FLT3 as a therapeutic target in AML: still challenging after all these years

Blood ◽  
2010 ◽  
Vol 116 (24) ◽  
pp. 5089-5102 ◽  
Author(s):  
Thomas Kindler ◽  
Daniel B. Lipka ◽  
Thomas Fischer
Keyword(s):  
Acute Myeloid Leukemia ◽  
Tyrosine Kinase ◽  
Myeloid Leukemia ◽  
Kinase Inhibitors ◽  
Genetic Alterations ◽  
Molecular Target ◽  
Lessons Learned ◽  
Laboratory Studies ◽  
Flt3 Inhibitor ◽  
Acute Myeloid

Abstract Mutations within the FMS-like tyrosine kinase 3 (FLT3) gene on chromosome 13q12 have been detected in up to 35% of acute myeloid leukemia (AML) patients and represent one of the most frequently identified genetic alterations in AML. Over the last years, FLT3 has emerged as a promising molecular target in therapy of AML. Here, we review results of clinical trials and of correlative laboratory studies using small molecule FLT3 tyrosine kinase inhibitors (TKIs) in AML patients. We also review mechanisms of primary and secondary drug resistance to FLT3-TKI, and from the data currently available we summarize lessons learned from FLT3-TKI monotherapy. Finally, for using FLT3 as a molecular target, we discuss novel strategies to overcome treatment failure and to improve FLT3 inhibitor therapy.

scholarly journals A phase 1/2 study of the oral FLT3 inhibitor pexidartinib in relapsed/refractory FLT3-ITD–mutant acute myeloid leukemia

2020 ◽  
Vol 4 (8) ◽  
pp. 1711-1721 ◽  
Author(s):  
Catherine C. Smith ◽  
Mark J. Levis ◽  
Olga Frankfurt ◽  
John M. Pagel ◽  
Gail J. Roboz ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Tyrosine Kinase ◽  
Myeloid Leukemia ◽  
Drug Exposure ◽  
Kinase Inhibitors ◽  
Response Rate ◽  
Phase 1 ◽  
Complete Response ◽  
Flt3 Inhibitor ◽  
Acute Myeloid

Abstract FMS-like tyrosine kinase 3 (FLT3) tyrosine kinase inhibitors (TKIs) have activity in acute myeloid leukemia (AML) patients with FLT3 internal tandem duplication (ITD) mutations, but efficacy is limited by resistance-conferring kinase domain mutations. This phase 1/2 study evaluated the safety, tolerability, and efficacy of the oral FLT3 inhibitor PLX3397 (pexidartinib), which has activity against the FLT3 TKI–resistant F691L gatekeeper mutation in relapsed/refractory FLT3-ITD–mutant AML. Ninety patients were treated: 34 in dose escalation (part 1) and 56 in dose expansion (part 2). Doses of 800 to 5000 mg per day in divided doses were tested. No maximally tolerated dose was reached. Plasma inhibitory assay demonstrated that patients dosed with ≥3000 mg had sufficient levels of active drug in their trough plasma samples to achieve 95% inhibition of FLT3 phosphorylation in an FLT3-ITD AML cell line. Based on a plateau in drug exposure, the 3000-mg dose was chosen as the recommended phase 2 dose. The most frequently reported treatment-emergent adverse events were diarrhea (50%), fatigue (47%), and nausea (46%). Based on modified response criteria, the overall response rate to pexidartinib among all patients was 21%. Twenty-three percent of patients treated at ≥2000 mg responded. The overall composite complete response rate for the study was 11%. Six patients were successfully bridged to transplantation. Median overall survival (OS) of patients treated in dose expansion was 112 days (90% confidence interval [CI], 77-150 days), and median OS of responders with complete remission with or without recovery of blood counts was 265 days (90% CI, 170-422 days). This trial was registered at www.clinicaltrials.gov as #NCT01349049.

Gilteritinib use in the treatment of relapsed or refractory acute myeloid leukemia with a FLT3 mutation

2020 ◽  
Author(s):  
Octavio Ballesta-López ◽  
Antonio Solana-Altabella ◽  
Juan Eduardo Megías-Vericat ◽  
David Martínez-Cuadrón ◽  
Pau Montesinos
Keyword(s):  
Acute Myeloid Leukemia ◽  
Tyrosine Kinase ◽  
Myeloid Leukemia ◽  
Kinase Inhibitors ◽  
Salvage Chemotherapy ◽  
Mechanisms Of Resistance ◽  
Flt3 Inhibitor ◽  
Refractory Acute Myeloid Leukemia ◽  
Dose Reductions ◽  
Acute Myeloid

The prognosis of patients with relapsed or refractory acute myeloid leukemia (R/R AML) is dismal with salvage standard approaches, and mutations of FMS-like tyrosine kinase 3 ( FLT3) gene, occurring in around 30% of AML patients may confer even poorer outcomes. Several targeted tyrosine kinase inhibitors have been developed to improve FLT3-mutated AML patient´s survival. Gilteritinib, a highly specific second-generation class I oral FLT3 inhibitor, has demonstrated superiority to salvage chemotherapy (SC) in R/R FLT3 mutated AML based on significantly longer OS in the gilteritinib arm than in the SC arm. Gilteritinib is generally well tolerated, but some clinically relevant adverse events should be monitored, especially myelosuppression, QTc prolongation and differentiation syndrome, usually manageable (dose reductions, interruption or discontinuation) and reversible. We discuss clinical development, efficacy, safety and mechanisms of resistance of gilteritinib in the treatment of R/R patients with FLT3 mutated AML.

Quizartinib in the treatment of FLT3-internal-tandem duplication-positive acute myeloid leukemia

2019 ◽  
Vol 15 (34) ◽  
pp. 3885-3894 ◽  
Author(s):  
Shilpa Paul ◽  
Adam J DiPippo ◽  
Farhad Ravandi ◽  
Tapan M Kadia
Keyword(s):  
Acute Myeloid Leukemia ◽  
Tyrosine Kinase ◽  
Myeloid Leukemia ◽  
Tandem Duplication ◽  
Kinase Inhibitors ◽  
Single Agent ◽  
Tyrosine Kinase Domain ◽  
Missense Mutations ◽  
Internal Tandem Duplication ◽  
Acute Myeloid

FLT3 mutations, characterized by an internal-tandem duplication or missense mutations in the tyrosine kinase domain, are observed in a third of patients with newly diagnosed acute myeloid leukemia. FLT3-ITD mutations are associated with high relapse rates and short overall survival with conventional chemotherapy. Several tyrosine kinase inhibitors targeting FLT3 have been developed in an effort to improve survival and therapeutic options. This review focuses on quizartinib, a second-generation FLT3 inhibitor that has demonstrated efficacy and safety as a single agent and in combination with chemotherapy. We discuss its clinical development as well as its place in the treatment of FLT3-mutated acute myeloid leukemia among the other FLT3 inhibtors currently available and its mechanisms of resistance.

scholarly journals Tyrosine kinase inhibitors targeting FLT3 in the treatment of acute myeloid leukemia

2017 ◽  
Vol 4 (6) ◽  
pp. 48-48 ◽  
Author(s):  
Yun Chen ◽  
Yihang Pan ◽  
Yao Guo ◽  
Wanke Zhao ◽  
Wanting Tina Ho ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Tyrosine Kinase ◽  
Tyrosine Kinase Inhibitors ◽  
Myeloid Leukemia ◽  
Kinase Inhibitors ◽  
Acute Myeloid

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

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.

scholarly journals MEK inhibition enhances the response to tyrosine kinase inhibitors in acute myeloid leukemia

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
María Luz Morales ◽  
Alicia Arenas ◽  
Alejandra Ortiz-Ruiz ◽  
Alejandra Leivas ◽  
Inmaculada Rapado ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Acute Myeloid Leukemia ◽  
Tyrosine Kinase ◽  
Tyrosine Kinase Inhibitors ◽  
Myeloid Leukemia ◽  
Kinase Inhibitors ◽  
Resistance Pathway ◽  
Acute Myeloid

AbstractFMS-like tyrosine kinase 3 (FLT3) is a key driver of acute myeloid leukemia (AML). Several tyrosine kinase inhibitors (TKIs) targeting FLT3 have been evaluated clinically, but their effects are limited when used in monotherapy due to the emergence of drug-resistance. Thus, a better understanding of drug-resistance pathways could be a good strategy to explore and evaluate new combinational therapies for AML. Here, we used phosphoproteomics to identify differentially-phosphorylated proteins in patients with AML and TKI resistance. We then studied resistance mechanisms in vitro and evaluated the efficacy and safety of rational combinational therapy in vitro, ex vivo and in vivo in mice. Proteomic and immunohistochemical studies showed the sustained activation of ERK1/2 in bone marrow samples of patients with AML after developing resistance to FLT3 inhibitors, which was identified as a common resistance pathway. We examined the concomitant inhibition of MEK-ERK1/2 and FLT3 as a strategy to overcome drug-resistance, finding that the MEK inhibitor trametinib remained potent in TKI-resistant cells and exerted strong synergy when combined with the TKI midostaurin in cells with mutated and wild-type FLT3. Importantly, this combination was not toxic to CD34+ cells from healthy donors, but produced survival improvements in vivo when compared with single therapy groups. Thus, our data point to trametinib plus midostaurin as a potentially beneficial therapy in patients with AML.

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