Identification of Phenotype Profile Related to the Extramedullary Involvement in Multiple Myeloma Relapse

Abstract

Background: Multiple myeloma (MM) is characterised by proliferation of malignant plasma cells (PCs) usually in bone marrow (BM). The mechanisms of extramedullary (EM) spread in MM are poorly understood. It probably involves possible changes in expression of adhesive molecules. An increase incidence of aggressive and mostly resistant EM relapses was reported in the era of new treatment approaches. Finding a marker allowing predict a risk of EM relapse could help to improve treatment strategies and prolong patient life. Aim: Phenotype profile of PCs in BM and tumor tissue (TU) samples of EM relapses and comparison with "intramedullary" (IM) relapses of MM. Material and methods: There were analysed 40 patients with confirmed EM relaps and 17 patients with IM relaps (without EM spread). Analysis of 57 BM and 34 TU was done by polychromatic flow cytometry (FC). Phenotype of CD38+CD138+ PC was analysed using CD19, CD27, CD28, CD44, CD56, CD81, CD117 and nestin. PCs were considered positive for given marker when its expression on PCs was higher than 25 %. Results: There were detected CD38+CD138+ PCs in 95.0 % (38/40) of EM-BM samples (due to sample dilution), in 100 % IM-BM samples and in 88.2 % (30/34) of analysed TU samples (probably acquired not from tumor site). PC infiltration was statistically significantly higher in TU then in EM-BM [median of infiltration 51.7 % (range 0.0-98.9) vs. 1.5 % (0.01-68.9); p<0.001]; IM-BM has higher PC infiltration then EM-BM [5.7 % (0.7-66.1) vs. 1.5 % (0.0-68.9); p<0.05]. Although TU PCs have relatively similar phenotype like EM-BM PCs, there was found significant increase in median of expression of CD81 on abnormal PCs (A-PCs) [2.6 % (0.0-96.9) in EM-BM vs. 11.2 % (0.0-99.2) in TU; p<0.02] and also in number of CD81+ cases (positivity) [20 % (4/20) of EM-BM vs. 41.2 % (7/17) of TU]. Moreover, no presence of CD19+ normal PCs was found in TU even if mixture of CD19+ normal and CD19- A-PCs was detected in EM-BM. TU PCs we almost negative for C27 and CD117 (median of expression 2.6 and 0.1 %; positivity 17.9 and 14.3 %; respectively); slightly positive for CD28 (median of expression 2.6 %; positivity 33.3 %) and usually positive for CD56 and nestin (median of expression 97.8 and 45.7 %; positivity 69.0 and 57.9 %; respectively). There was found significant increase of CD44 and nestin expression in EM-BM when compared to IM-BM [median of expression 91.8 (3.4-99.9) vs. 25.6 (1.4-99.8) %; p<0.04 and 52.7 (0-100) vs. 0.2 (0-99.4) %; p<0.01; respectively], other markers were expressed similarly. Conclusion: Almost all EM PCs (BM and/or TU) usually express nestin, a marker of stem/progenitor cells, and CD44, a glycoprotein involved in cell-cell interactions, cell adhesion and migration. Adhesion molecule CD56, which loss is considered as a marker of extramedullary spread, was not changed in different MM cases (EM vs. IM). Flow cytometry analysis of EM PCs allowed to identify a phenotype profile of A-PCs (CD19-CD27-CD56+CD81+CD117-CD44+nestin+) related to possible extramedullary involvement in MM. Disclosures Hájek: TAKEDA: Consultancy, Honoraria, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria; Novartis: Research Funding.

Multiple Extramedullary-Bone Related and/or Extramedullary Extraosseous Are Independent Poor Prognostic Factors in Patients With Newly Diagnosed Multiple Myeloma

“…The current data did not find that the incidence of 17p deletion, 1q amplification, and chromosome 14 translocation increased in EMM. Furthermore, EMM has different characteristics from MM at the molecular level, which is mainly involved in the downregulation of cell adhesion and chemokines, while the upregulation of cell migration, proliferation, and immune escape ( 2 , 23 , 24 ). In addition, the gene expression profiles showed that EMM had high-risk characteristics, such as the proportion of MF subtype and PR subtype, which were significantly higher than those of patients without EM ( 12 , 25 , 26 ).…”

Necessity of flow cytometry assessment of circulating plasma cells and its connection with clinical characteristics of primary and secondary plasma cell leukaemia

“…High nestin levels in MM patients were strongly associated with the presence of 1q21 gain and seemed to be a predictor of worse response to therapy; its higher expression was observed in disease progression 49,50 . Increased nestin expression was also found in MM with extramedullary involvement 37 . Nestin was described only on a limited number of PCLs with a low level of expression in pPCL 50 .…”

“…20 As our group published previously, expression of CD56 was also not changed in different MM cases (extramedullary vs. intramedullary relapses), so its loss probably should not be considered as a marker of extramedullary spread. 37 A larger decrease in expression of CD56 in PB than in BM is not easily explained. Rawstron et al revealed the same composite phenotype in paired samples of PB and BM in MM, with significantly lower expression of CD56 and CD138 in PB.…”

“… 46 On the other hand, overexpression of CD44 has been reported to be a putative biomarker of sensitivity to lenalidomide. 47 Further, extramedullary disease in MM expresses more CD44 than MM without extramedullary involvement; 37 thus, CD44 should be related to possible extramedullary involvement in MGs.…”

“… 49 , 50 Increased nestin expression was also found in MM with extramedullary involvement. 37 Nestin was described only on a limited number of PCLs with a low level of expression in pPCL. 50 Here we have presented the largest group of patients with PCL, to date, in which nestin has been analysed.…”