FLT3 and NPM-1 mutations in a cohort of acute promyelocytic leukemia patients from India

Clinicopathological Significance of Common Genetic Alterations in Patients With Acute Promyelocytic Leukemia

OBJECTIVE/BACKGROUND

Acute myeloid leukemia (AML) is one of the common forms of hematological malignancy and acute promyelocytic leukemia (APL) is a unique subtype of AML conferring favorable prognosis. We aimed to determine the prevalence and prognostic impact of Fms-like tyrosine kinase 3 (FLT3), nucleophosmin 1 (NPM1) mutation, epidermal growth factor receptor (EGFR), and flow marker's expression in patients with APL.

METHODS

In the present study, 165 de novo APL patients were molecularly characterized for promyelocytic leukemia (PML) breakpoint and additional genetic alterations. Reverse transcriptase polymerase chain reaction (PCR) and real-time PCR assays were used to detect genetic alterations.

RESULTS

PML/RARα was detected in 29/165 (17.5%) samples with breakpoint cluster region 1 (bcr1) in 17/29 (58.5%) and bcr3 in 12/29 (41.5%) samples. The prevalence of FLT3-ITD, NPM1, and EGFR were detected in 5/29 (17.5%), 11/29 (38%), and 5/29 (17.5%) patients, respectively. Patients expressing bcr-3 hybrid transcript had lower overall survival compared with bcr1 ( p = .254). White blood cell (WBC) count was significantly higher in bcr3 in comparison with bcr1 patients ( p = .002). Patients with positive EGFR expression ( p = .042) and higher WBC ( p = .002) were significantly associated with poor survival ( p < .05).

CONCLUSIONS

We documented the higher prevalence of bcr1 and confirmed that the association of FLT3-ITD significantly reduced the chances of survival in APL. The mortality rate of bcr3 was comparatively higher than that of bcr1. Higher WBC count and EGFR expression were significantly associated with poor survival.

'FLT3-ITD Mutation Does Not Influence Survival Outcome in Adult Acute Promyelocytic Leukemia Patients Treated With ATO and ATRA-Based Therapeutic Regimen: Experience From a North Indian Tertiary Care Centre'

INTRODUCTION

NPM1 and FLT3-ITD are frequently mutated genes in acute myeloid leukemia. We studied clinico-hematological profile and survival outcome of adult acute promyelocytic leukemia (APL) patients harboring these mutations.

MATERIALS AND METHODS

De novo APL cases (> 12 years), enrolled between January 2019 and June 2020, were evaluated for FLT3-ITD and NPM1 mutations (A, B, D mutations) by conventional and real-time qualitative PCR respectively.

RESULTS

FLT3-ITD mutation was detected in 12 of 36 (33.3%) de novo APLs cases while NPM1 mutation was not detected. FLT3-ITD was more frequently associated with Sanz high-risk category as compared to the intermediate-risk category (75% vs. 29%, P = .02), with BCR3 transcript type (P = .08) and higher median WBC count [22.7 × 10⁹/L)(range 1.3-184), P = .018]. One and half-years overall survival (OS) and event-free survival (EFS) were not significantly altered by the presence/absence of FLT3-ITD mutation (OS 86% vs. 70%, P = .32; EFS 86% vs. 70%, P = .33), between genders (OS, EFS both 89% in males vs. 69% in females, P = .15) and between adolescent and younger adults (AYA) (≤ 30 years) and older adult APL cases (> 30 years) (OS 86% vs. 78%, P = .55; EFS 85% vs. 77%, P = .55), however were significantly lower with BCR3 transcript as compared to BCR1 transcript (OS 56% vs. 91%, P = .019; EFS 56% vs. 91%, P = .016) in univariate analysis, although not in multivariate analysis. One and half-year OS and EFS was 57% (6/14, P = .009 for each) in high-risk APL.

CONCLUSION

FLT3-ITD mutation did not influence survival outcome in adult APL treated with ATO and ATRA-based therapeutic regimen.

The potential role of nucleophosmin (NPM1) in the development of cancer

Nucleophosmin (NPM1) is a well-known nucleocytoplasmic shuttling protein that performs several cellular functions such as ribosome biogenesis, chromatin remodeling, genomic stability, cell cycle progression, and apoptosis. NPM1 has been identified to be necessary for normal cellular functions, and its altered regulation by overexpression, mutation, translocation, loss of function, or sporadic deletion can lead to cancer and tumorigenesis. In this review, we focus on the gene and protein structure of NPM1 and its physiological roles. Finally, we discuss the association of NPM1 with various types of cancer including solid tumors and leukemia.

A comprehensive review of genetic alterations and molecular targeted therapies for the implementation of personalized medicine in acute myeloid leukemia

Acute myeloid leukemia (AML) is an extremely heterogeneous disease defined by the clonal growth of myeloblasts/promyelocytes not only in the bone marrow but also in peripheral blood and/or tissues. Gene mutations and chromosomal abnormalities are usually associated with aberrant proliferation and/or block in the normal differentiation of hematopoietic cells. So far, the combination of cytogenetic profiling and molecular and gene mutation analyses remains an essential tool for the classification, diagnosis, prognosis, and treatment for AML. This review gives an overview on how the development of novel innovative technologies has allowed us not only to detect the genetic alterations as early as possible but also to understand the molecular pathogenesis of AML to develop novel targeted therapies. We also discuss the remarkable advances made during the last decade to understand the AML genome both at primary and relapse diseases and how genetic alterations might influence the distinct biological groups as well as the clonal evolution of disease during the diagnosis and relapse. Also, the review focuses on how the persistence of epigenetic gene mutations during morphological remission is associated with relapse. It is suggested that along with the prognostic and therapeutic mutations, the novel molecular targeted therapies either approved by FDA or those under clinical trials including CART-cell therapy would be of immense importance in the effective management of AML.

Chemogenomics analysis of drug targets for the treatment of acute promyelocytic leukemia

The main challenges in treating acute promyelocytic leukemia (APL) are currently early mortality, relapse, refractory disease after induction therapy, and drug resistance to ATRA and ATO. In this study, a computational chemogenomics approach was used to identify new molecular targets and drugs for APL treatment. The transcriptional profiles induced by APL were compared with those induced by genetic or chemical perturbations. The genes that can reverse the transcriptional profiles induced by APL when perturbed were considered to be potential therapeutic targets for APL. Drugs targeting these genes or proteins are predicted to be able to treat APL if they can reverse the APL-induced transcriptional profiles. To improve the target identification accuracy of the above correlation method, we plotted the functional protein association networks of the predicted targets by STRING. The results determined PML, RARA, SPI1, HDAC3, CEBPA, NPM1, ABL1, BCR, PTEN, FOS, PDGFRB, FGFR1, NUP98, AFF1, and MEIS1 to be top candidates. Interestingly, the functions of PML, RARA, HDAC3, CEBPA, NPM1, ABL, and BCR in APL have been previously reported in the literature. This is the first chemogenomics analysis predicting potential APL drug targets, and the findings could be used to guide the design of new drugs targeting refractory and recurrent APL.

The Impact of Flt3 Gene Mutations in Acute Promyelocytic Leukemia: A Meta-Analysis

The association of FLT3 mutations with white blood cell (WBC) counts at diagnosis and early death was studied in patients with acute promyelocytic leukemia (APL). Publications indexed in databases of biomedical literature were analyzed. Potential publication bias was evaluated by analyzing the standard error in funnel plots using the estimated relative risk (RR). Mixed-effect models were used to obtain the consolidated RR. All analyses were conducted using the R statistical software package. We used 24 publications in the final meta-analysis. Of 1005 males and 1376 females included in these 24 publications, 645 had FLT3-ITD (internal tandem duplication) mutations. Information on FLT3-D835 mutations was available in 10 publications for 175 patients. Concurrent occurrence of the two mutations was rare. WBC count at diagnosis was ≥10 × 109/L in 351 patients. For patients with the FLT3-ITD mutation, RR was 0.59 for overall survival (OS) and 1.62 for death during induction. For those with FLT3-D835 mutations, the RR was 0.50 for OS and 1.77 for death during induction. RR for WBC count ≥10 × 109/L was 3.29 and 1.48 for patients with FLT3-ITD and FLT3-D835, respectively. APL patients with FLT3-ITD or FLT3-D835 are more likely to present with elevated WBC counts and poorer prognosis than those without these mutations.

High fms-like tyrosine kinase-3 (FLT3) receptor surface expression predicts poor outcome in FLT3 internal tandem duplication (ITD) negative patients in adult acute myeloid leukaemia: A prospective pilot study from India

Background & objectives:

Mutations in fms-like tyrosine kinase 3 (FLT3) receptor have significant role in assessing outcome in patients with acute myeloid leukaemia (AML). Data for FLT3 surface expression in relation to FLT3 internal tandem duplication (ITD) status and outcome are not available from India. The objective of the current study was to investigate adult patients with AML for FLT3 expression and FLT3 ITD mutation, and their association with long-term outcome.

Methods:

Total 51 consecutive de novo AML patients aged 18-60 yr were enrolled in the study. FLT3 ITD was detected by polymerase chain reaction (PCR); flowcytometry and qPCR (Taqman probe chemistry) were used for assessment of FLT3 protein and transcript, respectively. Kaplan Meier curves were obtained for survival analysis followed by log rank test.

Results:

FLT3 ITD was present in eight (16%) patients. Complete remission was achieved in 33 (64.6%) patients. At 57.3 months, event free survival (EFS) was 26.9±6.3 per cent, disease free survival (DFS) 52.0±9.2 per cent, and overall survival event (OS) 34.5±7.4 per cent. FLT3 surface expression was positive (>20%) by flow-cytometry in 38 (88%) of the 51 patients. FLT3 surface expression and transcripts were not associated with FLT3 ITD status. FLT3 expression was significantly associated with inferior EFS (P=0.026) and OS (P=0.018) in those who were negative for FLT3 ITD.

Interpretation & conclusions:

This study evaluated FLT3 ITD mutation along with FLT3 expression in AML patients, and associated with survival. Negative impact of FLT3 surface expression on survival was observed in AML patients who were FLT3 ITD negative.

Prevalence and Clinical Significance of FLT3 and NPM1 Mutations in Acute Myeloid Leukaemia Patients of Assam, India

Acute Myeloid Leukaemia (AML) is one of the common forms of haematological malignancy in adults. We analysed the prevalence and clinical significance of FMS-like tyrosine kinase 3 (FLT3) and Nucleophosmin 1 (NPM1) mutations in AML patients of North East India. Co-prevalence and clinical significance of three recurrent chromosomal translocations namely t(15; 17), t(8; 21), t(16; 16) and expression of epidermal growth factor receptor (EGFR), flow markers were also documented and co-related with disease progress. We analysed bone marrow aspirates or peripheral blood samples from 165 newly diagnosed AML patients. All clinical samples were analysed by Real Time PCR and DNA sequencing based assays. NPM1 was the most frequently detected mutation in the study population (46/165 = 27.90%, 95% CI 20.75-35.05). FLT3 mutations were detected in 27/165 (16.40%, 95% CI 10.45-22.35) patients with internal tandem duplication (FLT3-ITD) in 24/165 (14.60%, 95% CI 8.91-20.29) and FLT3-D835 in 3/165 (1.80%, 95% CI 0-4.13) patients. NPM1 mutations were associated with a higher complete remission rate and longer overall survival (P < 0.01) compared to FLT3-ITD whereas FLT3-ITD showed adverse impact with poor survival rate (P < 0.01), leukocytosis (P < 0.01) and a packed bone marrow. EGFR expression was more in patients with NPM1 mutation compared to FLT3 mutation (P = 0.09). Patients with FLT3 and NPM1 mutations uniformly expressed CD13 and CD33 whereas CD34 was associated with poor prognosis (P ≤ 0.01) in patients with NPM1 mutation. FLT3-ITD was associated with inferior overall survival. However the clinical significance of FLT3-D835 was not clear due to small number of samples. NPM1 mutation showed better prognosis with increased response to treatment in the absence of FLT3-ITD.