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Ref Type | Journal Article | ||||||||||||
PMID | (15256420) | ||||||||||||
Authors | Clark JJ, Cools J, Curley DP, Yu JC, Lokker NA, Giese NA, Gilliland DG | ||||||||||||
Title | Variable sensitivity of FLT3 activation loop mutations to the small molecule tyrosine kinase inhibitor MLN518. | ||||||||||||
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Abstract Text | FLT3 is constitutively activated by internal tandem duplications (ITDs) in the juxtamembrane domain or by activation loop mutations in acute myeloid leukemia (AML). We tested the sensitivity of 8 activation loop mutations to the small molecule FLT3 inhibitor, MLN518. Each FLT3 activation loop mutant, including D835Y, D835A, D835E, D835H, D835N, D835V, D835del, and I836del, transformed Ba/F3 cells to factor-independent proliferation and had constitutive tyrosine kinase activation, as assessed by FLT3 autophosphorylation and activation of downstream effectors, including STAT5 and ERK. MLN518 inhibited FLT3 autophosphorylation and phosphorylation of STAT5 and ERK in FLT3-ITD-transformed Ba/F3 cells with an IC(50) (50% inhibition of cell viability) of approximately 500 nM. However, there was a broad spectrum of sensitivity among the 8 activation loop mutants, with IC(50) ranging from approximately 500 nM to more than 10 microM for the inhibition of phosphorylation of FLT3, STAT5, and ERK. The relative sensitivity of the mutants to MLN518 in biochemical assays correlated with the cellular IC(50) for cytokine-independent proliferation of FLT3-transformed Ba/F3 cells in the presence of MLN518. Thus, certain activation loop mutations in FLT3 simultaneously confer resistance to small molecule inhibitors. These findings have implications for the evaluation of responses in clinical trials with FLT3 inhibitors and provide a strategy to screen for compounds that can overcome resistance. |
Molecular Profile | Treatment Approach |
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Gene Name | Source | Synonyms | Protein Domains | Gene Description | Gene Role |
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Therapy Name | Drugs | Efficacy Evidence | Clinical Trials |
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Drug Name | Trade Name | Synonyms | Drug Classes | Drug Description |
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Gene | Variant | Impact | Protein Effect | Variant Description | Associated with drug Resistance |
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FLT3 | D835A | missense | gain of function | FLT3 D835A lies within the activation loop in the protein kinase domain of the Flt3 protein (PMID: 25837374). D835A results in constitutive phosphorylation of Flt3 and activation of Stat5, Erk signaling, leading to transformation of cultured cells (PMID: 15256420). | |
FLT3 | D835del | deletion | gain of function | FLT3 D835del results in the deletion of an amino acid from the activation loop in the protein kinase domain of the Flt3 protein at amino acid 835 (PMID: 25837374). D835del results in constitutive phosphorylation of Flt3 and activation of Stat5, Erk signaling, leading to transformation of cultured cells (PMID: 15256420). | |
FLT3 | D835E | missense | gain of function | FLT3 D835E lies within the activation loop in the protein kinase domain of the Flt3 protein (PMID: 25837374). D835E results in constitutive phosphorylation of Flt3 and activation of Stat5, Erk signaling, leading to transformation of cultured cells (PMID: 15256420). | |
FLT3 | D835H | missense | gain of function | FLT3 D835H lies within the protein kinase domain activation loop of the Flt3 protein (PMID: 11290608). D835H results in constitutive phosphorylation of Flt3 and activation of Stat5, Erk signaling, leading to transformation of cultured cells (PMID: 15256420). | |
FLT3 | D835N | missense | gain of function | FLT3 D835N lies within the protein kinase domain activation loop of the Flt3 protein (PMID: 11290608). D835N results in constitutive phosphorylation of Flt3 and activation of Stat5, Erk signaling, leading to transformation of cultured cells (PMID: 15256420). | |
FLT3 | D835V | missense | gain of function | FLT3 D835V lies within the protein kinase domain activation loop of the Flt3 protein (PMID: 11290608). D835V results in constitutive phosphorylation of Flt3 and activation of Stat5, Erk signaling, leading to transformation of cultured cells (PMID: 15256420), and has been demonstrated to promote secondary drug resistance in the context of FLT3 internal tandem duplication (FLT3-ITD) mutations (PMID: 22504184, PMID: 29187377). | Y |
FLT3 | D835X | missense | unknown | FLT3 D835X indicates any Flt3 missense mutation that results in the replacement of the aspartic acid (D) at amino acid 835 by a different amino acid. FLT3 codon 835 mutations are hotspot mutations that often result in constitutive phosphorylation of Flt3 and activation of downstream signaling (PMID: 11290608, PMID: 15256420). | |
FLT3 | D835Y | missense | gain of function | FLT3 D835Y lies within the protein kinase domain activation loop of the Flt3 protein (UniProt.org, PMID: 11290608). D835Y results in constitutive phosphorylation of Flt3 and activation of Stat5, Erk signaling, leading to transformation of cultured cells (PMID: 15256420, PMID: 30651561), and has been demonstrated to promote secondary drug resistance in the context of FLT3 internal tandem duplication (FLT3-ITD) mutations (PMID: 22504184, PMID: 29187377). | Y |
FLT3 | I836del | deletion | gain of function | FLT3 I836del results in the deletion of an amino acid in the protein kinase domain activation loop of the Flt3 protein at amino acid 836 (PMID: 12663439). I836del results in constitutive phosphorylation of Flt3 and activation of Stat5, Erk signaling, leading to transformation of cultured cells (PMID: 15256420). |
Molecular Profile | Indication/Tumor Type | Response Type | Therapy Name | Approval Status | Evidence Type | Efficacy Evidence | References |
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FLT3 I836del | cancer | sensitive | Tandutinib | Preclinical - Cell culture | Actionable | In a preclinical study, Tandutinib (CT53518) inhibited phosphorylation of FLT3 and activation of ERK and STAT5, and reduced growth of transformed cells expressing FLT3 I836del in culture (PMID: 15256420). | 15256420 |