Differential Diagnosis of Waldenström's Macroglobulinemia and Early Management: Perspectives from Clinical Practice

Tumor-Associated Macrophage (TAM)-Related Cytokines, sCD163, CCL2, and CCL4, as Novel Biomarkers for Overall Survival and Time to Treatment in Waldenstrom's Macroglobulinemia: Emphasis on Asymptomatic WM

Waldenstrom's Macroglobulinemia (WM) is a heterogeneous disease, and the majority of patients tend to have a long course. Nevertheless, it is imperative to detect patients who have a high risk of progression and who benefit from closer follow-up. Many recent studies have displayed the CD163-positive tumor-associated macrophages (TAMs) contribution in the pathogenesis of various hematological neoplasms and solid tumors. Soluble CD163 (sCD163) can be measured in serum, along with other TAM-chemoattractant cytokines, such as CCL2 and CCL4, and their levels are used to determine macrophage activation. In the current study, we investigated the correlation between sCD163, CCL2, and CCL4, with parameters of WM progression and survival. Out of a total of 204 WM patients, serum sCD163, CCL2, and CCL4 were measured in 75, 64, and 65 patients' frozen sera at diagnosis, along with 30 healthy individuals (HIs) using an enzyme-linked immunosorbent assay (ELISA). We achieved to demonstrate that shorter Time to Treatment (TTT) was observed in 2 years and 7 years intervals in all patients with a ratio of CD163/CCL4 above median (p = 0.003 and p = 0.024, respectively) and decreased TTT was observed in all asymptomatic WM (AWM) patients with values of CCL4 above the median (p = 0.018). Moreover, significantly decreased overall survival (OS) (p = 0.033) was observed in all WM patients with CCL2 values above the median. Our results indicate that sCD163, CCL2, and CCL4 could be utilized as prognostic markers in WM.

Immunophenotypic assessment of clonal plasma cells and B-cells in bone marrow and blood in the diagnostic classification of early stage monoclonal gammopathies: an iSTOPMM study

Monoclonal gammopathy of undetermined significance (MGUS) is the earliest discernible stage of multiple myeloma (MM) and Waldenström's macroglobulinemia (WM). Early diagnosis of MG may be compromised by the low-level infiltration, undetectable to low-sensitive methodologies. Here, we investigated the prevalence and immunophenotypic profile of clonal (c) plasma cells (PC) and/or cB-lymphocytes in bone marrow (BM) and blood of subjects with a serum M-component from the iSTOPMM program, using high-sensitive next-generation flow cytometry (NGF), and its utility in the diagnostic classification of early-stage MG. We studied 164 paired BM and blood samples from 82 subjects, focusing the analysis on: 55 MGUS, 12 smoldering MM (SMM) and 8 smoldering WM (SWM). cPC were detected in 84% of the BM samples and cB-lymphocytes in 45%, coexisting in 39% of cases. In 29% of patients, the phenotypic features of cPC and/or cB-lymphocytes allowed a more accurate disease classification, including: 19/55 (35%) MGUS, 1/12 (8%) SMM and 2/8 (25%) SWM. Blood samples were informative in 49% of the BM-positive cases. We demonstrated the utility of NGF for a more accurate diagnostic classification of early-stage MG.

A Canadian Perspective on the Treatment of Waldenström Macroglobulinemia

Waldenström macroglobulinemia (WM) is a slowly progressing B-cell non-Hodgkin lymphoma characterized by monoclonal IgM gammopathy in the blood and infiltration of the bone marrow by clonal lymphoplasmacytic cells. As an incurable disease, the goals for therapy for WM are to relieve symptoms, slow disease progression, prevent organ damage, and maintain quality of life. However, given the rarity of WM, clinical trials comparing treatments for WM are limited and there is no definitive standard of care. The selection of first-line WM therapy is thus based on patient factors, disease characteristics, and drug access, with bendamustine-rituximab and Bruton's tyrosine kinase (BTK) inhibitor therapy considered preferred treatments. Other treatments such as proteasome inhibitor- or purine analogue-based therapy, alternative chemoimmunotherapy, and autologous stem cell transplantation are generally reserved for the relapsed setting but may be used in rare circumstances in earlier lines of therapy. This paper summarizes the efficacy and safety of these WM therapies and discusses considerations for treatment from a Canadian perspective.