A Novel FLT3 Inhibitor FI-700 Selectively Suppresses the Growth of Leukemia Cells with FLT3 Mutations

Abstract Activating FLT3 mutations have been identified as prognostic factors in multiple myeloid malignancies. Recent studies have demonstrated that ligand-independent activation of FLT3 can also result from overexpression of wild-type FLT3. In addition, ligand-dependent activation has been observed in leukemic cells co-expressing FLT3 ligand (FLT3L), resulting in autocrine FLT3 signaling which is independent of FLT3 mutations. In Juvenile Myelo-Monocytic Leukemia (JMML), FLT3 internal tandem duplications (FLT3/ITDs) mutations affecting the tyrosine kinase domain (TKD) are rare. However, no data are yet available on the frequency of expression levels of FLT3 and FLT3L in JMML. If activated FLT3 occurs in JMML, one could imagine that these patients might benefit from treatment with small molecule FLT3 inhibitors, especially as to date the curative treatment of JMML is limited to allogeneous bone marrow transplantation. In 36 JMML patients FLT3 and FLT3L mRNA levels were assessed using real-time quantitative PCR (Taqman). Furthermore these samples were screened for the presence of activating FLT3/ITDs and FLT3/TKD mutations. MTT assays were performed to assess the response of JMML cells to the known FLT3 inhibitor PKC412 (Novartis). FLT3 appeared to be expressed only at basal levels and FLT3L expression was very low. In none of the 36 JMML samples FLT3/ITDs or TDK mutations were found, consistent with the observation that PKC412 was not cytotoxic in JMML samples (n=12), in contrast to leukemic cells of children with ALL which carried an activated FLT3. These data suggest that constitutively activated FLT3 does not occur in JMML. Therefore targeting FLT3 by tyrosine kinase inhibitors like PKC412 is unlikely to be effective in JMML.

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FLT3 Inhibitor Therapy for Patients with Myelodysplastic Syndromes (MDS) and Acute Myeloid Leukemia (AML): Impact On Survival According to FLT3 Status.

Blood ◽

10.1182/blood.v114.22.1026.1026 ◽

2009 ◽

Vol 114 (22) ◽

pp. 1026-1026 ◽

Cited By ~ 4

Author(s):

Naveen Pemmaraju ◽

Hagop M. Kantarjian ◽

Farhad Ravandi ◽

Guillermo Garcia-Manero ◽

Borthakur Gautam ◽

...

Keyword(s):

Research Funding ◽

Initial Therapy ◽

Inhibitor Therapy ◽

Clinical Activity ◽

Term Outcome ◽

Long Term Outcome ◽

Flt3 Inhibitor ◽

Flt3 Mutations ◽

Flt3 Inhibitors ◽

Impact On Survival

Abstract Abstract 1026 Poster Board I-48 Background: FLT3 mutations (ITD or D835 point mutation) are frequently observed in patients (pts) with AML and they confer an adverse prognosis, particularly among pts with diploid karyotype. This has made FLT3 an important target for drug development in AML. Several FLT3 inhibitors are currently being developed (eg, sorafenib, PKC-412, AC-220, CEP-701, IMC EB10, sunitinib). Results from early trials with many of these agents suggest they have clinical activity in the treatment of MDS and AML, although most responses are represented by a marked decrease in blast counts, with few complete remissions(CR). Whether these responses ultimately improve long-term outcome of pts, and whether they may be particularly beneficial for pts with FLT3 mutations compared to those with FLT3 wild-type (WT) is being investigated. Aims: To ascertain outcomes of patients given treatment with FLT3 inhibitors, alone or in combination with other therapies, and to compare outcomes in those patients with FLT3 mutations (ITD or D835) versus those with FLT3-WT. Methods: We reviewed the records of patients with MDS and AML who were enrolled on clinical trials with FLT3 inhibitors at our institution. We compared patient outcomes in those who received a FLT3 inhibitor in both FLT3 positive and FLT3 negative patients. Pts were classified as receiving FLT3 inhibitors 1) as part of their initial therapy, 2) as first salvage, or 3) as second salvage or beyond. Results: A total of 128 pts were included: 51 (40%) with FLT3-WT, 56 (44%) with FLT3-ITD, 11 (9%) with D835, and 10 (8%) had both FLT3-ITD and D835. The overall median age was 62 yrs (range, 17-88); by FLT3 status, median age was 70 yrs (35-88) for FLT3-WT pts and 58 yrs (17-81) for FLT3 mutated. Sixty-four pts (50%) were female. Twenty-three (18%) pts received FLT3 inhibitors as part of their induction therapy (18 FLT3-WT, 5 FLT3 mutated; median age 74 yrs); 22 (17%) as first salvage (4 FLT3-WT, 18 mutated; median age 67 yrs); and 83 (65%) as second or later salvage (29 FLT3-WT, 54 mutated; median age 59 yrs). Nine pts overall, all of whom were FLT3 mutated, achieved either CR (n=6) or CRp (n=3) with FLT3 inhibitors. Eight of the nine CR/CRp have been lost with a median CR duration of 8 months (mo) (3-12+). After a median follow-up of 3.5 mo, 115 (90%) pts have died, including 47 (92%) FLT3-WT, and 68 (88%) FLT3 mutated. The median survival is 3.8 mo for the total population. Survival by mutation status and timing of FLT3 inhibitor therapy is presented in table 1. Conclusions: Despite the inferior outcome expected for pts with FLT3 mutations, and the low rate of CR/CRp with FLT3 inhibitors, these results suggest that therapy with FLT3 inhibitors has the potential to improve the outcome of pts with FLT3 mutations. Additional studies incorporating these agents in AML therapy are warranted. Disclosures: Off Label Use: Sorafenib has not been FDA approved for use in MDS and AML. Kantarjian:Novartis: Research Funding. Cortes:Ambit: Research Funding; Novartis: Research Funding; ImClone: Research Funding.

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Incorporating a FLT3 inhibitor into AML therapy

Journal of Clinical Oncology ◽

10.1200/jco.2007.25.18_suppl.7060 ◽

2007 ◽

Vol 25 (18_suppl) ◽

pp. 7060-7060 ◽

Cited By ~ 1

Author(s):

M. J. Levis ◽

D. Small

Keyword(s):

Kinase Inhibitor ◽

Clinical Results ◽

In Vitro Cytotoxicity ◽

Leukemia Cells ◽

Assay Method ◽

Pharmacokinetic Analysis ◽

Activating Mutations ◽

Flt3 Mutations ◽

To Receive

7060 Background: Activating mutations of FLT3 occur in 30% of adults with AML and are associated with worse survival. Lestaurtinib (CEP-701), an oral FLT3 kinase inhibitor, has activity as monotherapy in relapsed/refractory AML patients with FLT3 mutations. Using the results of pre-clinical models, a trial was designed in which patients with AML and FLT3 mutations in first relapse were randomized 1:1 to receive chemotherapy alone or chemotherapy followed by treatment with lestaurtinib. The primary endpoint was complete remission (CR), with a target accrual of 220 patients. We present here correlative data from this trial. Methods: Efficacy of FLT3 inhibition was measured using the plasma inhibitory activity (PIA) assay for FLT3. This assay method has been previously published (Blood 108(10):3477–83). Prior to initiation of chemotherapy, leukemia cells of the patients randomized to lestaurtinib were tested for in vitro sensitivity to lestaurtinib using a cytotoxicity assay. Plasma samples were obtained at baseline and at trough time points on Days 15 and 42. PIA assay and in vitro cytotoxicity results were correlated with the clinical results from the first 40 patients enrolled. In addition, plasma levels of lestaurtinib and alpha-1 acid glycoprotein (AAG; the principle plasma binding protein for this drug) were measured. Results: Accrual is ongoing. Twenty-three of 35 patients treated with lestaurtinib achieved a PIA result of 85% or greater (i.e., successful FLT3 inhibition). Of the first 40 patients enrolled, all those who achieved a FLT3 PIA results of 85% or greater and whose pretreatment leukemia cells were sensitive in vitro to lestaurtinib achieved a clinical response. Conversely, patients with insensitive cells or inadequate PIA did not respond. Ten of 17 patients randomized to lestaurtinib showed response (5 CR, 3 CRp, 2 PR). Four of 17 patients randomized to receive chemotherapy alone responded (2 CR, 2 CRp). Conventional pharmacokinetic analysis showed no correlation whatsoever with response, due to the high degree to which lestaurtinib is bound to AAG. Conclusions: These results demonstrate that the PIA assay for FLT3 is able to accurately predict response to lestaurtinib, and provides important evidence that targeting FLT3 remains a valid therapeutic approach for AML with FLT3 activating mutations. No significant financial relationships to disclose.

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A novel irreversible FLT3 inhibitor, FF-10101, shows excellent efficacy against AML cells with FLT3 mutations

Blood ◽

10.1182/blood-2017-05-786657 ◽

2018 ◽

Vol 131 (4) ◽

pp. 426-438 ◽

Cited By ~ 39

Author(s):

Takeshi Yamaura ◽

Toshiyuki Nakatani ◽

Ken Uda ◽

Hayato Ogura ◽

Wigyon Shin ◽

...

Keyword(s):

Covalent Bond ◽

Activation Loop ◽

High Efficacy ◽

Flt3 Inhibitor ◽

Key Points ◽

Flt3 Mutations ◽

Inhibitory Activities

Key Points FF-10101 has selective and potent inhibitory activities against FLT3 by forming a covalent bond to the C695 residue. FF-10101 shows high efficacy against AML cells with FLT3 mutations including quizartinib-resistant activation loop mutations.

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Abstract 1806: The indolocarbazole derivative Go6976 suppresses the growth of leukemia cells with FLT3 mutations

10.1158/1538-7445.am2012-1806 ◽

2012 ◽

Author(s):

Akira Yoshida ◽

Kouichi Zokumasu ◽

Takanori Ueda

Keyword(s):

Leukemia Cells ◽

Flt3 Mutations

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Selective FLT3 Inhibitor FI-700 Neutralizes Mcl-1 and Enhances p53-Mediated Apoptosis in Acute Myeloid Leukemia (AML) Cells with Activating Mutations of FLT3 Via Mcl-1/Noxa Axis.

Blood ◽

10.1182/blood.v114.22.2597.2597 ◽

2009 ◽

Vol 114 (22) ◽

pp. 2597-2597

Author(s):

Kensuke Kojima ◽

Marina Konopleva ◽

Twee Tsao ◽

Michael Andreeff ◽

Hiroshi Ishida ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Activating Mutations ◽

Phosphatidylserine Externalization ◽

Flt3 Inhibitor ◽

Flt3 Mutations ◽

Flt3 Inhibitors ◽

Induced Apoptosis ◽

Apoptotic Effects ◽

Acute Myeloid

Abstract Abstract 2597 Poster Board II-573 Introduction: Activating mutations of the Fms-like tyrosine kinase-3 gene (FLT3) occur in approximately 30–40% of acute myeloid leukemia (AML) patients. FLT3 mutations confer numerous oncogenic properties, including dysregulated proliferation, resistance to apoptosis and a block in differentiation. FLT3 mutations result in abnormal activation of the downstream pathways, including signal transducer and activator of transcription 5 (STAT5), mitogen-activated protein kinase kinase (Mek)/extracellular signal–regulated kinase (Erk) and phosphatidylinositol-3 kinase (PI3K)/Akt. Activation of these downstream effectors has been thought to allow leukemia cells to evade apoptosis. Targeting of FLT3 mutations is a promising approach to overcome the dismal prognosis of acute myeloid leukemia (AML) with activating FLT3 mutations. Current trials are combining FLT3 inhibitors with p53-activating conventional chemotherapy. The mechanisms of cytotoxicity of FLT3 inhibitors are poorly understood. We investigated the interaction of FLT3 and p53 pathways after their simultaneous blockade using the selective FLT3 inhibitor FI-700 and the MDM2 inhibitor Nutlin-3 in AML. Results: FI-700 induced G1-phase cell cycle arrest and apoptosis as evidenced by increased sub-G1 DNA content and phosphatidylserine externalization in FLT3/ITD MOLM-13 (FLT3-ITD, wild-type (wt)-p53) and MV4-11NR (FLT3-ITD, mutated-p53) AML cells. FI-700 did not affect cell cycle distribution patterns nor did it induce apoptosis in FLT3/WT OCI-AML-3 (FLT3/WT, wt-p53) and HL-60 (FLT3/WT, del (del)-p53). Wt-p53 MOLM-13 and OCI-AML-3 cells were susceptible to Nutlin-induced apoptosis. FI-700 augmented Nutlin-induced Bax activation, mitochondrial membrane potential (MMP) loss, caspase-3 activation and phosphatidylserine externalization in MOLM-13 cells. FI-700 rapidly reduced Mcl-1 levels in FLT3/ITD cells, mainly by enhancing proteasomal Mcl-1 degradation. Levels of other Bcl-2 family proteins examined did not change significantly. Mcl-1 levels were only modestly reduced upon Nutlin treatment. The FI-700/Nutlin-3 combination profoundly reduced Mcl-1 levels. Immunoprecipitation/ immunoblotting results suggested that the drug combination results in a profound decrease in Mcl-1-bound Bim. FI-700 enhanced doxorubicin-induced apoptosis in FLT3/ITD MOLM-13 and MV4-11NR cells, suggesting that FI-700 can enhance both the p53-dependent and the p53-independent apoptotic effects of doxorubicin. Finally, cooperative apoptotic effects of FI-700/Nutlin-3 were seen in primary AML cells with FLT3/ITD. Conclusion: FLT3 inhibition by FI-700 immediately reduces anti-apoptotic Mcl-1 levels and enhances Nutlin-induced p53-mediated mitochondrial apoptosis in FLT3/ITD-expressing AML cells via the Mcl-1/Noxa axis. FLT3 inhibition, in combination with p53-inducing agents, might represent a potential therapeutic approach in AML with FLT3/ITD. Disclosures: No relevant conflicts of interest to declare.

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KW-2449, a novel multikinase inhibitor, suppresses the growth of leukemia cells with FLT3 mutations or T315I-mutated BCR/ABL translocation

Blood ◽

10.1182/blood-2009-01-199307 ◽

2009 ◽

Vol 114 (8) ◽

pp. 1607-1617 ◽

Cited By ~ 83

Author(s):

Yukimasa Shiotsu ◽

Hitoshi Kiyoi ◽

Yuichi Ishikawa ◽

Ryohei Tanizaki ◽

Makiko Shimizu ◽

...

Keyword(s):

Inhibitory Activity ◽

Leukemia Cells ◽

Significant Activity ◽

Wild Type ◽

Down Regulation ◽

Multikinase Inhibitor ◽

Growth Inhibitory ◽

Imatinib Resistant ◽

Flt3 Mutations ◽

Potent Growth

Abstract KW-2449, a multikinase inhibitor of FLT3, ABL, ABL-T315I, and Aurora kinase, is under investigation to treat leukemia patients. In this study, we examined its possible modes of action for antileukemic effects on FLT3-activated, FLT3 wild-type, or imatinib-resistant leukemia cells. KW-2449 showed the potent growth inhibitory effects on leukemia cells with FLT3 mutations by inhibition of the FLT3 kinase, resulting in the down-regulation of phosphorylated-FLT3/STAT5, G1 arrest, and apoptosis. Oral administration of KW-2449 showed dose-dependent and significant tumor growth inhibition in FLT3-mutated xenograft model with minimum bone marrow suppression. In FLT3 wild-type human leukemia, it induced the reduction of phosphorylated histone H3, G2/M arrest, and apoptosis. In imatinib-resistant leukemia, KW-2449 contributed to release of the resistance by the simultaneous down-regulation of BCR/ABL and Aurora kinases. Furthermore, the antiproliferative activity of KW-2449 was confirmed in primary samples from AML and imatinib-resistant patients. The inhibitory activity of KW-2449 is not affected by the presence of human plasma protein, such as α1-acid glycoprotein. These results indicate KW-2449 has potent growth inhibitory activity against various types of leukemia by several mechanisms of action. Our studies indicate KW-2449 has significant activity and warrants clinical study in leukemia patients with FLT3 mutations as well as imatinib-resistant mutations.

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