Simultaneous detection of NPM1 and FLT3-ITD mutations by capillary electrophoresis in acute myeloid leukemia

A practical algorithm for acute myeloid leukaemia diagnosis following the updated 2022 classifications

Disease classification of complex and heterogenous diseases, such as acute myeloid leukaemia (AML), is continuously updated to define diagnoses, appropriate treatments, and assist research and education. Recent availability of molecular profiling techniques further benefits the classification of AML. The World Health Organization (WHO) classification of haematolymphoid tumours and the International Consensus Classification of myeloid neoplasms and acute leukaemia from 2022 are two updated versions of the WHO 2016 classification. As a consequence, the European LeukemiaNet 2022 recommendations on the diagnosis and management of AML in adults have been also updated. The current review provides a practical interpretation of these guidelines to facilitate the diagnosis of AML and discusses genetic testing, disease genetic heterogeneity, and FLT3 mutations. We propose a practical algorithm for the speedy diagnosis of AML. Future classifications may need to incorporate gene mutation combinations to enable personalised treatment regimens in the management of patients with AML.

Prognostic value of the mutation types and dynamics of FLT3-ITD in acute myeloid leukemia

OBJECTIVE

The prognostic value of the mutation types and dynamics of FLT3-ITD in acute myeloid leukemia (AML) and other known factors were studied.

METHODS

Initial and follow-up samples from 45 AML patients with FLT3-ITD mutations were analyzed by fragment length analysis, Sanger sequencing, and next-generation sequencing.

RESULTS

Some patients (13%) had multiple FLT3-ITD mutations, and many of them had acute promyelocytic leukemia (APL). FLT3-ITD mutations were classified according to mutation types, including duplication-only FLT3-ITD (52%) and FLT3-ITD with duplications and insertions (dup + ins) (48%). The dup + ins FLT3-ITD variant was independently associated with poor prognosis among non-APL patients (odds ratio, 2.92) in addition to FLT3-ITD with ≥50% variant allele frequency (VAF). The VAFs of FLT3-ITD were low (median 2.2%) when detected during morphologic complete remission (CR) after conventional chemotherapy; however, in two patients treated with gilteritinib after relapse, the VAFs of FLT3-ITD were much higher (>95% and 8.1%) in the morphologic CR state.

CONCLUSIONS

The type of FLT3-ITD mutation is important in prognosis, and the dup + ins type of FLT3-ITD can be an indicator of poor prognosis. In addition, the FLT3-ITD mutation status may unexpectedly not match the morphologic examination results after gilteritinib treatment.

Azacitidine Post-Remission Therapy for Elderly Patients with AML: A Randomized Phase-3 Trial (QoLESS AZA-AMLE)

This phase-3 randomized multicenter trial evaluated the efficacy of subcutaneous azacitidine (AZA) post-remission therapy vs. best supportive care (BSC) in elderly acute myeloid leukemia (AML) patients. The primary endpoint was the difference in disease-free survival (DFS) from complete remission (CR) to relapse/death. Patients with newly diagnosed AML aged ≥61 years received two courses of induction chemotherapy ("3+7" daunorubicin and cytarabine) followed by consolidation (cytarabine). At CR, 54 patients were randomized (1:1) to receive BSC (N = 27) or AZA (N = 27) at a dose of 50 mg/m² for 7 days every 28 days and the dose increased after the 1st cycle to 75 mg/m² for a further 5 cycles, followed by cycles every 56 days for 4.5 years. At 2 years, median DFS was 6.0 (95% CI: 0.2-11.7) months for patients receiving BSC vs. 10.8 months (95% CI: 1.9-19.6, p = 0.20) months for AZA. At 5 years, DFS was 6.0 (95% CI: 0.2-11.7) months in the BSC arm vs. 10.8 (95% CI: 1.9-19.6, p = 0.23) months in the AZA arm. Significant benefit was afforded by AZA on DFS at 2 and 5 years in patients aged >68 years (HR = 0.34, 95% CI: 0.13-0.90, p = 0.030 and HR = 0.37, 95% CI: 0.15-0.93, p = 0.034, respectively). No deaths occurred prior to leukemic relapse. Neutropenia was the most frequent adverse event. There were no differences in patient-reported outcome measures between study arms. In conclusion, AZA post-remission therapy was found to provide benefit in AML patients aged >68 years.

Pre-transplant gene profiling characterization by next-generation DNA sequencing might predict relapse occurrence after hematopoietic stem cell transplantation in patients affected by AML

Background

In the last decade, many steps forward have been made in acute myeloid leukemia prognostic stratification, adding next-generation sequencing techniques to the conventional molecular assays. This resulted in the revision of the current risk classification and the introduction of new target therapies.

Aims and methods

We wanted to evaluate the prognostic impact of acute myeloid leukemia (AML) mutational pattern on relapse occurrence and survival after allogeneic stem cell transplantation. A specific next-generation sequencing (NGS) panel containing 26 genes was designed for the study. Ninety-six patients studied with NGS at diagnosis were included and retrospectively studied for post-transplant outcomes.

Results

Only eight patients did not show any mutations. Multivariate Cox regression revealed FLT3 (HR, 3.36; p=0.02), NRAS (HR, 4.78; p=0.01), TP53 (HR, 4.34; p=0.03), and WT1 (HR 5.97; p=0.005) mutations as predictive variables for relapse occurrence after transplantation. Other independent variables for relapse recurrence were donor age (HR, 0.97; p=0.04), the presence of an adverse cytogenetic risk at diagnosis (HR, 3.03; p=0.04), and the obtainment of complete remission of the disease before transplantation (HR, 0.23; p=0.001). Overall survival appeared to be affected only by grade 2-4 acute GvHD occurrence (HR, 2.29; p=0.05) and relapse occurrence (HR, 4.33; p=0.0001) in multivariate analysis.

Conclusions

The small number of patients and the retrospective design of the study might affect the resonance of our data. Although results on TP53, FLT3, and WT1 were comparable to previous reports, the interesting data on NRAS deserve attention.

Midostaurin in patients with acute myeloid leukemia and FLT3-TKD mutations: a subanalysis from the RATIFY trial

The results from the RATIFY trial (ClinicalTrials.gov: NCT00651261; CALGB 10603) showed that midostaurin combined with standard chemotherapy significantly improved outcomes in patients with FMS-like tyrosine kinase 3 (FLT3)-mutated acute myeloid leukemia (AML), compared with placebo. In this post hoc subgroup analysis from the trial, we evaluated the impact of midostaurin in 163 patients with FLT3-tyrosine kinase domain (TKD) mutations. At a median follow-up of 60.7 months (95% CI, 55.0-70.8), the 5-year event-free survival (EFS) rate was significantly higher in patients treated with midostaurin than in those treated with placebo (45.2% vs 30.1%; P = .044). A trend toward improved disease-free survival was also observed with midostaurin (67.3% vs 53.4%; P = .089), whereas overall survival (OS) was similar in the 2 groups. Patients with AML and NPM1mut/FLT3-TKDmut or core binding factor (CBF)-rearranged/FLT3-TKDmut genotypes had significantly prolonged OS with or without censoring at hematopoietic cell transplantation (HCT), compared with NPM1WT/CBF-negative AMLs. The multivariable model for OS and EFS adjusted for allogeneic HCT in first complete remission as a time-dependent covariable, revealed NPM1 mutations and CBF rearrangements as significant favorable factors. These data show that NPM1 mutations or CBF rearrangements identify favorable prognostic groups in patients with FLT3-TKD AMLs, independent of other factors, also in the context of midostaurin treatment.

SETBP1 overexpression acts in the place of class-defining mutations to drive FLT3-ITD-mutant AML

Advances in cancer genomics have revealed genomic classes of acute myeloid leukemia (AML) characterized by class-defining mutations, such as chimeric fusion genes or in genes such as NPM1, MLL, and CEBPA. These class-defining mutations frequently synergize with internal tandem duplications in FLT3 (FLT3-ITDs) to drive leukemogenesis. However, ∼20% of FLT3-ITD-positive AMLs bare no class-defining mutations, and mechanisms of leukemic transformation in these cases are unknown. To identify pathways that drive FLT3-ITD mutant AML in the absence of class-defining mutations, we performed an insertional mutagenesis (IM) screening in Flt3-ITD mice, using Sleeping Beauty transposons. All mice developed acute leukemia (predominantly AML) after a median of 73 days. Analysis of transposon insertions in 38 samples from Flt3-ITD/IM leukemic mice identified recurrent integrations at 22 loci, including Setbp1 (20/38), Ets1 (11/38), Ash1l (8/38), Notch1 (8/38), Erg (7/38), and Runx1 (5/38). Insertions at Setbp1 led exclusively to AML and activated a transcriptional program similar, but not identical, to those of NPM1-mutant and MLL-rearranged AMLs. Guide RNA targeting of Setbp1 was highly detrimental to Flt3ITD/+/Setbp1IM+, but not to Flt3ITD/+/Npm1cA/+, AMLs. Also, analysis of RNA-sequencing data from hundreds of human AMLs revealed that SETBP1 expression is significantly higher in FLT3-ITD AMLs lacking class-defining mutations. These findings propose that SETBP1 overexpression collaborates with FLT3-ITD to drive a subtype of human AML. To identify genetic vulnerabilities of these AMLs, we performed genome-wide CRISPR-Cas9 screening in Flt3ITD/+/Setbp1IM+ AMLs and identified potential therapeutic targets, including Kdm1a, Brd3, Ezh2, and Hmgcr. Our study gives new insights into epigenetic pathways that can drive AMLs lacking class-defining mutations and proposes therapeutic approaches against such cases.

Venetoclax-Based Regimens for Relapsed/Refractory Acute Myeloid Leukemia in a Real-Life Setting: A Retrospective Single-Center Experience

Relapsed/refractory (R/R) acute myeloid leukemia (AML) is a largely unmet medical need, owing to the lack of standardized, effective treatment approaches, resulting in an overall dismal outcome. The only curative option for R/R AML patients is allogeneic hematopoietic stem cell transplantation (HSCT) which is only applicable in a fraction of patients due to the scarce efficacy and high toxicity of salvage regimens. Recently, a number of targeted agents with relatively favorable toxicity profiles have been explored in clinical trials for R/R AML patients. The Bcl-2 inhibitor venetoclax, in combination with hypomethylating agents or low dose cytarabine, has produced impressive results for newly diagnosed AML, while its role in R/R disease is not well defined yet. We retrospectively analyzed the clinical outcomes of 47 R/R AML patients treated with venetoclax-based regimens between March 2018 and December 2020 at our institution. Overall, we report a composite complete response rate of 55% with an overall acceptable toxicity profile. Outcomes were particularly favorable for NPM1 mutated patients, unlike for FLT3-ITD positive patients irrespective of NPM1 status. For patients treated with intention to transplant, the procedure could be finally performed in 54%. These findings suggest a role for venetoclax-based regimens in R/R AML patients and support the design of prospective studies.

NPM1 and FLT3-ITD/TKD Gene Mutations in Acute Myeloid Leukemia

Background: A number of mutations have been reported to occur in patients with acute myeloid leukemia (AML), of which NPM1 and FLT3 genes mutations are the commonest and have important diagnostic and therapeutic implications.

Material and Methods: Molecular testing for NPM1 and FLT3 genes was performed in 92 de-novo AML patients. The frequency and characteristics of NPM1 and FLT3 mutations were analyzed.

Results: Nucleophosmin 1(NPM1) and fms-like tyrosine kinase 3 (FLT3) mutations were seen in 22.8% and 16.3% of patients, respectively. Amongst FLT3 mutations, FLT3-ITD mutation was seen in 8.7% cases, FLT3-TKD in 5.4%, and FLT3-ITD+TKD in 2.2% cases. Certain associations between the gene mutations and clinical characteristics were found, including in NPM1 mutated group- female preponderance, higher incidence in M4/M5 categories and decreased expression of CD34 and HLA-DR; and in FLT3-ITD mutated group- higher age of presentation, higher total leucocyte count and blast percentage.

Conclusion- AML patients with NPM1 and FLT3 mutations have differences in clinical and hematological features, which might represent their different molecular mechanism in leukemogenesis. The frequency of NPM1 and FLT3 mutations in this study was comparable to reports from Asian countries but lower than that reported from western countries. However, as the number of patients in the study was less, a larger number of patients need to be studied to corroborate these findings.

Early peripheral blast cell clearance predicts minimal residual disease status and refines disease prognosis in acute myeloid leukemia

Minimal residual disease (MRD) assessment in acute myeloid leukemia (AML) is increasingly used in risk stratification. However, several issues around this use are unresolved, including, among others, the most suitable time-point(s) for its application. Overall, late assessments appear more effective at distinguishing outcome but, in some studies, the early evaluations were already highly informative, anticipating the value of later ones. Our work integrated MRD with peripheral blast clearance (PBC), a treatment-related biomarker previously demonstrated to be a powerful predictor of response. From 2007 to 2014, we have studied 120 patients treated according to the NILG 02-06 trial and who achieved CR after induction. Patients in PBC-defined categories (separated by a 1.5-log threshold) showed significantly different probabilities of attaining MRD negativity, after either induction (MRD1) or consolidation (MRD2). Peripheral blast clearance combined with MRD1 largely anticipated MRD2-related information: when both biomarkers predicted chemosensitive disease (PBC_high /MRD1_neg ), the rate of MRD2-negativity was 90%, and DFS and OS estimates were 68% and 76% at 3 years, respectively. When both markers were unfavorable (PBC_low /MRD1_pos ), rates of MRD2 negativity, DFS, and OS were 20%, 34%, and 24%, respectively, at 3 years. In fact, MRD2 added prognostic value only in cases with discordant PBC/MRD1 data. Our data support a reasoned timing for MRD-based therapeutic decisions, modulated on individual chemosensitivity, an approach we have implemented in a forthcoming prospective multi-center trial by Gruppo Italiano Malattie EMatologiche dell'Adulto (GIMEMA).

Multilineage Dysplasia as Assessed by Immunophenotype in Acute Myeloid Leukemia: A Prognostic Tool in a Genetically Undefined Category

Simple Summary

The prognostic role of multi-lineage dysplasia is still debated in acute myeloid leukemia. The aim of our work was to study dysplasia by a technique alternative to the conventional morphological method, which is multi-parameter flow cytometry. To this end, we used an immune-phenotypic score (IPS), able to estimate dysplasia by the extent of deviation from normal profile, obtained in a control group. IPS provided no insight into prognosis when considered overall nor within well-defined genetic categories. Of interest, IPS-related dysplasia conveyed significant prognostic information when we focused on genetically undefined patients, triple-negative for NPM1, FLT3 and CEBPA. This category still represents a non-negligible fraction of patients, that lack specific molecular features either for targeted drugs or for proper risk assessment. In this context, our data could help address the relative unmet needs in treatment strategy, and provide insight into response prediction in the rapidly evolving therapeutic scenario of AML.

Abstract

Acute myeloid leukemia (AML) “with myelodysplasia-related changes (MRC)” is considered a separate entity by the World Health Organization (WHO) classification of myeloid neoplasms. While anamnestic and cytogenetic criteria provide objective attribution to this subset, with clear unfavorable prognostic significance, the actual role of multi-lineage dysplasia (MLD) as assessed by morphology is debated. The aim of our work was to study MLD by a technique alternative to morphology, which is multiparameter flow cytometry (MFC), in a large series of 302 AML patients intensively treated at our Center. The correlation with morphology we observed in the unselected analysis reiterated the capability of the MFC-based approach at highlighting dysplasia. MLD data, estimated through an immune-phenotypic score (IPS), provided no insight into prognosis when considered overall nor within well-defined genetic categories. Of interest, IPS-related dysplasia conveyed significant prognostic information when we focused on genetically undefined patients, triple-negative for NPM1, FLT3 and CEBPA (TN-AML). In this context, the lack of dysplastic features (IPS_0) correlated with a significantly higher CR rate and longer survival compared to patients showing dysplasia in one or both (neutrophil and erythroid) cell lineages. The impact of IPS category maintained its validity after censoring at allogeneic HSCT and in a multivariate analysis including baseline and treatment-related covariates. In a subgroup featured by the lack of genetic determinants, our data could help address the relative unmet needs in terms of risk assessment and treatment strategy, and provide insight into prediction of response in the rapidly evolving therapeutic scenario of AML.

Preferential transcription of the mutated allele in NPM1 mutated acute myeloid leukaemia

Nucleophosmin is commonly both over-expressed and mutated in acute myeloid leukemia (AML). NPM1 mutations are always heterozygous. In addition, NPM1 has a number of different splice variants with the major variant encoded by exons 1–9 and 11–12 (NPM1.1). Further variants include NPM1.2 which lacks exons 8 and 10 and NPM1.3 which comprises exons 1–10 (and so lacks the region of sequence mutated in AML). In this study we quantified the expression of these three variants in 108 AML patient samples with and without NPM1 mutations and also assessed the level of expression from the wild-type and mutant alleles in variants NPM1.1 and NPM1.2. The results show that NPM1.1 is the most commonly expressed variant, however transcripts from wild-type and mutated alleles do not occur at equal levels, with a significant bias toward the mutated allele. Considering the involvement of mutant nucleophosmin in the progression and maintenance of AML, a bias towards mutated transcripts could have a significant impact on disease maintenance.

Terminal deoxynucleotidyl transferase (TdT) expression is associated with FLT3-ITD mutations in Acute Myeloid Leukemia

The terminal deoxynucleotidyl transferase (TdT) is a DNA polymerase expressed in acute myeloid leukemias (AMLs), where it may be involved in the generation of NPM1 and FLT3-ITD mutations. We studied the correlations between TdT expression and FLT3-ITD or NPM1 mutations in primary AML samples, and the impact on patients' survival. TdT expression was analyzed in 143 adult AML patients by flow cytometry as percentage of positivity and mean fluorescence intensity (MFI) on blasts. TdT was positive in 49 samples (34.2%), with a median of 48% TdT-positivity (range 7-98) and a median MFI of 2.70 (range 1.23-30.54). FLT3-ITD and NPM1 mutations were present in 24 (16.7%) and 34 (23.7%) cases, respectively. Median TdT expression on blasts was significantly higher in FLT3-ITD+, as compared with FLT3-ITD- AMLs (median 8% vs 0% respectively, p = 0.035). NPM1 mutational status, FLT3-ITD allelic ratio, karyotype, and ELN risk groups, did not correlate with TdT expression or MFI on blasts. TdT + patients had poorer survival as compared to TdT-, but this result was not confirmed by the multivariable analysis, where ELN risk stratification as well as age and type of treatment remained independent prognostic factors for OS. In summary, our results support the possible implication of TdT enzyme in the generation of FLT3-ITD mutations in AML.

Proteostasis unbalance of nucleophosmin 1 in Acute Myeloid Leukemia: An aggregomic perspective

The role exerted by the nucleus in the regulation of proteostasis in both health and disease is recognized of outmost importance, even though not fully understood. Many recent investigations are focused on its ability to modulate and coordinate protein quality control machineries in mammalian cells. Nucleophosmin 1 (NPM1) is one of the most abundant nucleolar proteins and its gene is mutated in ~30% of Acute Myeloid Leukemia (AML) patients. Mutations are localized in the C-terminal domain of the protein and cause cytoplasmatically delocalized and possibly aggregated forms of NPM1 (NPM1c+). Therapeutic interventions targeted on NPM1c+ are in demand and, to this end, deeper knowledge of NPM1c+ behavior in the blasts' cytosol is required. Here by means of complementary biophysical techniques we compared the conformational and aggregative behavior of the entire C-terminal domains of NPM1wt and type A NPM1c+ (bearing the most common mutation). Overall data show that only Cterm_mutA is able to form amyloid-like assemblies with fibrillar morphology and that the oligomers are toxic in human neuroblastoma SHSY cells. This study adds a novel piece of knowledge to the comprehension of the molecular roles exerted by cytoplasmatic NPM1c+ and suggests the exploitation of the amyloidogenic propensity of NPM1c+ as a new strategy for targeting AML with NPM1 mutations.

Digital Droplet PCR is a Specific and Sensitive Tool for Detecting IDH2 Mutations in Acute Myeloid LeuKemia Patients

Isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) interfere with cellular metabolism contributing to oncogenesis. Mutations of IDH2 at R140 and R172 residues are observed in 20% of acute myeloid leukemias (AML), and the availability of the IDH2 inhibitor Enasidenib made IDH2 mutational screening a clinical need. The aim of this study was to set a new quantitative polymerase chain reaction (PCR) technique, the drop-off digital droplet PCR (drop-off ddPCR), as a sensitive and accurate tool for detecting IDH2 mutations. With this technique we tested 60 AML patients. Sanger sequencing identified 8/60 (13.5%) mutated cases, while ddPCR and the amplification refractory mutation system (ARMS) PCR, used as a reference technique, identified mutations in 13/60 (21.6%) cases. When the outcome of IDH2-mutated was compared to that of wild-type patients, no significant difference in terms of quality of response, overall survival, or progression-free survival was observed. Finally, we monitored IDH2 mutations during follow-up in nine cases, finding that IDH2 can be considered a valid marker of minimal residual disease (MRD) in 2/3 of our patients. In conclusion, a rapid screening of IDH2 mutations is now a clinical need well satisfied by ddPCR, but the role of IDH2 as a marker for MRD still remains a matter of debate.

Absence of FGFR3-TACC3 rearrangement in hematological malignancies with numerical chromosomal alteration

FGFR-TACC, found in different tumor types, is characterized by the fusion of a member of fibroblast grown factor receptor (FGFR) tyrosine kinase (TK) family to a member of the transforming acidic coiled-coil (TACC) proteins. Because chromosome numerical alterations, hallmarks of FGFR-TACC fusions are present in many hematological disorders and there are no data on the prevalence, we studied a series of patients with acute myeloid leukemia and myelodysplastic syndrome who presented numerical alterations using cytogenetic traditional analysis. None of the analyzed samples showed FGFR3-TACC3 gene fusion, so screening for this mutation at diagnosis is not recommended.

Early peripheral clearance of leukemia-associated immunophenotypes in AML: centralized analysis of a randomized trial

Although genetics is a relevant risk factor in acute myeloid leukemia (AML), it can be minimally informative and/or not readily available for the early identification of patients at risk for treatment failure. In a randomized trial comparing standard vs high-dose induction (ClinicalTrials.gov #NCT00495287), we studied early peripheral blast cell clearance (PBC) as a rapid predictive assay of chemotherapy response to determine whether it correlates with the achievement of complete remission (CR), as well as postremission outcome, according to induction intensity. Individual leukemia-associated immunophenotypes (LAIPs) identified pretherapy by flow cytometry were validated and quantified centrally after 3 days of treatment, expressing PBC on a logarithmic scale as the ratio of absolute LAIP+ cells on day 1 and day 4. Of 178 patients, 151 (84.8%) were evaluable. Patients in CR exhibited significantly higher median PBC (2.3 log) compared with chemoresistant patients (1.0 log; P < .0001). PBC < 1.0 predicted the worst outcome (CR, 28%). With 1.5 log established as the most accurate cutoff predicting CR, 87.5% of patients with PBC >1.5 (PBChigh, n = 96) and 43.6% of patients with PBC ≤1.5 (PBClow, n = 55) achieved CR after single-course induction (P < .0001). CR and PBChigh rates were increased in patients randomized to the high-dose induction arm (P = .04) and correlated strongly with genetic/cytogenetic risk. In multivariate analysis, PBC retained significant predictive power for CR, relapse risk, and survival. Thus, PBC analysis can provide a very early prediction of outcome, correlates with treatment intensity and disease subset, and may support studies of customized AML therapy.

Salvage treatment for refractory or relapsed acute myeloid leukemia: a 10-year single-center experience

OBJECTIVES

The outcomes of refractory and relapsed acute myeloid leukemia (AML) patients in developing countries are underreported, even though the similar classic regimens are widely used.

METHODS

We conducted a retrospective comparison of "MEC" (mitoxantrone, etoposide, and cytarabine) and "FLAG-IDA" (fludarabine, cytarabine, idarubicin, and filgrastim) in adults with first relapse or refractory AML.

RESULTS

In total, 60 patients were included, of which 28 patients received MEC and 32 received FLAG-IDA. A complete response (CR) rate of 48.3% was observed. Of the included patients, 16 (27%) died before undergoing bone marrow assessment. No statiscally significant difference in CR rate was found between the two protocols (p=0.447). The median survival in the total cohort was 4 months, with a 3-year overall survival (OS) rate of 9.7%. In a multivariable model including age, fms-like tyrosine kinase 3 (FLT3) status, and stem-cell transplantation (SCT), only the last two indicators remained significant: FLT3-ITD mutation (hazard ratio [HR]=4.6, p<0.001) and SCT (HR=0.43, p=0.01).

CONCLUSION

In our analysis, there were no significant differences between the chosen regimens. High rates of early toxicity were found, emphasizing the role of supportive care and judicious selection of patients who are eligible for intensive salvage therapy in this setting. The FLT3-ITD mutation and SCT remained significant factors for survival in our study, in line with the results of previous studies.

AML through the prism of molecular genetics

Modern management of acute myeloid leukaemia (AML) relies on the integration of phenotypic and genetic data to assign classification, establish prognosis, enhance monitoring and guide treatment. The prism through which we can now disperse a patient's leukaemia, interpret and apply our understanding has fundamentally changed since the completion of the first whole-genome sequencing (WGS) of an AML patient in 2008 and where possible, many clinicians would now prefer to delay treatment decisions until the karyotype and genetic status of a new patient is known. The success of global sequencing initiatives such as The Cancer Genome Atlas (TCGA) have brought us significantly closer to cataloguing the full spectrum of coding mutations involved in human malignancy. Indeed, genetic capability has raced ahead of our capacity to apply much of this knowledge into clinical practice and we are in the peculiar position of having routine access to genetic information on an individual patient's leukaemia that cannot be reliably interpreted or utilised. This is a measure of how rapid the progress has been, and this rate of change is likely to continue into the foreseeable future as research intensifies on the non-coding genome and the epigenome, as we scrutinise disease at a single cell level, and as initiatives like Beat AML and the Harmony Alliance progress. In this review, we will examine how interrogation of the coding genome is revolutionising our understanding of AML and improving our ability to underscore differences between paediatric and adult onset, sporadic and inherited forms of disease. We will look at how this knowledge is informing improvements in outcome prediction and the development of novel treatments, bringing us a step closer to personalised therapy for myeloid malignancy.

Identification of FLT3 and NPM1 Mutations in Patients with Acute Myeloid Leukaemia

Objective:

The most frequent acquired molecular abnormalities and important prognostic indicators in patients with Acute Myeloid Leukaemia (AML) are fms-like tyrosine kinase-3 gene (FLT3) and nucleophosmin-1 (NPM1) mutations. Our study aims to develop a cost effective and comprehensive in-house conventional PCR method for detection of FLT3-ITD, FLT3-D835 and NPM1 mutations and to evaluate the frequency of these mutations in patients with cytogenetically normal (CN) AML in our population.

Methods:

A total of 199 samples from AML patients (95 women, 104 men) were included in the study. Mutation analyses were performed using polymerase chain reaction (PCR) and gene sequencing.

Result:

Sixty-eight patients were positive for the mutations. FLT3-ITD mutations were detected in 32 patients (16.1%), followed by FLT3-D835 in 5 (2.5%) and NPM1 in 54 (27.1%). Double mutations of NPM1 and FLT3-ITD were detected in 23 cases (11.6%). Assays validation were performed using Sanger sequencing and showed 100% concordance with in house method.

Conclusion:

The optimized in-house PCR assays for the detection of FLT3-ITD, FLT3-D835 and NPM1 mutations in AML patients were robust, less labour intensive and cost effective. These assays can be used as diagnostic tools for mutation detection in AML patients since identification of these mutations are important for prognostication and optimization of patient care.

NPM1 alternative transcripts are upregulated in acute myeloid and lymphoblastic leukemia and their expression level affects patient outcome

Background

Expression of the NPM1 gene, encoding nucleophosmin, is upregulated in cancers. Although more than ten NPM1 transcripts are known, the reports were usually limited to one predominant transcript. In leukemia, the NPM1 expression has not been widely studied so far. In acute myeloid leukemia (AML), the mutational status of the gene seems to play a pivotal role in carcinogenesis. Therefore, the aim of the study was to quantify alternative NPM1 transcripts in two types of acute leukemia, AML and ALL (acute lymphoblastic leukemia).

Methods

Using droplet digital PCR, we analyzed the levels of three protein-coding NPM1 transcripts in 66 samples collected from AML and ALL patients and 16 control samples. Using RNA-seq, we detected 8 additional NPM1 transcripts, including non-coding splice variants with retained introns. For data analysis, Welch two sample t-test, Pearson’s correlation and Kaplan–Meier analysis were applied.

Results

The levels of the particular NPM1 transcripts were significantly different but highly correlated with each other in both leukemia and control samples. Transcript NPM1.1, encoding the longest protein (294 aa), had the highest level of accumulation and was one of the most abundant transcripts in the cell. Comparing to NPM1.1, the levels of the NPM1.2 and NPM1.3 transcripts, encoding a 265-aa and 259-aa proteins, were 30 and 3 times lower, respectively. All three NPM1 transcripts were proportionally upregulated in both types of leukemia compared to control samples. In AML, the levels of NPM1 transcripts decreased in complete remission and increased again with relapse of the disease. Low levels of NPM1.1 and NPM1.3 were associated with better prognosis. The contribution of non-coding transcripts to the total level of NPM1 gene seemed to be marginal, except for one short 5-end transcript accumulated at high levels in AML and control cells. Aberrant proportions of particular NPM1 splice variants could be linked to abnormal expression of genes encoding alternative splicing factors.

Conclusions

The levels of the studied NPM1 transcripts were different but highly correlated with each other. Their upregulation in AML and ALL, decrease after therapy and association with patient outcome suggests the involvement of elevated NPM1 expression in the acute leukemia pathogenesis.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1608-2) contains supplementary material, which is available to authorized users.

Molecular remission at the end of treatment is a necessary goal for a good outcome in ELN favorable-risk acute myeloid leukemia: a real-life analysis on 201 patients by the Rete Ematologica Lombarda network

Favorable acute myeloid leukemia (AML) patients (pts.) demonstrate a relatively good outcome with standard induction; thus, pts. are generally not addressed to allogeneic transplant in first remission. However, it is not clear if also in a real-life setting, the outcome is homogeneous in the different favorable molecular groups and which are the parameters significantly associated to an increased relapse risk, useful to suggest the need of an intensified approach. In order to clarify this point, we collected clinical data on consecutive unselected AML pts. assigned to favorable category (modified ELN 2010 due to the inclusion of double-mutated CEBPA-positive cases), diagnosed and treated in six centers of the Italian network Rete Ematologica Lombarda (REL) from 2007 to 2015. We assessed response (CR, mCR), relapse rate (CIR), and outcome (OS, DFS) after first-line treatment. A total of 201 pts. was studied and the analysis was performed globally and in each molecular group: t(8;21)(q22;q22)/RUNX1-RUNX1T1 (30 pts., 14.9%), inv. (16)(p13q22) or t(16;16)(p13q22)/CBFB-MIH11 (35 pts., 17.4%), normal karyotype and mutated NPM1 and negative FLT3-ITD (116 pts., 57.7%) or double-mutated CEBPA (CEBPAdm) (20 pts., 10%). Complete remission (CR) was obtained in 188 pts. (93.5%), molecular CR (mCR) in 114 (67.5%); After a median follow-up of 2.4 years, cumulative incidence of relapse (CIR) was documented in 78 of 188 responding pts. (41%) after a median time of 11.3 months. CIR was higher in the CBFB-MIH11 group, in pts. achieving only a hematological response without mCR (72.1 vs 28.1%, p < 0.001), in older pts. and it resulted independently associated with a lower median cytarabine cumulative dose (CCD). Median OS was not reached: after 5 years it was 66.3%, and median DFS was 5.3 years, both without difference among groups. Molecular CR reached at any time, during or after the end of first-line treatment, was significantly associated with better DFS, and in particular, mCR assessed at the end of treatment was confirmed in multivariate analysis as an independent prognostic factor both for DFS and OS. In conclusion, the present study confirms in a real-life context the overall good prognosis of favorable-risk AML; the achievement of any molecular negativity during first-line treatment, particularly when assessed at the end of treatment, is associated with lower relapse and better survival. Increasing age at diagnosis has a negative prognostic impact, while CCD higher than 18 g/sqm is associated with better outcome.

RNA-based FLT3-ITD allelic ratio is associated with outcome and ex vivo response to FLT3 inhibitors in pediatric AML

Controversy exists whether internal tandem duplication of FMS-like tyrosine kinase 3 (FLT3-internal tandem duplication [ITD]) allelic ratio (AR) and/or length of the ITD should be taken into account for risk stratification of pediatric acute myeloid leukemia (AML) and whether it should be measured on RNA or DNA. Moreover, the ITD status may be of relevance for selecting patients eligible for FLT3 inhibitors. Here, we included 172 pediatric AML patients, of whom 36 (21%) harbored FLT3-ITD as determined on both RNA and DNA. Although there was a good correlation between both parameters AR_spearman = 0.62 (95% confidence interval, 0.22-0.87) and ITDlength_spearman = 0.98 (95% confidence interval, 0.90-1.00), only AR ≥ 0.5 and length ≥48 base pairs (bps) based on RNA measurements were significantly associated with overall survival (AR: P_logrank = .008; ITDlength: P_logrank = .011). In large ITDs (>156 bp on DNA) a remarkable 90-bp difference exists between DNA and RNA, including intron 14, which is spliced out in RNA. Ex vivo exposure (n = 30) to FLT3 inhibitors, in particular to the FLT3-specific inhibitor gilteritinib, showed that colony-forming capacity was significantly more reduced in FLT3-ITD-AR ≥ 0.5 compared with ITD-AR-low and ITD^- patient samples (P < .001). RNA-based FLT3-ITD measurements are recommended for risk stratification, and the relevance of AR regarding eligibility for FLT3-targeted therapy warrants further study.

High-dose ascorbate and arsenic trioxide selectively kill acute myeloid leukemia and acute promyelocytic leukemia blasts in vitro

The use of high-dose ascorbate (ASC) for the treatment of human cancer has been attempted several decades ago and has been recently revived by several in vitro and in vivo studies in solid tumors. We tested the cytotoxic effects of ASC, alone or in combination with arsenic trioxide (ATO) in acute myeloid leukemia (AML) and acute promyelocytic leukemia (APL). Leukemic cell lines and primary blasts from AML and APL patients were treated with graded concentrations of ASC, alone or in association with standard concentration (1 μM) of ATO. The ASC/ATO combination killed myeloid blasts, including leukemic CD34⁺ cells, while sparing CD34⁺ progenitors obtained from normal cord blood and bone marrow. Actually, approximately one-third (11/36) of primary AML cases were highly sensitive to the ASC/ATO combination. The mechanism of cell killing appeared to be related to increased oxidative stress and overproduction of ROS in a non-quantitative fashion, which resulted in induction of apoptosis. These effects were reverted by the addition of the antioxidant N-Acetyl-Cysteine (NAC). In the APL NB4 model, ASC induced direct degradation of the PML and PML/RARA proteins via caspase activation, while the transcriptional repressor DAXX was recruited in re-constituted PML nuclear bodies. Our findings encourage the design of pilot studies to explore the potential clinical benefit of ASC alone or in combination with ATO in advanced AML and APL.

Involvement of central nervous system in adult patients with acute myeloid leukemia: Incidence and impact on outcome

Incidence and effect on outcome of central nervous system (CNS) involvement in adult patients with acute myeloid leukemia (AML) is not clearly defined. To address this issue, 103 consecutive adult patients with newly diagnosed AML, regardless of neurologic symptoms, were submitted to a routine explorative lumbar puncture. Cerebrospinal fluid (CSF) samples were collected from 65 males and 38 females. All 103 CSF samples were examined by conventional cytology (CC) whereas 95 (92%) also by flow cytometry (FCM). At diagnosis, 70 patients (68%) were CNS negative (CNS-), whereas 33 (32%) were CNS positive (CNS+). In 11 of 33 (33%), CNS infiltration was documented either by CC or FCM , in 21 (67%) only by FCM. CNS positivity was significantly associated with a M4-M5 phenotype of the underlying AML (P = .0003) and with high levels of lactate dehydrogenase (P = .006). Overall, 80 of 103 (78%) achieved complete remission with no significant differences between CNS+ and CNS- patients. Five-year disease-free survival and overall survival were found to be shorter in CNS+ patients than in those CNS- (18% vs 50%, P = .006 and 19% vs 46%, P = .02, respectively). In multivariate analysis, CNS status and age were found to affect independently overall survival. In conclusion, the incidence of CNS involvement in adult patients with newly diagnosed AML is higher than expected. Regardless of neurologic symptoms, it should always be searched at diagnosis; CSF samples should routinely be investigated by FCM since a certain proportion of CNS involvements might remain undetected if examination is exclusively CC based.

Evaluation of the European LeukemiaNet recommendations for predicting outcomes of patients with acute myeloid leukemia treated in low- and middle-income countries (LMIC): A Brazilian experience

BACKGROUND

Current results regarding treatment outcomes in acute myeloid leukemia (AML) point to significant differences between low- and middle-income countries (LMIC) and high-income countries (HIC). Excluding well-known socioeconomic issues, genetic markers important for prognosis have not been properly incorporated into the clinical practice so far and their usefulness outside of well-controlled clinical trials remain unknown.

METHODS

Here, we assessed the clinical significance of the European LeukemiaNet (ELN) recommendations in 196 consecutive patients with AML in a real-life setting. All patients were younger than 60 years of age (49% male) and treated with conventional chemotherapy for induction and consolidation in three Brazilian Institutions that well represent Brazilian geographic and socioeconomic diversity.

FINDINGS

Multivariable analysis showed that ELN recommendations had a slight association with complete remission achievement (odds ratio: 0.74, 95% confidence interval, CI: 0.53-1.01; P=0.06), but were independently associated with poor overall survival (OS) (hazard ratio, HR: 1.3, 95% CI: 1.1-1.54; P=0.002), disease-free survival (DFS) (HR: 1.42, 95% CI: 1.03-1.95; P=0.028) and event-free survival (EFS) (HR: 1.24, 95% CI: 1.06-1.47; P=0.007), considering initial leukocyte counts and age as confounders. ELN recommendations had no impact on cumulative incidence of relapse (P=0.09).

INTERPRETATION

Our results suggest that within the context of LMIC, the prognostic markers recommended by ELN may be useful to predict patient's clinical outcomes; however, the OS, DFS and EFS were shorter than the reported in Europe and US for the respective risk groups.

CEBPA-double-mutated acute myeloid leukemia displays a unique phenotypic profile: a reliable screening method and insight into biological features

Mutations in CCAAT/enhancer binding protein α (CEBPA) occur in 5-10% of cases of acute myeloid leukemia. CEBPA-double-mutated cases usually bear biallelic N- and C-terminal mutations and are associated with a favorable clinical outcome. Identification of CEBPA mutants is challenging because of the variety of mutations, intrinsic characteristics of the gene and technical issues. Several screening methods (fragment-length analysis, gene expression array) have been proposed especially for large-scale clinical use; although efficient, they are limited by specific concerns. We investigated the phenotypic profile of blast and maturing bone marrow cell compartments at diagnosis in 251 cases of acute myeloid leukemia. In this cohort, 16 (6.4%) patients had two CEBPA mutations, whereas ten (4.0%) had a single mutation. First, we highlighted that the CEBPA-double-mutated subset displays recurrent phenotypic abnormalities in all cell compartments. By mutational analysis after cell sorting, we demonstrated that this common phenotypic signature depends on CEBPA-double-mutated multi-lineage involvement. From a multidimensional study of phenotypic data, we developed a classifier including ten core and widely available parameters. The selected markers on blasts (CD34, CD117, CD7, CD15, CD65), neutrophil (SSC, CD64), monocytic (CD14, CD64) and erythroid (CD117) compartments were able to cluster CEBPA-double-mutated cases. In a validation set of 259 AML cases from three independent centers, our classifier showed excellent performance with 100% specificity and 100% sensitivity. We have, therefore, established a reliable screening method, based upon multidimensional analysis of widely available phenotypic parameters. This method provides early results and is suitable for large-scale detection of CEBPA-double-mutated status, allowing gene sequencing to be focused in selected cases.

Establishment of a quenching probe method for detection of NPM1 mutations in acute myeloid leukemia cells

Nucleophosmin (NPM1) mutations, generally consisting of a four base-pair insertion, are present in ~60% of all cytogenetically normal acute myeloid leukemia (AML) cases. The mutation is clinically significant as an important prognostic factor. Direct sequencing is the current standard method of mutation detection, however, it is quite costly and time consuming. The present study aimed to establish a highly sensitive quenching probe (QP) method to detect NPM1 mutations efficiently. Melting curve analysis was performed using a QP, following polymerase chain reaction for amplification of the involved region of the gene. The curve derived from the fluorescent intensity with respect to the temperature of OCI/AML3, a heterozygous NPM1 mutant AML cell line, was W-shaped with melting peaks at 61°C and 68°C. That of M-07e, the homozygous wild type cell line, was V-shaped with a melting peak at 68°C. Thus, the curve derived from the mutant allele was easily discriminated from that of the wild-type allele. The mutant allele was detected in concentrations as low as 3% as determined by a subsequent sensitivity study. With a short testing time and a high sensitivity, this assay was applicable for NPM1-mutated AML patient samples and is appropriate for screening NPM1 mutations. It does require further examination as to whether it would be useful as a detection method for other mutant alleles since NPM1 mutations may consist of 61 known types of mutant sequences. To the best of our knowledge, this is the first report describing the QP method for the detection of NPM1 mutations.

Simultaneous detection of mutations and copy number variation of NPM1 in the acute myeloid leukemia using multiplex ligation-dependent probe amplification

The NPM1 gene encodes nucleophosmin, a protein involved in multiple cell functions and carcinogenesis. Mutation of the NPM1 gene, causing delocalization of the protein, is the most frequent genetic lesion in acute myeloid leukemia (AML); it is considered a founder event in AML pathogenesis and serves as a favorable prognostic marker. Moreover, in solid tumors and some leukemia cell lines, overexpression of the NPM1 gene is commonly observed. Therefore, the purpose of this study was to develop a new method for the detection of NPM1 mutations and the simultaneous analysis of copy number alterations (CNAs), which may underlie NPM1 gene expression deregulation. To address both of the issues, we applied a strategy based on multiplex ligation-dependent probe amplification (MLPA). A designed NPM1mut+ assay enables the detection of three of the most frequent NPM1 mutations: A, B and D. The accuracy of the assay was tested using a group of 83 samples from Polish patients with AML and other blood-proliferative disorders. To verify the results, we employed traditional Sanger sequencing and next-generation transcriptome sequencing. With the use of the NPM1mut+ assay, we detected mutations A, D and B in 14, 1 and 0 of the analyzed samples, respectively. All of these mutations were confirmed by complementary sequencing approaches, proving the 100% specificity and sensitivity of the proposed test. The performed sequencing analysis allowed the identification of two additional rare mutations (I and ZE). All of the mutations were identified exclusively in AML cases, accounting for 25% of those cases. We did not observe any CNAs (amplifications) of the NPM1 gene in the studied samples, either with or without the mutation. The presented method is simple, reliable and cost-effective. It can be easily introduced into clinical practice or developed to target both less-frequent mutations in the NPM1 gene and other cancer-related genes.

Multicentre survey to explore current survival of patients with acute myeloid leukaemia who failed induction chemotherapy

BACKGROUND

Acute myeloid leukaemia not responsive to first induction chemotherapy (PIF-AML) still remains a challenge, and there are only few recent epidemiological data regarding the outcome of these patients. In this multicentre survey, we evaluate the prognosis and outcome of patients with PIF-AML, who were diagnosed and treated in the last 5 yrs in four Italian institutions.

RESULTS

One hundred PIF-AML were recorded, 57 males and 43 females, with a median age of 63 yrs (19-79), 42% were younger than 60 yrs; 42% had a secondary AML and 40% had an adverse karyotype. According to cytogenetic/molecular risk stratification at diagnosis, 33% of patients were classified as favourable/intermediate-1 risk and 56% as intermediate-2/adverse risk. After a median follow-up of 11 months (1-49), 77% of patients died, while 23% were alive (with 12/23 in cCR). Thirty-six patients underwent allogeneic SCT, and of these, 11 of 36 (31%) were alive at last follow-up. The 12- and 24-month OS probability of the whole population was 45% and 21%, respectively. In multivariate analysis, the probability of OS of the whole population was significantly improved by Allo-SCT procedure (12-month OS probability 60% vs. 35%; P < 0.0001) and was better in patients with favourable/intermediate-1 risk at diagnosis (12-month OS probability 58% vs. 40%; P = 0.028). In transplanted cases, a pretransplant responsive disease was the only significant factor to predict a favourable outcome after Allo-SCT (P = 0.006).

CONCLUSION

Treatment options of PIF-AML still are limited and the prognosis, even recently, remains extremely poor. This survey shows that PIF-AML is still rarely cured without Allo-SCT and confirms the importance of initiating an urgent unrelated donor search in cases without a matched sibling donor. Moreover, the outcome of Allo-SCT is better in patients who achieve a good AML debulking before transplant. To reach this goal, new predictive scores and new protocols of salvage therapy (with target drugs or combinations) need to be explored urgently in PIF-AML.

A Leukemia-Associated CD34/CD123/CD25/CD99+ Immunophenotype Identifies FLT3-Mutated Clones in Acute Myeloid Leukemia

PURPOSE

We evaluated leukemia-associated immunophenotypes (LAIP) and their correlation with fms-like tyrosine kinase 3 (FLT3) and nucleophosmin (NPM1) gene mutational status in order to contribute a better identification of patients at highest risk of relapse in acute myeloid leukemia (AML).

EXPERIMENTAL DESIGN

Bone marrow samples from 132 patients with AML were analyzed by nine-color multiparametric flow cytometry. We confirmed the presence of the mutation in diagnostic samples and in sorted cells by conventional RT-PCR and by patient-specific RQ-PCR.

RESULTS

Within the CD34(+) cell fraction, we identified a discrete population expressing high levels of the IL3 receptor α-chain (CD123) and MIC-2 (CD99) in combination with the IL2 receptor α-chain (CD25). The presence of this population positively correlated with the internal tandem duplications (ITD) mutation in the FLT3 gene (r = 0.71). Receiver operating characteristics showed that, within the CD34(+) cell fraction a percentage of CD123/CD99/CD25(+) cells ≥11.7% predicted FLT3-ITD mutations with a specificity and sensitivity of >90%. CD34/CD123/CD99/CD25(+) clones were also detectable at presentation in 3 patients with FLT3 wild-type/NPM1(+) AML who relapsed with FLT3-ITD/NPM1(+) AML. Quantitative real-time PCR designed at relapse for each FLT3-ITD in these three cases confirmed the presence of low copy numbers of the mutation in diagnostic samples.

CONCLUSIONS

Our results suggest that the CD34/CD25/CD123/CD99(+) LAIP is strictly associated with FLT3-ITD-positive cells.

Retinoic acid receptors: from molecular mechanisms to cancer therapy

Retinoic acid (RA), the major bioactive metabolite of retinol or vitamin A, induces a spectrum of pleiotropic effects in cell growth and differentiation that are relevant for embryonic development and adult physiology. The RA activity is mediated primarily by members of the retinoic acid receptor (RAR) subfamily, namely RARα, RARβ and RARγ, which belong to the nuclear receptor (NR) superfamily of transcription factors. RARs form heterodimers with members of the retinoid X receptor (RXR) subfamily and act as ligand-regulated transcription factors through binding specific RA response elements (RAREs) located in target genes promoters. RARs also have non-genomic effects and activate kinase signaling pathways, which fine-tune the transcription of the RA target genes. The disruption of RA signaling pathways is thought to underlie the etiology of a number of hematological and non-hematological malignancies, including leukemias, skin cancer, head/neck cancer, lung cancer, breast cancer, ovarian cancer, prostate cancer, renal cell carcinoma, pancreatic cancer, liver cancer, glioblastoma and neuroblastoma. Of note, RA and its derivatives (retinoids) are employed as potential chemotherapeutic or chemopreventive agents because of their differentiation, anti-proliferative, pro-apoptotic, and anti-oxidant effects. In humans, retinoids reverse premalignant epithelial lesions, induce the differentiation of myeloid normal and leukemic cells, and prevent lung, liver, and breast cancer. Here, we provide an overview of the biochemical and molecular mechanisms that regulate the RA and retinoid signaling pathways. Moreover, mechanisms through which deregulation of RA signaling pathways ultimately impact on cancer are examined. Finally, the therapeutic effects of retinoids are reported.

Comparing i.v. BU dose intensity between two regimens (FB2 vs FB4) for allogeneic HCT for AML in CR1: a report from the Acute Leukemia Working Party of EBMT

This retrospective analysis compared two regimens of fludarabine combined with i.v. BU 6.4 mg/kg (FB2) or BU 12.8 mg/kg (FB4) for allografting of AML in first CR. A total of 437 patients (median age: 50 years) were administered FB2 (n = 225, 51%) or FB4 (n = 212, 49%). Median follow-up time was 28 months. Use of FB2 resulted in a longer time to neutrophil engraftment (17 vs 15 days, P < 0.0001) but no difference in incidence of grade II-IV acute (P = 0.54) or chronic GVHD (P = 0.51). In patients < 50 years of age, FB2 was associated with a higher 2-year cumulative incidence of relapse (33 ± 6% vs 20 ± 4%, P = 0.04), but there was no difference in 2-year leukemia-free survival (LFS) (P = 0.45), OS (P = 0.53) or non-relapse mortality (P = 0.17). In recipients ⩾ 50 years of age, FB2 resulted in better 2-year LFS (63 ± 4% vs 42 ± 7%, P = 0.02) and OS (68 ± 4% vs 45 ± 7%, P = 0.006); a lower 2-year non-relapse mortality, albeit not statistically significant (15 ± 3% vs 29 ± 6%, P = 0.06), was observed with FB2. FB2 is an effective and well-tolerated regimen in patients ⩾ 50 years of age and does not compromise survival when used in patients <50 years undergoing allogeneic transplantation for AML in first CR.

Prognostic significance of NPM1 mutations in acute myeloid leukemia: A meta-analysis

Nucleophosmin 1 (NPM1) mutations have been identified in a substantial number of patients with acute myeloid leukemia (AML). Favorable outcomes in AML cases with NPM1 mutations have been previously reported. However, widely differing survival estimates have been indicated. Therefore, a meta-analysis of nine studies including a total of 4509 subjects was performed. The frequency of NPM1 mutations was found to be 6.45-56.08%. NPM1-mutation type (NPM1-mt) patients had >2-fold higher odds of achieving complete remission compared with NPM1-wild-type (NPM1-wt). The summary hazard ratio (HR) of NPM1-mt/NPM1-wt for disease-free survival (DFS) and OS was 0.67 and 0.63, respectively. In conclusion, these findings suggest that the NPM1 mutation has a favorable effect on the outcome for AML. The present meta-analysis was based on data abstracted from observational studies. However, the results obtained may justify the risk-adapted therapeutic strategies for AML according to the NPM1 status.

CD34 expression predicts an adverse outcome in patients with NPM1-positive acute myeloid leukemia

Patients with acute myeloid leukemia (AML) harboring an NPM1 mutation exhibit a heterogeneous clinical outcome. Recent studies have shown that the absence of FLT3 internal tandem duplication (FLT3-ITD) mutation confers a favorable prognosis in NPM1-positive AML. However, the prognostic impact of immunophenotypes in this subgroup remains unclear. In this study, FLT3 mutation status and immunophenotypic profile of 85 NPM1-positive patients with de novo AML were retrospectively analyzed and correlated with their clinical features and survival outcomes. Univariate analysis detected 5 markers with prognostic relevance: older age (≥60 years), high white blood cell (WBC) count (>30 × 10(9)/L), FLT3-ITD, CD7, and CD34 expression. Multivariate analysis showed that high WBC count was the only independent predictor of a lower complete remission rate (P = .019). Older age (P = .035), high WBC count (P = .008), FLT3-ITD (P = .012), and CD34 expression (P = .006) were independent predictors of a shorter event-free survival (EFS). High WBC count (P = .014), FLT3-ITD (P = .005), and CD34 expression (P = .047) were independent predictors of a shorter overall survival (OS). Furthermore, based on FLT3-ITD status in NPM1 mutation-positive patients, we showed that both high WBC and CD34 expression conferred a poor EFS (P = .010 and P = .016, respectively) and OS (P = .032 and P = .001, respectively) in the FLT3-ITD-negative group, whereas high WBC predicted a poor EFS (P = .016) and OS (P = .027) in the FLT3-ITD-positive group. Our results confirm the prognostic value of assessing FLT3-ITD mutations in NPM1-positive AML and identify the adverse prognostic impact of high WBC and CD34 expression in this subgroup of AML.