Author:

Keywords:

Science & Technology, Life Sciences & Biomedicine, Hematology, Medicine, Research & Experimental, Research & Experimental Medicine, IDIOPATHIC HYPEREOSINOPHILIC SYNDROME, TYROSINE KINASE INHIBITOR, EOL-1 CELL-LINE, LEUKEMIA/HYPEREOSINOPHILIC SYNDROME, IMATINIB MESYLATE, IN-VITRO, LEUKEMIA, FUSION, CLASSIFICATION, RESISTANCE, Amino Acid Substitution, Annexin A5, Apoptosis, Cell Line, Tumor, Cell Movement, Cell Proliferation, Drug Screening Assays, Antitumor, Eosinophils, Female, Gene Expression Regulation, Leukemic, Humans, Hypereosinophilic Syndrome, Imidazoles, Male, Mutation, Missense, Oncogene Proteins, Fusion, Proto-Oncogene Proteins c-akt, Pyridazines, Receptor, Platelet-Derived Growth Factor alpha, Ribosomal Protein S6 Kinases, STAT5 Transcription Factor, Tetraspanin 30, mRNA Cleavage and Polyadenylation Factors, 1102 Cardiorespiratory Medicine and Haematology, Immunology, 3201 Cardiovascular medicine and haematology

Abstract:

In chronic eosinophilic leukemia (CEL), the transforming oncoprotein FIP1L1-PDGFRA is a major target of therapy. In most patients, the tyrosine kinase inhibitor (TKI) imatinib induces complete remission. For patients who are intolerant or resistant, novel TKI have been proposed. We examined the in vitro effects of 14 kinase blockers on growth and function of EOL-1 cells, a FIP1L1-PDGFRA+ eosinophil cell line. Major growth-inhibitory effects were seen with all PDGFR-blocking agents, with IC50 values in the low nM-range: ponatinib: 0.1-0.2 nM, sorafenib: 0.1-0.2 nM, masitinib: 0.2-0.5 nM, nilotinib: 0.2-1 nM, dasatinib: 0.5-2 nM, sunitinib: 1-2 nM, midostaurin: 5-10 nM. These drugs were also found to block activation of PDGFR-downstream signaling molecules, including Akt, S6, and STAT5 in EOL-1 cells. All effective TKI produced apoptosis in EOL-1 cells as determined by microscopy, Annexin-V/PI, and caspase-3-staining. In addition, PDGFR-targeting TKI were found to inhibit cytokine-induced migration of EOL-1 cells. In all bioassays employed, ponatinib was found to be the most potent compound in EOL-1 cells. In addition, ponatinib was found to downregulate expression of the activation-linked surface antigen CD63 on EOL-1 cells, and to suppress growth of primary neoplastic eosinophils. We also examined drug effects on Ba/F3 cells expressing two clinically relevant imatinib-resistant mutant-forms of FIP1L1-PDGFRA, namely T674I and D842V. Strong inhibitory effects on both mutants were only seen with ponatinib. In summary, novel PDGFR-targeting TKI may be alternative agents for the treatment of patients with imatinib-resistant CEL. Although several different PDGFR-targeting agents are effective, the most potent drug appears to be ponatinib.