Analysis of cyclin D1 mRNA expression levels in plasma cell dyscrasias: A systematic review of published literature

Overexpression of cyclin D1 (CCND1) occurs often in tumoral plasma cells, mainly - but not exclusively - as a result of the presence of the t(11;14) translocation. Of note, CCND1 mRNA overexpression or the presence of the t(11;14) translocation was shown to impact on the response to anti-plasma cell drugs and influence prognosis, both in patients with multiple myeloma and with immunoglobulin light chain (AL) amyloidosis. In this study, we performed a systematic revision of published literature on molecular assays to measure CCND1 transcript levels in plasma cell dyscrasias, in order to describe currently available assays, their technical characteristics and main applications. Relevant scientific articles were search on PubMed as of October 2020 using combinations of appropriate key words. Of 165 unique studies retrieved, 11 articles fulfilled the inclusion criteria and were further analyzed. Overall, 8 different molecular assays were described and characterized. Most of the studies focused on multiple myeloma, with some studies including also MGUS, plasma cell leukemia and/or AL amyloidosis. Assay design, technical validation and field of application of each assay were systematically reviewed. As more knowledge is gained about the impact of CCND1 expression levels on the biology of tumoral plasma cells and their response to anti-plasma cell drugs, including novel agents specifically targeting t(11;14)-positive clones, molecular assays to quantify CCND1 expression levels in tumoral plasma cells may become a useful complementation to molecular cytogenetics, towards a precision medicine approach to diagnose and treat plasma cell disorders which is based on laboratory medicine.