Low frequency and variability of FLT3 mutations in Korean patients with acute myeloid leukemia

Clinical insights into hematologic malignancies and comparative analysis of molecular signatures of acute myeloid leukemia in different ethnicities using an artificial intelligence offering

Next generation sequencing generates copious amounts of genomics data, causing manual interpretation to be laborious and non-scalable while remaining subjective (even for highly trained specialists). We evaluated the performance of the artificial intelligence-based offering Watson for Genomics (WfG), a variant interpretation platform, in hematologic malignancies for the first time.Next generation sequencing was performed for patients treated for various hematological malignancies at Hallym University Sacred Heart Hospital, South Korea, between December 2017 and August 2020 using a 54-gene panel. Both WfG and expert manual curation were used to evaluate the performance of WfG. Acute myeloid leukemia (AML) molecular profiles were compared between Koreans and other ethnic groups using a publicly available dataset.Seventy-seven patients were analyzed (AML: 45, myeloproliferative neoplasms: 12, multiple myeloma: 7, myelodysplastic syndromes: 6, and others: 7). The concordance between the manual and WfG interpretations of 35 variants in 11 random patients was 94%. Among all patients, WfG identified 39 (51%) with at least 1 clinically actionable therapeutic alteration (i.e., a variant targeted by a United States Food and Drug Administration [US FDA]-approved drug, off-label drug, or clinical trial). Moreover, 46% of these patients (18/39) had genes that were targeted by a US FDA-approved therapy. WfG identified diagnostic or prognostic insights in 65% of the patients with no targetable alterations. In those with AML, FLT3-internal tandem duplications or tyrosine kinase domain mutations were less frequent among Koreans than among Caucasians (6.7% vs 30.2%, P < .001) or Hispanics (6.7% vs 28.3%, P = .005), suggesting ethnic differences.Variant interpretation using WfG correlated well with manually curated expert opinions. WfG provided therapeutic insights (including variant-specific drugs and clinical trials that cannot easily be provided by expert manual curation), as well as diagnostic and/or prognostic information.

Impact of race on outcomes in intermediate-risk acute myeloid leukemia

PURPOSE

Racial disparities in acute myeloid leukemia (AML) have been reported but the relative contribution of disease versus patient-specific factors including comorbidities and access to care is unclear.

METHODS

We conducted a retrospective analysis of patient characteristics, treatment patterns and outcomes in a racially diverse patient cohort controlling for cytogenetic risk group. Patients were classified into four groups: non-Hispanic White (NHW), non-Hispanic Black (NHB), Hispanic and Other.

RESULTS

We evaluated 106 patients from 84 zipcodes incorporating demographics, clinicopathologic features, treatment patterns and outcomes. We identified significant differences in BMI and geographic poverty based on ethnoracial group, while prognostic mutations in NPM1 and FLT3 did not differ significantly. Utilization of intensive chemotherapy and transplant rate did not differ by ethnoracial group. However, there was a significantly higher use of alternate donor transplants in minority populations. There was a notably increased rate of clinical trial enrollment in NHW patients compared to other groups. In log-rank analysis, NHW patients had increased overall survival (OS) compared to NHB, Hispanic and Other patients (31.6 months vs. 16.7 months vs. 14.3 months, vs 18.1 months, p = 0.021). In bivariate analysis, overall survival was negatively influenced by advanced age and race. Obesity and zip code poverty levels approached statistical significance in predicting OS. In multivariate analysis, the only factors independently influencing OS were race and allogeneic stem cell transplant.

CONCLUSION

These results suggest that race impacts survival in intermediate-risk AML, highlighting the need to dissect biologic and nonbiologic factors that contribute to this disparity.

[Analysis of induction efficacy and prognostic factors in FLT3-ITD positive acute myeloid leukemia in the real world]

Objective: To investigate the efficacy and prognostic factors of induction therapy in FLT3-ITD(+) acute myeloid leukemia (AML) in the real world data. Methods: From January 2013 to December 2016, 114 de novo patients with FLT3-ITD(+)AML were enrolled in this study. Out of 114 cases, 75 were male, and 39 were female. The median age was 42 years old (ranged from 14 to 72 years old) . The chemotherapy regimens were used for induction therapy and all cases were followed up. The treatment response was evaluated by MICM and the comparison of the ratio were analyzed by chi-square test and the survival was estimated by Kaplan-Meier analysis and Cox proportional hazards model was used to identify independent prognostic factors. Results: There were 52 FLT3-ITD(+)AML patients with favorable prognosis genes (46 cases with NPM1, 5 cases with RUNX1-RUNX1T1, 1 case with CEBPA double mutation) and 62 patients with other types of FLT3-ITD(+)AML at diagnosis. All patients completed at least one cycle of induction therapy and the clinical curative effect was evaluated, complete remission (CR) rate was 50.0% (57/114) in one cycle and total CR rate was 72.5% (74/104) in two cycles. The CR rate of the FLT3-ITD(+) AML patients with favorable prognosis genes was 67.3% (35/52) in one cycle and 83.3% (40/48) in two cycles; for the other types FLT3-ITD(+)AML patients, the CR rate was 35.5% (22/62) in one cycle and 64.8% (35/54) in two cycles. There was a significant difference in CR rate between the FLT3-ITD(+)AML patients with and without favorable prognosis genes (P<0.05) . This indicates that the FLT3-ITD(+)AML patients with favorable prognosis gene had relatively good therapeutic effect. Among other types of FLT3-ITD(+)AML patients who did not achieve remission from one cycle of chemotherapy, 9 patients were given sorafenib plus chemotherapy and 6 cases (66.7%) achieved CR; 23 patients were given conventional chemotherapy and 7 cases (30.4%) achieved CR. There was a significant difference between sorafenib plus chemotherapy and conventional chemotherapy groups (χ(2)=4.47, P<0.05) and this indicates that sorafenib plus chemotherapy can significantly improve the CR rate of FLT3-ITD(+)AML patients. Comparing overall survival (OS) and disease free survival (DFS) , there was no significant difference between sorafenib plus chemotherapy and conventional chemotherapy groups (P values were 0.641 and 0.517, respectively) . Conclusion: The overall prognosis of FLT3-ITD(+)AML patients is poor, and the stratification therapeutic efficacy of FLT3-ITD(+)AML without favorable prognosis gene can be improved by sorafenib combined with chemotherapy.

T-LAK cell-originated protein kinase presents a novel therapeutic target in FLT3-ITD mutated acute myeloid leukemia

Gain-of-function mutations of FLT3 (FLT3-ITD), comprises up to 30% of normal karyotype acute myeloid leukemia (AML) and is associated with an adverse prognosis. Current FLT3 kinase inhibitors have been tested extensively, but have not yet resulted in a survival benefit and novel therapies are awaited. Here we show that T-LAK cell-originated protein kinase (TOPK), a mitotic kinase highly expressed in and correlated with more aggressive phenotype in several types of cancer, is expressed in AML but not in normal CD34+ cells and that TOPK knockdown decreased cell viability and induced apoptosis. Treatment of AML cells with TOPK inhibitor (OTS514) resulted in a dose-dependent decrease in cell viability with lower IC₅₀ in FLT3-mutated cells, including blasts obtained from patients relapsed after FLT3-inhibitor treatment. Using a MV4-11-engrafted mouse model, we found that mice treated with 7.5 mg/kg IV daily for 3 weeks survived significantly longer than vehicle treated mice (median survival 46 vs 29 days, P < 0.001). Importantly, we identified TOPK as a FLT3-ITD and CEBPA regulated kinase, and that modulating TOPK expression or activity resulted in significant decrease of FLT3 expression and CEBPA phosphorylation. Thus, targeting TOPK in FLT3-ITD AML represents a novel therapeutic approach for this adverse risk subset of AML.

CALR, JAK2, and MPL mutation profiles in patients with four different subtypes of myeloproliferative neoplasms: primary myelofibrosis, essential thrombocythemia, polycythemia vera, and myeloproliferative neoplasm, unclassifiable

OBJECTIVES

We investigated mutation profiles of CALR, JAK2, and MPL in 199 Korean patients with myeloproliferative neoplasms (MPNs).

METHODS

In total, 199 patients with MPN (54 primary myelofibrosis [PMF], 79 essential thrombocythemia [ET], 58 polycythemia vera [PV], and eight MPN-unclassifiable [MPN-U]) and 4 patients with acute panmyelosis with myelofibrosis (APMF) were retrospectively subjected to Sanger sequencing for CALR, JAK2, and MPL.

RESULTS

The overall frequency of CALR mutations was 12.6% (type 1 mutation, 16 patients; type 2 mutation, nine patients): most frequent in MPN-U (37.5%), followed by ET (17.7%) and PMF (14.8%). CALR mutations were not found in PV or APMF. CALR and JAK2 or MPL mutations were mutually exclusive. In PMF, the CALR mutations were associated with lower levels of leukocytes, lower bone marrow cellularity, and higher number of megakaryocytes. Patients with CALR-mutated ET more frequently progressed to the accelerated or blast phases compared with patients with JAK2 mutations. CALR mutations were frequently observed in the JAK2-negative MPNs, most frequently in MPN-U.

CONCLUSIONS

The prognostic significance of CALR mutations likely differs among the MPN subtypes.

Lower frequency of NPM1 and FLT3-ITD mutations in a South African adult de novo AML cohort

INTRODUCTION

Acute myeloid leukemia (AML) is a heterogeneous clonal disorder of hemopoietic progenitor cells diagnosed in individuals of any age, but with a median age of 67 years at presentation in adults. Assessment of the mutation status of nucleophosmin protein-1 (NPM1) and FMS-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) is essential for the prognosis, and treatment of AML.

METHODS

A total of 160 de novo AML cases, both cytogenetically normal and abnormal, were analyzed for the presence of NPM1 and FLT3-ITD mutations, and the results assessed in conjunction with epidemiological, clinical, and laboratory findings.

RESULTS

Nucleophosmin protein-1 mutations were found in 7.5%, while FLT3-ITD was present in 12% of these cases. Both of these were lower than expected. The median age at diagnosis of AML was 41 years, and for the FLT3-ITD only cases, median age was 33 years; these ages were younger than expected.

CONCLUSION

The lower reported frequencies and younger median age at diagnosis of AML and these specific mutations may be contributed to by a number of factors including effects of race on age of presentation, inclusion of patients diagnosed with de novo AML only, and a generally younger median age of the South African population.

Silvestrol exhibits significant in vivo and in vitro antileukemic activities and inhibits FLT3 and miR-155 expressions in acute myeloid leukemia

Background

Activating mutations [internal tandem duplication (ITD)] or overexpression of the FMS-like tyrosine kinase receptor-3 (FLT3) gene are associated with poor outcome in acute myeloid leukemia (AML) patients, underscoring the need for novel therapeutic approaches. The natural product silvestrol has potent antitumor activity in several malignancies, but its therapeutic impact on distinct molecular high-risk AML subsets remains to be fully investigated. We examined here the preclinical activity of silvestrol in FLT3-ITD and FLT3 wild-type (wt) AML.

Methods

Silvestrol in vitro anti-leukemic activity was examined by colorimetric cell viability assay, colony-forming and flow cytometry assays assessing growth inhibition and apoptosis, respectively. Pharmacological activity of silvestrol on FLT3 mRNA translation, mRNA and protein expression was determined by RNA-immunoprecipitation, qRT-PCR and immunoblot analyses, respectively. Silvestrol in vivo efficacy was investigated using MV4-11 leukemia-engrafted mice.

Results

Silvestrol shows antileukemia activity at nanomolar concentrations both in FLT3-wt overexpressing (THP-1) and FLT3-ITD (MV4-11) expressing AML cell lines (IC₅₀ = 3.8 and 2.7 nM, respectively) and patients’ primary blasts [IC₅₀ = ~12 nM (FLT3-wt) and ~5 nM (FLT3-ITD)]. Silvestrol increased apoptosis (~4fold, P = 0.0001), and inhibited colony-formation (100%, P < 0.0001) in primary blasts. Silvestrol efficiently inhibited FLT3 translation reducing FLT3 protein expression by 80–90% and decreased miR-155 levels (~60%), a frequently co-regulated onco-miR in FLT3-ITD-positive AML. The median survival of silvestrol-treated vs vehicle-treated mice was 63 vs 29 days post-engraftment, respectively (P < 0.0001).

Conclusions

Silvestrol exhibits significant in vivo and in vitro antileukemic activities in AML through a novel mechanism resulting in inhibition of FLT3 and miR-155 expression. These encouraging results warrant a rapid translation of silvestrol for clinical testing in AML.

Analysis of FLT3-ITD and FLT3-Asp835 mutations in de novo acute myeloid leukemia: evaluation of incidence, distribution pattern, correlation with cytogenetics and characterization of internal tandem duplication from Indian population

Mutation of the FMS-like tyrosine kinase 3 (FLT3) gene in Indian population remains unclear till date. Here, we found FLT3-ITD mutations in 19.1%, FLT3-Asp835 mutations in 4.7%, and dual mutations in 4.2%, accounting for overall mutation in 28% of acute myeloid leukemia (AML) patients. FLT3 mutation was more prevalent in APL than non-APL patients (32.2% vs 26.3%), adults tend to show higher incidence than children (30.6% vs 18.2%, p = .1), and were significantly associated with normal karyotype, high WBCs, with no specific distribution in FAB subtypes. Notably, FLT3 mutation was present in 50% of patients with NPM1-Mt, when compared to only 22.6% of patients with NPM1-wt (p < .001). Sequence analyses of internal tandem duplications (ITDs) revealed that duplications were mostly restricted to JM domain (3 to 165 nucleotides). Interestingly, 92.3% cases showed duplication of at least one amino acid (AA) within the stretch Y589 to K602 that includes the two SH2-binding motifs. Analysis of frequency of single AA in the duplicated region revealed that E598 was the most frequently duplicated single AA in 72%, followed by R595 (69.2%), and Y599 (66.7%). Finally, three types of point mutations were identified, including D835Y, D835H, and D835A.