-
Blood Apr 2020Systemic mastocytosis (SM) has greatly benefited from the broad application of precision medicine techniques to hematolymphoid neoplasms. Sensitive detection of the... (Review)
Review
Systemic mastocytosis (SM) has greatly benefited from the broad application of precision medicine techniques to hematolymphoid neoplasms. Sensitive detection of the recurrent KIT D816V mutation and use of next-generation sequencing (NGS) panels to profile the genetic landscape of SM variants have been critical adjuncts to the diagnosis and subclassification of SM, and development of clinical-molecular prognostic scoring systems. Multilineage KIT involvement and multimutated clones are characteristic of advanced SM (advSM), especially SM with an associated hematologic neoplasm (AHN). A major challenge is how to integrate conventional markers of mast cell disease burden (percentage of bone marrow mast cell infiltration and serum tryptase levels) with molecular data (serial monitoring of both KIT D816V variant allele frequency and NGS panels) to lend more diagnostic and prognostic clarity to the heterogeneous clinical presentations and natural histories of advSM. The approval of the multikinase/KIT inhibitor midostaurin has validated the paradigm of KIT inhibition in advSM, and the efficacy and safety of second-generation agents, such as the switch-control inhibitor ripretinib (DCC-2618) and the D816V-selective inhibitor avapritinib (BLU-285) are being further defined in ongoing clinical trials. Looking forward, perhaps the most fruitful marriage of the advances in molecular genetics and treatment will be the design of adaptive basket trials that combine histopathology and genetic profiling to individualize treatment approaches for patients with diverse AHNs and relapsed/refractory SM.
Topics: Animals; Chromosome Aberrations; Hematopoietic Stem Cell Transplantation; Humans; Mastocytosis, Systemic; Mutation; Prognosis; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-kit; Pyrazoles; Pyrroles; Staurosporine; Triazines
PubMed: 32106312
DOI: 10.1182/blood.2019000932 -
Frontiers in Oncology 2020The FLT3 receptor is overexpressed on the majority of acute myeloid leukemia (AML) blasts. Mutations in are the most common genetic alteration in AML, identified in... (Review)
Review
The FLT3 receptor is overexpressed on the majority of acute myeloid leukemia (AML) blasts. Mutations in are the most common genetic alteration in AML, identified in approximately one third of newly diagnosed patients. internal tandem duplication mutations (ITD) are associated with increased relapse and inferior overall survival. Multiple small molecule inhibitors of FLT3 signaling have been identified, two of which (midostaurin and gilteritinib) are currently approved in the United States, and many more of which are in clinical trials. Despite significant advances, resistance to FLT3 inhibitors through secondary mutations, upregulation of parallel pathways, and extracellular signaling remains an ongoing challenge. Novel therapeutic strategies to overcome resistance, including combining FLT3 inhibitors with other antileukemic agents, development of new FLT3 inhibitors, and FLT3-directed immunotherapy are in active clinical development. Multiple questions regarding mutated AML remain. In this review, we highlight several of the current most intriguing controversies in the field including the role of FLT3 inhibitors in maintenance therapy, the role of hematopoietic cell transplantation in mutated AML, use of FLT3 inhibitors in wild-type disease, significance of non-canonical mutations, and finally, emerging concerns regarding clonal evolution.
PubMed: 33425766
DOI: 10.3389/fonc.2020.612880 -
American Journal of Hematology Mar 2022Gilteritinib is approved for the treatment of relapsed/refractory (R/R) acute myeloid leukemia (AML) with an FLT3-mutation (FLT3 ). However, the gilteritinib phase 3...
Gilteritinib is approved for the treatment of relapsed/refractory (R/R) acute myeloid leukemia (AML) with an FLT3-mutation (FLT3 ). However, the gilteritinib phase 3 ADMIRAL study (Perl et al NEJM 2019) was conducted prior to widespread adoption of either midostaurin as a component of standard intensive induction and consolidation or posttransplant FLT3 inhibitor maintenance. We performed a retrospective analysis using data from 11 US centers and where we identified 113 patients who received gilteritinib alone or as combination therapy for the treatment of R/R FLT3 AML. The composite complete remission (CR) rate (CRc, defined as CR + CR + CR with incomplete platelet recovery [CRp]) was 48.7% (n = 55). The CRc rate after treatment with gilteritinib in patients who were treated with only prior 7+3 and midostaurin with or without consolidation was 58% with a median survival of 7.8 months. Survival was longest in patients who obtained a CR, particularly a cMRD (clinical minimal or measurable residual disease) negative response; this remained significant after censoring at the time of stem cell transplant. The mitogen-activated protein kinase pathway activating mutations that are known for gilteritinib resistance (NRAS, KRAS, and PTPN11) had lower CRc (35% vs. 60.5%) and lower median overall survival than patients' whose leukemia did not express these mutations (4.9 months vs. 7.8 months) (HR 2.4; 95% CI 1. 5.4) p value <.01.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Aniline Compounds; Disease-Free Survival; Female; Humans; Leukemia, Myeloid, Acute; Male; Middle Aged; Mutation; Pyrazines; Recurrence; Retrospective Studies; Staurosporine; Survival Rate; fms-Like Tyrosine Kinase 3
PubMed: 34981560
DOI: 10.1002/ajh.26447 -
Blood Jan 2020The acute myeloid leukemia (AML) treatment landscape has changed substantially since 2017. New targeted drugs have emerged, including venetoclax to target B-cell...
The acute myeloid leukemia (AML) treatment landscape has changed substantially since 2017. New targeted drugs have emerged, including venetoclax to target B-cell lymphoma 2, midostaurin and gilteritinib to target FLT3, and ivosidenib and enasidenib to target mutant isocitrate dehydrogenase 1 and 2, respectively. Other additions include reapproval of gemtuzumab ozogomycin to target CD33, glasdegib to target the hedgehog pathway, and a liposomal formulation of daunorubicin and cytarabine (CPX-351). Genomically heterogeneous AML has a tendency to evolve, particularly under selective treatment pressure. For decades, treatment decisions have largely centered around chemotherapy drug intensity. Physicians now have access to an increasing number of drugs with novel mechanisms of action and distinctive side-effect profiles. Key issues faced by hematologists in this era of new drugs include (1) the timely identification of actionable mutations at diagnosis and at relapse; (2) deciding which drug to use among several therapeutic options; and (3) increasing awareness of how to anticipate, mitigate, and manage common complications associated with these new agents. This article will use 3 case presentations to discuss some of the new treatment challenges encountered in AML management, with the goal of providing practical guidance to aid the practicing physician.
Topics: Adult; Aged; Aminopyridines; Aniline Compounds; Antineoplastic Agents; Biomarkers, Tumor; Bridged Bicyclo Compounds, Heterocyclic; Cytarabine; Daunorubicin; Female; Glycine; Humans; Isocitrate Dehydrogenase; Leukemia, Myeloid, Acute; Male; Molecular Targeted Therapy; Mutation; Prognosis; Pyrazines; Pyridines; Sialic Acid Binding Ig-like Lectin 3; Staurosporine; Sulfonamides; Triazines; fms-Like Tyrosine Kinase 3
PubMed: 31765470
DOI: 10.1182/blood.2019001239 -
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 -
Leukemia Sep 2021The prospective randomized, placebo-controlled CALGB 10603/RATIFY trial (Alliance) demonstrated a statistically significant overall survival benefit from the addition of... (Randomized Controlled Trial)
Randomized Controlled Trial
The prospective randomized, placebo-controlled CALGB 10603/RATIFY trial (Alliance) demonstrated a statistically significant overall survival benefit from the addition of midostaurin to standard frontline chemotherapy in a genotypically-defined subgroup of 717 patients with FLT3-mutant acute myeloid leukemia (AML). The risk of death was reduced by 22% on the midostaurin-containing arm. In this post hoc analysis, we analyzed the cumulative incidence of relapse (CIR) on this study and also evaluated the impact of 12 4-week cycles of maintenance therapy. CIR analyses treated relapses and AML deaths as events, deaths from other causes as competing risks, and survivors in remission were censored. CIR was improved on the midostaurin arm (HR = 0.71 (95% CI, 0.54-0.93); p = 0.01), both overall and within European LeukemiaNet 2017 risk classification subsets when post-transplant events were considered in the analysis as events. However, when transplantation was considered as a competing risk, there was overall no significant difference between the risks of relapse on the two randomized arms. Patients still in remission after consolidation with high-dose cytarabine entered the maintenance phase, continuing with either midostaurin or placebo. Analyses were inconclusive in quantifying the impact of the maintenance phase on the overall outcome. In summary, midostaurin reduces the CIR.
Topics: Adolescent; Adult; Antineoplastic Agents; Biomarkers, Tumor; Female; Follow-Up Studies; Humans; Leukemia, Myeloid, Acute; Male; Middle Aged; Mutation; Neoplasm Recurrence, Local; Prognosis; Prospective Studies; Staurosporine; Survival Rate; Young Adult; fms-Like Tyrosine Kinase 3
PubMed: 33654204
DOI: 10.1038/s41375-021-01179-4 -
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 -
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