Prognostic implications of NPM1 mutations and FLT3 internal tandem duplications in Egyptian patients with cytogenetically normal acute myeloid leukemia

Nucleophosmin (NPM1) and fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) gene mutations represent the most frequent molecular aberrations in patients with cytogenetically normal-acute myeloid leukemia (CN-AML). We analyzed the prognostic impact of these mutations and their interactions in adults with CN-AML. NPM1 mutation (NPM1mut) and FLT3-ITD mutation (FLT3-ITD+) were analyzed by polymerase chain reaction and GeneScan assays of bone marrow samples obtained from newly diagnosed 104 CN-AML patients. FLT3-ITD+ and NPM1mut were detected in 36 (34.6%) and 30 (28.8%) out of 104 subjects, respectively, 16 cases (15.4%) had double NPM1mut/FLT3-ITD+. The incidence of FLT3-ITD+ was significantly higher in the NPM1mut group than in the NPM1 wild (NPM1wt) group (P = 0.018). Statistical analysis revealed that isolated NPM1mut group had a better clinical outcomes in terms of higher complete response (CR) rate (P = 0.01) and a trend towards favorable overall survival (OS) and disease-free survival (DFS) (P = 0.28, 0.40, respectively). In contrast, the isolated FLT3-ITD+ group had an unfavorable outcome in terms of lower CR rate (P = 0.12), shorter OS, and DFS (P < 0.0001 for both). The NPM1mut/FLT3-ITD-group had the best OS and DFS, while the NPM1wt/FLT3-ITD+ group had the worst OS and DFS than other groups (NPM1mut/FLT3-ITD+ or NPM1wt/FLT3-ITD?) (P < 0.0001 for both). Multivariate Cox regression analysis showed that age and FLT3/ITD+ were independent poor prognostic factors for OS (P = 0.006, <0.0001, respectively), while FLT3/ITD+ was independent predictor for DFS (P = 0.04). However, NPM1mut did not have a significant impact on OS and DFS. In conclusion, adult patients with CN-AML carrying isolated NPM1mut and isolated FLT3-ITD+ exhibit different clinical outcomes than those with NPM1mut/FLT3-ITD+ or NPM1wt/FLT3-ITD?. Patients with NPM1mut/FLT3-ITD? had the best prognosis in terms of higher CR, OS, and DFS, while those with NPM1mut/FLT3-ITD+ had the worst CR rate, and NPM1wt/FLT3-ITD+ had the lowest OS and DFS.     

DNMT3A (R882) mutation features and prognostic effect in acute myeloid leukemia in Coexistent with NPM1 and FLT3 mutations

Objective/Background

In the absence of high-risk cytogenetic, DNMT3A (DNA Methyltransferase 3a) mutation status has an impact on outcome in the presence of FLT3 (FMS-like Tyrosine Kinase3) and/or NPM1 (Nucleophosmin). In this study, we focus on the features and effect of DNMT3A (R882) mutation in acute myeloid leukemia (AML) in the presence or absence of NPM1 and FLT3 mutations.

Size of FLT3 internal tandem duplication has prognostic significance in patients with acute myeloid leukemia

FLT3 internal tandem duplications (FLT3/ITDs) in the juxtamembrane domain are found in approximately 25% of acute myeloid leukemia (AML) patients, ranging in size from 3 to hundreds of nucleotides. We examined whether the sizes of FLT3/ITDs were associated with clinical outcomes in 151 AML patients enrolled in Southwest Oncology Group studies: S9333 and S9500. FLT3/ITDs were identified in 32% of patients (median ITD size = 39 nucleotides; range, 15-153 nucleotides). The CR rates were 35%, 67%, and 52% for patients with large (>or= 40), small (< 40), and no ITDs, respectively (P = .19). Increasing ITD size was associated with decreasing OS (estimated 5-year OS: large = 13%, small = 26%, and no ITD = 21%, P = .072) and RFS (estimated 5-year RFS: large = 13%, small = 27%, and no ITD = 34%, P = .017). These studies suggest that ITD size may have prognostic significance.     

FLT3 internal tandem duplication in childhood acute myeloid leukaemia: association with hyperleucocytosis in acute promyelocytic leukaemia

We evaluated the incidence of FLT3/internal tandem duplication (ITD) mutation in childhood acute myeloid leukaemia (AML) diagnosed over 15 years. FLT3/ITD was found in 10 of 45 (22.2%) non-acute promyelocytic leukaemia (non-APL) patients. The 5-year event-free survival of non-APL patients was higher in FLT3/ITD-negative versus -positive patients (48.9%, SE 8.9, vs 20.0%, SE 16.1, P = 0.03). In childhood APL, FLT3/ITD incidence was higher than in non-APL, although not statistically significant (10 out of 29 patients, 34.5%, P = 0.29). In APL patients, FLT3/ITD was strongly correlated to a higher white blood cell count at diagnosis and the M3 French-American-British subtype.     

异基因造血干细胞移植治疗Fms样酪氨酸激酶3基因内部串联重复(FLT3-ITD)阳性的急性髓性白血病的疗效分析

 目的 分析异基因造血干细胞移植(allo-HSCT)治疗伴有Fms样酪氨酸激酶3基因内部串联重复(FLT3-ITD)阳性的急性髓性白血病(AML)的疗效,探讨不同移植方式及疾病状态对该类患者预后的影响。方法 2006年10月至2012年10月在苏州大学附属第一医院行allo-HSCT的AML患者共314例,其中FLT3-ITD阳性54例,回顾性分析allo-HSCT对FLT3-ITD阳性AML患者的临床疗效。结果 54例FLT3-ITD阳性患者3年总生存(OS)率为56%, 3年无白血病生存(LFS)率为47%。其中同胞人类白细胞抗原(HLA)全相合及亲缘HLA单倍型相合造血干细胞移植的患者3年OS率分别为56%和60%,3年LFS率为45%和54%。两组在OS时间及LFS时间方面的差异均无统计学意义(χ²=0.074,P=0.786; χ²=0.006,P=0.941)。47例(87.0%)患者移植前本病处于首次完全缓解(CR1),7例(13.0%)患者移植前本病处于非CR1期。处于CR1期的患者的生存显著优于非CR1期患者。结论 allo-HSCT是FLT3-ITD阳性AML患者的有效治疗方法,亲缘HLA单倍型相合造血干细胞移植与同胞HLA全相合移植疗效相似。疾病复发是影响其疗效的主要因素。
        

FLT3 internal tandem duplication mutations in adult acute myeloid leukaemia define a high-risk group

Genomic DNA from 106 cases of adult de novo acute myeloid leukaemia (AML) was screened by polymerase chain reaction (PCR) and gel electrophoresis for FLT3 internal tandem duplication (ITD) mutations within the juxtamembrane (JM) domain. FLT3 mutations were detected in 14 cases (13.2%) and occurred in FAB types M1 (4 out of 14 cases), M3 (1 out of 10 cases), M4 (5 out of 37 cases) and M5 (4 out of 11 cases). Sequence analysis of four cases with abnormal PCR electrophoretic patterns revealed in frame duplications in the region of exon 11 of between 27 and 111 base pairs. Three are predicted to result in the tandem duplication of adjacent amino acid residues and one to result in a tandem duplication plus insertion of a novel amino acid motif. Statistical analysis showed the FLT3 mutations to be a strong prognostic factor, with patients lacking the mutation surviving significantly longer from diagnosis (mean 29.1 months) than those with an ITD (mean 12.8 months; P = 0.0002). Thirteen of the 14 patients with FLT3 mutations died within 18 months of diagnosis. FLT3 mutations were of prognostic significance in good risk disease (P = 0.04), as well as in patients with standard risk disease (P = 0.0096). This study demonstrates that the FLT3 ITD mutation occurs in a significant percentage of adult AML cases and is an important adverse prognostic factor that appears independent of conventional karyotypic findings.     

Incorporating FLT3 inhibitors in the frontline treatment of FLT3 mutant acute myeloid leukemia

FLT3 mutations occur in up to a third of newly diagnosed patients with acute myeloid leukemia (AML) and confer poor prognosis. Clinical development of FLT3 tyrosine kinase inhibitors for AML initially involved broad-spectrum inhibitors (midostaurin, sorafenib) targeting multiple kinases. Addition of midostaurin to upfront intensive chemotherapy for younger patients with FLT3 mutant AML significantly improved overall survival and validated FLT3 as a therapeutic target. Other regimens such as sorafenib and hypomethylating agents (azacitidine, decitabine) have expanded the use of FLT3 inhibitors to other populations with FLT3 mutant AML. However, emerging data on new highly potent and specific FLT3 inhibitors such as quizartinib, gilteritinib, and crenolanib suggest that these agents may soon supplant midostaurin and sorafenib in the upfront setting. Using case presentations, this review provides guidelines and practical management strategies for frontline therapy of patients with newly diagnosed FLT3 mutant AML in the current era.     

Activating internal tandem duplication mutations of the fms-like tyrosine kinase-3 (FLT3-ITD) at complete response and relapse in patients with acute myeloid leukemia

FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) mutations are among the most frequent molecular aberrations in patients with acute myeloid leukemia. We retrospectively analyzed 324 patients with acute myeloid leukemia treated with front-line induction chemotherapy between October 2004 and March 2010. Fifty-six patients had FLT3-ITD mutation at diagnosis. Fifty-one (91%) patients with FLT3-ITD achieved complete remission. Thirteen patients had FLT3 analysis at complete remission. None had FLT3-ITD. Twenty-five (49%) patients with FLT3-ITD relapsed. Of these, 13 (52%) had FLT3-ITD at relapse (3 negative and 9 not done). Among the 201 patients without FLT3-ITD at diagnosis who achieved complete remission, 77 (38%) relapsed among whom 8 (10%) patients acquired FLT3-ITD clone. We conclude that FLT3-ITD mutations are unstable at follow up and may occur for the first time at relapse. Therefore, FLT3-ITD is not a reliable marker for minimal residual disease in acute myeloid leukemia.     

Clinical impact of internal tandem duplications and activating point mutations in FLT3 in acute myeloid leukemia in elderly patients

BACKGROUND: The FLT3 gene is frequently mutated in acute myeloid leukemia (AML), either by an internal tandem duplication (ITD) of the juxtamembrane domain or by activating point mutations in the second tyrosine kinase domain (ATKD). Only a few investigations have focused on the prognostic significance of FLT3 alterations in AML among the elderly, yielding conflicting results. In the present study, the frequency and clinical relevance of FLT3 abnormalities were ascertained in a cohort of elderly AML patients. PATIENTS AND METHODS: A total of 109 AMLs, occurring in patients above the age of 60 yr (median 71.5), were investigated. DNA was extracted from fresh bone marrow cells or from cells in fixative and investigated for the presence of ITD of exons 14 and 15 and the ATKD D835 in exon 20. RESULTS: ITDs and ATKDs were identified in 20 (18%) and 11 (10%) of the cases, respectively. Three cases displayed both an ITD and an ATKD. FLT3 abnormalities were associated with leukocytosis (ITD P < 0.01; ATKD P = 0.069), and the monocytic FAB subtypes M4 and M5 [ITD (P < 0.05), ATKD (P = 0.05)], and ITD and ATKD were significantly (P < 0.05) more common in cases with a normal karyotype. There was no correlation between the presence of FLT3 abnormalities and complete remission rates or overall survival. CONCLUSION: A correlation was observed between FLT3 abnormalities and leukocytosis, a normal karyotype, and the M4/M5 subtypes of leukemia. However, no clear-cut prognostic impact of FLT3 abnormalities was identified in elderly AML patients.     

Importance of early detection and follow-up of FLT3 mutations in patients with acute myeloid leukemia

Mutations in the fms-like tyrosine kinase 3 (FLT3) gene, such as internal tandem duplication (FLT3/ITD) in the juxtamembrane domain and point mutations in the tyrosine kinase domain, are the most common abnormalities in acute myeloid leukemia (AML). FLT3/ITD and FLT3/D835 mutations were analyzed in 113 Serbian adult AML patients using polymerase chain reaction. Twenty patients were found to be FLT3/ITD positive (17.7%). The mutations occurred most frequently in M5 and M0 subtypes of AML. They were mainly associated with the normal karyotype. All patients harboring FLT3/ITD had a higher number of white blood cells than patients without it (p = 0.027). FLT3/ITD mutations were associated with lower complete remission (CR) rate (χ ²= 5.706; p = 0.017) and shorter overall survival (OS; Log rank = 8.76; p = 0.0031). As for disease-free survival, the difference between FLT3/ITD-positive and FLT3/ITD-negative patients was not statistically significant (Log rank = 0.78; p = 0.3764). In multivariate analysis, the presence of FLT3/ITD mutations was the most significant prognostic factor for both OS and CR rate (p = 0.0287; relative risk = 1.73; 95% CI = 1.06–2.82). However, in the group of patients with the intermediate-risk karyotype, the mere presence of FLT3/ITD was not associated with inferior clinical outcome. FLT3/D835 point mutation was found in four patients (3.5%) only. Follow-up of the FLT3/ITD-positive patients revealed stability of this mutation during the course of the disease. However, changes in the pattern of FLT3/D835 mutations in initial and relapsed AML were observed. Our results indicate an association of FLT3/ITD with the adverse outcome in AML patients treated with standard induction chemotherapy. Because FLT3/ITD mutation is a target for specific therapeutic inhibition, its early detection could be helpful in clinical practice. Ms. Colovic and Ms. Tosic contributed equally to this work.