Peripheral blood monoclonal B-cells predict the event free survival in multiple myeloma

High-dose therapy and autologous peripheral blood stem cell transplantation in patients with multiple myeloma

Since its introduction in 1983, high-dose therapy followed by autologous peripheral blood stem cell transplantation is a pillar of the treatment of patients with multiple myeloma. In the last decades, a multitude of clinical trials helped to improve strategies based on high-dose therapy and autologous stem cell transplantation resulting in a continuously prolongation of overall survival of patients. In this chapter we will review the progress, which has been made in order to enhance the mobilisation of autologous stem cells and increase the effectiveness of this treatment.

Multiple myeloma may include microvessel endothelial cells of malignant origin

Multiple myeloma (MM) comprises B and plasma cell compartments that originate from the same parent B cell and share as a cancer signature the same clonotypic IgH VDJ gene rearrangement. Here, we hypothesize that functional interactions between MM plasma cells (MM-PC) and their sister population of MM monocytoid B cells lead to the generation of microvessel endothelium of malignant origin from the monocytoid B cell progenitors. Published reports confirm that endothelial cells can harbor a molecular cancer signature characteristic of a given malignancy. We predict that MM monocytoid B cells-in response to both paracrine and autocrine pathways-contribute to tumor neovascularization in the bone marrow of MM patients. Our hypothesis further predicts that in MM, endothelial cells of malignant origin coexist with those of normal origin. We speculate that malignant development of MM incorporates functionally distinct sister lineages arising from the same MM progenitor that-by working together-ensure survival of the MM clone. We hypothesize that these two arms of the malignant MM clone are functionally interlinked to promote growth of the MM-PC compartment; by providing its own microenvironment, MM clonal evolution may ensure neovascularization to support an expanding malignancy.

Novel Analysis of Clonal Diversification in Blood B Cell and Bone Marrow Plasma Cell Clones in Immunoglobulin Light Chain Amyloidosis

Immunoglobulin light chain amyloidosis (AL) is characterized by a limited clonal expansion of plasma cells and amyloid formation. Here, we report restriction in the diversity of VL gene usage with a dominance of clonally related B cells in the peripheral blood (PB) isotype-specific repertoire of AL patients. A rigorous quantification of lineage trees reveals presence of intraclonal variations in the PB clones compared to the bone marrow (BM) clones, which suggests a common precursor that is still subject to somatic mutation. When compared to normal BM and PB B cells, AL clones showed significant but incomplete impairment of antigenic selection, which could not be detected by conventional R and S mutation analysis. Therefore, graphical analysis of B cell lineage trees and mathematical quantification of tree properties provide novel insights into the process of B cell clonal evolution in AL.

Molecular monitoring of minimal residual disease in patients with multiple myeloma

Improvement of transplantation strategies and a multitude of emerging novel therapies result in a better treatment outcome in patients with multiple myeloma (MM). This gives rise to the need for sensitive methods to detect minimal residual disease (MRD) in MM. Qualitative molecular monitoring using allele-specific oligonucleotide PCR for the immunoglobulin heavy chain (IgH) is well established to detect clonotypic cells after therapy or in stem cell harvests. Recently, real-time IgH PCR or limiting dilution based PCR assays offer the possibility to quantify the amount of residual tumour cells. In this review, different qualitative and quantitative IgH PCR techniques will be discussed as well as the current clinical role of molecular monitoring of MRD in patients with MM.

T-cell receptor excision circles: a novel prognostic parameter for the outcome of transplantation in multiple myeloma patients

This study investigated whether T-cell receptor excision circles (TRECs) are a prognostic marker for the outcome of myeloma patients undergoing a tandem autologous peripheral blood stem cell transplantation (PBSCT). Twenty-five patients were enrolled. Samples were obtained at study enrollment, after conventional therapy, between first and second transplantation and 3, 6, 12 and 24 months after the second PBSCT. TRECs were quantified using real-time polymerase chain reaction. A high variation in TREC levels was found at diagnosis (median TREC level 136/10(5) peripheral blood mononuclear cells (PBMCs); range 1-1729), suggesting individual differences in thymic output of naive T cells. Patients with more than 136 TRECs/10(5) P BMCs at diagnosis had a statistically significant better overall survival (P=0.05) and event-free survival (P=0.045), whereas low TREC levels correlated with a higher incidence of infectious complications. Median TREC values were lowest after the first PBSCT (52/10(5) PBMCs) and reached the baseline 12 months after the second transplantation. Patients with high TREC levels after the second PBSCT had a significantly higher probability of being in complete or partial remission 30 months after the second PBSCT. TREC levels were not correlated with beta2-microglobulin and C-reactive protein levels at diagnosis. These data suggest that TRECs could be a relevant prognostic factor for patients who receive high-dose chemotherapy and autologous PBSCT.