The Prognostic Value of Immunophenotypic Characteristics of Plasma Cells in Newly Diagnosed Multiple Myeloma Patients Treated with First-Generation Proteasome Inhibitor Bortezomib

Abstract

Aim. To assess the number of plasma cells (PC) in the bone marrow and their immunophenotype using flow cytometry (FC) and light microscopy. To analyze clinical and prognostic value of the data obtained in newly diagnosed multiple myeloma (MM) patients treated with first-generation proteasome inhibitor bortezomib. Materials & Methods. The study enrolled 153 newly diagnosed MM patients treated and followed-up at the IP Pavlov First Saint Petersburg State Medical University in the period from 2007 to 2017. The median age of patients was 69 years. In 115 patients, the regimens based on first-generation proteasome inhibitor bortezomib were used as induction therapy. To determine the immunophenotypic profile of PC, the CD19, CD20, CD27, CD38, CD45, CD56, CD138, and CD117 monoclonal antibodies were used. PC immunophenotyping in the bone marrow was performed by FC using Cytomics FC500 (Beckman Coulter, USA). Results. Patients with different phenotypes did not show any considerable differences in monocloncal production of certain classes and types of immunoglobulin heavy and/ or light chains. In case of immunophenotypic profile of CD20+CD27- myeloma cells, the secretion of the monoclonal к-chain predominated over that of Л-chain. By and large, the secretion of light chains was observed more often in ММ CD20+ and more seldom in ММ CD56+. In case of CD56 expression, IgM secretion was more often reported; IgAK secretion was more common in case of CD117 expression. Worst survival scores were shown by patients with PC immunophenotype CD27-CD56-. At the primary MM diagnosis, the advanced stages of the disease, according to the ISS, were more commonly characterized by phenotype CD45-CD27-CD56+. Conclusion. The flow cytometry characteristics of PC immunophenotype can be applied to evaluate the prognosis of MM and to optimize the therapy.