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.