Emerging treatment strategies for acute myeloid leukemia (AML) in the elderly

Inhibitors of Chemoresistance Pathways in Combination with Ara-C to Overcome Multidrug Resistance in AML. A Mini Review

Acute myeloid leukemia (AML), the most common type of leukemia in older adults, is a heterogeneous disease that originates from the clonal expansion of undifferentiated hematopoietic progenitor cells. These cells present a remarkable variety of genes and proteins with altered expression and function. Despite significant advances in understanding the molecular panorama of AML and the development of therapies that target mutations, survival has not improved significantly, and the therapy standard is still based on highly toxic chemotherapy, which includes cytarabine (Ara-C) and allogeneic hematopoietic cell transplantation. Approximately 60% of AML patients respond favorably to these treatments and go into complete remission; however, most eventually relapse, develop refractory disease or chemoresistance, and do not survive for more than five years. Therefore, drug resistance that initially occurs in leukemic cells (primary resistance) or that develops during or after treatment (acquired resistance) has become the main obstacle to AML treatment. In this work, the main molecules responsible for generating chemoresistance to Ara-C in AML are discussed, as well as some of the newer strategies to overcome it, such as the inclusion of molecules that can induce synergistic cytotoxicity with Ara-C (MNKI-8e, emodin, metformin and niclosamide), subtoxic concentrations of chemotherapy (PD0332991), and potently antineoplastic treatments that do not damage nonmalignant cells (heteronemin or hydroxyurea + azidothymidine).

Targeting LSD1 for acute myeloid leukemia (AML) treatment

Targeted therapy for acute myeloid leukemia (AML) is an effective strategy, but currently there are very limited therapeutic targets for AML treatment. Histone lysine specific demethylase 1 (LSD1) is highly expressed in many cancers, impedes the differentiation of cancer cells, promotes the proliferation, metastasis and invasion of cancer cells, and is associated with poor prognosis. Targeting LSD1 has been recognized as a promising strategy for AML treatment in recent years. Based on these features, in the review, we discussed the main epigenetic drugs targeting LSD1 for AML therapy. Thus, this review focuses on the progress of LSD1 inhibitors in AML treatment, particularly those such as tranylcypromine (TCP), ORY-1001, GSK2879552, and IMG-7289 in clinical trials. These inhibitors provide novel scaffolds for designing new LSD1 inhibitors. Besides, combined therapies of LSD1 inhibitors with other drugs for AML treatment are also highlighted.

Potent and Highly Selective Aldo-Keto Reductase 1C3 (AKR1C3) Inhibitors Act as Chemotherapeutic Potentiators in Acute Myeloid Leukemia and T-Cell Acute Lymphoblastic Leukemia

Aldo-keto reductase 1C3 (AKR1C3) catalyzes the synthesis of 9α,11β-prostaglandin (PG) F_2α and PGF_2α prostanoids that sustain the growth of myeloid precursors in the bone marrow. The enzyme is overexpressed in acute myeloid leukemia (AML) and T-cell acute lymphoblastic leukemia (T-ALL). Moreover, AKR1C3 confers chemotherapeutic resistance to the anthracyclines: first-line agents for the treatment of leukemias. The highly homologous isoforms AKR1C1 and AKR1C2 inactivate 5α-dihydrotestosterone, and their inhibition would be undesirable. We report herein the identification of AKR1C3 inhibitors that demonstrate exquisite isoform selectivity for AKR1C3 over the other closely related isoforms to the order of >2800-fold. Biological evaluation of our isoform-selective inhibitors revealed a high degree of synergistic drug action in combination with the clinical leukemia therapeutics daunorubicin and cytarabine in in vitro cellular models of AML and primary patient-derived T-ALL cells. Our developed compounds exhibited >100-fold dose reduction index that results in complete resensitization of a daunorubicin-resistant AML cell line to the chemotherapeutic and >100-fold dose reduction of cytarabine in both AML cell lines and primary T-ALL cells.

The clinical and prognostic significance of FIS1, SPI1, PDCD7 and Ang2 expression levels in acute myeloid leukemia

OBJECTIVES

The marked heterogeneity of acute myeloid leukemia (AML) renders precisely predicting patient prognosis extremely difficult. Genetic alterations, fusions and mutations, may result in misexpression of key genes in AML. We aimed to investigate the expression patterns of 4 novel genes; FIS1, SPI1, PDCD7 and Ang2 to determine their potential prognostic role in AML patients.

METHODS

Bone marrow mononuclear cells were analyzed for of FIS1, SPI1, PDCD7 and Ang2 expression levels by real-time quantitative PCR as well as of FLT3/ITD and NPM1 mutations in 100 newly diagnosed cytogenetically normal (CN-AML) patients, and 100 non-malignant controls.

RESULTS

FIS1, SPI1, PDCD7 and Ang2 were significantly overexpressed in CN-AML patients (p < 0.001). Their high expression levels were significantly associated with lower complete remission (CR) rate, shorter relapse-free survival (RFS) and overall survival (OS). On multivariate analysis, high FIS1 expression showed a significant impact on CR response after induction therapy (OR = 88.777, 95% C.I: 2.85-2765.78, p = 0.011) while high PDCD7 appeared to be an independent risk factor for RFS (HR = 5.107, 95% C.I: 1.731-15.066, p = 0.003) and OS (HR = 7.353, 95% C.I: 1.859-29.079, p = 0.004) in CN-AML patients.

CONCLUSIONS

FIS1 and PDCD7 expression are considered independent risk factors and should be integrated into the current AML stratification system.

The clinical significance of the alternative Wilms tumor gene overexpression-hypermethylation signature in acute myeloid leukemia

BACKGROUND

Wilms tumor 1 (WT1) gene is overexpressed in numerous cancers, including acute myeloid leukemia (AML). The alternative WT1 gene (AWT1) is generated from alternative transcription start site in the WT1 first intron and encodes an N-terminal-truncated protein lacking the repressor domain. Although WT1 overexpression is a common feature in AML, the expression levels of the AWT1 and its underlying epigenetic alterations, as well as their clinical relevance in AML remain unknown.

METHODS

Quantitative assessment of AWT1 gene transcripts was performed using real-time polymerase chain reaction (PCR). Bisulfite PCR followed by pyrosequencing was done to determine the methylation status of the AWT1 promoter. The bone marrow samples were collected at diagnosis and after completion of induction chemotherapy from 80 newly diagnosed AML patients. Forty non-malignant BM samples were recruited as controls.

RESULTS

The AWT1 was significantly overexpressed in AML patients. Robust hypermethylation of the AWT1 promoter was found to be a highly specific and sensitive marker for AML (p < 0.001). Significant positive correlations between the AWT1 expression and methylation levels with BM blast counts at both initial diagnosis and after induction therapy were observed (p < 0.001). AWT1 overexpression at the initial diagnosis of AML was found to be an independent negative factor for complete remission response after induction therapy (p = 0.014).

CONCLUSION

The AWT1 gene overexpression-hypermethylation signature is a characteristic marker that positively correlates with the leukemic burden in AML. AWT1 overexpression at AML diagnosis is an independent negative predictor for CR after induction chemotherapy.

The success and the challenge of all-trans retinoic acid in the treatment of cancer

All-trans retinoic acid (ATRA), an active metabolite of vitamin A, plays important roles in cell proliferation, cell differentiation, apoptosis, and embryonic development. The effects of ATRA are mediated by nuclear retinoid receptors as well as non-genomic signal pathway, such as MAPK and PKA. The great success of differentiation therapy with ATRA in acute promyelocytic leukemia (APL) not only improved the prognosis of APL but also spurred the studies of ATRA in the treatment of other tumors. Since the genetic and physiopathological simplicity of APL is not common in human malignancies, the combination of ATRA with other agents (chemotherapy, epigenetic modifiers, and arsenic trioxide, etc) had been extensively investigated in a variety of tumors. In this review, we will discuss in details about ATRA and its role in cancer treatment.

Absolute Monocyte Count is Superior than Absolute Lymphocyte Count at Day 28 as an Independent Prognostic Factor in Acute Myeloid Leukemia

Leukemia is one of leading causes of death despite the significant improvement of survival. This study aimed at assessing the impact of absolute monocytic count (AMC), and absolute lymphocytic count (ALC) recovery on overall survival (OS) and leukemia free survival (LFS) in AML. 83 de novo AML cases were enrolled in this study. The hemogram parameters including differential leukocyte counts were determined and collected sequentially at days 1, 14, 21 and 28. There was no significant difference regarding AMC or ALC at any time points in relation to the cytogenetics prognostic groups. High AMC ≥ 0.8 × 10⁹/L at day 28 was associated with shorter OS and LFS, P value 0.012 and 0.003 respectively. On multivariate models, high AMC was shown as an independent prognostic factor associated with poor OS and LFS (HR 3, 95% CI 1.1-8.1 and P value 0.02) and (HR 5, 95% CI 1.5-17.4 and P value 0.01) respectively. High ALC-D28 (≥ 0.35 × 10⁹/L) was associated with prolonged OS and LFS survival, P value 0.032 and 0.016 respectively. However, it failed to prove the same significance using multivariate analysis. It was concluded that low AMC is an emerging independent predictor of better outcome in AML.

Gene mutational pattern and expression level in 560 acute myeloid leukemia patients and their clinical relevance

Background

Cytogenetic aberrations and gene mutations have long been regarded as independent prognostic markers in AML, both of which can lead to misexpression of some key genes related to hematopoiesis. It is believed that the expression level of the key genes is associated with the treatment outcome of AML.

Methods

In this study, we analyzed the clinical features and molecular aberrations of 560 newly diagnosed non-M3 AML patients, including mutational status of CEBPA, NPM1, FLT3, C-KIT, NRAS, WT1, DNMT3A, MLL-PTD and IDH1/2, as well as expression levels of MECOM, ERG, GATA2, WT1, BAALC, MEIS1 and SPI1.

Results

Certain gene expression levels were associated with the cytogenetic aberration of the disease, especially for MECOM, MEIS1 and BAALC. FLT3, C-KIT and NRAS mutations contained conversed expression profile regarding MEIS1, WT1, GATA2 and BAALC expression, respectively. FLT3, DNMT3A, NPM1 and biallelic CEBPA represented the mutations associated with the prognosis of AML in our group. Higher MECOM and MEIS1 gene expression levels showed a significant impact on complete remission (CR) rate, disease free survival (DFS) and overall survival (OS) both in univariate and multivariate analysis, respectively; and an additive effect could be observed. By systematically integrating gene mutational status results and gene expression profile, we could establish a more refined system to precisely subdivide AML patients into distinct prognostic groups.

Conclusions

Gene expression abnormalities contained important biological and clinical informations, and could be integrated into current AML stratification system.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-017-1279-4) contains supplementary material, which is available to authorized users.

XPO1 Inhibition using Selinexor Synergizes with Chemotherapy in Acute Myeloid Leukemia by Targeting DNA Repair and Restoring Topoisomerase IIα to the Nucleus

PURPOSE

Selinexor, a selective inhibitor of XPO1, is currently being tested as single agent in clinical trials in acute myeloid leukemia (AML). However, considering the molecular complexity of AML, it is unlikely that AML can be cured with monotherapy. Therefore, we asked whether adding already established effective drugs such as topoisomerase (Topo) II inhibitors to selinexor will enhance its anti-leukemic effects in AML.

EXPERIMENTAL DESIGN

The efficacy of combinatorial drug treatment using Topo II inhibitors (idarubicin, daunorubicin, mitoxantrone, etoposide) and selinexor was evaluated in established cellular and animal models of AML.

RESULTS

Concomitant treatment with selinexor and Topo II inhibitors resulted in therapeutic synergy in AML cell lines and patient samples. Using a xenograft MV4-11 AML mouse model, we show that treatment with selinexor and idarubicin significantly prolongs survival of leukemic mice compared with each single therapy.

CONCLUSIONS

Aberrant nuclear export and cytoplasmic localization of Topo IIα has been identified as one of the mechanisms leading to drug resistance in cancer. Here, we show that in a subset of patients with AML that express cytoplasmic Topo IIα, selinexor treatment results in nuclear retention of Topo IIα protein, resulting in increased sensitivity to idarubicin. Selinexor treatment of AML cells resulted in a c-MYC-dependent reduction of DNA damage repair genes (Rad51 and Chk1) mRNA and protein expression and subsequent inhibition of homologous recombination repair and increased sensitivity to Topo II inhibitors. The preclinical data reported here support further clinical studies using selinexor and Topo II inhibitors in combination to treat AML. Clin Cancer Res; 22(24); 6142-52. ©2016 AACR.

Frontline treatment of acute myeloid leukemia in adults

Recent years have highlighted significant progress in understanding the underlying genetic and epigenetic signatures of acute myeloid leukemia(AML). Most importantly, novel chemotherapy and targeted strategies have led to improved outcomes in selected genetic subsets. AML is a remarkably heterogeneous disease, and individualized therapies for disease-specific characteristics (considering patients' age, cytogenetics, and mutations) could yield better outcomes. Compared with the historical 5-to 10-year survival rate of 10%, the survival of patients who undergo modern treatment approaches reaches up to 40-50%, and for specific subsets, the improvements are even more dramatic; for example, in acute promyelocytic leukemia, the use of all-trans retinoic acid and arsenic trioxide improved survival from 30 to 40% up to 80 to 90%. Similar progress has been documented in core-binding-factor-AML, with an increase in survival from 30% to 80% upon the use of high-dose cytarabine/fludarabine/granulocyte colony-stimulating factor combination regimens. AML treatment was also recently influenced by the discovery of the superiority of regimens with higher dose Ara-C and nucleoside analogues compared with the "7+3"regimen, with about a 20% improvement in overall survival. Despite these significant differences, most centers continue to use the "7+3" regimen, and greater awareness will improve the outcome. The discovery of targetable molecular abnormalities and recent studies of targeted therapies (gemtuzumab ozagomycin, FLT3 inhibitors, isocitrate dehydrogenase inhibitors, and epigenetic therapies), future use of checkpoint inhibitors and other immune therapies such as chimeric antigen receptor T-cells, and maintenance strategies based on the minimal residual disease evaluation represent novel, exciting clinical leads aimed to improve AML outcomes in the near future.

Association between DCK 35708 T>C variation and clinical outcomes of acute myeloid leukemia in South Chinese patients

AIM

DCK is a rate-limiting enzyme in cytarabine activation. rs4643786 and rs67437265 (P122S) variants are reported to affect DCK activity.

PATIENTS & METHODS

A total of 282 newly diagnosed acute myeloid leukemia (AML) patients were treated with cytarabine combined chemotherapy and genotyped for rs4643786 and rs67437265. Prognosis data were obtained through regular follow-up. DCK mRNA expression was detected in pretreatment blood or bone marrow mononuclear cells.

RESULTS

rs4643786 showed strong linkage disequilibrium with rs67437265. rs4643786 CT heterozygotes showed significantly higher complete remission rate (p = 0.028), superior overall survival (p = 0.006) and relapse-free survival (p = 0.020) than wild-type TT homozygotes. rs4643786 polymorphism was an independent predictor for AML prognosis.

CONCLUSION

DCK rs4643786 may serve as an independent predictor of drug response and AML outcome.

Selective AKR1C3 Inhibitors Potentiate Chemotherapeutic Activity in Multiple Acute Myeloid Leukemia (AML) Cell Lines

We report the design, synthesis, and evaluation of potent and selective inhibitors of aldo-keto reductase 1C3 (AKR1C3), an important enzyme in the regulatory pathway controlling proliferation, differentiation, and apoptosis in myeloid cells. Combination treatment with the nontoxic AKR1C3 inhibitors and etoposide or daunorubicin in acute myeloid leukemia cell lines, elicits a potent adjuvant effect, potentiating the cytotoxicity of etoposide by up to 6.25-fold and the cytotoxicity of daunorubicin by >10-fold. The results validate AKR1C3 inhibition as a common adjuvant target across multiple AML subtypes. These compounds in coadministration with chemotherapeutics in clinical use enhance therapeutic index and may avail chemotherapy as a treatment option to the pediatric and geriatric population currently unable to tolerate the side effects of cancer drug regimens.

Gelatin-coated Gold Nanoparticles as Carriers of FLT3 Inhibitors for Acute Myeloid Leukemia Treatment

This study presents the design of a gold nanoparticle (AuNPs)-drug system with improved efficiency for the treatment of acute myeloid leukemia. The system is based on four different FLT3 inhibitors, namely midostaurin, sorafenib, lestaurtinib, and quizartinib, which were independently loaded onto gelatin-coated gold nanoparticles. Detailed investigation of the physicochemical properties of the formed complexes lead to the selection of quizartinib-loaded AuNPs for the in vitro evaluation of the biological effects of the formed complex against OCI-AML3 acute myeloid leukemia cells. Viability tests by MTT demonstrated that the proposed drug complex has improved efficacy when compared with the drug alone. The obtained results constitute a premise for further in vivo investigation of such drug vehicles based on AuNPs. To the best of our knowledge, this is the first study that investigates the delivery of the above-mentioned FLT3 inhibitors via gelatin-coated gold nanoparticles.

High-Intensity Induction Chemotherapy Is Feasible for Elderly Patients with Acute Myeloid Leukemia

BACKGROUND

The prognosis of elderly patients with acute myeloid leukemia (AML) is poor, and the best treatment is controversial. Since the majority of AML patients are older than 60 years, identification of those who might benefit from intensive treatment is essential.

METHODS

Data from electronic charts of consecutive AML patients treated in our center were analyzed. Eligibility criteria included newly diagnosed de novo or secondary AML, an age of 60 years or older, and intensive induction treatment.

RESULTS

Sixty-two patients were included in the analysis. Forty-six patients (74%) achieved complete remission (CR) after 1-2 intensive induction courses. Twenty of them received consolidation with conventional chemotherapy, 20 proceeded to allogeneic hematopoietic cell transplantation (allo-HCT), and 6 were ineligible for further treatment. The projected overall survival (OS) at 2 and 3 years was 28 and 23%, respectively. A normal karyotype, CR achievement, and allo-HCT were associated with improved OS, while an Eastern Cooperative Oncology Group performance status of 0-1 was borderline associated. The median survival and disease-free survival at 2 years was 18.7 months and 49%, respectively, for patients who underwent allo-HCT in CR1, compared to 12.8 months and 25%, respectively, for those who did not.

CONCLUSION

Based on our data, selected eligible elderly AML patients might benefit from intensive treatment.

New IDH1 mutant inhibitors for treatment of acute myeloid leukemia

Neomorphic mutations in isocitrate dehydrogenase 1 (IDH1) are driver mutations in acute myeloid leukemia (AML) and other cancers. We report the development of new allosteric inhibitors of mutant IDH1. Crystallographic and biochemical results demonstrated that compounds of this chemical series bind to an allosteric site and lock the enzyme in a catalytically inactive conformation, thereby enabling inhibition of different clinically relevant IDH1 mutants. Treatment of IDH1 mutant primary AML cells uniformly led to a decrease in intracellular 2-HG, abrogation of the myeloid differentiation block and induction of granulocytic differentiation at the level of leukemic blasts and more immature stem-like cells, in vitro and in vivo. Molecularly, treatment with the inhibitors led to a reversal of the DNA cytosine hypermethylation patterns caused by mutant IDH1 in the cells of individuals with AML. Our study provides proof of concept for the molecular and biological activity of novel allosteric inhibitors for targeting different mutant forms of IDH1 in leukemia.

Wilms Tumor 1 rs16754 predicts favorable clinical outcomes for acute myeloid leukemia patients in South Chinese population

The single nucleotide polymorphism (SNP) rs16754 in WT1 shows a clinical implication in Caucasus population. However, the results were not reproducible in different population cohorts. We evaluated the clinical significance of rs16754 for 205 de novo acute myeloid leukemia (AML) patients in South Chinese population, 188 healthy volunteers were recruited as healthy controls. WT1 mRNA expression was investigated in 81 pretreatment bone marrow specimens. WT1(GA/AA) patients showed better overall survival (OS, P=0.006) and relapse-free survival (RFS, P=0.025) as compared with WT1(GG) patients, and the favorable clinical outcomes were most prominent in older patients with superior OS (P=0.001) and RFS (P=0.003). In multivariable analysis, rs16754 was still associated with favorable OS (HR=1.533, P=0.042). The WT1(GG) patients showed significantly higher WT1 mRNA expression than the WT1(GA/AA) patients (P=0.01). In summary, WT1 rs16754 may serve as an independent biomarker in AML patients from South Chinese.

Treatment of relapsed undifferentiated acute myeloid leukemia (AML-M0) with Ayurvedic therapy

A 16-year-old boy was detected with acute myeloid leukemia (AML – M0) with bone marrow pathology showing 85% blasts in February 07, 1997. He received two cycles of induction chemotherapy (3+7 protocol) with daunomycin and cytosar, following which he achieved incomplete remission with bone marrow aspirate showing 14% blasts. Subsequently, the patient received two cycles of high-dose cytosine arabinoside Ara-C and achieved remission. However, his disease relapsed on August 29, 1997. Peripheral blood smear showed 6% blast cells and bone marrow showed 40% blast cells. The patient refused further chemotherapy and/or bone marrow transplant and volunteered for Ayurvedic therapy (AYT) advocated by the author from September 09, 1997. Bone marrow studies done after six months of AYT indicated that the disease was in remission. The AYT was continued for five years and stopped. Thereafter, the patient received intermittent maintenance AYT for three months in the next two years. At present, the patient is normal and healthy and has completed 12 years of disease-free survival with AYT.

Global initiative for interdisciplinary approach to improve innovative clinical research and treatment outcomes in geriatrics: biological cell-based targeted drug delivery systems for geriatrics

At the intersection of the late 20(th) century and early 21(st) century, a worldwide challenge began to emerge--how can the quality of life be improved for a steadily increasing elderly population. It is well known that elderly patients show increased susceptibility to infections and a higher incidence of co-morbidity rates. Older adults frequently demonstrate pharmacokinetic and pharmacodynamic changes promoting adverse drug reactions and complications. Analysis of world literature and practical observations indicate that new approaches are required in gerontology and geriatric medicine due to recent significant advances in biomedical science. Global interdisciplinary approaches to improve medical science and medical care services for growing elderly population are indicated. This global, interdisciplinary initiative should integrate select, tangible clinical results achieved in leading research centers and universities that are applicable in the field of geriatrics and helpful to geriatricians. Among past scientific and clinically significant study results in the field of biomedicine, one must consider targeted drug delivery systems (DDS), which are designed to minimize drug side effects, increase the efficacy of drugs, and prolong and target drug interactions with particular pathological foci in sick patients. Many review articles focus on various methods of drug encapsulation and pharmacokinetics, but not on developing clinical modalities. This article attempts to further the discussion with researchers and clinicians from various fields, as well as to encourage comprehensive and elderly patient-oriented research focused on clinical implementation of DDS, especially erythrocyte-based DDS.

RAS mutation analysis in a large cohort of Chinese patients with acute myeloid leukemia

OBJECTIVE

We examined RAS mutational status and correlated this with presenting morphology, cytogenetics, clinical outcome and other gene aberrations in a large cohort of Chinese acute myeloid leukemia (AML) patients.

DESIGNS AND METHODS

N-RAS and K-RAS were screened for mutations at hot-spot codons 12, 13 and 61 using high resolution melting analysis (HRMA) and direct DNA sequencing in 504 Chinese AML patients and their clinical relevance was analyzed.

RESULTS

The frequencies of mutations of N-RAS and K-RAS were 9.7% (49/504) and 2.9% (15/504), respectively. c.35G>A (rs121913237: G>A; p.Gly12Asp and rs121913529: G>A; p.Gly12Asp) and c.38G>A (rs121434596: G>A; p.Gly13Asp and rs112445441: G>A; p.Gly13Asp) were the most common base substitutions (46% in N-RAS and 60% in K-RAS, respectively). AML patients with RAS mutations presented significantly higher white blood cell count (WBC) at diagnosis than those without mutations (p<0.001). RAS mutations were underrepresented in patients with t(15;17) (2.9%, p=0.01), while overrepresented in cases with abn11q23 (50%, p=0.002) and inv(16) (66.6%, p=0.04). In the FAB subtypes M4 and M5, RAS mutations were more frequent (21.6% and 20.6%, respectively) than they were in other subtypes (7.5%, p=0.006 and 0.005, respectively). FLT3-ITD and RAS mutation were rarely coexistent (p=0.03). RAS mutation didn't influence overall survival (OS) either in the entire cohort or within some defined subgroups.

CONCLUSIONS

RAS mutations are associated with some biologically specific subtypes of AML but don't impact clinical outcome in Chinese patients.

Casein induces the proliferation of bone marrow mononuclear cells, apoptosis of WEHI-3 leukaemic cells and increased survival in a leukaemia mouse model

Acute myeloid leukaemia results from the neoplastic transformation of haematopoietic stem cells. Although advances have been made in its treatment, the mortality rate remains high. As a result, therapeutic alternatives continue to be explored. In this study, we present evidence that suggests that casein, the principal protein in milk, possesses significant antileukaemic properties. We investigated whether casein inhibited the in vitro proliferation and induced the apoptosis of the mouse myelomonocytic leukaemia cell line WEHI-3. By contrast, under identical conditions, casein markedly promotes the proliferation of mouse normal mononuclear bone marrow cells. Since the selective elimination of leukaemia cells is an ideal therapeutic strategy, we also evaluated the antileukaemic potential of casein in vivo. The results showed that casein increases the survival of mice bearing WEHI-3-induced tumours, suggesting that this molecule is also capable of inhibiting the proliferation of these cells in vivo. The evidence that casein inhibited cell proliferation and induced apoptosis in leukaemia cells in vitro, but increased survival in vivo in a leukaemia mouse model, indicates that casein may be useful in leukaemia therapy.

Retinoid differentiation therapy for common types of acute myeloid leukemia

Many cancers arise in a tissue stem cell, and cell differentiation is impaired resulting in an accumulation of immature cells. The introduction of all-trans retinoic acid (ATRA) in 1987 to treat acute promyelocytic leukemia (APL), a rare subtype of acute myeloid leukemia (AML), pioneered a new approach to obtain remission in malignancies by restoring the terminal maturation of leukemia cells resulting in these cells having a limited lifespan. Differentiation therapy also offers the prospect of a less aggressive treatment by virtue of attenuated growth of leukemia cells coupled to limited damage to normal cells. The success of ATRA in differentiation therapy of APL is well known. However, ATRA does not work in non-APL AML. Here we examine some of the molecular pathways towards new retinoid-based differentiation therapy of non-APL AML. Prospects include modulation of the epigenetic status of ATRA-insensitive AML cells, agents that influence intracellular signalling events that are provoked by ATRA, and the use of novel synthetic retinoids.

Gene mutation patterns and their prognostic impact in a cohort of 1185 patients with acute myeloid leukemia

To evaluate the prognostic value of genetic mutations for acute myeloid leukemia (AML) patients, we examined the gene status for both fusion products such as AML1 (CBFα)-ETO, CBFβ-MYH11, PML-RARα, and MLL rearrangement as a result of chromosomal translocations and mutations in genes including FLT3, C-KIT, N-RAS, NPM1, CEBPA, WT1, ASXL1, DNMT3A, MLL, IDH1, IDH2, and TET2 in 1185 AML patients. Clinical analysis was mainly carried out among 605 cases without recognizable karyotype abnormalities except for 11q23. Of these 605 patients, 452 (74.7%) were found to have at least 1 mutation, and the relationship of gene mutations with clinical outcome was investigated. We revealed a correlation pattern among NPM1, DNMT3A, FLT3, IDH1, IDH2, CEBPA, and TET2 mutations. Multivariate analysis identified DNMT3A and MLL mutations as independent factors predicting inferior overall survival (OS) and event-free survival (EFS), whereas biallelic CEBPA mutations or NPM1 mutations without DNMT3A mutations conferred a better OS and EFS in both the whole group and among younger patients < 60 years of age. The use of molecular markers allowed us to subdivide the series of 605 patients into distinct prognostic groups with potential clinical relevance.

Therapy-related myeloid leukemia after treatment for epithelial ovarian carcinoma: an epidemiological analysis

OBJECTIVE

Therapy related acute myeloid leukemia (t-AML) is a potential late complication of cytotoxic therapy, and it is of particular concern in the treatment of patients with epithelial ovarian carcinoma (EOC) exposed to multiple courses of chemotherapy during the course of their disease. This study examines the incidence, characteristics and clinical outcomes of patients who developed secondary myeloid-type leukemia after a diagnosis of EOC.

METHODS

National Cancer Institute's Surveillance, Epidemiology and End Results database was pooled for diagnosis of secondary myeloid leukemia after an initial diagnosis of EOC. This group of patients was compared to patients with de novo AML, and to EOC patients who did not develop secondary myeloid leukemia. Demographic, cytopathological and survival data were recorded. Cox Proportional Hazards model was used to calculate hazard ratios (HR) for developing secondary leukemia and to determine the statistically significant variables impacting survival. Kaplan-Meier estimates of survival were obtained and comparisons between the groups were performed using log-rank test.

RESULTS

One hundred and nine myeloid leukemia cases were identified among 63,359 patients with a prior diagnosis of EOC for an overall incidence of 0.17%. The median latency to development of leukemia was 4 years (range 0-27 years). Median survival from the time of secondary leukemia diagnosis was 3 months and significantly worse than the 6 month median survival in patients with de novo AML (p<0.001). Age at leukemia diagnosis greater than 65 and development of secondary vs. de novo leukemia had a statistically worse prognosis on multivariate analysis (HR of 2.69, 95%CI 2.60-2.78 and 1.81, 95%CI 1.49-2.20 respectively). The development of secondary leukemia was more common with EOC diagnosis made prior to the platinum/taxane era (HR 6.70, 95%CI 3.69-12.18). There was no difference in median survival between EOC patients who developed AML and those who did not.

CONCLUSION

Development of t-AML is a rare but lethal event among EOC patients, and its incidence has decreased significantly since the use of platinum/taxane-based chemotherapy became the standard of care.

Acute myeloid leukaemia in the elderly: a review

The majority of patients with acute myeloid leukaemia (AML) are elderly. Advancements in supportive care and regimen intensification have resulted in improvements in clinical outcomes for younger AML patients, but analogous improvements in older patients have not been realized. While outcomes are compromised by increased comorbidities and susceptibility to toxicity from therapy, it is now recognized that elderly AML represents a biologically distinct disease that is more aggressive and less responsive to therapy. Some patients tolerate and benefit from intensive remission-induction approaches, while others are best managed with less aggressive strategies. The challenge is to differentiate these groups based on host-related and biological features, in order to maximize the therapeutic benefit and minimize toxicity. As more is understood about the complicated pathogenesis and molecular basis of AML, there are more opportunities to develop and test targeted therapies. Elderly patients, with their narrow therapeutic window, are well positioned to derive a benefit from these novel agents, and therefore, despite a difficult past, there are reasons to be optimistic about the future of elderly AML.

Reduced-intensity conditioning allogeneic stem cell transplantation for older adults: is it the standard of care?

PURPOSE OF REVIEW

We reviewed reduced-intensity hematopoietic cell transplantation for older patients in the context of recently published studies.

RECENT FINDINGS

Most studies describe applicability of reduced-intensity transplantation to older patients with overall survival rates that compare favorably to chemotherapy alone, though relapse and graft-versus-host disease remain complicating factors. Though transplant recipients likely represent a highly selected population, current studies do not demonstrate an upper age for transplantation and suggest that myeloablative regimens may be considered in older patients with limited comorbidities. Avenues being pursued to improve transplant outcomes include natural killer cell immunotherapy and regulatory T-cell modulation.

SUMMARY

Until prospective studies show otherwise, transplant conditioning intensity for the older patient should be based on individual patient and disease characteristics. Enrollment into clinical trials is paramount in efforts to reduce transplant-related mortality and improve outcomes.

Inhibition of NEDD8-activating enzyme: a novel approach for the treatment of acute myeloid leukemia

NEDD8 activating enzyme (NAE) has been identified as an essential regulator of the NEDD8 conjugation pathway, which controls the degradation of many proteins with important roles in cell-cycle progression, DNA damage, and stress responses. Here we report that MLN4924, a novel inhibitor of NAE, has potent activity in acute myeloid leukemia (AML) models. MLN4924 induced cell death in AML cell lines and primary patient specimens independent of Fms-like tyrosine kinase 3 expression and stromal-mediated survival signaling and led to the stabilization of key NAE targets, inhibition of nuclear factor-kappaB activity, DNA damage, and reactive oxygen species generation. Disruption of cellular redox status was shown to be a key event in MLN4924-induced apoptosis. Administration of MLN4924 to mice bearing AML xenografts led to stable disease regression and inhibition of NEDDylated cullins. Our findings indicate that MLN4924 is a highly promising novel agent that has advanced into clinical trials for the treatment of AML.

Targeting integrin linked kinase and FMS-like tyrosine kinase-3 is cytotoxic to acute myeloid leukemia stem cells but spares normal progenitors

Acute myeloid leukemia (AML) is maintained by rare leukemia-initiating cells (L-ICs). FLT3 and/or PI3K pathways are often dysregulated in AML and may be important for L-IC survival. The presence of PI3K pathway intermediate integrin linked kinase (ILK), and FLT3 was confirmed in five L-IC-enriched AML patient samples. Treatment of AML cells with QLT0267, an inhibitor of ILK and FLT3, decreased survival of long-term suspension culture-initiating cells and NOD/SCID mouse L-IC. In contrast, little toxicity toward normal bone marrow progenitors was observed, demonstrating that candidate leukemic stem cells can be eliminated by inhibition of these targets while normal hematopoietic counterparts are spared.

Current and emerging therapies for acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) is a clonal disease characterized by the proliferation and accumulation of myeloid progenitor cells in the bone marrow, which ultimately leads to hematopoietic failure. The incidence of AML increases with age, and older patients typically have worse treatment outcomes than do younger patients.

OBJECTIVE

This review is focused on current and emerging treatment strategies for nonpromyelocytic AML in patients aged <60 years.

METHODS

A literature review was conducted of the PubMed database for articles published in English. Publications from 1990 through March 2009 were scrutinized, and the search was updated on August 26, 2009. The search terms used were: acute myeloid leukemia in conjunction with treatment, chemotherapy, stem cell transplantation, and immunotherapy. Clinical trials including adults with AML aged > or =19 years were selected for analysis. Conference proceedings from the previous 5 years of The American Society of Hematology, The European Hematology Association, and The American Society for Blood and Marrow Transplantation were searched manually. Additional relevant publications were obtained by reviewing the references from the chosen articles.

RESULTS

Cytarabine (AraC) is the cornerstone of induction therapy and consolidation therapy for AML. A standard form of induction therapy consists of AraC (100-200 mg/m(2)), administered by a continuous infusion for 7 days, combined with an anthracycline, administered intravenously for 3 days. Consolidation therapy comprises treatment with additional courses of intensive chemotherapy after the patient has achieved a complete remission (CR), usually with higher doses of the same drugs as were used during the induction period. High-dose AraC (2-3 g/m(2)) is now a standard consolidation therapy for patients aged <60 years. Despite substantial progress in the treatment of newly diagnosed AML, 20% to 40% of patients do not achieve remission with the standard induction chemotherapy, and 50% to 70% of first CR patients are expected to relapse within 3 years. The optimum strategy at the time of relapse, or for patients with the resistant disease, remains uncertain. Allogeneic stem cell transplantation has been established as the most effective form of antileukemic therapy in patients with AML in first or subsequent remission. New drugs are being evaluated in clinical studies, including immunotoxins, monoclonal antibodies, nucleoside analogues, hypomethylating agents, farnesyltransferase inhibitors, alkylating agents, FMS-like tyrosine kinase 3 inhibitors, and multidrug-resistant modulators. However, determining the success of these treatment strategies ultimately requires well-designed clinical trials, based on stratification of the patient risk, knowledge of the individual disease, and the drug's performance status.

CONCLUSIONS

Combinations of AraC and anthracyclines are still the mainstay of induction therapy, and use of high-dose AraC is now a standard consolidation therapy in AML patients aged <60 years. Although several new agents have shown promise in treating AML, it is unlikely that these agents will be curative when administered as monotherapy; it is more likely that they will be used in combination with other new agents or with conventional therapy.

Combined bezafibrate and medroxyprogesterone acetate have efficacy without haematological toxicity in elderly and relapsed acute myeloid leukaemia (AML)

Acute myeloid leukaemia (AML) causes life-threatening deficits of functional blood cells that require management using red cell and platelet transfusion and aggressive treatment of neutropenic infections. Current cytotoxic chemotherapy further worsens the problem of reduced haemopoiesis and two-thirds of patients are too frail to tolerate intensive chemotherapy at all. Median survival amongst these patients remains at <3 months emphasizing the urgent need for anti-AML therapies that do not suppress haemopoiesis. Our laboratory studies showed combined Bezafibrate and Medroxyprogesterone acetate (BaP) had activity against AML without toxicity to normal stem cells. Here we report the safety and efficacy of BaP in 20 patients (19 AML, 1 high-risk myelodysplasia) for whom intensive chemotherapy was not an option. No patient exhibited haematological toxicity from BaP. Eleven patients took BaP alone for >4 weeks. One reverted from high risk myelodysplasia and remains transfusion independent after 201 weeks of therapy. Three AML patients gained major haematological improvements for 22-30 weeks; in one, marrow was available to document a partial AML response. Thus, this trial indicates that BaP therapy has potential for treatment of elderly and relapsed AML.