Rifaximin Versus No Intervention for the Treatment of IgA Monoclonal Gammopathy of Undetermined Significance

NCT07209371 | Recruiting Phase 2 DMC FDA Drug

• 3 other identifiers: RG1125814NCI-2025-06773FHIRB0020984
• Study Type: interventional
• Target: 50
• Locations: 1 country
• Sites: 1

Brief Summary

This phase II trial compares the effect of rifaximin to no intervention for the treatment of IgA monoclonal gammopathy of undetermined significance (MGUS). Rifaximin is a type of antibiotic that is only used in cancer chemotherapy (antineoplastic antibiotic). It works by damaging the cell's DNA and may kill cancer cells or precancerous cells like those found with MGUS. Giving rifaximin may kill more precancerous cells in patients with IgA MGUS.

Conditions

IgA Monoclonal Gammopathy of Undetermined Significance

Outcome Measures

Primary Outcomes (1)

• Overall response rate

  Defined as the proportion of patients with \> 25% decline in clonal Ig at any point within 90 days after the initiation of drug or no intervention. Logistic regression will be conducted to evaluate the association between endpoint of interest and treatment (Arm A versus \[vs\] B).

  From the start of therapy, up to 90 days

Secondary Outcomes (1)

• Proportion of patients experiencing > grade 2 adverse events

  From the start of therapy, up to 90 days

Study Arms (2)

Arm A (Rifaximin)

EXPERIMENTAL

Patients receive rifaximin orally (PO) three times daily (TID) for 14 days in the absence of disease progression or unacceptable toxicity. Patients undergo blood sample collection throughout the study.

Drug: Rifaximin; Procedure: Biospecimen Collection

Arm B (No intervention)

OTHER

Patients undergo blood sample collection throughout the study.

Procedure: Biospecimen Collection

Interventions

Rifaximin DRUG

Given PO

Also known as: Xifaxan

Arm A (Rifaximin)

Biospecimen Collection PROCEDURE

Undergo blood sample collection

Also known as: Biological Sample Collection, Biospecimen Collected, Specimen Collection

Arm A (Rifaximin); Arm B (No intervention)

Eligibility Criteria

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

You may qualify if:

• Age ≥ 18 years
• Ability to understand and willingness to sign a written informed consent document. Legally authorized representatives may sign and give informed consent on behalf of potential study participants
• Clinical diagnosis of IgA monoclonal gammopathy of undetermined significance (MGUS) based on International Myeloma Working Group (IMWG)-2014 criteria (Rajkumar et al, Lancet Oncology, 2014)
• Agree to use adequate contraception
• For women of child-bearing potential: prior to study entry and for the duration of study participation
• For men: prior to study entry, for the duration of study participation, and one month after completion of rifaximin administration (for men)
• No antibiotic use in the preceding 2 weeks

You may not qualify if:

• Participants who are receiving other investigational agents
• Pregnant women
• Known hypersensitivity to rifaximin

Sponsors & Collaborators

• Rising Tide Foundation: collaborator
• Fred Hutchinson Cancer Center: lead

Study Sites (1)

Fred Hutch/University of Washington Cancer Consortium

Seattle, Washington, 98109, United States

RECRUITING

MeSH Terms

Interventions

Rifaximin; Specimen Handling

Intervention Hierarchy (Ancestors)

Rifamycins; Heterocyclic Compounds, 4 or More Rings; Heterocyclic Compounds, Fused-Ring; Heterocyclic Compounds; Lactams, Macrocyclic; Macrocyclic Compounds; Polycyclic Compounds; Clinical Laboratory Techniques; Diagnostic Techniques and Procedures; Diagnosis; Investigative Techniques

Study Officials

• Madhav Dhodapkar, MBBS

  Fred Hutch/University of Washington Cancer Consortium

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Madhav Dhodapkar, MBBS

CONTACT

206-606-4888; mdhodapk@fredhutch.org

Study Design

• Study Type: interventional
• Phase: phase 2
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: October 1, 2025
• First Posted: October 7, 2025
• Study Start: January 22, 2026
• Primary Completion (Estimated): May 1, 2028
• Study Completion (Estimated): May 1, 2028
• Last Updated: April 20, 2026

Record last verified: 2026-04

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)