pazopanib and Multiple-Myeloma

Topics: Adult; Aged; Drug Resistance, Neoplasm; Female; Humans; Indazoles; Male; Maximum Tolerated Dose; Middle Aged; Multiple Myeloma; Neoplasm Recurrence, Local; Prognosis; Pyrimidines; Safety; Salvage Therapy; Sulfonamides; Treatment Outcome; Vascular Endothelial Growth Factor A

Topics: Activin Receptors, Type II; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; beta-Thalassemia; Graft vs Host Disease; Hematologic Diseases; Humans; Immunoglobulin Fc Fragments; Indazoles; Interleukin-1 Receptor-Associated Kinases; Internet; Leukemia, Lymphocytic, Chronic, B-Cell; Leukemia, Myeloid, Acute; Lymphoma, B-Cell; Multiple Myeloma; Protein Kinase Inhibitors; Pyrimidines; Recombinant Fusion Proteins; Sulfonamides; Telangiectasia, Hereditary Hemorrhagic

A critical role for vascular endothelial factor (VEGF) has been demonstrated in multiple myeloma (MM) pathogenesis. Here, we characterized the effect of the small-molecule VEGF receptor inhibitor pazopanib on MM cells in the bone marrow milieu. Pazopanib inhibits VEGF-triggered signaling pathways in both tumor and endothelial cells, thereby blocking in vitro MM cell growth, survival, and migration, and inhibits VEGF-induced up-regulation of adhesion molecules on both endothelial and tumor cells, thereby abrogating endothelial cell-MM cell binding and associated cell proliferation. We show that pazopanib is the first-in-class VEGF receptor inhibitor to inhibit in vivo tumor cell growth associated with increased MM cell apoptosis, decreased angiogenesis, and prolonged survival in a mouse xenograft model of human MM. Low-dose pazopanib demonstrates synergistic cytotoxicity with conventional (melphalan) and novel (bortezomib and immunomodulatory drugs) therapies. Finally, gene expression and signaling network analysis show transcriptional changes of several cancer-related genes, in particular c-Myc. Using siRNA, we confirm the role of c-Myc in VEGF production and secretion, as well as angiogenesis. These preclinical studies provide the rationale for clinical evaluation of pazopanib, alone and in combination with conventional and novel therapies, to increase efficacy, overcome drug resistance, reduce toxicity, and improve patient outcome in MM.

Topics: Animals; Apoptosis; Blotting, Western; Cell Line, Tumor; Cell Movement; Endothelial Cells; Enzyme-Linked Immunosorbent Assay; Gene Expression Regulation, Neoplastic; Humans; Immunohistochemistry; Immunoprecipitation; Indazoles; Mice; Microarray Analysis; Multiple Myeloma; Neovascularization, Pathologic; Proto-Oncogene Proteins c-myc; Pyrimidines; Receptors, Vascular Endothelial Growth Factor; Reverse Transcriptase Polymerase Chain Reaction; RNA, Small Interfering; Signal Transduction; Sulfonamides