Multiple myeloma patients with low proportion of circulating plasma cells had similar survival with primary plasma cell leukemia patients

Abstract

The common features shared by primary plasma cell leukemia (pPCL) and multiple myeloma (MM) with circulating plasma cells (CPCs) are peripheral blood invasion and expansion of plasma cells independent of the protective bone marrow (BM) microenvironment niche. However, few studies have addressed the relationship between pPCL and MM with CPCs. Here, we quantitated the number CPCs by conventional morphology in 767 patients with newly diagnosed MM; their clinic features were compared with those of 33 pPCL cases. When the presence of CPCs was defined as more than 2 % plasma cells per 100 nucleated cells on Wright-Giemsa stained peripheral blood smears, the incidence of MM with CPCs was 14.1 % in newly diagnosed MM. Patients with CPCs shared many clinical features with pPCL, especially clinical parameters related to tumor burden. However, no commonalities were found in immunophenotyping and cytogenetics. The prognosis of pPCL was poor, with a median progression free survival (PFS) of 12 months and an overall survival (OS) of 15 months. MM patients with CPCs had a clearly inferior PFS and OS as compared with the control cohort. Most interestingly, although the CPCs were not high enough to meet the diagnostic criteria for pPCL, the survival of MM patients with CPCs was comparable with that of pPCL, with a median PFS of 17 months and an OS of 25 months.

Prognostic impact of circulating plasma cells in patients with multiple myeloma: implications for plasma cell leukemia definition

“…16 In that case, patients with circulating plasma cells constituted 14.1% of the overall series and had a median survival of 25 months. The results of the present study are consistent with the ominous prognostic impact of peripheral blood plasmacytosis; however, the definition of a high-risk group found was different; ≥2% circulating PCs in the study by An et al .…”

“…The presence of circulating PCs, identified by cytology, 16 multiparameter flow cytometry 17,18 or slide-based immunofluorescence, 19 is also associated with a worse prognosis in myeloma patients not fulfilling the criteria of PCL. The presence of circulating PCs is also a risk factor of progression to active disease in patients with monoclonal gammopathy of undetermined significance 20 and smoldering MM.…”

A CD138‐independent strategy to detect minimal residual disease and circulating tumour cells in multiple myeloma

“…CTCs are considered an unfavourable prognostic factor and indicate an aggressive form of the disease (An, et al 2015, Paiva, et al 2013), and therefore detecting CTCs can be a powerful prognostic tool for MM (Peceliunas, et al 2012). We have previously shown that CTCs derive from a hypoxic sub-population that intravasated from the BM to the circulation and have enhanced homing (thus metastasis) to new BM niches (Azab, et al 2012a, Azab, et al 2013, Muz, et al 2015, Muz, et al 2014a, Muz, et al 2014b).…”

“…In MM, circulating tumour cells (CTCs) are considered an unfavourable prognostic factor and indicate an aggressive form of the disease (An, et al 2015, Paiva, et al 2013), and therefore detecting CTCs can be used as a powerful prognostic tool in this disorder (Peceliunas, et al 2012). In the clinical setting, CTCs in MM patients are detected using flow cytometry with CD138 (also termed SDC1) as the principle marker (An, et al 2015, Paiva, et al 2013, Peceliunas, et al 2012); however, recent studies suggest the presence of circulating clonal B-cells in MM that do not express CD138 (Thiago, et al 2014).…”

“…In the clinical setting, CTCs in MM patients are detected using flow cytometry with CD138 (also termed SDC1) as the principle marker (An, et al 2015, Paiva, et al 2013, Peceliunas, et al 2012); however, recent studies suggest the presence of circulating clonal B-cells in MM that do not express CD138 (Thiago, et al 2014). In agreement with these findings, CTCs in MM have different biological characteristics compared to MM cells in the BM, in which the expression of several adhesion molecules, including CD138 was downregulated on CTCs (Paiva, et al 2013).…”