CLI24-001: First-in-human study of SEL24/MEN1703, an oral dual PIM/FLT3 kinase inhibitor, in patients with acute myeloid leukemia.

TPS7062 Background: FLT3-ITD is one of the most common genetic lesions in acute myeloid leukemia (AML). PIM kinases are oncogenic FLT3-ITD targets expressed in AML cells and increased PIM kinase expression is found in relapse samples from AML patients treated with FLT3 inhibitors. In addition, inhibition of PIM kinases restores sensitivity to FLT3 inhibitors and dual FLT3/PIM inhibition eradicates FLT3-ITD+ cells including primary AML cells. SEL24/MEN1703, a potent PIM/FLT3 dual inhibitor, demonstrates a significantly broader spectrum of activity in AML cell lines and primary AML blasts, irrespective of FLT3 status, compared to monotherapy with either FLT3 or PIM inhibitors such as quizartinib or AZD1208. Methods: CLI24-001 is a First in Human, open label, non-randomized, multi-center, Phase I/II dose-escalation and cohort expansion study of SEL24/MEN1703 in AML patients (excluding APL) not suitable for chemotherapy. SEL24/MEN1703 is given orally, QD, for 14 days in a 21-day cycle with cycles repeated until disease progression or unacceptable toxicity. Dose escalation follows a 3+3 design to identify the recommended phase 2 dose (RP2D). In the phase 2 part/cohort expansion, subjects will receive SEL24/MEN1703 at the RP2D, to further investigate the safety profile and signs of antileukemic activity. In both study parts, patients are eligible regardless of mutational status and/or prior exposure to FLT3 inhibitors; prior treatment with PIM inhibitors is not allowed. Main inclusion criteria comprise a white blood count (WBC) of ≤30 x 109/L (hydroxyurea/leukoapheresis permitted to lower WBC). Key secondary objectives include pharmacokinetics (PK) and single agent efficacy. The study is enrolling at 5 US sites and will be extended, both in US and EU, in the cohort expansion part. This is the first trial testing a dual PIM/FLT3 inhibitor with the potential to be active in AML regardless of FLT3 status andwith a potential to overcome FLT3 inhibitor resistance. (Sci Adv. 2015;1:e1500221; Oncotarget. 2018 Mar 30;9(24):16917-16931) Clinical trial information: NCT03008187.

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ATM/G6PD-driven redox metabolism promotes FLT3 inhibitor resistance in acute myeloid leukemia

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1603876113 ◽

2016 ◽

Vol 113 (43) ◽

pp. E6669-E6678 ◽

Cited By ~ 35

Author(s):

Mark A. Gregory ◽

Angelo D’Alessandro ◽

Francesca Alvarez-Calderon ◽

Jihye Kim ◽

Travis Nemkov ◽

...

Keyword(s):

Oxidative Stress ◽

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Mitochondrial Oxidative Stress ◽

Flt3 Inhibitor ◽

A Genome ◽

Flt3 Inhibitors ◽

Acute Myeloid

Activating mutations in FMS-like tyrosine kinase 3 (FLT3) are common in acute myeloid leukemia (AML) and drive leukemic cell growth and survival. Although FLT3 inhibitors have shown considerable promise for the treatment of AML, they ultimately fail to achieve long-term remissions as monotherapy. To identify genetic targets that can sensitize AML cells to killing by FLT3 inhibitors, we performed a genome-wide RNA interference (RNAi)-based screen that identified ATM (ataxia telangiectasia mutated) as being synthetic lethal with FLT3 inhibitor therapy. We found that inactivating ATM or its downstream effector glucose 6-phosphate dehydrogenase (G6PD) sensitizes AML cells to FLT3 inhibitor induced apoptosis. Examination of the cellular metabolome showed that FLT3 inhibition by itself causes profound alterations in central carbon metabolism, resulting in impaired production of the antioxidant factor glutathione, which was further impaired by ATM or G6PD inactivation. Moreover, FLT3 inhibition elicited severe mitochondrial oxidative stress that is causative in apoptosis and is exacerbated by ATM/G6PD inhibition. The use of an agent that intensifies mitochondrial oxidative stress in combination with a FLT3 inhibitor augmented elimination of AML cells in vitro and in vivo, revealing a therapeutic strategy for the improved treatment of FLT3 mutated AML.

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Monocytic Maturation Induced by FLT3 Inhibitor Therapy of Acute Myeloid Leukemia: Morphologic and Immunophenotypic Characteristics

Laboratory Medicine ◽

10.1093/labmed/lmz094 ◽

2019 ◽

Vol 51 (5) ◽

pp. 478-483

Author(s):

Cade D Arries ◽

Sophia L Yohe

Keyword(s):

Bone Marrow ◽

Acute Myeloid Leukemia ◽

Tyrosine Kinase ◽

Cell Population ◽

Myeloid Leukemia ◽

Inhibitor Therapy ◽

Molecular Abnormalities ◽

Flt3 Inhibitor ◽

Flt3 Inhibitors ◽

Acute Myeloid

Abstract Background FMS-like tyrosine kinase-3 (FLT3-ITD) mutations are some of the most common mutations in acute myeloid leukemia (AML), and patient outcomes have improved since the advent of tyrosine kinase inhibitors. First, granulocytic differentiation was described in FLT3-positive AML treated with FLT3 inhibitors, and more recently, monocytic differentiation was reported. Methods Two patients with myelomonocytic cells in their bone marrow were identified during routine follow-up after AML treatment that included FLT3 inhibitors. The bone marrow study was done as standard of care. Results Both patients had FLT3-ITD+ AML and showed an atypical maturing monocytic cell population and a decrease in the leukemic blast cell population after FLT3 inhibitor therapy. Concurrent genetic testing revealed persistent genetic abnormalities. Conclusions These cases illustrate monocytic maturation in FLT3+ AML after FLT3 inhibitor treatment. It is critical for pathologists and clinicians to be aware of the differentiation phenomenon, as these patients have persistent molecular abnormalities despite response to treatment and normalization of blast counts.

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FLT3 ligand impedes the efficacy of FLT3 inhibitors in vitro and in vivo

Blood ◽

10.1182/blood-2010-01-266742 ◽

2011 ◽

Vol 117 (12) ◽

pp. 3286-3293 ◽

Cited By ~ 147

Author(s):

Takashi Sato ◽

Xiaochuan Yang ◽

Steven Knapper ◽

Paul White ◽

B. Douglas Smith ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Therapeutic Strategy ◽

Newly Diagnosed ◽

Flt3 Ligand ◽

Flt3 Inhibitor ◽

Flt3 Inhibitors ◽

Acute Myeloid

AbstractWe examined in vivo FLT3 inhibition in acute myeloid leukemia patients treated with chemotherapy followed by the FLT3 inhibitor lestaurtinib, comparing newly diagnosed acute myeloid leukemia patients with relapsed patients. Because we noted that in vivo FLT3 inhibition by lestaurtinib was less effective in the relapsed patients compared with the newly diagnosed patients, we investigated whether plasma FLT3 ligand (FL) levels could influence the efficacy of FLT3 inhibition in these patients. After intensive chemotherapy, FL levels rose to a mean of 488 pg/mL on day 15 of induction therapy for newly diagnosed patients, whereas they rose to a mean of 1148 pg/mL in the relapsed patients. FL levels rose even higher with successive courses of chemotherapy, to a mean of 3251 pg/mL after the fourth course. In vitro, exogenous FL at concentrations similar to those observed in patients mitigated FLT3 inhibition and cytotoxicity for each of 5 different FLT3 inhibitors (lestaurtinib, midostaurin, sorafenib, KW-2449, and AC220). The dramatic increase in FL level after chemotherapy represents a possible obstacle to inhibiting FLT3 in this clinical setting. These findings could have important implications regarding the design and outcome of trials of FLT3 inhibitors and furthermore suggest a rationale for targeting FL as a therapeutic strategy.

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Autophagy Activation Induces Resistance to FLT3 Inhibitors in Acute Myeloid Leukemia with FLT3-ITD Mutation

10.21203/rs.3.rs-676343/v1 ◽

2021 ◽

Author(s):

Dan Xu ◽

Zhao Yin ◽

Ying Yang ◽

Yishan Chen ◽

Changfen Huang ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Critical Role ◽

Leukemic Cells ◽

Sorafenib Treatment ◽

Downstream Signaling ◽

Flt3 Inhibitor ◽

Flt3 Inhibitors ◽

Inhibitor Resistance ◽

Acute Myeloid

Abstract Background: Autophagy plays a critical role in drug resistance in acute myeloid leukemia (AML), including the subtype with FLT3-ITD mutation. Yet how autophagy is activated and mediates resistance to FLT3 inhibitors in FLT3-ITD-positive AML remains unsure. Methods: We detected the alteration of autophagy in FLT3-ITD-positive leukemic cells after versus before acquired resistance to FLT3 inhibitors; tested the stimulative effect of acquired D835Y mutation and bone marrow micro-environment (BME) on autophagy; explored the mechanism of autophagy mediating FLT3 inhibitor resistance. Results: Sorafenib-resistant cells markedly overexpressed autophagy in comparison with sorafenib-sensitive cells or the cells before sorafenib treatment. Both acquired D835Y mutation and BME activated cytoprotective autophagy to induce FLT3 inhibitor resistance. Autophagy activation decreased the suppression efficacy of FLT3 inhibitors on FLT3 downstream signaling and then weakened their anti-leukemia effect. Inhibition of autophagy with CQ significantly enhanced the suppressive effect of FLT3 inhibitor on FLT3 downstream signaling, in the end overcame FLT3 inhibitor resistance. Conclusions: Autophagy might be stimulated by acquired mutation or BME, and bypass activate FLT3 downstream signaling to mediate FLT3 inhibitor resistance in FLT3-ITD-positive AML. Targeting autophagy could be a promising strategy to overcome resistance.

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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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PP2A Activators Enhance Efficacy of FLT3 Inhibitors in FLT3-ITD Acute Myeloid Leukemia Cells through AKT Inactivation-Dependent Pim-1 and c-Myc Proteasomal Degradation

Blood ◽

10.1182/blood-2019-129011 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 1276-1276

Author(s):

Mario Scarpa ◽

Prerna Singh ◽

Shivani Kapoor ◽

Jonelle K. Lee ◽

Sandrine Niyongere ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Proteasome Inhibitor ◽

Myeloid Leukemia ◽

Research Funding ◽

Concurrent Treatment ◽

Dual Targeting ◽

Flt3 Inhibitor ◽

Flt3 Inhibitors ◽

Acute Myeloid ◽

In Cells

Introduction fms-like tyrosine like kinase 3 internal tandem duplication (FLT3-ITD), present in acute myeloid leukemia (AML) cells of 30% of patients, results in constitutive and aberrant FLT3 signaling and, clinically, short disease-free survival. Efficacy of FLT3 inhibitors is limited and transient, but may be enhanced by dual targeting of FLT3-ITD signaling pathways. The tumor suppressor protein phosphatase 2A (PP2A) is inhibited in cells with FLT3-ITD. The oncogenic serine/threonine kinase Pim-1 is transcriptionally upregulated and also stabilized by PP2A inhibition in cells with FLT3-ITD. Pim-1 contributes directly to FLT3-ITD proliferative and anti-apoptotic effects, and also phosphorylates and stabilizes FLT3-ITD in a positive feedback loop. Moreover FLT3-ITD, PP2A and Pim-1 all regulate the transcription factor c-Myc. PP2A-activating drugs enhance efficacy of FLT3 inhibitors. We sought to identify mechanisms underlying the efficacy of this combination. Methods Ba/F3-ITD and MV4-11 cells, with FLT3-ITD, and blasts from patients with AML with FLT3-ITD were cultured with the FLT3 inhibitors gilteritinib (15 nM) or quizartinib (1 nM) and/or the PP2A-activating drugs FTY720 (2-4 µM) or DT-061 (10 µM), or with DMSO control. Pim-1, c-Myc, p-AKT (S473 and T308) and AKT protein expression was measured by immunoblotting, along with p-STAT5 (Y694), STAT5, p-PP2A (Y307) and PP2A expression. To study post-translational regulation, cells were cultured with cycloheximide (100 µg/mL) with and without the proteasome inhibitor MG-132 (20 µM). Ubiquitinated c-Myc was measured by co-immunoprecipitation and immunoblotting with c-Myc and ubiquitin antibodies. Ba/F3-ITD cells were stably transfected with estrogen receptor (ER)-c-Myc, kinase-dead Pim-1 or myristoylated AKT plasmids or corresponding empty vectors. Apoptosis was detected by Annexin V and propidium iodine staining, measured by flow cytometry. Cells were also cultured with the pan-Pim kinase inhibitor AZD1208 (1 µM), the Myc inhibitor 10058-F4 (100 µM) or the pan-AKT inhibitor MK-2206 (5 µM). Results Concurrent treatment of Ba/F3-ITD and MV4-11 cells and primary AML cells with FLT3-ITD with a FLT3 inhibitor (gilteritinib or quizartinib) and a PP2A-activating drug (FTY720 or DT-061) decreased growth and increased apoptosis induction, relative to treatment with single drugs. Concurrent FLT3 inhibitor and PP2A-activating drug treatment decreased expression of both Pim-1 and c-Myc protein. Concurrent treatment decreased Pim-1 half-life from 15 to 5 minutes, and c-Myc half-life from 30 to 5 minutes, while half-lives were restored by concurrent treatment with the proteasome inhibitor MG-132. Concurrent treatment was also shown to increase c-Myc ubiquitination. Effects of concurrent treatment on Pim-1 and c-Myc were independent, as transfection with kinase-dead Pim-1 or treatment with Pim inhibitor AZD1208 did not alter c-Myc downregulation, and c-Myc overexpression or treatment with Myc inhibitor 10058-F4 did not alter Pim-1 downregulation. Concurrent treatment with FLT3 inhibitor and PP2A-activating drug did not alter expression of c-Myc deubiquitinases, but rapidly decreased AKT S473 and T308 phosphorylation. FLT3 inhibitor and PP2A activator co-treatment did not induce downregulation or increased turnover of Pim-1 and c-Myc protein or apoptosis in cells with constitutive AKT activation caused by transfection of myristoylated AKT. Moreover, AKT inhibition downregulated Pim-1 and c-Myc protein expression, decreased Pim-1 and c-Myc protein half-lives from 15 to 5 minutes and 30 to 10 minutes, respectively, and induced apoptosis of cells with FLT3-ITD, replicating the effects of FLT3 inhibitor and PP2A activator co-treatment. Conclusion PP2A activators enhance the efficacy of FLT3 inhibitors in AML cells with FLT3-ITD through AKT inactivation-dependent increased Pim-1 and c-Myc proteasomal degradation, which is a novel mechanism. The data support further preclinical and clinical testing of this dual targeting approach to treatment of AML with FLT3-ITD. Disclosures Baer: Takeda: Research Funding; Incyte: Research Funding; Kite: Research Funding; Forma: Research Funding; AI Therapeutics: Research Funding; Abbvie: Research Funding; Astellas: Research Funding.

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Concurrent Inhibition of Pim-1 and FLT3 Kinases in FLT3-ITD Acute Myeloid Leukemia Post-Translationally Downregulates the Anti-Apoptotic Protein Mcl-1 through Downregulation of the Mcl-1 Deubiquitinase USP9X

Blood ◽

10.1182/blood.v128.22.35.35 ◽

2016 ◽

Vol 128 (22) ◽

pp. 35-35 ◽

Cited By ~ 2

Author(s):

Patrick R. Baldwin ◽

Shivani Kapoor ◽

Karthika Natarajan ◽

Rossana Trotta ◽

Adriana Tron ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Proteasomal Degradation ◽

Protein Levels ◽

Flt3 Inhibitor ◽

Apoptotic Protein ◽

Flt3 Inhibitors ◽

Acute Myeloid

Abstract Internal tandem duplication (ITD) mutations of the receptor tyrosine kinase fms-like tyrosine kinase 3 (FLT3) are present in acute myeloid leukemia (AML) cells in 30% of cases and are associated with high relapse rate and short disease-free survival following both chemotherapy and allogeneic hematopoietic stem cell transplantation. Inhibitors of FLT3 signaling have shown activity in clinical trials in FLT3-ITD AML, but efficacy has generally been limited and transient. Concurrent inhibition of other targets in FLT3-ITD signaling pathways is being explored as an approach to increasing the depth and duration of responses to FLT3 inhibitors. The oncogenic serine/threonine kinase Pim-1 is transcriptionally upregulated downstream of FLT3-ITD and phosphorylates and stabilizes FLT3, thereby promoting FLT3 signaling in a positive feedback loop in cells with FLT3-ITD. Pim kinase inhibitors are in clinical trials. We previously showed that combinations of clinically active Pim kinase and FLT3 inhibitors at pharmacologically relevant concentrations enhance apoptosis and decrease clonogenic growth of FLT3-ITD AML cell lines and primary patient cells in vitro and suppress growth of FLT3-ITD AML cells in vivo, in relation to treatment with FLT3 or Pim inhibitors alone. Here we studied the mechanistic effects of concurrent Pim kinase and FLT3 inhibition, demonstrating a novel mechanism of Mcl-1 downregulation in FLT3-ITD AML cells. Ba/F3-ITD cells, transfected with FLT3-ITD, were cultured with the pan-Pim kinase inhibitor AZD1208 at 1 μM, a concentration chosen based on in vitro and phase I clinical trial data, and/or the FLT3 inhibitor quizartinib at 1 nM, its IC50 concentration, and expression of the anti-apoptotic proteins Mcl-1, Bcl2 and Bcl-xL and the pro-apoptotic proteins BAD/S112 p-BAD, BAK, BAX and Bim was measured by western blot analysis. Mcl-1 expression decreased in a time-dependent manner with AZD1208 and quizartinib co-treatment, but not with treatment with either inhibitor alone, while levels of the other proteins did not change. Mcl-1 downregulation with Pim kinase and FLT3 inhibitor combination treatment was then confirmed in the human FLT3-ITD AML cell lines MV4-11 and MOLM-14. Mcl-1 expression is regulated at multiple levels, and we next sought to determine the mechanism(s) by which it is downregulated by concurrent Pim and FLT3 inhibition. While Mcl-1 protein levels decreased, Mcl-1 mRNA levels did not change, indicating post-transcriptional regulation. Additionally, levels of miR-29b, a negative regulator of Mcl-1 translation,decreased similarly in Ba/F3-ITD cells treated with AZD1208 and quizartinib, compared to quizartinib alone. Polysome profiling showed decreased total mRNA translation, but no selective reduction in Mcl-1 translation. In contrast, the progressive decrease in Mcl-1 protein expression with AZD1208 and quizartinib co-treatment was abrogated by addition of the proteasome inhibitor MG-132, demonstrating that Mcl-1 protein is downregulated by enhanced Mcl-1 proteasomal degradation. This mechanism was further confirmed by demonstration of an increase in ubiquitinated Mcl-1 prior to Mcl-1 downregulation in cells co-treated with AZD1208 and quizartinib, but not with each inhibitor alone or with DMSO control. The deubiquitinase USP9X decreases Mcl-1 ubiquitination and consequent proteasomal degradation, and we found that USP9X expression is downregulated prior to the increase in ubiquitinated Mcl-1 and the subsequent decrease in Mcl-1 protein levels during AZD1208 and quizartinib co-treatment, but was not altered by treatment with either inhibitor alone. In contrast, expression of the ubiquitin E3 ligases Mule/ARF-BP1, SCFβ-TrCP and Trim17, which mediate Mcl ubiquitination, did not change prior to Mcl-1 downregulation. Preclinical studies in our laboratory and others have shown in vitro and in vivo efficacy of combination treatment with Pim kinase and FLT3 inhibitors in FLT3-ITD AML, suggesting clinical promise of this approach. Here we show that, mechanistically, concurrent Pim kinase and FLT3 inhibition causes a post-translational decrease in expression of the anti-apoptotic protein Mcl-1 via enhanced proteasomal degradation, preceded by downregulation of the Mcl-1 deubiquitinase USP9X and an increase in ubiquitinated Mcl-1, a novel mechanism of Mcl-1 downregulation in FLT3-ITD AML cells. Disclosures Tron: AstraZeneca: Employment; AstraZeneca: Employment. Huszar:AstraZeneca: Employment.

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Pim kinases modulate resistance to FLT3 tyrosine kinase inhibitors in FLT3-ITD acute myeloid leukemia

Science Advances ◽

10.1126/sciadv.1500221 ◽

2015 ◽

Vol 1 (8) ◽

pp. e1500221 ◽

Cited By ~ 42

Author(s):

Alexa S. Green ◽

Thiago T. Maciel ◽

Marie-Anne Hospital ◽

Chae Yin ◽

Fetta Mazed ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Tyrosine Kinase ◽

Tyrosine Kinase Inhibitors ◽

Myeloid Leukemia ◽

Kinase Inhibitors ◽

Myeloproliferative Neoplasm ◽

Pim Kinases ◽

Flt3 Inhibitors ◽

Long Term Prognosis ◽

Acute Myeloid

ABSTRACTFms-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) is frequently detected in acute myeloid leukemia (AML) patients and is associated with a dismal long-term prognosis. FLT3 tyrosine kinase inhibitors provide short-term disease control, but relapse invariably occurs within months. Pim protein kinases are oncogenic FLT3-ITD targets expressed in AML cells. We show that increased Pim kinase expression is found in relapse samples from AML patients treated with FLT3 inhibitors. Ectopic Pim-2 expression induces resistance to FLT3 inhibition in both FLT3-ITD–induced myeloproliferative neoplasm and AML models in mice. Strikingly, we found that Pim kinases govern FLT3-ITD signaling and that their pharmacological or genetic inhibition restores cell sensitivity to FLT3 inhibitors. Finally, dual inhibition of FLT3 and Pim kinases eradicates FLT3-ITD+ cells including primary AML cells. Concomitant Pim and FLT3 inhibition represents a promising new avenue for AML therapy.

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Efficacy Analysis of Different FLT3 Inhibitors in Relapsed/Refractory Acute Myeloid Leukemia and High-Risk Myelodysplastic Syndrome Patients - a Systematic Review and Meta-Analysis

Blood ◽

10.1182/blood-2021-154098 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 1225-1225

Author(s):

Mahesh Swaminathan ◽

Mai M M Aly ◽

Katherine G. Akers ◽

Seongho Kim ◽

Harry Ramos ◽

...

Keyword(s):

Systematic Review ◽

Clinical Trials ◽

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Response Rate ◽

Meta Analysis ◽

Complete Response ◽

Flt3 Inhibitor ◽

Flt3 Inhibitors ◽

Acute Myeloid

Abstract Background: Mutations in FMS like tyrosine kinase gene 3 (FLT3) are the most common genetic aberrations in acute myeloid leukemia (AML). Internal tandem duplications (ITD) are the most frequent FLT3 mutations, occurring in 20-30% of patients (pts) with newly diagnosed AML, and a minority are tyrosine kinase domain mutations. FLT3 mutation confers adverse prognosis in pts treated with standard chemotherapy (chemo) alone, and relapse risk is also higher compared to FLT3-wild type AML (HR-1.75). Studies of FLT3 inhibitors as monotherapy or in combination with chemo in the treatment of pts with FLT3-ITD relapsed/refractory (R/R) AML are associated with mixed results. No evidence synthesis has yet focused on the effect of FLT3 inhibitor alone in the treatment of R/R AML and high-risk myelodysplastic syndrome (HR-MDS). Hence, we analyzed the efficacy of various FLT3 inhibitors from different clinical trials used as monotherapy to treat pts with R/R AML and HR-MDS. Methods: We conducted a systematic review and meta-analysis of clinical trials of FLT3 inhibitors for pts with R/R AML and HR-MDS. We searched EMBASE and PubMed for clinical trials published between 1/1/2000 and 5/26/2021 using a combination of keywords and subject headings related to FLT3 inhibitors and AML. Titles/abstracts and full texts were screened by two independent reviewers, with conflicts arbitrated by a third reviewer. Studies were included if they were (1) full-length published journal articles that (2) reported the results of single-arm or double-arm phase I/II/III clinical R/R AML or HR-MDS. Outcomes of interest were composite response rate (CRc=complete response + complete response with incomplete count recovery) and overall response rate (ORR). Results: Thirty studies were included after the application of inclusion criteria (Figure 1). Two were excluded due to inadequate representation of pts with R/R AML and outcomes reported for stem cell transplant following FLT3 inhibitor use, respectively. Hence, 28 studies were included in the meta-analysis, with a total of 1927 pts. Quizartinib and sorafenib were the most frequently studied inhibitors (6 and 5 studies, respectively, Table 1). Heterogeneity testing was performed using Cochran's Q test and I 2 values. The Cochran's Q test p-value was less than 0.10 (p<0.01), and the I 2 value was more than 50% (I 2=87%), indicating the presence of heterogeneity. Thus, random-effects models were used. Asymmetry test was performed using Egger's linear regression test, which suggested the presence of publication bias (p=0.001; Figure 2). Thus, the trim-and-fill method was used to adjust for publication bias. Pooled ORR was 53% (95% CI, 43-63%) (Figure 2). Similarly, pooled CRc was 34% (95% CI, 26-44%, Figure 3). Pooled CRc and ORR were higher in studies involving quizartinib (40% and 61%, respectively) and gilteritinib (40% and 52%, respectively, Table 1). The CRc rates seen with FLT3 inhibitors are higher than the historical comparison of pts with FLT3-mutated-R/R AML treated with chemo only (CRc ~15%). This meta-analysis shows that FLT3 inhibitors as monotherapy leads to meaningful clinical responses in pts with FLT3-mutated-R/R AML. Conclusion: Most FLT3 inhibitors are effective as monotherapy for the treatment of pts with FLT3-mutated-R/R AML. Pooled response rates are notably higher in studies involving second-generation FLT3 inhibitors, particularly quizartinib and gilteritinib. Though not conclusive, the efficacy spectrum of various FLT3 inhibitors in the R/R setting could help design future studies and guide appropriate treatment selection; however, further validation is needed. Prospective clinical trials are required to compare the effectiveness of newer generation FLT3 inhibitors in pts with FLT3-mutated-R/R AML. Figure 1 Figure 1. Disclosures Maciejewski: Bristol Myers Squibb/Celgene: Consultancy; Novartis: Consultancy; Regeneron: Consultancy; Alexion: Consultancy. Balasubramanian: Servier Pharmaceuticals: Research Funding.

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A dual inhibitor overcomes drug-resistant FLT3-ITD acute myeloid leukemia

Journal of Hematology & Oncology ◽

10.1186/s13045-021-01098-y ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Peihong Wang ◽

Xinhua Xiao ◽

Yuyin Zhang ◽

Baoyuan Zhang ◽

Donghe Li ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Point Mutations ◽

Genetic Alterations ◽

Tyrosine Kinase Domain ◽

Drug Resistant ◽

Dual Inhibitor ◽

Flt3 Mutations ◽

Flt3 Inhibitors ◽

Acute Myeloid

AbstractFLT3 mutations are the most frequently identified genetic alterations in acute myeloid leukemia (AML) and are associated with poor prognosis. Multiple FLT3 inhibitors are in various stages of clinical evaluation. However, resistance to FLT3 inhibitors resulting from acquired point mutations in tyrosine kinase domain (TKD) have limited the sustained efficacy of treatments, and a “gatekeeper” mutation (F691L) is resistant to most available FLT3 inhibitors. Thus, new FLT3 inhibitors against both FLT3 internal tandem duplication (FLT3-ITD) and FLT3-TKD mutations (including F691L) are urgently sought. Herein, we identified KX2-391 as a dual FLT3 and tubulin inhibitor and investigated its efficacy and mechanisms in overcoming drug-resistant FLT3-ITD-TKD mutations in AML. KX2-391 exhibited potent growth inhibitory and apoptosis promoting effects on diverse AML cell lines harboring FLT3-ITD mutations and AC220-resistant mutations at the D835 and F691 residues in TKD and inhibited FLT3 phosphorylation and its downstream signaling targets. Orally administered KX2-391 significantly prolonged the survival of a murine leukemia model induced by FLT3-ITD-F691L. KX2-391 also significantly inhibited the growth of 4 primary AML cells expressing FLT3-ITD and 2 primary AML cells expressing FLT3-ITD-D835Y. Our preclinical data highlight KX2-391 as a promising FLT3 inhibitor for the treatment of AML patients harboring FLT3 mutations, especially refractory/relapsed patients with F691L and other FLT3-TKD mutations.

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