[Novel therapies for higher-risk myelodysplastic syndromes]

Recent advances in drug treatment for higher-risk myelodysplastic syndromes (MDS) have focused on DNA hypomethylating agents (HMAs). Azacitidine (AZA), a representative HMA available in Japan, has demonstrated a survival benefit over conventional treatment. However, unsatisfactory treatment profiles of AZA exemplified by a low response rate of <20% complete remission (CR), a short duration of response (usually <1 year), and dismal outcomes after the failure to fulfil unmet needs in AZA treatments have highlighted the urgent need for the development of novel therapeutic modalities. In this manuscript, an array of novel agents under clinical investigation for higher-risk MDS is introduced. The drugs in the most advanced phase of development include SGI-110, a next-generation DNA hypomethylating agent that is designed to prolong cellular exposure time, and the multi-kinase inhibitor rigosertib, which is specifically active against patients with higher-risk MDS who fail to respond to conventional HMAs. Other lines of agents under investigation include a combination of histone deacetylase inhibitors and hypomethylating agents, immune checkpoint inhibitors, spliceosome inhibitors, BCL2 inhibitors, and IDH1/2 inhibitors, all of which have been developed by exploiting the recent understanding of the molecular pathogenesis of MDS, including the tumorigenic role of common mutations and disturbance of tumor immunity.