, 2020), 19.29 million new malignant tumors and 9.96 million cancer deaths occurred worldwide, \>90% being solid cancers. Lung cancer alone accounted for 2.2 million new cases and 1.8 million deaths; \>75% of patients were already at an advanced stage at diagnosis. Current options for late-stage solid tumors are limited: surgery is often impossible because of metastasis; cytotoxic chemotherapy produces dose-limiting toxicities (grade III-IV myelosuppression 15-40%, mucositis 50-80%); radiotherapy risks pneumonitis (5-15%) or enteritis (5-20%) when tumors abut vital organs; targeted agents succumb to acquired resistance after a median 9-13 months; and immune-checkpoint inhibitors achieve \<40% objective response with 7-15% grade 3-4 immune-related adverse events. Dietary intervention is therefore emerging as a promising adjunct. Dietary fibre protects against cardiovascular and metabolic diseases, yet intake is universally low. WHO and the Chinese Nutrition Society recommend 25-30 g total fibre per day (approximately 15-21 g insoluble), whereas Chinese adults consume only approximately 11 g insoluble fibre. High-fibre diets reshape gut microbiota, augment short-chain fatty acid (SCFA) production, strengthen intestinal barrier function, activate CD8⁺ T cells and dampen regulatory T cells, thereby enhancing anti-tumour immunity. A melanoma cohort showed improved progression-free survival under immunotherapy when fibre intake was high. Similar microbiota-immune axes may operate in colorectal and other solid cancers, but clinical data are scarce. This study examines whether supplementation with 16-20 g/day of dietary fibre for 6 weeks modulates gut-microbiota composition, faecal short-chain fatty acid profiles, and peripheral-blood immune-cell subsets in patients with solid tumours. The findings may clarify whether fibre-driven microbiota-immune crosstalk can be harnessed as a personalised nutritional strategy in patients with cancer.

Conditions

Diet Habits; High-fibre Diet; Solid Tumor Cancer

Keywords

high-fibre diet; Solid Tumor Cancer

Outcome Measures

Primary Outcomes (1)

• Incidence, Type, Frequency, and Severity of Intervention-Emergent Adverse Events

  The incidence, type, frequency, and severity of intervention-emergent adverse events, with particular attention to gastrointestinal adverse events, including constipation, abdominal distension, abdominal pain, nausea, vomiting, and diarrhea.

  From the first intake of the dietary fiber supplement through the end of the 6-week intervention period

Secondary Outcomes (3)

• Change in fecal gut microbiota composition

  Baseline and week 6 after initiation of the dietary intervention.

• Change in fecal short-chain fatty acid concentrations

  Baseline and week 6 after initiation of the dietary intervention.

• Change in peripheral blood immune-cell subsets

  Baseline and week 6 after initiation of the dietary intervention.

Study Arms (1)

high-insoluble-fibre diet

EXPERIMENTAL

Dietary Supplement: High-fibre diet

Interventions

High-fibre diet DIETARY_SUPPLEMENT

Dietary fibre, recommended at 25-30 g/day (15-21 g/day insoluble fibre), is chronically under-consumed (approximately 11 g/day in China). High-fibre diets increase short-chain fatty acid (SCFA) production, enhance gut-barrier integrity, and boost antitumour immunity, and higher dietary fibre intake has been associated with better immunotherapy outcomes in patients with melanoma. Clinical evidence in patients with solid tumours remains limited. Participants received 16-20 g/day of supplemental dietary fibre for 6 weeks in addition to their usual diet while continuing their prescribed anticancer treatment. The study evaluates whether this dietary intervention is associated with changes in gut microbiota composition, faecal short-chain fatty acid concentrations, and peripheral blood immune-cell subsets.

high-insoluble-fibre diet

Eligibility Criteria

• Age: 18 Years - 75 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• (1) Sign a written informed consent form before any study-related procedures are carried out.
• (2) Males or females, aged 18-75 years old.
• (3) Diagnosed with solid tumors by pathological tissue biopsy.
• (4) According to the RECIST v1.1 (Response Evaluation Criteria in Solid Tumors Version 1.1) criteria, there is at least 1 measurable lesion (lesions previously treated with local therapies such as radiotherapy cannot be regarded as measurable lesions).
• (5) ECOG (Eastern Cooperative Oncology Group Performance Status) score of 0-1.
• (6) NRS-2002 (Nutritional Risk Screening 2002) score \< 3.
• (7) BMI (Body Mass Index) ≥ 18.5 (can be adjusted appropriately according to the actual situation).
• (8) Patients who can eat orally or through a feeding tube and can tolerate enteral nutrition.
• (9) Sufficient organ function, and the subjects need to meet the following laboratory indicators: In the absence of granulocyte-colony-stimulating factor use in the past 14 days, the absolute neutrophil count ≥ 1.5×10⁹/L.
• Platelets ≥ 75×10⁹/L. In the absence of blood transfusion or erythropoietin use in the past 7 days, hemoglobin ≥ 8 g/dL.
• Serum albumin ≥ 3.0 g/dL. Total bilirubin ≤ 1.5× the upper limit of normal (ULN). Aspartate Aminotransferase (AST) and Alanine Aminotransferase (ALT) ≤ 2.5×ULN. In case of liver metastasis, ALT and/or AST ≤ 5×ULN, and total bilirubin ≤ 3×ULN. In case of liver or bone metastasis, Alkaline Phosphatase (AKP) ≤ 5×ULN.
• Creatinine clearance rate ≥ 50 mL/min (calculated according to the Cockcroft - Gault formula) or serum creatinine ≤ 1.5×ULN.
• International Normalized Ratio (INR) ≤ 1.5×ULN, Prothrombin Time (PT) and Activated Partial Thromboplastin Time (APTT) ≤ 1.5×ULN.
• Urine protein \< 2+ (if urine protein ≥ 2+, a 24-hour urine protein quantification can be performed, and subjects with a 24-hour urine protein quantification \< 2.0 g can be enrolled).
• (10) Women of childbearing potential must agree to abstain from heterosexual intercourse or use a reliable and effective contraceptive method from the time of signing the informed consent form until at least 6 months after the last administration of concomitant anticancer treatment. A serum human chorionic gonadotropin (HCG) test must be negative within 3 days before initiation of the study intervention, and the participant must not be breastfeeding. Women are considered to be of childbearing potential unless they are postmenopausal, defined as amenorrhea for at least 12 consecutive months without an alternative medical cause, or have undergone surgical sterilization, such as hysterectomy, bilateral tubal ligation, or bilateral oophorectomy.

You may not qualify if:

• (1) Patients with cognitive impairment or mental illness who are unable to understand the study content.
• (2) Patients with central nervous system or meningeal metastases.
• (3) Patients with clinically symptomatic moderate or severe ascites (that is, those who require therapeutic paracentesis within 2 weeks before the start of study treatment; patients with only a small amount of ascites shown on imaging and no clinical symptoms can be enrolled).
• (4) Patients with uncontrolled or moderate to severe pleural effusion and pericardial effusion.
• (5) Patients with severe diarrhea, intractable vomiting, severe malabsorption syndrome, paralytic and mechanical intestinal obstruction; tracheoesophageal fistula, gastrointestinal perforation or gastrointestinal fistula, or abdominal abscess; patients with extra - gastrointestinal bleeding with a CTCAE (Common Terminology Criteria for Adverse Events) grade 3 or above within 6 months before the start of study treatment or grade 2 or above within 3 months (such as abnormal vaginal bleeding, hematemesis).
• (6) Patients known to be allergic to any component of the dietary fiber supplement.
• (7) Patients with poorly controlled diabetes.
• (8) Patients with poorly controlled hypertension (systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg under routine antihypertensive treatment), with a history of hypertensive crisis or hypertensive encephalopathy.
• (9) Patients with severe cardiovascular and cerebrovascular diseases, including cerebrovascular accident (CVA), transient ischemic attack (TIA), myocardial infarction, and major vascular diseases within 6 months before enrollment (including but not limited to aortic aneurysms requiring surgical repair or recent arterial thrombosis); patients with poorly controlled clinical symptoms or heart diseases, such as unstable angina pectoris, NYHA (New York Heart Association) heart failure grade II or above, left ventricular ejection fraction \< 50% on color Doppler echocardiography, or severe arrhythmias that cannot be controlled by drug treatment.
• (10) Pregnant or lactating women.
• (11) Other situations considered by the investigator as inappropriate for enrollment.

Sponsors & Collaborators

• West China Hospital: lead
• Xinjin District Hospital of Traditional Chinese Medicine: collaborator

Study Sites (2)

Xinjin District Hospital of Traditional Chinese Medicine

Chengdu, Sichuan, 611430, China

Location

West China Hospital

Chengdu, Sichuan, China

Location

MeSH Terms

Conditions

Feeding Behavior

Condition Hierarchy (Ancestors)

Behavior, Animal; Behavior

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Deputy Director (Medical) of the Department of Biotherapy, Cancer Center, West China Hospital, Sichuan University; Associate Director of the Stem Cell Research and Translational Research Laboratory; PhD Supervisor; Professor/Researcher

Model Details: high-fibre diet

Study Record Dates

• First Submitted: March 12, 2026
• First Posted: March 17, 2026
• Study Start: December 1, 2025
• Primary Completion: June 25, 2026
• Study Completion: June 30, 2026
• Last Updated: September 3, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will not share

Locations

CN (2)