[New treatment and diagnostic test for multiple myeloma]

Multiple myeloma (MM) is a malignancy of plasma cells of the final maturation stage of B cells, characterized by atypical plasma cell proliferation in bone marrow and the production of monoclonal immunoglobulin. The history of chemotherapy for MM began in the early 1960s, when the efficacy of alkylating agents, particularly melphalan, was shown. High-dose therapy (HDT) has been the standard treatment for patients younger than 65 years since the superiority in terms of OS as well as PFS of HDT supported by autologous stem cell transplantation (ASCT) was reported. From the 2000s, the emergence of novel agents involving proteasome inhibitors such as bortezomib, and IMiDs such as thalidomide and lenalidomide, has been markedly changing MM treatment and improving the prognosis. As initial treatment, novel agents are frequently used since high response rates have been reported. For MM patients who are not candidates for HDT ASCT because of aging and/or organ dysfunction, combined therapies that consist of conventional chemotherapy and novel agents are usually recommended. The chromosomal aberrations frequently found in MM are 'hyperdiploid' or 'non-hyperdiploid' and immunoglobulin gene (Ig) translocation of chromosomes. It is known that the chromosomal aberration is associated with the treatment response and prognosis of MM patients, and this information is indispensable. Because chromosomal translocation is not readily detected by G banding, the FISH method is essential. In recent years, molecular mechanisms of MM have been revealed by microarrays (Gene Expression Profiles) and whole genome sequencing using next-generation sequencers. Furthermore, in-depth sequencing by such next-generation sequencers has revealed that MM is monoclonal, but shows intra-clonal heterogeneity at the onset of the disease from the viewpoint of genetic abnormality.