New concepts in multiple myeloma by returning to cytogenetics

Abstract

Multiple myeloma (MM) is characterized by genomic instability, which causes multiple genetic and chromosomal alterations and leads to disease progression and therapeutic resistance. Overlapping mechanisms, including defective genome repair machinery such as the loss of TP53 activity, as well as chromosomal segregation error represented by the abnormality of mitotic checkpoint kinases such as BUB1, cell cycle dysregulation, and tumor environment, cause structural and numerical chromosomal abnormalities. Cytogenetic abnormalities are important prognostic factors, and they are also linked to the use of proteasome inhibitors, immunomodulatory drugs, monoclonal antibodies, and the BCL2 inhibitor venetoclax. We developed new diagnostic modalities for chromosomal analysis to improve the sensitivity and convenience of chromosomal diagnosis. The immunophenotyped-suspension-multiplex (ISM)-fluorescence in situ hybridization (FISH) can use imaging flow to examine three IGH-related chromosomal translocations at the same time. We also created a new FISH method called amplified FISH (amFISH) to detect microdeletion involving narrow chromosomal regions (approximately<100 kb), such as the microdeletions of 1p32 (CDKN2C) or of 14q32 (TRAF3), by using a fluorescent antibody to amplify the signals of small probes. Even in the era of clinical sequencing, these convenient modalities may hasten the cytogenetics-oriented therapeutic approach for MM.