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Fiber-Boost Randomized Controlled Trial

Multicenter, Randomized, Controlled Trial to Study the Effects of a High-Fiber Dietary Intervention on ctDNA Clearance and the Microbial and Immunological Landscape in Patients With Advanced Non-Small Cell Lung Cancer Receiving PD-1/PD-L1-Targeted Monotherapy (Fiber-Boost)

Status
Recruiting
Phases
Unknown
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT07483112
Acronym
Fiber-Boost
Enrollment
42
Registered
2026-03-19
Start date
2025-10-07
Completion date
2027-12-31
Last updated
2026-03-19

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Non-Small Cell Carcinoma of Lung

Keywords

non-small cell lung cancer, immunotherapy, high-fiber diet, microbiome

Brief summary

In the present study 'Fiber-Boost', we investigate how a high-fiber diet affects the immunotherapy of advanced lung cancer and what effects it has on the gut microbiome (i.e., the bacteria in the gut) as well as the immune system. Study participants will be assigned to either a test group or a control group. Only patients in the test group will undergo a high-fiber diet. The study lasts 6 weeks per patient and will be conducted at 4 centers within Switzerland. A total of 42 patients are planned to be included in the study.

Detailed description

The activity of immune checkpoint blockade (ICB) mechanistically depends on the host microbiome and is manipulable through diet. In this study termed Fiber-Boost, we propose a multicenter trial of a supplement-based high-fiber diet (HFD) in non-small cell lung cancer (NSCLC) treated with first-line ICB monotherapy. Using a randomized, controlled design, we mechanistically explore the role of dietary fibers in cancer immunotherapy. Circulating tumor DNA (ctDNA) quantification as well as a rich pipeline of companion microbiome and immune profiling technologies will improve the understanding of the diet-microbiome-immune axis in therapeutic anticancer immunity and treatment response. The overarching goal is to elucidate novel therapeutic strategies for ICB sensitization in NSCLC using microbiome-centered, non-pharmaceutical interventions. Sex and gender dimensions are biologically not sufficiently relevant for the current study to merit corresponding stratification or analyses.

Interventions

DIETARY_SUPPLEMENTHigh-fiber diet

Patients in the intervention arm will receive a high-fiber diet through daily consumption of a defined amount of plant-based fibers from a commercial product.

Sponsors

Cantonal Hospital of St. Gallen
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No

Inclusion criteria

* Age ≥18 years * Written informed consent according to Swiss law and ICH/GCP regulations before inclusion and prior to any trial-specific procedures * Histologically or cytologically confirmed NSCLC * Advanced or recurrent NSCLC not amenable to curative treatment * PD-L1 expression ≥50% (TPS) determined by an approved IHC test * No actionable genetic alterations in genes such as EGFR, ALK, ROS1, HER2, BRAF, RET, MET, NTRK * First-line palliative PD-1/PD-L1-targeted monotherapy at a 3-weekly schedule indicated per local investigator * Willingness and ability to undergo study interventions * ECOG performance status 0-2 * Adequate organ function: * Hemoglobin ≥70 g/L, platelet count ≥50 G/L, granulocytes ≥1 G/L * Bilirubin, ALT, AST ≤3 x ULN * Glomerular filtration rate (Cockroft-Gault) ≥30 mL/min/1.73m² * Measurable or evaluable disease per RECIST 1.1 * Patients with CNS metastases are eligible, provided there is no requirement for corticosteroids as therapy for CNS disease and no evidence of clinical progression * Women with child-bearing potential use effective contraception (two independent methods), are not currently pregnant or lactating, and agree to not become pregnant during the trial treatment and during 3 months thereafter. A negative pregnancy test in either urine or blood is required for women with child-bearing potential before trial inclusion. * Men who are not sterile agree to use contraceptive methods (condoms) or abstain from sexual intercourse during the trial treatment and 3 months thereafter.

Exclusion criteria

-History of malignancy, unless in remission for at least 3 years before inclusion with the exception of pT1-2 prostate cancer Gleason score \<6, adequately treated cervical carcinoma in situ or localized non-melanoma skin cancer Adjuvant or additive systemic ICB treatment within 6 months prior to inclusion * Systemic treatment with an antibiotic within 10 days of ICB treatment/HFD intervention start * Concomitant immunosuppressive drugs including corticosteroids at a daily dose of ≥10mg prednisone equivalents, methotrexate, azathioprine, TNF-α inhibitors * Concurrent treatment with other experimental drugs or other anticancer therapy * Major surgical procedures within 14 days prior to inclusion as judged by the investigator * Active autoimmune disease requiring systemic immunosuppressive treatment that is seen as contraindication for the use of PD-1/PD-L1-targeted monoclonal antibodies * Uncontrolled diabetes mellitus * Severe or uncontrolled cardiovascular disease * Any other serious underlying medical, psychiatric, psychological, familial or geographical condition, which in the judgment of the investigator may interfere with the planned staging, treatment and follow-up, affect patient compliance or place the patient at high risk from treatment-related complications * Had an allogeneic tissue/solid organ transplant * Ongoing supplementation with OptiFibre® or another fiber supplement

Design outcomes

Primary

MeasureTime frameDescription
ctDNA clearance6 weeksFraction of patients achieving complete ctDNA clearance at 6 weeks

Secondary

MeasureTime frameDescription
Radiological treatment response6 weeks and 6 monthsObjective radiological response (RECIST 1.1)
Disease control rate6 months6-months disease control rate (non-progressive disease at 6 months)
Microbiota dynamics6 weeksGut microbiota dynamics by shotgun metagenomics
Systemic immune response6 monthsSystemic immune response dynamics by high-dimensional flow cytometry
ctDNA dynamics3 and 6 weeksctDNA dynamics over 6 weeks

Countries

Switzerland

Contacts

CONTACTMaximilian Boesch, Ph.D.
maximilian.boesch@h-och.ch0041714947143

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Mar 20, 2026