Non-IgM Monoclonal Gammopathy of Undetermined Significance

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.