Reference Detail

Ref Type

Journal Article

PMID

(16150941)

Authors

Heidel F, Solem FK, Breitenbuecher F, Lipka DB, Kasper S, Thiede MH, Brandts C, Serve H, Roesel J, Giles F, Feldman E, Ehninger G, Schiller GJ, Nimer S, Stone RM, Wang Y, Kindler T, Cohen PS, Huber C, Fischer T

Title

Clinical resistance to the kinase inhibitor PKC412 in acute myeloid leukemia by mutation of Asn-676 in the FLT3 tyrosine kinase domain.

Journal	Vol	Issue	Date	Pages	Journal Short Title
Blood	107	1	2006 Jan 01	293-300	Blood

URL

Abstract Text

Activating mutations in the FLT3 tyrosine kinase (TK) occur in approximately 35% of patients with acute myeloid leukemia (AML). Therefore, targeting mutated FLT3 is an attractive therapeutic strategy, and early clinical trials testing FLT3 TK inhibitors (TKI) showed measurable clinical responses. Most of these responses were transient; however, in a subset of patients blast recurrence was preceded by an interval of prolonged remission. The etiology of clinical resistance to FLT3-TKI in AML is unclear but is of major significance for the development of future therapeutic strategies. We searched for mechanisms of resistance in 6 patients with AML who had relapses upon PKC412 treatment. In an index AML patient, an algorithm of analyses was applied using clinical material. In vivo and in vitro investigation of primary blasts at relapse revealed persistent TK phosphorylation of FLT3 despite sufficient PKC412 serum levels. Through additional molecular analyses, we identified a single amino acid substitution at position 676 (N676K) within the FLT3 kinase domain as the sole cause of resistance to PKC412 in this patient. Reconstitution experiments expressing the N676K mutant in 32D cells demonstrated that FLT3-ITD-N676K was sufficient to confer an intermediate level of resistance to PKC412 in vitro. These studies point out that a genetically complex malignancy such as AML may retain dependence on a single oncogenic signal.

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Molecular Profile	Treatment Approach

Gene Name	Source	Synonyms	Protein Domains	Gene Description	Gene Role

Therapy Name	Drugs	Efficacy Evidence	Clinical Trials

Drug Name	Trade Name	Synonyms	Drug Classes	Drug Description

Gene	Variant	Impact	Protein Effect	Variant Description	Associated with drug Resistance
FLT3	N676K	missense	gain of function	FLT3 N676K lies within the protein kinase domain of the Flt3 protein (UniProt.org). N676K results in constitutive phosphorylation of Flt3, activation of Akt and Mapk signaling, leading to malignant hematological transformation in animal models (PMID: 26891877), and has been demonstrated to occur as a resistance mutation in the context of FLT3 internal tandem duplication (FLT3-ITD) mutations (PMID: 16150941).	Y

Molecular Profile	Indication/Tumor Type	Response Type	Therapy Name	Approval Status	Evidence Type	Efficacy Evidence	References
FLT3 exon 14 ins FLT3 N676K	acute myeloid leukemia	predicted - resistant	Midostaurin	Case Reports/Case Series	Actionable	In a clinical case study, a patient with acute myeloid leukemia harboring a FLT3-ITD mutation progressed on Rydapt (midostaurin) after 288 days and was found to have acquired a FLT3 N676K mutation, and resistance was also confirmed in patient-derived cells in culture (PMID: 16150941).	16150941