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Steiner N, Jöhrer K, Plewan S, Brunner-Véber A, Göbel G, Nachbaur D, Wolf D, Gunsilius E, Untergasser G. The FMS like Tyrosine Kinase 3 (FLT3) Is Overexpressed in a Subgroup of Multiple Myeloma Patients with Inferior Prognosis. Cancers (Basel) 2020; 12:cancers12092341. [PMID: 32825035 PMCID: PMC7565188 DOI: 10.3390/cancers12092341] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Revised: 08/05/2020] [Accepted: 08/16/2020] [Indexed: 11/16/2022] Open
Abstract
Therapy resistance remains a major challenge in the management of multiple myeloma (MM). We evaluated the expression of FLT3 tyrosine kinase receptor (FLT3, CD135) in myeloma cells as a possible clonal driver. FLT3 expression was analyzed in bone marrow biopsies of patients with monoclonal gammopathy of undetermined significance or smoldering myeloma (MGUS, SMM), newly diagnosed MM (NDMM), and relapsed/refractory MM (RRMM) by immunohistochemistry (IHC). FLT3 gene expression was analyzed by RNA sequencing (RNAseq) and real-time PCR (rt-PCR). Anti-myeloma activity of FLT3 inhibitors (midostaurin, gilteritinib) was tested in vitro on MM cell lines and primary MM cells by 3H-tymidine incorporation assays or flow cytometry. Semi-quantitative expression analysis applying a staining score (FLT3 expression IHC-score, FES, range 1-6) revealed that a high FES (>3) was associated with a significantly shorter progression-free survival (PFS) in NDMM and RRMM patients (p = 0.04). RNAseq and real-time PCR confirmed the expression of FLT3 in CD138-purified MM samples. The functional relevance of FLT3 expression was corroborated by demonstrating the in vitro anti-myeloma activity of FLT3 inhibitors on FLT3-positive MM cell lines and primary MM cells. FLT3 inhibitors might offer a new targeted therapy approach in a subgroup of MM patients displaying aberrant FLT3 signaling.
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Affiliation(s)
- Normann Steiner
- Department of Internal Medicine V (Hematology and Medical Oncology), Medical University of Innsbruck, Anichstraße 35, A-6020 Innsbruck, Austria; (S.P.); (D.N.); (D.W.); (E.G.); (G.U.)
- Correspondence: ; Tel.: +43-(0)-512-504-82926
| | - Karin Jöhrer
- Tyrolean Cancer Research Institute, Innrain 66, A-6020 Innsbruck, Austria;
| | - Selina Plewan
- Department of Internal Medicine V (Hematology and Medical Oncology), Medical University of Innsbruck, Anichstraße 35, A-6020 Innsbruck, Austria; (S.P.); (D.N.); (D.W.); (E.G.); (G.U.)
| | - Andrea Brunner-Véber
- Department of Pathology, Neuropathology and Molecular Pathology, Medical University of Innsbruck, Müllerstraße 44, A-6020 Innsbruck, Austria;
| | - Georg Göbel
- Department of Medical Statistics, Informatics and Health Economics, Medical University of Innsbruck, Schöpfstraße 41/1, A-6020 Innsbruck, Austria;
| | - David Nachbaur
- Department of Internal Medicine V (Hematology and Medical Oncology), Medical University of Innsbruck, Anichstraße 35, A-6020 Innsbruck, Austria; (S.P.); (D.N.); (D.W.); (E.G.); (G.U.)
| | - Dominik Wolf
- Department of Internal Medicine V (Hematology and Medical Oncology), Medical University of Innsbruck, Anichstraße 35, A-6020 Innsbruck, Austria; (S.P.); (D.N.); (D.W.); (E.G.); (G.U.)
| | - Eberhard Gunsilius
- Department of Internal Medicine V (Hematology and Medical Oncology), Medical University of Innsbruck, Anichstraße 35, A-6020 Innsbruck, Austria; (S.P.); (D.N.); (D.W.); (E.G.); (G.U.)
| | - Gerold Untergasser
- Department of Internal Medicine V (Hematology and Medical Oncology), Medical University of Innsbruck, Anichstraße 35, A-6020 Innsbruck, Austria; (S.P.); (D.N.); (D.W.); (E.G.); (G.U.)
- Tyrolean Cancer Research Institute, Innrain 66, A-6020 Innsbruck, Austria;
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