Go6976, a Potent FLT3 Kinase Inhibitor, Exerts Antiproliferative Activity Against Acute Myeloid Leukemia Via Inhibition Of Survivin and Mcl-1 In The Presence Of Human Serum

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3839-3839
Author(s):  
Akira Yoshida ◽  
Kouichi Zokumasu ◽  
Takanori Ueda

Abstract The FMS-like tyrosine kinase 3 (FLT3) is a class III receptor tyrosine kinase involved in hematopoietic progenitor cell development. Mutations of FLT3 have been reported in about a third of patients with acute myeloid leukemia (AML). The presence of FLT3 mutations confers a poor prognosis, and thus recent studies are directed at developing and testing novel FLT3 inhibitors for the treatment of AML. Go6976 is an indolocarbazole with a simillar structural backbone to staurosporine. In the present study, we demonstrated that Go6976 displays a potent inhibitory activity against recombinant FLT3 using in vitro kinase assay. Its IC50 value is 0.7nM. We also tested the effect of Go6976 on several kinds of other kinases. Go6976 inhibited the kinase activity of Aurora-A, Aurora-B and JAK2 with IC50 values of 118.2 nM, 77.7 nM and 92.7 nM, respectively. Go6976 did not show the inhibitory activity against the FGFR3 even at 1 microM. These data indicated Go6976 preferentially and potently inhibit the FLT3. Go6976 significantly inhibited the proliferation of human leukemia cells having FLT3-ITD. The IC50 values of Go6976 against MV4-11 and MOLM-13 were 0.044 and 0.008 microM, respectively. In contrast, human leukemia HL-60 and U937 cells which lack FLT3-ITD showed strong resistance to Go6976 treatment. Furthermore, we observed that Go6976 shows minimal toxicity for purified human normal CD34(+) cells. Go6976 suppressed the phosphorylation of FLT3 in MV4-11 and MOLM13 cells. Consistent with FLT3 inhibition, Go6976 potently inhibited phosphorylation of constitutively activated STAT3/5, Erk1/2, and Akt. Western blotting analysis revealed that MV4-11 and MOLM13 cells possess abundant survivin and Mcl-1 protein. We hypothesized that the expression of survivin and Mcl-1 may be regulated by constitutive activation of FLT3. In order to test this hypothesis, the effect of siRNA for FLT3-ITD was examined. Indeed, we observed that siRNA-induced down-regulation of FLT3 decreased survivin and Mcl-1 expression in MOLM13 cells, suggesting that up-regulated survivin and Mcl-1 may be closely associated with FLT3 signaling. Interestingly, we found that both survivin mRNA and protein were rapidly downregulated by Go6976 treatment in MOLM13 and MV4-11 cells. It was also observed that Go6976 significantly suppressed Mcl-1 mRNA and protein. It has been reported that STAT-3 and STAT-5 signaling play a pivotal role in the regulation of survivin and Mcl-1, respectively. Thus, inhibitory effects of Go6976 on the expression Survivin and Mcl-1 may be a consequence of the suppression of phosphorylation of STAT-3 and STAT-5 by Go6976 in FLT3-ITD cells. This inhibition of anti-apoptotic proteins by Go6976 may be critical for its antiproliferative effect in FLT3-ITD cells. It has been known that previous FLT3 inhibitors such as PKC412 and CEP-701 bind to the human plasma protein, alpha1-acid glycoprotein, resulting in significantly diminished inhibitory activity against FLT3. Indeed, inhibitory effect of PKC412 on FLT3 was significantly decreased, when MOLM13 cells were treated with PKC412 in the presence of human serum. In contrast, we found that Go6976 potently inhibits phosphorylation of FLT3 and exerts cytotoxicity even in the presence of human serum or human alpha1-acid glycoprotein. In conclusion, our data indicate that Go6976 may have a unique therapeutic potential for FLT3-driven acute myeloid leukemia. Disclosures: No relevant conflicts of interest to declare.

Cells ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 2493
Author(s):  
Sebastian Scholl ◽  
Maximilian Fleischmann ◽  
Ulf Schnetzke ◽  
Florian H. Heidel

Treatment of FMS-like tyrosine kinase 3 (FLT3)-internal tandem duplication (ITD)-positive acute myeloid leukemia (AML) remains a challenge despite the development of novel FLT3-directed tyrosine kinase inhibitors (TKI); the relapse rate is still high even after allogeneic stem cell transplantation. In the era of next-generation FLT3-inhibitors, such as midostaurin and gilteritinib, we still observe primary and secondary resistance to TKI both in monotherapy and in combination with chemotherapy. Moreover, remissions are frequently short-lived even in the presence of continuous treatment with next-generation FLT3 inhibitors. In this comprehensive review, we focus on molecular mechanisms underlying the development of resistance to relevant FLT3 inhibitors and elucidate how this knowledge might help to develop new concepts for improving the response to FLT3-inhibitors and reducing the development of resistance in AML. Tailored treatment approaches that address additional molecular targets beyond FLT3 could overcome resistance and facilitate molecular responses in AML.


2020 ◽  
Vol 12 (10) ◽  
pp. 961-981 ◽  
Author(s):  
Lexian Tong ◽  
Xuemei Li ◽  
Yongzhou Hu ◽  
Tao Liu

Fms-like tyrosine kinase-3 (FLT3) mutations occur in approximately 30% of acute myeloid leukemia (AML) cases, suggesting FLT3 as an attractive target for AML treatment. Early FLT3 inhibitors enhance antileukemia efficacy by inhibiting multiple targets, and thus had stronger off-target activity, increasing their toxicity. Recently, a number of potent and selective FLT3 inhibitors have been developed, many of which are effective against multiple mutations. This review outlines the evolution of AML-targeting FLT3 inhibitors by focusing on their chemotypes, selectivity and activity over FLT3 wild-type and FLT3 mutations as well as new techniques related to FLT3. Compounds that currently enter the late clinical stage or have entered the market are also briefly reported.


2019 ◽  
Vol 51 (5) ◽  
pp. 478-483
Author(s):  
Cade D Arries ◽  
Sophia L Yohe

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.


2019 ◽  
Vol 10 ◽  
pp. 204062071982731 ◽  
Author(s):  
Nicholas J. Short ◽  
Hagop Kantarjian ◽  
Farhad Ravandi ◽  
Naval Daver

Mutations in the fms-like tyrosine kinase 3 ( FLT3) gene are detected in approximately one-third of patients with newly diagnosed acute myeloid leukemia (AML). These consist of the more common FLT3-internal tandem duplication (ITD) in approximately 20–25% of AML cases, and point mutations in the tyrosine kinase domain (TKD) in approximately 5–10%. FLT3 mutations, especially FLT3-ITD, are associated with proliferative disease, increased risk of relapse, and inferior overall survival when treated with conventional regimens. However, the recent development of well tolerated and active FLT3 inhibitors has significantly improved the outcomes of this aggressive subtype of AML. The multikinase inhibitor midostaurin was approved by the United States Food and Drug Administration (US FDA) in April 2017 for the frontline treatment of patients with FLT3-mutated (either ITD or TKD) AML in combination with induction chemotherapy, representing the first new drug approval in AML in nearly two decades. In November 2018, the US FDA also approved the second-generation FLT3 inhibitor gilteritinib as a single agent for patients with relapsed or refractory FLT3-mutated AML. Promising phase I and II efficacy data for quizartinib is likely to lead to a third regulatory approval in relapsed/refractory AML in the near future. However, despite the significant progress made in managing FLT3-mutated AML, many questions remain regarding the best approach to integrate these inhibitors into combination regimens, and also the optimal sequencing of different FLT3 inhibitors in various clinical settings. This review comprehensively examines the FLT3 inhibitors currently in clinical development, with an emphasis on their spectra of activity against different FLT3 mutations and other kinases, clinical safety and efficacy data, and their current and future roles in the management of AML. The mechanisms of resistance to FLT3 inhibitors and potential combination strategies to overcome such resistance pathways are also discussed.


Blood ◽  
2006 ◽  
Vol 108 (3) ◽  
pp. 1030-1036 ◽  
Author(s):  
Lars Palmqvist ◽  
Bob Argiropoulos ◽  
Nicolas Pineault ◽  
Carolina Abramovich ◽  
Laura M. Sly ◽  
...  

Abstract In leukemogenesis, several genetic changes conferring a proliferative and/or survival advantage to hematopoietic progenitor cells in addition to a block in differentiation are required. Here, we demonstrate that overexpression of the wild-type (wt) Flt3 receptor tyrosine kinase collaborates with NUP98-HOX fusions (NUP98-HOXA10 and NUP98-HOXD13) to induce aggressive acute myeloid leukemia (AML). We used a mouse transplantation model to show their synergism in cotransduced bone marrow cells as well as in a cellular model of leukemic progression. Furthermore, our data support the finding that Meis1 overexpression leads to marked elevation in Flt3 transcription and extend it to the context of NUP98-HOX–induced leukemia. Together, these results support a multistep model where the synergism between NUP98-HOX and wt-Flt3 is the result of the ability of Flt3 to increase proliferation of myeloid progenitors blocked in differentiation by NUP98-HOX fusions and reveal a direct role for wt-Flt3 in the pathobiology of AML. Given the similarities in the leukemogenic role of native HOX and NUP98-fused HOX genes, our results underscore the clinical significance of the recurrent co-overexpression of wt-FLT3 and HOX in human leukemia and suggest that specific FLT3 inhibitors could be useful in treatment of HOX-induced AML or acute lymphoblastic leukemia (ALL).


2015 ◽  
Vol 1 (8) ◽  
pp. e1500221 ◽  
Author(s):  
Alexa S. Green ◽  
Thiago T. Maciel ◽  
Marie-Anne Hospital ◽  
Chae Yin ◽  
Fetta Mazed ◽  
...  

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.


2018 ◽  
Vol 25 (1) ◽  
pp. 163-171 ◽  
Author(s):  
Christan M Thomas ◽  
Peter Campbell

FMS-like tyrosine kinase 3 (FLT3) is a receptor tyrosine kinase that is responsible for the proliferation and survival of hematopoietic stem cells in acute myeloid leukemia. Although patients with FLT3 mutations have similar rates of remission following induction chemotherapy, relapse rates are significantly higher and patients with FLT3 mutations have significantly worse outcomes for overall survival and disease-free survival. Early FLT3 inhibitors, such as sorafenib, were non-selective and inhibited several tyrosine kinase receptors resulting in significant toxicity. The treatment of FLT3-positive acute myeloid leukemia has advanced recently with the development of a several FLT3-targeting agents that are either approved or in development. Midostaurin represents the first FDA-approved treatment targeted against FLT3, and there are several promising agents currently undergoing clinical trials. Although certain mutations confer resistance to earlier generation FLT3-targeted tyrosine kinase inhibitors, newer agents show activity in the presence of these mutations.


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