Pre-surgery metronidazole and chlorhexidine to lower bacteria in oral cavity tumors

A Phase II Single-arm Cohort Study Establishing the Effect of Antibiotic Treatment on Intratumoral Bacteria in Surgical Patients With Oral Cancer

Phase 2 Interventional Case Comprehensive Cancer Center · NCT06627270

This study will try a short course of the antibiotic metronidazole plus chlorhexidine mouthwash before surgery to see if it lowers bacteria inside tumors in adults with oral squamous cell carcinoma.

Quick facts

PhasePhase 2
Study typeInterventional
Enrollment30 (estimated)
Ages18 Years and up
SexAll
SponsorCase Comprehensive Cancer Center Academic / other
Drugs / interventionsradiation
Locations1 site (Cleveland, Ohio)
Trial IDNCT06627270 on ClinicalTrials.gov

What this trial studies

Patients with oral cavity squamous cell carcinoma will receive a preoperative regimen of oral metronidazole and chlorhexidine rinses in a single-arm phase II protocol. The study team will measure the absolute amount of bacteria inside the tumor at the time of surgery and analyze changes in the intratumoral bacterial community. Investigators will also profile infiltrating immune cells to see whether microbial modulation is associated with changes in the tumor immune microenvironment. All interventions are given prior to planned curative-intent surgery and tissue sampling occurs at resection.

Who should consider this trial

Good fit: Adults with pathologically confirmed oral cavity squamous cell carcinoma who are scheduled for curative-intent surgery and can take oral metronidazole and use chlorhexidine rinses are ideal candidates.

Not a fit: Patients with allergies to metronidazole or chlorhexidine, severe liver or kidney disease, recent antibiotic use, recurrent or unresectable disease, inability to tolerate oral treatment, active alcohol use during the antibiotic period, or pregnancy are unlikely to be eligible or to benefit from this approach.

Why it matters

Potential benefit: If successful, reducing intratumoral bacteria could lower tumor-associated inflammation and immunosuppression, which might improve responses to surgery and future therapies.

How similar studies have performed: Preclinical and observational studies link the oral microbiome to tumor immunity, but clinical testing of combined antibiotic plus chlorhexidine regimens to reduce intratumoral bacteria is relatively novel with limited prior trial data.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Pathologically confirmed squamous cell carcinoma of the oral cavity
* Must have planned surgery for curative intent
* Participants ≥ 18 years of age
* Participants must have the ability to understand and the willingness to sign a written informed consent document

Exclusion Criteria:

* Known allergy to metronidazole and/or chlorhexidine
* Severe liver or kidney disease as determined by history of laboratory tests
* Participants actively drinking alcohol (unable to abstain for the 10 day antibiotic period)
* Recurrent oral cancer after prior radiation or chemoradiation
* Participants with unresectable oral cancer
* Participants unable to tolerate oral rinse or unable to have metronidazole administered by mouth or by feeding tube
* Participants currently or have taken other antibiotics within the prior 30 days
* Participant is pregnant

Where this trial is running

Cleveland, Ohio

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Oral Squamous Cell CarcinomaOral CancerHead and Neck CancerHead and Neck CarcinomaMetronidazoleChlorhexidine
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.