This clinical trial tests if oral vancomycin can safely treat active ulcerative colitis (UC) in adults who also have primary sclerosing cholangitis (PSC), a liver condition. The main questions it aims to answer are:

• Can oral vancomycin improve UC symptoms as measured by Mayo score at 4 weeks?
• Is oral vancomycin safe and tolerable in this patient group?

Participants will be compared to see if vancomycin works better than placebo. Participants will:

• Take oral vancomycin (250 mg twice daily) or identical placebo capsules for 4 weeks
• Have the option for 4 more weeks of open-label vancomycin after the blinded phase
• Attend clinic visits at baseline, week 4, and follow-up for Mayo scoring, endoscopy, blood/stool tests, and safety checks
• Track treatment adherence and side effects

The study primarily assesses if the trial can recruit 14 participants, retain them, achieve good adherence, and follow protocol procedures (feasibility). Secondary goals include safety (adverse events) and early signs of benefit in UC activity, liver tests, and gut bacteria balance. This pilot will guide larger future studies.

This is an investigator-initiated feasibility study designed to rigorously characterize clinical response signals, safety parameters, and feasibility metrics in adults with co-existing PSC and UC, a population where microbiome-targeted immune modulation is hypothesized to influence disease activity.

Randomization & Allocation Governance

• Randomization will be implemented using validated computer-generated randomization software, with the allocation sequence generated by a study statistician not involved in clinical assessments.
• Allocation concealment will be maintained through centralized pharmacy control. An independent pharmacist will assign treatment codes and release sequentially numbered study medication containers.
• Blinding integrity will be preserved through visual and packaging equivalence, sequential drug accountability logs, and restricted access to treatment codes until database lock.
• Emergency unblinding is permitted only when required for clinical management, and all unblinding events will be documented, timestamped, and reviewed by the DSMC.

Clinical Visit & Assessment Schedule

Participants will complete a structured study visit pathway:

• Screening (≤14 days before baseline): medical history review, infection risk screening, liver disease stability assessment, and confirmation of clinical trial eligibility documentation.
• Baseline (Week 0): clinical evaluation, safety labs, medication reconciliation, and flexible sigmoidoscopy performed by credentialed endoscopists using a standardized endoscopic scoring handbook.
• Week 2 & 4: in-clinic evaluation, adverse event review, safety labs, and compliance verification via pill count and participant diary reconciliation.
• Week 8 (extension follow-up): final safety labs, medication reconciliation, delayed adverse event capture, and optional qualitative feasibility interview.

Adherence & Safety Surveillance

• Participants will complete weekly digital symptom and adherence diaries capturing stool frequency, rectal bleeding trends, abdominal pain patterns, and missed doses.
• Safety labs include CBC, creatinine, liver panel, CRP, albumin, electrolytes, and will be evaluated at baseline, week 2, 4, and 8.
• A hepatologist co-investigator will review liver safety signals in real-time, given PSC-specific vulnerability to hepatic decompensation.
• Audiology risk is screened at entry, and any symptoms concerning for ototoxicity will prompt same-week clinical review.

Data Capture & Monitoring Integrity

• All data will be captured in a secure Excel file
• Endoscopic images will be stored in a secured institutional imaging server.
• A pre-registered statistical analysis plan will be finalized before unblinding, with analysis scripts locked prior to treatment code release.

Safety Governance Structure

The DSMC will provide independent oversight and safety adjudication:

• Quarterly DSMC meetings will evaluate cumulative safety logs, recruitment feasibility, protocol deviations, and unblinding reports.
• A real-time SAE notification system ensures DSMC alert within 24 hours of serious adverse event reporting.
• Pre-defined individual, arm-level, and whole-trial safety review thresholds are codified in the DSMC governance charter to support early pause or protocol modification when required.

Regulatory & Ethical Compliance

The trial will follow all institutional and international regulatory standards:

• ICH-GCP
• Institutional Research Ethics Board approval
• DSMC governance charter
• GMP-aligned pharmacy accountability procedures

Inclusion Criteria

• Adults aged ≥18 years.
• Confirmed diagnosis of UC and PSC.
• Moderate to severe UC disease activity (total Mayo score ≥5; endoscopic subscore ≥2).
• Informed consent provided. Exclusion Criteria
• Diagnosis of Crohn's disease or indeterminate colitis.
• Fulminant colitis or need for immediate surgical intervention.
• Use of antibiotics or probiotics within the past 4 weeks (for microbiome substudy).
• Decompensated liver disease (Child-Pugh B/C).
• Severe Renal Impairment (CrCl <30mL/min)
• Active untreated infection.
• Pregnancy or lactation.
• Prior allergy or intolerance to Vancomycin
• History of hearing loss or current hearing problems

Data sharing policies would follow institutional and regulatory standards on data confidentiality and sharing.

De-identified data shared upon request to qualified researchers with appropriate data use agreements, respecting participant confidentiality and ethical approvals.

Patient demographics, primary data and data analysis can be shared.

Start Date is estimated in January 2026 - end date is estimated in December 2026.

Access to IPD and supporting study documents will generally limited to qualified researchers who submit a reasonable scientific request and have the necessary expertise.

The data shared would be de-identified or anonymized to protect participant confidentiality.

Researchers might be granted access under data use agreements that specify the terms of use, including restrictions on re-identification and further sharing.

Access is often facilitated through secure data repositories or by request through the trial sponsor or coordinating research unit after review and approval of the request.