Colorectal CancerPhase 2NCT05748145
Metronidazole as Preoperative Therapy in CRC / FusoMetro-001
A Phase 2 study testing Metronidazole Oral in people with Colorectal Cancer, run by Oncology Institute of Southern Switzerland at 1 site in Switzerland.
Trial summary
The proposed proof-of concept trial aims at determining the effectiveness of metronidazole in decreasing the Fusobacterium nucleatum load in tissues and possibly on its detrimental effects on tumor cells and tumor microenvironment. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Colorectal Cancer
- What is being tested?
- Metronidazole Oral
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 40 participants
- Where
- 1 siteSwitzerland
- Study dates
- 11 Sep 2023to 31 Dec 2026
- Phase
- Phase 2
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Written informed consent according to ICH/GCP regulations before registration.
- Age ≥ 18 years old
- Untreated, primary colorectal adenocarcinoma (> 15 cm from the anal verge)
- Colonoscopy with endoscopic biopsy for disease confirmation and correlative studies.
- Candidates for surgical resection prior to administration of any therapy.
Who cannot join
- Insufficient material on the tissue biopsy to be left in the archives of the Cantonal Institute of Pathology for further evaluations/analyses
- Known prior history of hypersensitivity to metronidazole or other nitroimidazole derivatives
- Oral or parenteral antibiotic therapy within the six weeks prior to enrolment
- Emergency surgery (planned within less than 14 days), where no opportunity to administer preoperative oral antibiotics exists
- Other malignant disease within 5 years prior to study enrollment, except basocellular or squamous skin cancer and carcinoma in situ cervices uteri
- Any previous anticancer treatment prior resection
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- Women who are pregnant or breast feeding
- Fertile women or men who do not use safe contraception during the study period
- Other clinically significant concomitant disease states (e.g., renal failure, hepatic dysfunction, cardiovascular disease, etc.),
- Inability to consent and follow the procedures of the study e.g. due to language problems, psychological disorders, dementia, etc. of the participant,
- Participation in another study with investigational drug within the 30 days preceding and during the present study,
- 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, affect patient compliance or place the patient at high risk from treatment-related complications
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Switzerland1 site, 1 recruiting
- Recruiting
Oncology Institute of Southern Switzerland
Bellinzona, Canton Ticino, 6500
Sara De Dosso, MD, +41 91 811 93 02, sara.dedosso@eoc.ch
Luigi Tortola, PhD, +41 91 811 96 68, luigi.tortola@eoc.ch
About this study
Official title: Preoperative Treatment With Metronidazole to Evaluate the Efficacy in Reducing Fusobacterium Nucleatum Tumor Colonization in Patients With Colorectal Cancer (CRC): a Proof-of-concept Trial
The proposed proof-of concept trial aims at determining the effectiveness of metronidazole in decreasing the Fusobacterium nucleatum load in tissues and possibly on its detrimental effects on tumor cells and tumor microenvironment.
Read the detailed description
Colorectal cancer (CRC) is among the most frequent tumor types and is a leading cause of cancer-related death worldwide. Surgery represents the first therapeutic option, whereas advanced cases are usually treated by established chemotherapy protocols, yet with variable response rates.
Mechanisms underlying unresponsiveness are still largely unclear. Recently, the gut microbiota, consisting of trillions of microorganisms, which populate the gastrointestinal tract, has also been implicated in chemo-resistance.
Defined bacterial species have been reported to be associated with CRC. In particular, Fusobacterium nucleatum (F.n.), a commensal bacterium of the oral cavity, is enriched in CRC tissues and its abundance appears to be associated with reduced patient survival.
In experimental models F.n. promotes CRC cell proliferation and reduces tumor responsiveness to 5-fluorouracil (5-FU). Furthermore, it suppresses tumor infiltration by immune cells associated with improved prognosis.
Administration of metronidazole effectively reduces F.n. load and overall tumor growth in animal models.
However, its efficacy in reducing F.n. loads in human CRC has not been verified so far.
The proposed proof-of concept trial aims at determining the effectiveness of metronidazole in decreasing the F.n. load in tissues and possibly on its detrimental effects on tumor cells and tumor microenvironment.
- Conditions
- Colorectal Cancer
- Being tested
- Metronidazole Oral
- Medical subject headings
- Colorectal Neoplasms
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Metronidazole OralDrug
Metronidazole will be administered per os at 500 mg x 3/day, for 10 days prior to surgery.
| Study group | Role | What they receive |
|---|---|---|
| Metronidazole treated arm | Experimental | Administration of Metronidazole for 10 days prior to surgery in CRC patients Receives: Drug: Metronidazole Oral |
What is being measured
The primary outcome is the main question the study is designed to answer.
Impact of metronidazole on F.n. loads in CRC tissues.
F.n. load assessed by qRT-PCR analysis in excised tumor tissues upon antibiotic treatment, as compared to corresponding diagnostic biopsies prior to treatment.
Measured: 12 (+ 3) days after surgery
Secondary outcomes (4)
Potential effects of metronidazole on the expression of immune cell markers in CRC tissue samples
Expression of multiple immune cell markers will be assessed in tissue samples by immunohistochemistry and immunofluorescence. Number of positive cells/mm2 will be evaluated.
Measured: 12 (+ 3) days after surgery
Potential effects of metronidazole on the expression of autophagy markers in CRC tissue samples
Expression of multiple autophagy signaling elements will be assessed in tissue samples by immunohistochemistry and immunofluorescence. Number of positive cells/mm2 will be evaluated.
Measured: 12 (+ 3) days after surgery
Potential effects of metronidazole on microbiome
Differences in community diversity and/or abundance of specific bacterial taxa between the tumor-associated microbiome prior to or after antibiotic treatment.
Measured: 12 (+ 3) days after surgery
Potential effects of metronidazole on the intestinal metabolic profile
Measurement of changes in the biosynthesis pathways of intestinal bacteria by comparing the gut metabolic profile before and after antibiotic treatment. Fold changes in the abundance of bacterial metabolites will be evaluated.
Measured: 12 (+ 3) days after surgery
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted28 Feb 2023
- Study start11 Sep 2023
- Primary completion31 Dec 2026 (estimated)
- Study completion31 Dec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Colorectal CancerStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- Proof of concept
- Masking
- None (open label)
- Enrolment
- 40 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Oncology Institute of Southern Switzerland
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05748145
- Sponsor's protocol ID
- FusoMetro-001
- Status last verified
- Nov 2025
- First submitted
- 26 Jan 2023
- Last updated
- 18 Nov 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 18 Nov 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Preoperative Treatment With Metronidazole to Evaluate the Efficacy in Reducing Fusobacterium Nucleatum Tumor Colonization in Patients With Colorectal Cancer (CRC): a Proof-of-concept Trial
- ClinicalTrials.gov ID
- NCT05748145
- Acronym / sponsor ID
- FusoMetro-001
- Conditions
- Colorectal Cancer
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 40 participants (estimated)
- Lead sponsor
- Oncology Institute of Southern SwitzerlandUniversity, hospital or other
- Study start
- 11 Sep 2023 (actual)
- Primary completion
- 31 Dec 2026 (estimated)
- Study completion
- 31 Dec 2026 (estimated)
- First posted
- 28 Feb 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The proposed proof-of concept trial aims at determining the effectiveness of metronidazole in decreasing the Fusobacterium nucleatum load in tissues and possibly on its detrimental effects on tumor cells and tumor microenvironment.
Detailed description
Colorectal cancer (CRC) is among the most frequent tumor types and is a leading cause of cancer-related death worldwide. Surgery represents the first therapeutic option, whereas advanced cases are usually treated by established chemotherapy protocols, yet with variable response rates.
Mechanisms underlying unresponsiveness are still largely unclear. Recently, the gut microbiota, consisting of trillions of microorganisms, which populate the gastrointestinal tract, has also been implicated in chemo-resistance.
Defined bacterial species have been reported to be associated with CRC. In particular, Fusobacterium nucleatum (F.n.), a commensal bacterium of the oral cavity, is enriched in CRC tissues and its abundance appears to be associated with reduced patient survival.
In experimental models F.n. promotes CRC cell proliferation and reduces tumor responsiveness to 5-fluorouracil (5-FU). Furthermore, it suppresses tumor infiltration by immune cells associated with improved prognosis.
Administration of metronidazole effectively reduces F.n. load and overall tumor growth in animal models.
However, its efficacy in reducing F.n. loads in human CRC has not been verified so far.
The proposed proof-of concept trial aims at determining the effectiveness of metronidazole in decreasing the F.n. load in tissues and possibly on its detrimental effects on tumor cells and tumor microenvironment.
Study design
- Primary purpose
- Other
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- Proof of concept
| Arm | Type | Receives |
|---|---|---|
| Metronidazole treated arm | Experimental | Drug: Metronidazole OralAdministration of Metronidazole for 10 days prior to surgery in CRC patients |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Written informed consent according to ICH/GCP regulations before registration.
- Age ≥ 18 years old
- Untreated, primary colorectal adenocarcinoma (> 15 cm from the anal verge)
- Colonoscopy with endoscopic biopsy for disease confirmation and correlative studies.
- Candidates for surgical resection prior to administration of any therapy.
Key exclusion criteria (12 listed)
- Insufficient material on the tissue biopsy to be left in the archives of the Cantonal Institute of Pathology for further evaluations/analyses
- Known prior history of hypersensitivity to metronidazole or other nitroimidazole derivatives
- Oral or parenteral antibiotic therapy within the six weeks prior to enrolment
- Emergency surgery (planned within less than 14 days), where no opportunity to administer preoperative oral antibiotics exists
- Other malignant disease within 5 years prior to study enrollment, except basocellular or squamous skin cancer and carcinoma in situ cervices uteri
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Metronidazole OralMetronidazole will be administered per os at 500 mg x 3/day, for 10 days prior to surgery. | Drug | Metronidazole treated arm |
Primary outcome
Impact of metronidazole on F.n. loads in CRC tissues.
Time frame: 12 (+ 3) days after surgery
F.n. load assessed by qRT-PCR analysis in excised tumor tissues upon antibiotic treatment, as compared to corresponding diagnostic biopsies prior to treatment.
4 secondary outcomes
Potential effects of metronidazole on the expression of immune cell markers in CRC tissue samples
Time frame: 12 (+ 3) days after surgery
Potential effects of metronidazole on the expression of autophagy markers in CRC tissue samples
Time frame: 12 (+ 3) days after surgery
Potential effects of metronidazole on microbiome
Time frame: 12 (+ 3) days after surgery
Potential effects of metronidazole on the intestinal metabolic profile
Time frame: 12 (+ 3) days after surgery
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 18 Nov 2025.
- Individual participant dataSharing planned: Undecided
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing Metronidazole Oral in people with Colorectal Cancer, run by Oncology Institute of Southern Switzerland at 1 site in Switzerland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 12 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 18 Nov 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Sara De Dosso, MD (+41 91 811 93 02, sara.dedosso@eoc.ch), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Impact of metronidazole on F.n. loads in CRC tissues. (time frame: 12 (+ 3) days after surgery). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 18 Nov 2025.