-
Cancers Apr 2023mutations are present in 30% of newly diagnosed patients with acute myeloid leukemia. Two broad categories of mutations are ITD and TKD, with the former having... (Review)
Review
mutations are present in 30% of newly diagnosed patients with acute myeloid leukemia. Two broad categories of mutations are ITD and TKD, with the former having substantial clinical significance. Patients with -ITD mutation present with a higher disease burden and have inferior overall survival, due to high relapse rates after achieving remission. The development of targeted therapies with FLT3 inhibitors over the past decade has substantially improved clinical outcomes. Currently, two FLT3 inhibitors are approved for use in patients with acute myeloid leukemia: midostaurin in the frontline setting, in combination with intensive chemotherapy; and gilteritinib as monotherapy in the relapsed refractory setting. The addition of FLT3 inhibitors to hypomethylating agents and venetoclax offers superior responses in several completed and ongoing studies, with encouraging preliminary data. However, responses to FLT3 inhibitors are of limited duration due to the emergence of resistance. A protective environment within the bone marrow makes eradication of leukemic cells difficult, while prior exposure to FLT3 inhibitors leads to the development of alternative mutations as well as activating mutations in downstream signaling, promoting resistance to currently available therapies. Multiple novel therapeutic strategies are under investigation, including BCL-2, menin, and MERTK inhibitors, as well as FLT3-directed BiTEs and CAR-T therapy.
PubMed: 37190240
DOI: 10.3390/cancers15082312 -
Blood Jun 2021In the international randomized phase 3 RATIFY (Randomized AML Trial In FLT3 in patients less than 60 Years old) trial, the multikinase inhibitor midostaurin... (Clinical Trial)
Clinical Trial
In the international randomized phase 3 RATIFY (Randomized AML Trial In FLT3 in patients less than 60 Years old) trial, the multikinase inhibitor midostaurin significantly improved overall and event-free survival in patients 18 to 59 years of age with FLT3-mutated acute myeloid leukemia (AML). However, only 59% of patients in the midostaurin arm achieved protocol-specified complete remission (CR), and almost half of patients achieving CR relapsed. To explore underlying mechanisms of resistance, we studied patterns of clonal evolution in patients with FLT3-internal tandem duplications (ITD)-positive AML who were entered in the RATIFY or German-Austrian Acute Myeloid Leukemia Study Group 16-10 trial and received treatment with midostaurin. To this end, paired samples from 54 patients obtained at time of diagnosis and at time of either relapsed or refractory disease were analyzed using conventional Genescan-based testing for FLT3-ITD and whole exome sequencing. At the time of disease resistance or progression, almost half of the patients (46%) became FLT3-ITD negative but acquired mutations in signaling pathways (eg, MAPK), thereby providing a new proliferative advantage. In cases with FLT3-ITD persistence, the selection of resistant ITD clones was found in 11% as potential drivers of disease. In 32% of cases, no FLT3-ITD mutational change was observed, suggesting either resistance mechanisms bypassing FLT3 inhibition or loss of midostaurin inhibitory activity because of inadequate drug levels. In summary, our study provides novel insights into the clonal evolution and resistance mechanisms of FLT3-ITD-mutated AML under treatment with midostaurin in combination with intensive chemotherapy.
Topics: Adolescent; Adult; Aged; Clonal Evolution; Female; Humans; Leukemia, Myeloid, Acute; Male; Middle Aged; Mutation; Staurosporine; Tandem Repeat Sequences; Exome Sequencing; fms-Like Tyrosine Kinase 3
PubMed: 33598693
DOI: 10.1182/blood.2020007626 -
Expert Opinion on Pharmacotherapy 2023Traditional treatment strategies for acute myeloid leukemia (AML) have primarily relied on standard chemotherapy regimens for four decades. Indeed, the landscape of AML... (Review)
Review
INTRODUCTION
Traditional treatment strategies for acute myeloid leukemia (AML) have primarily relied on standard chemotherapy regimens for four decades. Indeed, the landscape of AML therapy has evolved substantially in recent years, mainly due to the introduction of hypomethylating agents and small molecules.Bcl2 inhibitor venetoclax, Fms-like tyrosine kinase 3 (FLT3) inhibitors such as midostaurin and gilteritinib, and isocitrate dehydrogenases 1 and 2 (IDH1 and IDH2) inhibitors ivosidenib and enasidenib, as well as hedgehog (HH) pathway inhibitor glasdegib represented a significant step forward in AML therapeutic armamentarium. Smoothened (SMO) inhibitor in combination with low-dose cytarabine marks a recent milestone.
AREAS COVERED
Ivosidenib, the first-in-class, selective, allosteric IDH1R132 inhibitor, showed the capability to induce differentiation of primary mIDH1 AML blasts. Clinical data highlighted its exceptional safety profile, as a standalone therapy and in combination strategy. Additionally, comprehensive studies consistently demonstrated its effectiveness, both in monotherapy and in association with chemotherapy.
EXPERT OPINION
The identified ivosidenib's strengths, including its remarkable safety record and ability to yield positive therapeutic outcomes, position it as an ideal partner for both classic chemotherapy and biological treatments, i.e. hypometilant agents and/or venetoclax. Further studies are warranted to explore strategies for overcoming the occurrence of ivosidenib resistance.
Topics: Humans; Hedgehog Proteins; Leukemia, Myeloid, Acute; Pyridines; Antineoplastic Agents; Mutation
PubMed: 37874005
DOI: 10.1080/14656566.2023.2272659 -
Blood Cancer Journal Sep 2023FLT3 is the most frequently mutated gene in acute myeloid leukemia (AML), with FLT3 internal tandem duplication (ITD) mutations being associated with a more aggressive... (Review)
Review
FLT3 is the most frequently mutated gene in acute myeloid leukemia (AML), with FLT3 internal tandem duplication (ITD) mutations being associated with a more aggressive clinical course. While two large, randomized clinical trials have shown a survival benefit with the frontline use of an oral FLT3 inhibitor (midostaurin or quizartinib) in patients with FLT3-mutated AML, the role of FLT3 inhibitors in older adults with newly diagnosed FLT3-mutated AML remains unclear. A definitive improvement in survival has not been observed in intensively treated patients over 60 years of age receiving frontline FLT3 inhibitors. Furthermore, many patients with FLT3-mutated AML are unsuitable for intensive chemotherapy due to age and/or comorbidities, and this population represents a particular unmet need. For these older patients who are unfit for intensive approaches, azacitidine + venetoclax is a new standard of care and is used by many clinicians irrespective of FLT3 mutation status. However, FLT3-ITD mutations confer resistance to venetoclax and are a well-established mechanism of relapse to lower-intensity venetoclax-based regimens, leading to short durations of remission and poor survival. Preclinical and clinical data suggest synergy between FLT3 inhibitors and venetoclax, providing rationale for their combination. Novel strategies to safely incorporate FLT3 inhibitors into the standard hypomethylating agent + venetoclax backbone are now being explored in this older, less fit population with newly diagnosed FLT3-mutated AML, with encouraging early results. Herein, we discuss the frontline use of FLT3 inhibitors in older adults with FLT3-mutated AML, including the potential role of FLT3 inhibitors in combination with intensive chemotherapy and as part of novel, lower-intensity doublet and triplet regimens in this older population.
Topics: Humans; Middle Aged; Aged; Sulfonamides; Protein Kinase Inhibitors; Leukemia, Myeloid, Acute; Mutation; fms-Like Tyrosine Kinase 3
PubMed: 37696819
DOI: 10.1038/s41408-023-00911-w -
Leukemia Jan 2023The real-world efficacy and safety of gilteritinib was assessed in an ambispective study that included 167 R/R FLT3-mutated AML patients. Among them, 140 received...
Gilteritinib activity in refractory or relapsed FLT3-mutated acute myeloid leukemia patients previously treated by intensive chemotherapy and midostaurin: a study from the French AML Intergroup ALFA/FILO.
The real-world efficacy and safety of gilteritinib was assessed in an ambispective study that included 167 R/R FLT3-mutated AML patients. Among them, 140 received gilteritinib as single agent (cohort B), including 67 previously treated by intensive chemotherapy and midostaurin (cohort C). The main differences in patient characteristics in this study compared to the ADMIRAL trial were ECOG ≥ 2 (83.6% vs. 16.6%), FLT3-TKD mutation (21.0% vs. 8.5%), primary induction failure (15.0% vs. 40.0%) and line of treatment (beyond 2nd in 37.1% vs. 0.0%). The rates of composite complete remission, excluding those that occurred after hematopoietic stem cell transplantation (HSCT), were similar at respectively 25.4% and 27.5% in cohorts B and C. Median overall survival (OS) for these two groups was also similar at respectively 6.4 and 7.8 months. Multivariate analyses for prognostic factors associated with OS identified female gender (HR 1.61), adverse cytogenetic risk (HR 2.52), and allogenic HSCT after gilteritinib (HR 0.13). Although these patients were more heavily pretreated, these real-world data reproduce the results of ADMIRAL and provide new insights into the course of patients previously treated by intensive chemotherapy and midostaurin and beyond the 2nd line of treatment who can benefit from treatment in an outpatient setting.
Topics: Humans; Female; Mutation; Leukemia, Myeloid, Acute; Staurosporine; fms-Like Tyrosine Kinase 3
PubMed: 36376378
DOI: 10.1038/s41375-022-01742-7 -
Blood Mar 2023Fms-like tyrosine kinase 3 (FLT3) is often overexpressed or constitutively activated by internal tandem duplication (ITD) and tyrosine kinase domain (TKD) mutations in...
Fms-like tyrosine kinase 3 (FLT3) is often overexpressed or constitutively activated by internal tandem duplication (ITD) and tyrosine kinase domain (TKD) mutations in acute myeloid leukemia (AML). Despite the use of receptor tyrosine kinase inhibitors (TKI) in FLT3-ITD-positive AML, the prognosis of patients is still poor, and further improvement of therapy is required. Targeting FLT3 independent of mutations by antibody-drug conjugates (ADCs) is a promising strategy for AML therapy. Here, we report the development and preclinical characterization of a novel FLT3-targeting ADC, 20D9-ADC, which was generated by applying the innovative P5 conjugation technology. In vitro, 20D9-ADC mediated potent cytotoxicity to Ba/F3 cells expressing transgenic FLT3 or FLT3-ITD, to AML cell lines, and to FLT3-ITD-positive patient-derived xenograft AML cells. In vivo, 20D9-ADC treatment led to a significant tumor reduction and even durable complete remission in AML xenograft models. Furthermore, 20D9-ADC demonstrated no severe hematotoxicity in in vitro colony formation assays using concentrations that were cytotoxic in AML cell line treatment. The combination of 20D9-ADC with the TKI midostaurin showed strong synergy in vitro and in vivo, leading to reduction of aggressive AML cells below the detection limit. Our data indicate that targeting FLT3 with an advanced new-generation ADC is a promising and potent antileukemic strategy, especially when combined with FLT3-TKI in FLT3-ITD-positive AML.
Topics: Humans; fms-Like Tyrosine Kinase 3; Protein Kinase Inhibitors; Antineoplastic Agents; Leukemia, Myeloid, Acute; Mutation
PubMed: 35981498
DOI: 10.1182/blood.2021015246 -
Current Treatment Options in Oncology Mar 2022Treatment options in acute myeloid leukemia (AML) have improved significantly over the last decade with better understanding of disease biology and availability of a... (Review)
Review
Treatment options in acute myeloid leukemia (AML) have improved significantly over the last decade with better understanding of disease biology and availability of a multitude of targeted therapies. The use of FLT3 inhibitors (FLT3i) in FLT3-mutated (FLT3) AML is one such development; however, the clinical decisions that govern their use and dictate the choice of the FLT3i are evolving. Midostaurin and gilteritinib are FDA-approved in specific situations; however, available data from clinical trials also shed light on the utility of sorafenib maintenance post-allogeneic stem cell transplantation (allo-SCT) and quizartinib as part of combination therapy in FLT3 AML. The knowledge of the patient's concurrent myeloid mutations, type of FLT3 mutation, prior FLT3i use, and eligibility for allo-SCT helps to refine the choice of FLT3i. Data from ongoing studies will further precisely define their use and help in making more informed choices. Despite improvements in FLT3i therapy, the definitive aim is to enable the eligible patient with FLT3 AML (esp. ITD) to proceed to allo-SCT with regimens containing FLT3i incorporated prior to SCT and as maintenance after SCT.
Topics: Hematopoietic Stem Cell Transplantation; Humans; Leukemia, Myeloid, Acute; Mutation; Protein Kinase Inhibitors; Transplantation, Homologous; fms-Like Tyrosine Kinase 3
PubMed: 35258791
DOI: 10.1007/s11864-022-00952-6 -
International Journal of Hematology Sep 2022Mutations in the FMS-like tyrosine kinase 3 (FLT3) gene are detected in approximately 30% of acute myeloid leukemia (AML). The high frequency of FLT3 mutations, along... (Review)
Review
Mutations in the FMS-like tyrosine kinase 3 (FLT3) gene are detected in approximately 30% of acute myeloid leukemia (AML). The high frequency of FLT3 mutations, along with their adverse effect on prognosis, makes FLT3 a promising therapeutic target, and has spurred development of FLT3 inhibitors. First-generation inhibitors, including midostaurin and sorafenib, lack specificity for FLT3 and act on multiple kinases, whereas second-generation inhibitors, including gilteritinib, and quizartinib, are highly specific to FLT3 and are more potent than first-generation inhibitors. Several FLT3 inhibitors have recently gained regulatory approval worldwide, and several others are under development. The advent of FLT3 inhibitors has changed the standard treatment for FLT3-mutated AML in the frontline and relapsed/refractory settings and contributed to improved outcomes for this formidable AML subtype. However, numerous unresolved issues remain owing to rapid changes in practice. These include identification of optimum FLT3 inhibitors and combination therapies, the role of maintenance therapy, and the indication for allogeneic hematopoietic cell transplantation. Furthermore, strategies to overcome resistance to FLT3 inhibitors must be pursued. Results of ongoing and future studies will improve our ability to use FLT3 inhibitors more effectively, which should provide significant benefits to a wider range of patients.
Topics: Antineoplastic Agents; Hematopoietic Stem Cell Transplantation; Humans; Leukemia, Myeloid, Acute; Mutation; Protein Kinase Inhibitors; fms-Like Tyrosine Kinase 3
PubMed: 35532877
DOI: 10.1007/s12185-022-03374-0 -
Immunology and Allergy Clinics of North... Nov 2023Systemic mastocytosis is associated with KIT D816V mutation in more than 90% of cases. Patients with non-advanced forms of mastocytosis (indolent systemic mastocytosis,... (Review)
Review
Systemic mastocytosis is associated with KIT D816V mutation in more than 90% of cases. Patients with non-advanced forms of mastocytosis (indolent systemic mastocytosis, bone marrow mastocytosis, and smoldering systenic mastocytosis) have a low rate of progession to advanced variants and generally have a comparable life expectancy to age-matched general population. Symptomatology in non-advanced mastocytosis is variable and is related to mast cell mediator release. While some patients require no or minimal symptomatic therapy with antimediator drugs, other may suffer from refractory symptoms impacting the quality of life despite being on multiple anti-mediator drugs. KIT tyrosine kinase inhibitors have been approved for advanced SM, and avapritinib has also been recently approved as the first such inhibitor for indolent systemic mastocytosis. Other TKIs are currently in clinical trials for patients with non-advanced SM who have persistent and severe symptoms despite optimized antimediator therapy. This article will review the current state of the science and available clinical data from trials of tyrosine kinase inhibitors in non-advanced systemic mastocytosis.
PubMed: 37758410
DOI: 10.1016/j.iac.2023.05.001 -
Annals of Hematology Oct 2023The addition of midostaurin to standard chemotherapy has improved survival in patients with FLT3-mutated AML. However, the impact of midostaurin and other FLT3... (Review)
Review
Treatment with midostaurin and other FLT3 targeting inhibitors is associated with an increased risk of cardiovascular adverse events in patients who underwent allogeneic hematopoietic stem cell transplantation with FLT3-mutated AML.
The addition of midostaurin to standard chemotherapy has improved survival in patients with FLT3-mutated AML. However, the impact of midostaurin and other FLT3 inhibitors (FLT3i) on cardiovascular adverse events (CAEs) has not been studied in patients who underwent allogeneic hematopoietic stem cell transplantation in a real-world setting. We reviewed 132 patients with AML who were treated with intensive induction therapy and consecutive allogeneic stem cell transplantation at our institution (42 FLT3-mutated AML and 90 with FLT3 wildtype). We identified treatment with midostaurin and/or FLT3i as an independent risk factor for CAEs not resulting in higher non-relapse mortality (NRM) or impaired overall survival (OS). Hence, close monitoring for CAEs is warranted for these patients.
Topics: Humans; Leukemia, Myeloid, Acute; Mutation; Staurosporine; Protein Kinase Inhibitors; Hematopoietic Stem Cell Transplantation; fms-Like Tyrosine Kinase 3
PubMed: 37552323
DOI: 10.1007/s00277-023-05396-y