Multiple myeloma

This article presents a review of multiple myeloma, precursor states, and related plasma cell disorders. The clinical roles of fluorodeoxyglucose PET/computed tomography (CT) and the potential to improve the management of patients with multiple myeloma are discussed. The clinical and research data supporting the utility of PET/CT use in evaluating myeloma and other plasma cell dyscrasias continues to grow.

Waldenström's macroglobulinemia - a review

Waldenström's macroglobulinemia (WM) is a lymphoproliferative disease of B lymphocytes, characterized by a lymphoplasmocytic lymphoma in the bone marrow and by IgM monoclonal hypergammaglobulinemia. It was first described in 1944 by Jan Gösta Waldenström, reporting two patients with oronasal bleeding, lymphadenopathy, anemia, thrombocytopenia, high erythrocyte sedimentation rate and serum viscosity, normal radiography and bone marrow infiltrated by lymphoid cells. The WM is a rare disease with a typically indolent clinical course, affecting mainly individuals aged between 63 and 68 years. Most patients have clinical signs and symptoms related to hyperviscosity resulting from IgM monoclonal gammopathy, and/or cytopenias resulting from bone marrow infiltration by lymphoma. The differential diagnosis with other lymphomas is essential for the assessment of prognosis and therapeutic approach. Treatment of patients with asymptomatic WM does not improve the quality of life of patients, or increase their survival, being recommended, therefore, their follow-up. For the treatment of symptomatic patients, alkylating agents, purine analogs and anti-CD20 monoclonal antibodies are used. However, the disease is incurable and the response to therapy is not always favorable. Recent studies have shown promising results with bortezomib, an inhibitor of proteasomes, and some patients respond to thalidomide. In patients with relapse or refractory to therapy, autologous transplantation may be indicated. The aim of this paper is to describe in detail the current knowledge on the pathophysiology of WM, main clinical manifestations, diagnosis, prognosis and treatment.

The role of 18F-FDG PET/CT imaging in Waldenstrom macroglobulinemia

Disease assessment in WM is dependent on the quantification of the IgM monoclonal protein and percent involvement of the bone marrow. There is a need for imaging studies that objectively measure tumor load in these patients. In this study, we sought to examine the role of combined FDG-PET/CT imaging in the detection of tumor load and in the assessment of response to therapy. Thirty-five patients were enrolled on a prospective study using bortezomib and rituximab therapy and were included in this study because they completed a pre- and post-treatment FDG-PET/CT imaging at one facility (12 newly diagnosed and 23 relapsed/refractory). The use of combined FDG-PET/CT imaging showed positive findings in 83% of patients with WM, unlike prior studies using conventional imaging that indicate that only 20% of patients have lymphadenopathy or hepatosplenomegaly. Moreover, 43% of patients had abnormal bone marrow uptake on FDG-PET imaging that can potentially help in the assessment of their tumor load, especially with heterogenous sampling of the bone marrow. There was no statistical correlation between EORTC response criteria for FDG-PET/CT and response by monoclonal protein. This is the first study to examine the role of FDG-PET/CT imaging in WM. Future studies should examine the role of FDG-PET/CT in conjunction with monoclonal protein response in the assessment of progression-free survival in patients with WM.

FGFR3 is overexpressed waldenstrom macroglobulinemia and its inhibition by Dovitinib induces apoptosis and overcomes stroma-induced proliferation

PURPOSE

There is no standard of therapy for the treatment of Waldenström macroglobulinemia (WM), therefore there is a need for the development of new agents. Fibroblast growth factor receptor 3 (FGFR3) was shown to play a major role in several types in cancer. Dovitinib, an inhibitor of FGFR3, was effective in hematologic malignancies. In this study, we tested FGFR3 as a therapeutic target in WM and tested the effect of dovitinib on cell proliferation and apoptosis of WM cells in the context of BM microenvironment.

METHODS

The expression of FGFR3 in WM cells was tested using immunofluorescence and flow cytometry. Cell signaling in response to stimulation with FGF3 and stromal cells, and its inhibition by dovitinib was performed using immunoblotting. Cell survival and cell proliferation were assessed by MTT and BrdU assays. Apoptosis was measured by detection of APO-2.7 and cleavage of caspase-3 using flow cytometry. Cell cycle was performed by PI staining of cells and flow cytometry. The combinatory effect of dovitinib with other drugs was analyzed using Calcusyn software. The effect of dovitinib was tested in vivo.

RESULTS

FGFR3 was overexpressed in WM cells and its activation induced cell proliferation. Inhibition of FGFR3 with dovitinib decreased cell survival, increased apoptosis, and induced cell cycle arrest. Inhibition of FGFR3 by dovitinib reduced the interaction of WM to bone marrow components, and reversed its proliferative effect. Dovitinib had an additive effect with other drugs. Moreover, dovitinib reduced WM tumor progression in vivo.

CONCLUSION

We report that FGFR3 is a novel therapeutic target in WM, and suggest dovitinib for future clinical trial the treatment of patients with WM.

Novel agents in Waldenström macroglobulinemia

Waldenström macroglobulinemia (WM) is a B-cell disorder characterized by the infiltration of the bone marrow with lymphoplasmacytic cells and the detection of an IgM monoclonal gammopathy in the serum. WM is considered an incurable disease, with a median overall survival of 87 months. The success of targeted therapy in multiple myeloma has led to the development and investigation of more than 30 new compounds in this disease and in other plasma cell dyscrasias, including WM, both in the preclinical settings and as part of clinical trials. Among therapeutic options, first-line therapies have been based on single-agent or combination regimens with alkylator agents, nucleoside analogues and the monoclonal antibody anti-CD20. Based on the understanding of the complex interaction between WM tumor cells and the bone marrow microenvironment, and the signaling pathways that are deregulated in WM pathogenesis, a number of novel therapeutic agents are now available and have demonstrated significant efficacy in WM. The range of the overall response rate for these novel agents is between 25 and 96%. Ongoing and planned future clinical trials include those using protein kinase C inhibitors such as enzastaurin, new proteasome inhibitors such as carfilzomib, histone deacetylase inhibitors such as LBH589, humanized CD20 antibodies such as ofatumumab and additional alkylating agents such as bendamustine. These agents, when compared with traditional chemotherapeutic agents, may lead in the future to higher responses, longer remissions and better quality of life for patients with WM. This article will mainly focus on those novel agents that have entered clinical trials for the treatment of WM.