Recruiting
Phase 2

Rifaximin

Sponsor:

Fred Hutchinson Cancer Center

Code:

NCT07209371

Conditions

IgA Monoclonal Gammopathy of Undetermined Significance

Non-IgM Monoclonal Gammopathy of Undetermined Significance

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Not accepted

Interventions

Rifaximin

Biospecimen Collection

Study Details

Brief summary:

This phase II trial compares the effect of rifaximin to no intervention for the treatment of IgG/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 IgG/IgA MGUS.

Conditions

IgA Monoclonal Gammopathy of Undetermined Significance

Non-IgM Monoclonal Gammopathy of Undetermined Significance

Study ID

NCT07209371

Start date

Jan 22, 2026

Status verified date

Aug, 2026

Completion date

May 1, 2028

Anticipated

Primary completion date

May 1, 2028

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Not accepted

Inclusion Criteria:

  • 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 IgG/IgA (non-IgM) monoclonal gammopathy of undetermined significance (MGUS) based on International Myeloma Working Group (IMWG)-2014 criteria (Rajkumar et al, Lancet Oncology, 2014). It is recognized that not all patients with clinical diagnosis of MGUS undergo bone marrow biopsy. Bone marrow biopsy confirmation will not be required if not clinically indicated per treating provider
  • 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

Exclusion Criteria:

  • Participants who are receiving other investigational agents
  • Pregnant women
  • Known hypersensitivity to rifaximin
  • Another concurrent malignancy requiring active therapy

Study Design

Enrollment

50 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: Arm A (Rifaximin)

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.

other: Arm B (No intervention)

Patients undergo blood sample collection throughout the study.

Interventions

Rifaximin

Given PO

Biospecimen Collection

Undergo blood sample collection

Primary outcome measure

  • Overall response rate [ Time Frame: From the start of therapy, up to 90 days ]

Central Contacts and Locations

Central contacts

Madhav Dhodapkar, MBBS

206-606-4888mdhodapk@fredhutch.org

Locations

Fred Hutch/University of Washington Cancer Consortium

Recruiting

Seattle, Washington, United States, 98109

Contacts

Madhav Dhodapkar, MBBS

206-606-4888mdhodapk@fredhutch.org

Principal Investigator:

Madhav Dhodapkar, MBBS

More Information

Sponsor

Fred Hutchinson Cancer Center

Last update posted

Aug 17, 2026

Last verified

Aug, 2026

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by Fred Hutchinson Cancer Center on 2026-08-17.