EXEL-0862, a novel tyrosine kinase inhibitor, induces apoptosis in vitro and ex vivo in human mast cells expressing the KIT D816V mutation

Blood ◽  
2006 ◽  
Vol 109 (1) ◽  
pp. 315-322 ◽  
Author(s):  
Jingxuan Pan ◽  
Alfonso Quintás-Cardama ◽  
Hagop M. Kantarjian ◽  
Cem Akin ◽  
Taghi Manshouri ◽  
...  

Abstract Gain-of-function mutations of the receptor tyrosine kinase KIT play a key role in the pathogenesis of systemic mastocytosis (SM), gastrointestinal stromal tumors (GISTs), and some cases of acute myeloid leukemia (AML). Whereas KIT juxtamembrane domain mutations seen in most patients with GIST are highly sensitive to imatinib, the kinase activation loop mutant D816V, frequently encountered in SM, hampers the binding ability of imatinib. We investigated the inhibitory activity of the novel tyrosine kinase inhibitor EXEL-0862 against 2 subclones of human mast cell line-1 (HMC-1)—HMC-1.1, harboring the juxtamembrane domain mutation V560G, and HMC-1.2, carrying V560G and the activation loop mutation D816V, found in more than 80% of patients with SM. EXEL-0862 inhibited the phosphorylation of KIT in a dose-dependent manner and decreased cell proliferation in both mast cell lines with higher activity against HMC-1.2 cells. The phosphorylation of KIT-dependent signal transducer and activator of transcription-3 (STAT3) and STAT5 was abrogated upon exposure to nanomolar concentrations of EXEL-0862. In addition, EXEL-0862 induced a time- and dose-dependent proapoptotic effect in both mast cell lines and caused a significant reduction in mast-cell content in bone marrow samples from patients with SM harboring D816V and from those without the D816V mutation. We conclude that EXEL-0862 is active against KIT activation loop mutants and is a promising candidate for the treatment of patients with SM and other KIT-driven malignancies harboring active site mutations.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3528-3528 ◽  
Author(s):  
Srdan Verstovsek ◽  
Cem Akin ◽  
Giles J. Francis ◽  
Manshouri Taghi ◽  
Ly Huynh ◽  
...  

Abstract Background. Majority of adult patients with systemic mastocytosis (SM) have activating mutation in codon 816 of c-kit (CD117), a receptor on the surface of mast cells. This abnormality is responsible for the pathogenesis of the disease. Methods. We investigated the effects of a newly designed tyrosine kinase inhibitor, AMN107, by comparing its in vitro inhibitory potency on c-kit mutated mast cell lines and patient samples with that of imatinib mesylate, another tyrosine kinase inhibitor, effective in some patients with SM. Two cell lines, subclones of HMC-1 cells, were used: HMC-1560 carrying juxtamembrane domain mutation in codon 560 of c-kit, and HMC-1560, 816 carrying both codon 560 mutation and tyrosine kinase domain mutation in codon 816 of c-kit. Results. In HMC-1560 mast cell line carrying wild-type codon 816, AMN107 was as potent as imatinib in inhibiting cellular proliferation, with IC50 values of 108 and 74 nM respectively, while in HMC-1560, 816 cell line carrying 816 mutation, neither medication had an effect. AMN107 was also as effective as imatinib in inhibiting phosphorylation of c-kit tyrosine kinase in HMC-1560 cells. The inhibition of cellular proliferation was associated with induction of apoptosis in HMC-1560 cells. AMN107 in concentrations up to 1 uM had no effect on bone marrow mast cells carrying D816V c-kit mutation obtained from patients with mastocytosis. Conclusions. Our results suggest similar potency of AMN107 and imatinib in mast cells that carry wild-type codon 816, but no activity against codon 816 mutation carrying cells.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Fulya Ustun-Alkan ◽  
Tülay Bakırel ◽  
Oya Üstüner ◽  
Ceren Anlas ◽  
Suzan Cinar ◽  
...  

Abstract Introduction Masitinib mesylate, a selective tyrosine kinase inhibitor of the c-KIT receptor, is used for the treatment of mast cell tumours in dogs. Masitinib has previously been investigated in various cancers; however, its potential anticancer effect in canine mammary tumours (CMTs) is unknown. In the present paper, we investigated the antiproliferative effect of masitinib in CMT cells and its possible mechanisms of action. Material and Methods The effect of masitinib on the proliferation of CMT-U27 and CMT-U309 cells was assessed by MTT assay and DNA fragmentation. Flow cytometric analysis was used to measure the effect of masitinib on apoptosis and the cell cycle. Additionally, vascular endothelial growth factor levels (VEGF) were measured, and the proliferation marker Ki-67 was visualised in immunocytochemical stainings in CMT cells. Results Treatment with masitinib inhibited the proliferation of CMT cells in a concentration-dependent manner. Maximal apoptotic activity and DNA fragmentation were observed at approximately IC50 of masitinib in both cell lines. In addition, cell cycle distribution was altered and VEGF levels and Ki-67 proliferation indices were decreased in masitinib-treated cells in comparison with control cells. Conclusion In this study, masitinib suppressed cell proliferation concomitantly via induction of apoptosis and cell cycle arrest by decreasing VEGF levels and the Ki-67 proliferation index in CMT-U27 and CMT-U309 cells in vitro, suggesting its potential as a therapeutic tool in the clinical setting of mammary cancer treatment in dogs.


2011 ◽  
Vol 52 (11) ◽  
pp. 2139-2147 ◽  
Author(s):  
Carine Tang ◽  
Lisa Schafranek ◽  
Dale B. Watkins ◽  
Wendy T. Parker ◽  
Sarah Moore ◽  
...  

2002 ◽  
Vol 50 (6) ◽  
pp. 479-489 ◽  
Author(s):  
Ioannis A. Avramis ◽  
Garyfallia Christodoulopoulos ◽  
Atsushi Suzuki ◽  
Walter E. Laug ◽  
Ignacio Gonzalez-Gomez ◽  
...  

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3358-3358
Author(s):  
Marcus M. Schittenhelm ◽  
Sharon Shiraga ◽  
Arin Schroeder ◽  
Amie S. Corbin ◽  
Diana Griffith ◽  
...  

Abstract Activating mutations of the activation loop (AL) of KIT are associated with certain human neoplasms, including a subset of patients with AML,systemic mast cell disorders (SM), seminoma, and Gastrointestinal Stromal Tumors (GIST). KIT AL mutations such as D816V that are typically found in AML and SM are resistant to imatinib (IM, IC50 > 5–10 μM). Dasatinib (BMS-354825) is a novel, oral, multi-targeted kinase inhibitor that targets BCR-ABL and SRC. Due to its potent inhibition of these kinases, dasatinib is currently being tested in clinical trials of patients with imatinib resistant/intolerant CML/Ph+ ALL. Based on previous observations of the ability of certain SRC/ABL inhibitors to also inhibit KIT kinase, we hypothesized that dasatinib might inhibit the kinase activity of both WT and mutant KIT isoforms. The inhibitory potential of dasatinib against WT KIT, KIT mutant isoforms and KIT-dependent downstream pathways was evaluated by immunoblotting. In addition, we evaluated the effects of dasatinib on cellular proliferation and induction of apoptosis. Dasatinib potently inhibited WT, juxtamembrane- (JM) and AL-mutant KIT autophosphorylation. Based on the ability of dasatinib to bind to BCR-ABL irrespective of the ATP AL conformation (inactive versus active), dasatinib was expected to be insensitive to KIT AL conformation. In contrast, we found that the IC50 for KIT autophosphorylation varied significantly among the various KIT mutant isoforms: WT KIT, D816Y, V560G (JM mutation) [IC50 1–10 nM] <D816F [IC50 100 nM] <D816V [IC50 200–250 nM]. These results indicate that the conformation of the KIT AL does influence dasatinib potency. Inhibition of KIT kinase activity by dasatinib reduced cellular proliferation and induced apoptosis in mast cell/leukemia cell lines expressing mutant KIT isoforms. In these cell lines, KIT activates downstream pathways important for cell viability and cell survival such as RAS/MAPK, JAK/STAT and PI3K/AKT. Dasatinib potently blocked activation of MAPK1/2 and STAT3. Inhibition of KIT by dasatinib abrogated phosphorylation of AKT S473, but not AKT T308. This partial inhibition of AKT activation was insufficient to inhibit phosphorylation of p70S6K, a kinase downstream of AKT and mTOR. Combining dasatinib with rapamycin, a known mTOR inhibitor, had an additive to synergistic anti-proliferative effect on cells expressing KIT D816V. Our studies suggest that dastatinib may have clinical activity against human neoplasms that are associated with gain-of-function KIT mutations such as AML, SM, seminoma, and GIST. Combining dasatinib with mTOR inhibitors may further increase efficacy against KIT-driven malignancies.


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