In preclinical models, RRx-001 decreased the levels of DNA methyltransferases (DNMTs) in colon cancer and multiple myeloma cells.26,27 Furthermore, a study on murine squamous cell carcinoma of the head and neck (SCC VII) model showed decreased global 5-methylcytosine levels, decreased protein expression of DNMT1 and DNMT3, and increased acetylation of histones H3 and H4 after treatment with RRx-001, suggesting its role as an inhibitor of both DNMT and histone deacetylase (HDAC).28 This evidence concerns the gene HDAC9 and plasma cell myeloma.