Acute myeloid leukemia

Modeling leukemia with pediatric acute leukemia patient-derived iPSCs

OBJECTIVE

ediatric acute leukemia (AL) is the most common hematological malignancy in childhood. However, the limitation of clinical specimens hindered the progress of research. Therefore, new research platforms are urgently needed to establish and clarify the pathogenesis of pediatric AL, and it is necessary to try to find novel targeted therapies for the clinical use. Here, the induced pluripotent stem cells (iPSCs) derived from AL provide a reliable model for basic research.

METHODS

eukemia cells were sorted by flow cytometry and then reprogrammed into iPSCs by Sendai virus. Cell cycle assay was used to analyze cell proliferation.

RESULTS

iPS cell lines from T cell acute lymphoblastic leukemia (T-ALL) and acute myeloid leukemia (AML) cells were successfully established. The reprogramming efficiency of AML cells was much higher than that of ALL cells. Disease iPS cells switched off the expression of the disease marker genes at iPS and HPC stage. When different subtypes of AML-iPSCs were differentiated into hematopoietic progenitor cells, iPS derived from acute megakaryocytic leukemia was more readily differentiated into megakaryocyte-erythroid progenitors. Whereas, the differentiation of multipotent lymphoid progenitor (MLP) and granulocyte macrophage progenitor (GMP) were blocked. The iPS derived from acute monocyte leukemia (AMCL) also showed the differentiation of common myeloid progenitors (CMP), GMP and monocytes significantly increased but MLP differentiation was inhibited. The AML-iPSC could form teratomas and we could obverse three germ layers in vivo, indicating that the AML-iPSCs have full pluripotency. However, there were not enough blood cells in teratoma to identify the leukemia.

CONCLUSIONS

Our results provide a novel platform for AL research and critical insight into the difference of hematopoietic differentiation between ALL and AML.

Peptidyl prolyl cis/trans isomerase activity on the cell surface correlates with extracellular matrix development

Interactions with the extracellular matrix (ECM) dictate cell fates. However, the complexity of dense ECM network and cell-surface molecules prevent the study of their dynamic interaction at the molecular level on living cells. Here, we focus on peptidyl prolyl cis/trans isomerases (PPIases) to dissect prolyl isomerization from other dynamic events. We reveal the contribution of PPIase on the mechanical properties of various ECM materials and on the dynamic cell–ECM interaction. To avoid complications associated with the existing spectroscopy-based methods such as light scattering, an assay was developed for detecting PPIase activity on living cell surface. This assay allows us to correlate PPIase activity with ECM development, and with the physiological and pathological states of the cells, including the functional properties of cancer cells and immune effector cells.

Weilin Lin et al. report a new assay for measuring the activity of peptidyl prolyl cis/trans isomerase (PPIase) at the cell surface using ultra performance liquid chromatography. They find that PPIase activity correlates with development and functional properties of the extracellular matrix in primary healthy and leukemic cells.

Analysis of Efficacy and Prognostic Factors of CLAG Treatment in Chinese Patients with Refractory or Relapsed Acute Myeloid Leukemia

BACKGROUND/AIMS

The aim of this work was to investigate the efficacy and predictive factors of CLAG treatment in refractory or relapsed (R/R) acute myeloid leukemia (AML) patients.

METHODS

Sixty-seven R/R AML patients were enrolled in this prospective cohort study and treated by a CLAG regimen: 5 mg/m2/day cladribine (days 1-5), 2 g/m2/day cytarabine (days 1-5), and 300 μg/day filgrastim (days 0-5). The median follow-up duration was 10 months.

RESULTS

A total of 57 out of 67 patients were evaluable for remission after CLAG therapy, of whom 57.9% achieved a complete remission (CR) and the overall remission rate was 77.2%. The median overall survival (OS) was 10.0 months, with a 1-year OS of 40.3 ± 6.0% and 3-year OS of 16.7 ± 5.7%. CR at first induction after the initial diagnosis was associated with a favorable CR. Age above 60 years, high risk stratification, second or higher salvage therapy, and bone marrow (BM) blasts ≥42.1% were correlated with an unfavorable CR. Secondary disease, age ≥60 years, high risk stratification, and second or higher salvage therapy were associated with worse OS. Patients developed thrombocytopenia (41, 61%), febrile neutropenia (37, 55%), leukopenia (33, 49%), neutropenia (18, 27%), and anemia (9, 13%).

CONCLUSION

CLAG was effective and well tolerated for R/R AML. BM blasts ≥42.1%, age ≥60 years, high risk stratification, and second or higher salvage therapy were independent factors for a poor prognosis.

Inhibition of IRE1α-driven pro-survival pathways is a promising therapeutic application in acute myeloid leukemia

Survival of cancer cells relies on the unfolded protein response (UPR) to resist stress triggered by the accumulation of misfolded proteins within the endoplasmic reticulum (ER). The IRE1α-XBP1 pathway, a key branch of the UPR, is activated in many cancers. Here, we show that the expression of both mature and spliced forms of XBP1 (XBP1s) is up-regulated in acute myeloid leukemia (AML) cell lines and AML patient samples. IRE1α RNase inhibitors [MKC-3946, 2-hydroxy-1-naphthaldehyde (HNA), STF-083010 and toyocamycin] blocked XBP1 mRNA splicing and exhibited cytotoxicity against AML cells. IRE1α inhibition induced caspase-dependent apoptosis and G1 cell cycle arrest at least partially by regulation of Bcl-2 family proteins, G1 phase controlling proteins (p21^cip1, p27^kip1 and cyclin D1), as well as chaperone proteins. Xbp1 deleted murine bone marrow cells were resistant to growth inhibition by IRE1α inhibitors. Combination of HNA with either bortezomib or AS₂O₃ was synergistic in AML cytotoxicity associated with induction of p-JNK and reduction of p-PI3K and p-MAPK. Inhibition of IRE1α RNase activity increased expression of many miRs in AML cells including miR-34a. Inhibition of miR-34a conferred cellular resistance to HNA. Our results strongly suggest that targeting IRE1α driven pro-survival pathways represent an exciting therapeutic approach for the treatment of AML.

Southwestern Oncology Group pretreatment risk criteria as predictive or prognostic factors in acute myeloid leukemia

Acute myeloid leukemia (AML) is a clonal hematological malignant condition and the implications of pretreatment risk criteria as predictive or prognostic factors are constantly under evaluation. With this study, the authors' intent was to characterize AML patients and to evaluate the clinical outcome associated with Southwestern Oncology Group (SWOG) coding pretreatment risk criteria/cytogenetic score. Between 2002 and 2010, 225 patients were diagnosed with AML at the Portuguese Institute of Oncology (Porto, Portugal). From this patient group, 128 patients aged <65 years were selected. The patients were treated using a combination of cytarabine and anthracycline, with the addition of cyclosporine when bone marrow dysplasia was observed. A median survival of 24 months was observed in this group. The patients were divided in subgroups according to the SWOG pretreatment risk criteria. We observed a statistically significant association of non-favorable SWOG coding with female gender [P=0.025; risk ratio (RR)=3.632, 95% confidence interval (CI): 1.113-11.852], indication for allogeneic bone marrow transplantation (P=0.023, RR=1.317, 95% CI: 1.184-1.465), complete response achievement (P=0.013, RR=1.385, 95% CI: 11.232-1.556) and relapse (P=0.048, RR=3.181, 95% CI: 10.966-10.478). Furthermore, SWOG pretreatment risk criteria also significantly affected global overall survival (OS; P=0.003) and OS at 5 years (P=0.001). A multivariate Cox regression analysis supported response to induction therapy (3-year OS: P=0.011, RR=0.385, 95% CI: 10.184-0.806; 5-year OS: P=0.012, RR=0.388, 95% CI: 10.597-1.994), consolidation (3-year OS: P=0.005, RR=0.328, 95% CI: 0.150-0.720; 5-year OS: P=0.002, RR=0.308, 95% CI: 0.144-0.657) and the diagnosis of therapy-related aml (3-year OS: P=0.016, RR=2.756, 95% CI: 0.486-1.281; 5-year OS: P=0.031, RR=2.369, 95% CI: 1.081-5.189) as prognostic factors, but this was not confirmed for SWOG pretreatment risk criteria. Therefore, we concluded that the reproducibility of the application of the SWOG pretreatment risk criteria may not be available as a prognostic factor in every acute leukemia population. However, its application as a predictive factor of response has been confirmed in our population.

Zebrafish as a Model for the Study of Human Myeloid Malignancies

Myeloid malignancies are heterogeneous disorders characterized by uncontrolled proliferation or/and blockage of differentiation of myeloid progenitor cells. Although a substantial number of gene alterations have been identified, the mechanism by which these abnormalities interact has yet to be elucidated. Over the past decades, zebrafish have become an important model organism, especially in biomedical research. Several zebrafish models have been developed to recapitulate the characteristics of specific myeloid malignancies that provide novel insight into the pathogenesis of these diseases and allow the evaluation of novel small molecule drugs. This report will focus on illustrative examples of applications of zebrafish models, including transgenesis, zebrafish xenograft models, and cell transplantation approaches, to the study of human myeloid malignancies.

Hierarchy in gene expression is predictive of risk, progression, and outcome in adult acute myeloid leukemia

Cancer progresses with a change in the structure of the gene network in normal cells. We define a measure of organizational hierarchy in gene networks of affected cells in adult acute myeloid leukemia (AML) patients. With a retrospective cohort analysis based on the gene expression profiles of 116 AML patients, we find that the likelihood of future cancer relapse and the level of clinical risk are directly correlated with the level of organization in the cancer related gene network. We also explore the variation of the level of organization in the gene network with cancer progression. We find that this variation is non-monotonic, which implies the fitness landscape in the evolution of AML cancer cells is non-trivial. We further find that the hierarchy in gene expression at the time of diagnosis may be a useful biomarker in AML prognosis.

Intestinal permeability in leukemic patients prior to chemotherapy

Objective

The objective of this study was to evaluate the intestinal barrier function in leukemia patients before the start of the chemotherapy with an intestinal permeability test using lactulose and mannitol as markers.

Methods

The study enrolled 20 patients diagnosed with leukemia (acute and chronic). Ten healthy volunteers were also submitted to the test as a control group.

Results

The median lactulose/mannitol ratio was 0.019 for the Leukemia Patient Group, whereas in healthy controls the median was 0.009 (p-value = 0.244). The median lactulose/mannitol ratio in acute leukemia patients was 0.034 giving a p-value of 0.069 when compared to healthy controls. This same comparison was made between acute myeloid leukemia patients and healthy controls with a p-value of 0.149. There was no significant difference in the intestinal permeability between acute and chronic leukemia patients (p-value = 0.098).

Conclusion

The intestinal barrier function measured using the intestinal permeability test was similar in leukemic patients overall and healthy controls, but a tendency toward a different pattern was found in the intestinal barrier function of acute leukemia patients.

The expression analysis of LATS2 gene in de novo AML patients

Acute myeloid leukemia is a heterogeneous disease with respect to presentation and clinical outcome. Acquired genetic alterations along with epigenetic changes in hematopoietic progenitor cells are associated with the disease development. LATS2, as a tumor suppressor, has been indicated to have expression variations in different cancers. The aim of the present study was to analyze the expression level of the LATS2 gene in acute myeloid leukemia (AML) patients. Using quantitative real-time PCR, the expression level of the LATS2 gene was detected in peripheral blood samples from 32 patients with de novo AML and 10 normal controls. LATS2 gene was significantly over-expressed in AML patients compared to normal subjects. Significant LATS2 over-expression was observed in all FAB types except for the M3 (p = 0.661). The present work provides the first evidence of the over-expression of LATS2 in AML patients and suggests that the gene might play a role in the disease development and hence may be a potential therapeutic target for AML treatment.

Interleukin-3-mediated regulation of β-catenin in myeloid transformation and acute myeloid leukemia

Aberrant activation of β-catenin is a common event in AML and is an independent predictor of poor prognosis. Although increased β-catenin signaling in AML has been associated with oncogenic translocation products and activating mutations in the FLT3R, the mechanisms that activate β-catenin in AML more broadly are still unclear. Here, we describe a novel link between IL-3 signaling and the regulation of β-catenin in myeloid transformation and AML. In a murine model of HoxB8 and IL-3 cooperation, we show that β-catenin protein levels are modulated by IL-3 and that Cre-induced deletion of β-catenin abolishes IL-3-dependent growth and colony formation. In IL-3-dependent leukemic TF-1.8 cells, we observed increased β-catenin protein levels and nuclear localization in response to IL-3, and this correlated with transcriptional induction of β-catenin target genes. Furthermore, IL-3 promoted β-catenin accumulation in a subset of AML patient samples, and gene-expression profiling of these cells revealed induction of WNT/β-catenin and TCF4 gene signatures in an IL-3-dependent manner. This study is the first to link β-catenin activation to IL-3 and suggests that targeting IL-3 signaling may be an effective approach for the inhibition of β-catenin activity in some patients with AML.

A phase I study of fludarabine, cytarabine, and oxaliplatin therapy in patients with relapsed or refractory acute myeloid leukemia

PURPOSE

The combination of cytarabine and fludarabine was associated with superior clinical outcomes compared with those of high-dose cytarabine in relapse acute myeloid leukemia (AML). We conducted a phase I study combining oxaliplatin with cytarabine and fludarabine therapy for patients with relapsed or refractory AML.

PATIENTS AND METHODS

Between January 2008 and November 2009, 27 patients were registered in the study. Patients had histologically confirmed disease, performance status 0 to 2, and adequate organ function. The treatment regimen consisted of increasing doses of oxaliplatin (25, 30, or 35 mg/m(2)/d) on days 1 to 4 (escalation phase), and fludarabine (30 mg/m²) and cytarabine (500 mg/m²) on days 2 to 6, every 28 days for ≤ 6 cycles. The dose-limiting toxicity was defined as any symptomatic grade ≥ 3 nonhematologic toxicity lasting ≥ 3 days and involving a major organ system.

RESULTS

Of 27 patients, 12 were treated in the dose-escalation phase and 15 at the maximum tolerated dose for oxaliplatin (30 mg/m²; expansion phase). All patients were evaluable for toxicity and response. Only 1 patient received the second cycle; the remaining patients received no further study treatment, owing to slow recovery from toxicities or physician decision. Grade 3-4 drug-related toxicities included diarrhea (grade 4) and elevated levels of bilirubin (grade 3) and aspartate transaminase (grade 3). In all, 3 patients had a complete remission and 2 patients complete response without platelet recovery.

CONCLUSION

Oxaliplatin, cytarabine, and fludarabine therapy had antileukemic activity in patients with poor-risk AML, but it was associated with toxicity. Different schedules and doses may be better tolerated.

Phase I clinical, pharmacokinetic, and pharmacodynamic study of the Akt-inhibitor triciribine phosphate monohydrate in patients with advanced hematologic malignancies

Akt, a serine/threonine protein kinase, is constitutively phosphorylated and hyperactivated in multiple cancers, including acute myeloid leukemia. High levels are linked to poor survival and inferior responses to chemotherapy, making Akt inhibition an attractive therapeutic target. In this phase I/II study of TCN-PM, a small-molecule Akt inhibitor, TCN-PM therapy was well tolerated in patients with advanced hematological malignancies, and reduced levels of phosphorylation of Akt and its substrate Bad were shown, consistent with inhibition of this survival pathway and induction of cell death. Further investigation of TCN-PM alone or in combination in patients with high Akt levels is warranted.

Generation of induced pluripotent stem cells from primary chronic myelogenous leukemia patient samples

Induced pluripotent stem cells (iPSCs) can be generated by the expression of defined transcription factors not only from normal tissue, but also from malignant cells. Cancer-derived iPSCs are expected to provide a novel experimental opportunity to establish the disease model. We generated iPSCs from imatinib-sensitive chronic myelogenous leukemia (CML) patient samples. Remarkably, the CML-iPSCs were resistant to imatinib although they consistently expressed BCR-ABL oncoprotein. In CML-iPSCs, the phosphorylation of ERK1/2, AKT, and JNK, which are essential for the maintenance of both BCR-ABL (+) leukemia cells and iPSCs, were unchanged after imatinib treatment, whereas the phosphorylation of signal transducer and activator of transcription (STAT)5 and CRKL was significantly decreased. These results suggest that the signaling for iPSCs maintenance compensates for the inhibition of BCR-ABL. CML-iPSC-derived hematopoietic cells recovered the sensitivity to imatinib although CD34(+)38(-)90(+)45(+) immature cells were resistant to imatinib, which recapitulated the pathophysiologic feature of the initial CML. CML-iPSCs provide us with a novel platform to investigate CML pathogenesis on the basis of patient-derived samples.

In vitro-induced response patterns of antileukemic T cells: characterization by spectratyping and immunophenotyping

Myeloid leukemic cells can be induced to differentiate into leukemia-derived dendritic cells (DCleu) regaining the stimulatory capacity of professional DCs while presenting the leukemic antigen repertoire. But so far, the induced antileukemic T-cell responses are variable both in specificity and in efficacy. In an attempt to elucidate the underlying causes of different T-cell response patterns, T-cell receptor (TR) Vβ chain rearrangements were correlated with the T cells corresponding immunophenotypic profile, as well as their proliferative response and cytolytic capacities. In three different settings, donor T cells, either human leukocyte antigen matched or mismatched (haploidentical), or autologous T cells were repeatedly stimulated with myeloid blasts or leukemia-derived DC/DCleus from the corresponding patients diseased from acute myeloid leukemia (AML). Although no significant differences in T-cell proliferation were observed, the T-cell-mediated cytolytic response pattern varied considerably and even caused blast proliferation in two cases. Spectratyping revealed a remarkable restriction (>75% of normal level) of the CD4+ or CD8+-TR repertoire of blast- or DC/DCleu-stimulated T cells. Although in absolute terms, DC/DCleu stimulation induced the highest grade of restriction in the CD8+ T-cell subset, the CD4+ T-cell compartment seemed to be relatively more affected. But most importantly, in vitro stimulation with DC/DCleu resulted into an identical TR restriction pattern (β chain) that could be identified in vivo in a patient sample 3 months after allo-SCT. Thus, in vitro tests combining functional flow cytometry with spectratyping might provide predictive information about T cellular response patterns in vivo.

NUP98-HOXA9-transgenic zebrafish develop a myeloproliferative neoplasm and provide new insight into mechanisms of myeloid leukaemogenesis

NUP98-HOXA9 [t(7;11) (p15;p15)] is associated with inferior prognosis in de novo and treatment-related acute myeloid leukaemia (AML) and contributes to blast crisis in chronic myeloid leukaemia (CML). We have engineered an inducible transgenic zebrafish harbouring human NUP98-HOXA9 under the zebrafish spi1(pu.1) promoter. NUP98-HOXA9 perturbed zebrafish embryonic haematopoiesis, with upregulated spi1 expression at the expense of gata1a. Markers associated with more differentiated myeloid cells, lcp1, lyz, and mpx were also elevated, but to a lesser extent than spi1, suggesting differentiation of early myeloid progenitors may be impaired by NUP98-HOXA9. Following irradiation, NUP98-HOXA9-expressing embryos showed increased numbers of cells in G2-M transition compared to controls and absence of a normal apoptotic response, which may result from an upregulation of bcl2. These data suggest NUP98-HOXA9-induced oncogenesis may result from a combination of defects in haematopoiesis and an aberrant response to DNA damage. Importantly, 23% of adult NUP98-HOXA9-transgenic fish developed a myeloproliferative neoplasm (MPN) at 19-23 months of age. In summary, we have identified an embryonic haematopoietic phenotype in a transgenic zebrafish line that subsequently develops MPN. This tool provides a unique opportunity for high-throughput in vivo chemical modifier screens to identify novel therapeutic agents in high risk AML.

Quantitative assessment of MLAA-34 expression in diagnosis and prognosis of acute monocytic leukemia

MLAA-34 is a newly identified monocytic leukemia-associated antigen. Previous data indicated that MLAA-34 might be a novel anti-apoptosis factor related closely to carcinogenesis or progression of acute monocytic leukemia. The over-expression of MLAA-34 is intuitively expected to be associated with unfavorable clinical features in acute myeloid leukemia. However, there have been no clinical studies about the prognostic relevance of MLAA-34 expression in human malignancies. This study was done to investigate the clinical relevance of the expression of MLAA-34 in de novo acute myeloid leukemia. In 126 patients with de novo acute myeloid leukemia, the level of MLAA-34 expression and protein expression ratio were determined by using quantitative reverse transcriptase-PCR and western blot, respectively. The results were analyzed with respect to the patients' clinical features and treatment outcomes. Both MLAA-34 expression rates and expression levels were found to be higher in patients with the French-American-British classification subtype M5, and the expression levels were also higher in patients with a leukocyte number of ≥ 20 × 10(9)/L and patients with extramedullary disease. In addition, MLAA-34 over-expression (≥ median expression) was associated with an unfavorable day 7 response to induction chemotherapy and also associated with a poor survival rate. In multivariate analysis, high MLAA-34 levels was independently associated with a poorer relapse-free survival and overall survival in AML patients. In conclusion, our data indicate that MLAA-34 may be used as a prognostic marker for treatment decision-making in acute monocytic leukemia through validation by further studies.

[General calculating model of the needs for allogenic stem cell transplantation for the patients with leukaemia and myelodysplastic syndrome in Vojvodina]

INTRODUCTION

Allogeneic stem cell transplantation (SCT) application represents a treatment of choice that enables the eradication of malignant clone and chance for remedy of the patients with hematological diseases. Only 30-40% of the potential patients for allogeneic SCT have an HLA identical sibling, due to the fact that families in most of the developed countries are relatively small.

MATERIAL AND METHODS

This study gives a general model for calculating the needs for allogeneic SCT which, enables calculation of the needs for allogeneic SCT per 1 million inhabitants of Vojvodina on basis of number of potential patients who could be treated by allogeneic SCT The number of beds required for transplanted patients, and of days in hospital per year as well as the estimation of financial aspect of allogeneic SCT have been calculated by means of the cummulative risk method, considering the following parameters: the relative number of patients suffering from ANLL, ALL, CML, CLL and MDS, 45 and 55-year-old and younger, total incidence/ 100,000 inhabitants for each investigated disease and the average number of days in hospital of transplanted patients.

RESULTS

Total annual needs for allogeneic SCT for the patients suffering from ANLL, ALL, CML, CLL and MDS together, in transplantation with stem cells from their related donors are 786 days, from the unrelated donors are 306 days, while for nonmyeloablative transplantation with stem cells from their related donors are 558 days and from the unrelated ones are 297 days.

CONCLUSION

The general calculating model of the needs for allogeneic SCT could be used as a basis for planning a regional bone marrow donor registry and for creating a similar calculating model of the needs for allogeneic SCT in other diseases treatable by HSCT.

Quality of T-cells after stimulation with leukemia-derived dendritic cells (DC) from patients with acute myeloid leukemia (AML) or myeloid dysplastic syndrome (MDS) is predictive for their leukemia cytotoxic potential

Myeloid leukemic cells can differentiate into leukemia-derived dendritic cells (DC(leu)), presenting known/unknown leukemic-antigens. Induced anti-leukemic T-cell-responses are variable. To further elicit DC/DC(leu)-induced T-cell-response-patterns we performed (functional)flow-cytometry/fluorolysis-assays before/after mixed lymphocyte cultures (MLC) of matched (allogeneic) donor-T-cells (n=6), T-cells prepared at relapse after stem cell transplantation (n=4) or (autologous) patients'-T-cells (n=7) with blast-containing-mononuclear-cells ('MNC') or DC(leu)-containing DC ('DC'). Compared to 'MNC' 'DC' were better mediators of anti-leukaemic T-cell-activity, although not in every case effective. We could define cut-off proportions of mature DC, DC(leu), proliferating, CD4(+), CD8(+) and non-naive T-cells after 'MNC'- or 'DC'-stimulation, that were predictive for an anti-leukemic-activity of stimulated T-cells as well as a response to immunotherapy. Interestingly especially ratios >1 of CD4:CD8 or CD45RO:CD45RA T-cells were predictive for anti-leukemic function after DC-stimulation. In summary the composition and quality of DC and T-cells after a MLC-stimulating-phase is predictive for a successful ex-vivo and in-vivo anti-leukemic response, especially with respect to proportions of proliferating, CD4(+) and CD45RO(+) T-cells. Successful cytotoxicity and the development of a T-cell-memory after 'DC'-stimulation could be predictive for the clinical course of the disease and may pave the way to develop adoptive immunotherapy, especially for patients at relapse after SCT.

Enrichment of N-Cadherin and Tie2-bearing CD34+/CD38-/CD123+ leukemic stem cells by chemotherapy-resistance

Acute myeloid leukemia (AML) arises from genetic changes at the level of stem cell, various mutations have been elucidated, including AML1-ETO fusion gene has been shown as the representative target of cellular transformation for LSCs originating from hematopoietic stem cells (HSCs) compartment. LSCs resemble HSCs with respect to self-renewal capacity and chemotherapy-resistance. However, LSCs possess specific cell-surface markers, they are proposed to reside within the CD34(+)/CD38(-)/CD123(+) compartment. And the interaction mediated by adhesion molecules between LSCs and niche played a role in chemoresistance of LSCs. Therefore, study on the LSCs surface makers related to niche is helpful for the potential target therapy in the future. In this study, the proportions of CD34(+)/CD38(-)/CD123(+) LSCs compartment co-expressing the three adhesion molecules, N-Cadherin, Tie2 and CD44, respectively, from AML patients before and after chemotherapy were analyzed. We demonstrated N-Cadherin and Tie2 positive CD34(+)/CD38(-)/CD123(+) LSCs populations could be enriched by chemotherapy. Furthermore, AML1/ETO fusion signals and MDR1 expression were detected on the CD34(+)/CD38(-)/CD123(+) LSCs populations expressing N-Cadherin and Tie2. Therefore, N-Cadherin and Tie2 are probably the potential markers for identification of LSCs.

Factors affecting neutrophil recovery after autologous bone marrow-derived stem cell transplantation in patients with acute myeloid leukemia

Bone marrow is currently regarded as the most appropriate source of stem cells for patients with acute myeloid leukemia (AML) undergoing autologous transplants. A total of 55 adult patients with AML in first complete remission receiving autologous bone marrow-derived stem cell (BMSC) transplantation (BMSCT) were analyzed to determine factors affecting the rate of neutrophil recovery. All patients were treated with standard induction and three to four courses of consolidation chemotherapy and, after collection of BMSC, conditioned with BuCy2. The median time to neutrophil reconstitution was 30 (10-62) days and was delayed in 24 patients. Neutrophil recovery was faster in patients who had received granulocyte-macrophage progenitors (CFU-GM) dose >23.5 x 10(4)/kg, CD34(+) cells >3.2 x 10(6)/kg, and mononuclear cells (MNCs) >3 x 10(8)/kg. The speed of neutrophil recovery correlated with the number of transplanted CFU-GM progenitors (P = .0077) and MNCs (P = .0015). CFU-GM progenitors dose was the only factor close to significance in univariate analysis of neutrophil engraftment. Probability for neutrophil recovery was higher in patients transplanted with a higher dose of MNCs. These data suggested that the content of CFU-GM progenitors and MNCs within the bone marrow graft was the most important factor for the quality of neutrophil recovery after autologous BMSCT in AML patients.

Single-Agent Laromustine, A Novel Alkylating Agent, Has Significant Activity in Older Patients With Previously Untreated Poor-Risk Acute Myeloid Leukemia

Purpose

An international phase II study of laromustine (VNP40101M), a sulfonylhydrazine alkylating agent, was conducted in patients age 60 years or older with previously untreated poor-risk acute myeloid leukemia (AML).

Patients and Methods

Laromustine 600 mg/m2 was administered as a single 60-minute intravenous infusion. Patients were age 70 years or older or 60 years or older with at least one additional risk factor—unfavorable AML karyotype, Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 2, and/or cardiac, pulmonary, or hepatic comorbidities.

Results

Eighty-five patients (median age, 72 years; range, 60 to 87 years) were treated. Poor-risk features included age 70 years or older, 78%; adverse karyotype, 47%; PS of 2, 41%; pulmonary disease, 77%; cardiac disease, 73%; and hepatic disease, 3%. Ninety-six percent of patients had at least two risk factors, and 39% had at least four risk factors. The overall response rate (ORR) was 32%, with 20 patients (23%) achieving complete response (CR) and seven (8%) achieving CR with incomplete platelet recovery (CRp). ORR was 20% in patients with adverse cytogenetics; 32% in those age 70 years or older; 32% in those with PS of 2; 32% in patients with baseline pulmonary dysfunction; 34% in patients with baseline cardiac dysfunction; and 27% in 33 patients with at least four risk factors. Twelve (14%) patients died within 30 days of receiving laromustine therapy. Median overall survival was 3.2 months, with a 1-year survival of 21%; the median duration of survival for those who achieved CR/CRp was 12.4 months, with a 1-year survival of 52%.

Conclusion

Laromustine has significant single-agent activity in elderly patients with poor-risk AML. Adverse events are predominantly myelosuppressive or respiratory. Response rates are consistent across a spectrum of poor-risk features.

A review of the potential association between childhood leukemia and benzene

Chronic exposure to high concentrations of benzene is an established cause of acute myeloid leukemia (AML) in occupationally exposed workers. Based on this association, it is not unreasonable to assume that children could also get AML if they were exposed to comparable levels of benzene. Fortunately, reports of such exposures and subsequent AML development in children are non-existent. However, the question of whether children can develop leukemia at far lower, environmental levels of benzene remains. The existing scientific evidence relevant to this question will be addressed in this review. While positive findings have been reported, the collective literature does not indicate that exposure to environmental levels of benzene is related to an increased risk of childhood leukemia. Our understanding of this important issue would be strengthened by additional studies that accurately characterize exposures as well as differentiate between the various forms of leukemias observed in children.

Phase 3 randomized, placebo-controlled, double-blind study of high-dose continuous infusion cytarabine alone or with laromustine (VNP40101M) in patients with acute myeloid leukemia in first relapse

Laromustine is a sulfonylhdrazine alkylator with significant antileukemia activity. An international, randomized (2:1), double-blind, placebo-controlled study was conducted to compare complete remission (CR) rates and overall survival (OS) in patients with first relapse acute myeloid leukemia (AML) treated with laromustine and high-dose cytarabine (HDAC) versus HDAC/placebo. Patients received 1.5 g/m(2) per day cytarabine continuous infusion for 3 days and laromustine 600 mg/m(2) (n = 177) or placebo (n = 86) on day 2. Patients in CR received consolidation with laromustine/HDAC or HDAC/placebo as per initial randomization. After interim analysis at 50% enrollment, the Data Safety Monitoring Board (DSMB) expressed concern that any advantage in CR would be compromised by the observed on-study mortality, and enrollment was held. The CR rate was significantly higher for the laromustine/HDAC group (35% vs 19%, P = .005). However, the 30-day mortality rate and median progression-free survival were significantly worse in this group compared with HDAC/placebo (11% vs 2%; P = .016; 54 days vs 34; P = .002). OS and median response durations were similar in both groups. Laromustine/HDAC induced significantly more CR than HDAC/placebo, but OS was not improved due to mortality associated with myelosuppression and its sequelae. The DSMB subsequently approved a revised protocol with laromustine dose reduction and recombinant growth factor support. The study was registered as NCT00112554 at http://www.clinicaltrials.gov.

Targeting of mTOR is associated with decreased growth and decreased VEGF expression in acute myeloid leukaemia cells

BACKGROUND

The mammalian target of rapamycin (mTOR) has recently been implicated in leukaemic cell growth, tumour-associated angiogenesis and expression of vascular endothelial growth factor (VEGF). We examined whether mTOR plays a role as regulator of growth and VEGF-expression in acute myeloid leukaemia (AML). Three mTOR-targeting drugs, rapamycin, everolimus (RAD001) and CCI-779, were applied. The effects of these drugs on growth, survival, apoptosis and VEGF expression in primary AML cells and various AML cell lines were examined.

MATERIALS AND METHODS

Growth of AML cells and AML-derived cell lines was assessed by (3)H-thymidine incorporation, survival was examined by light- and electron microscopy, by Tunel assay and by AnnexinV-staining, and the expression of VEGF by Northern blotting, RT-PCR and ELISA.

RESULTS

Rapamycin was found to counteract growth in the AML cell lines U937 and KG1a as well as in primary AML cells in 14/18 patients examined. The effects of rapamycin and its derivatives were dose-dependent (IC(50): 10 pM-100 nM). It was also found that exposure to mTOR-targeting drugs resulted in apoptosis and in decreased expression of VEGF in leukaemic cells.

CONCLUSIONS

mTOR-targeting drugs exert antileukaemic effects on AML cells in vitro through multiple actions, including direct inhibition of proliferation, induction of apoptosis and suppression of VEGF. Based on this study and other studies, mTOR can be regarded as a potential drug target in AML.

Outcome after allogeneic transplantation for adult acute myeloid leukemia patients exhibiting isolated or associated trisomy 8 chromosomal abnormality: a survey on behalf of the ALWP of the EBMT

The aim of this multicenter retrospective analysis was to carry out a survey of overall outcomes after allo-hematopoietic SCT of AML patients harboring trisomy 8 (+8) as the sole chromosomal abnormality or associated with other abnormalities. We have identified 182 de novo AML patients who underwent allo-hematopoietic SCT between 1990 and 2007 exhibiting isolated +8 (n=136) or +8 (n=46) associated with other favorable (n=8), intermediate (n=30), high-risk (n=7) or unknown (n=1) cytogenetic abnormalities reported to the European Group of Blood and Marrow Transplantation (EBMT). With a median follow-up of 48 months, 5-year non-relapse mortality, relapse rate, leukemia-free survival and OS were 25, 30, 45 and 47%, respectively. In a multivariate analysis, leukemia-free survival rate was improved when patients were female and transplanted in CR with an HLA-identical sibling donor. Five-year leukemia-free survival was 41, 88, 57 and 21% in patients bearing isolated +8 or +8 and other cytogenetic abnormalities of good, intermediate or poor-risk, respectively. Our retrospective data show that allo-hematopoietic SCT is an effective treatment for AML patients harboring +8. The accompanying cytogenetic abnormality to +8 seems to influence outcomes of these patients.

Quantitative expression of Toll-like receptor-2, -4, and -9 in dendritic cells generated from blasts of patients with acute myeloid leukemia

BACKGROUND

Dendritic cells (DCs) generated from leukemic blasts constitute a promising tool in immunotherapy for acute myeloid leukemia patients (AML-DCs), because AML-DCs express human leukocyte antigens and costimulatory molecules such as CD40, CD80, and CD86 at a higher level than leukemic blasts. Potentiation of AML-DC vaccine might become feasible by the addition of adjuvants such as lipopolysaccharides (LPS) or CPG-rich oligodeoxyribonucleotides binding to Toll-like receptors (TLR) and inducing a stronger Type 1 T-cell response.

STUDY DESIGN AND METHODS

mRNA and protein expression of TLR-2, -4, and -9 were analyzed with quantitative real-time polymerase chain reaction, Western blot, and flow cytometry for mature monocyte-derived DCs generated from 14 AML patients versus 14 healthy volunteers (HV-DCs), and the response of the AML- and HV-DCs to different microbial TLR ligands was determined by enzyme-linked immunosorbent assay for the proinflammatory cytokines tumor necrosis factor (TNF)-alpha, inducible protein (Ip)-10, and interleukin (IL)-6.

RESULTS

AML-DCs and HV-DCs strongly expressed TLR-2 and TLR-4, while TLR-9 was expressed at a lower level in both groups. There was no significant difference in TLR expression between the two groups of AML-DCs and HV-DCs. In accordance with the TLR expression levels, DCs generated from both AML patients and HVs responded to the known microbial ligands peptidoglycan (PGN) and lipoteichoic acid for TLR-2 and LPS as ligand for TLR-4, by producing TNF-alpha and IL-6. A response to the ODNs 2006 and 2216 binding to TLR-9 was only detected in AML-DCs.

CONCLUSION

Microbial ligands like ODNs and LPS constitute promising adjuvants for enhancing (AML-) DC vaccines.

Chromosomal aberrations in bone marrow mesenchymal stroma cells from patients with myelodysplastic syndrome and acute myeloblastic leukemia

OBJECTIVE

Bone marrow mesenchymal stroma cells (BMSC) are key components of the hematopoietic microenvironment. The question of whether BMSC from patients with hematological disorders have cytogenetic abnormalities is discussed controversially, some studies indicating that they are cytogenetically normal and others providing evidence of their aberrations.

PATIENTS AND METHODS

We performed standard and molecular cytogenetic analyses of both hematopoietic cells and BMSC from 31 patients with myelodysplastic syndrome (MDS, n = 18) and acute myeloid leukemia (AML, n = 13) and 7 healthy individuals. Mononuclear cells were isolated from fresh bone marrow aspirates at the time of initial diagnosis for cytogenetic analysis of hematopoietic cells (HC) and selection of BMSC.

RESULTS

Clonal cytogenetic aberrations were observed in HC from 8 (44%) MDS and 8 (61%) AML patients. Cytogenetic analyses of BMSC were successfully performed in 27 of the 31 cases. Structural chromosomal aberrations, including t(1;7), t(4;7), t(7;9), t(7;10), t(7;19), t(15;17), and others, were detectable in BMSC from 7 of 16 (44%) MDS and 6 of 11 (54%) AML patients. The breakpoints of chromosomes in BMSC were typical for leukemia aberrations. Two patients showed clonal chromosomal markers.

CONCLUSIONS

BMSC from MDS and AML patients show chromosomal abnormalities. Although the majority of cytogenetic aberrations in BMSC were not clonal and differed from chromosomal markers in HC from the same individual, detection of typical chromosomal changes in BMSC suggests enhanced genetic susceptibility of these cells in MDS/AML. This may indicate potential involvement of BMSC in the pathophysiology of MDS/AML.

Cloretazine (VNP40101M), a Novel Sulfonylhydrazine Alkylating Agent, in Patients Age 60 Years or Older With Previously Untreated Acute Myeloid Leukemia

Purpose

Cloretazine (VNP40101M) is a sulfonylhydrazine alkylating agent with significant antileukemia activity. A multicenter phase II study of cloretazine was conducted in patients 60 years of age or older with previously untreated acute myeloid leukemia (AML) or high-risk myelodysplastic syndrome (MDS).

Patients and Methods

Cloretazine 600 mg/m2was administered as a single intravenous infusion. Patients were stratified by age, performance score, cytogenetic risk category, type of AML, and comorbidity.

Results

One hundred four patients, median age 72 years (range, 60 to 84 years), were treated on study. Performance status was 2 in 31 patients (30%) and no patient had a favorable karyotype. Forty-seven patients (45%) had cardiac disease, 25 patients (24%) had hepatic disease, and 19 patients (18%) had pulmonary disease, defined as per the Hematopoietic Cell Transplantation–Specific Comorbidity Index, at study entry. The overall response rate was 32%, with 29 patients (28%) achieving complete response (CR) and four patients (4%) achieving CR with incomplete platelet recovery. Response rates in 44 de novo AML patients, 45 secondary AML patients, and 15 high-risk MDS patients were 50%, 11%, and 40%, respectively. Response by cytogenetic risk category was 39% in 56 patients with intermediate cytogenetic risk and 24% in 46 patients with unfavorable cytogenetic risk. Nineteen (18%) patients died within 30 days of receiving cloretazine therapy. Median overall survival was 94 days, with a 1-year survival of 14%; the median duration of survival was 147 days, with a 1-year survival of 28% for those who achieved CR.

Conclusion

Cloretazine has significant activity and modest extramedullary toxicity in elderly patients with AML or high-risk MDS. Response rates remain consistent despite increasing age and comorbidity.

Phase I/II Study of Continuous-Infusion Troxacitabine in Refractory Acute Myeloid Leukemia

Purpose

Troxacitabine is a non-natural nucleoside analog with unique structural and metabolic features. Bolus intravenous (IV) troxacitabine regimens have shown significant activity in patients with refractory acute myeloid leukemia (AML) and preclinical data suggest that administration via continuous infusion may result in enhanced antitumor activity.

Patients and Methods

Patients with refractory AML initially received troxacitabine 10.1 mg/m2 by continuous IV infusion (CIVI) for 48 hours. Infusion duration and daily dose were increased in subsequent patient cohorts.

Results

Forty-eight patients, median age 58 years (range, 21 to 81 years), were treated. Dose-limiting toxicities were mucositis and hand-foot syndrome, and 12.0 mg/m2/d for 5 days was established as the maximum-tolerated dose. Seven patients (15%) achieved complete remission (CR) or CR with incomplete platelet recovery (CRp), with a median survival among responders of 12 months. Steady-state concentrations of troxacitabine were found to be linearly and inversely proportionally related to calculated creatinine clearance at doses of 10.1 and 12.0 mg/m2/d. All patients responding to troxacitabine had steady-state serum drug concentration of more than approximately 80 ng/mL. In 27 patients achieving target troxacitabine plasma concentrations (ie, approximately 80 ng/mL) the CR + CRp rate was 26%.

Conclusion

Troxacitabine administered as a CIVI allows a significant increase in dose-intensity in comparison to IV bolus regimens, has antileukemic activity, and warrants additional investigation in patients with refractory AML. The recommended phase II study dose is 12.0 mg/m2 daily CIVI for 5 days.

Expression of tumor-associated antigens in acute myeloid leukemia: implications for specific immunotherapeutic approaches

The expression of tumor-associated antigens (TAAs) might play a critical role in the control of minimal residual disease (MRD) in acute myeloid leukemia (AML), and therefore might be associated with clinical outcome in AML. In a DNA microarray analysis of 116 AML samples, we found a significant correlation between high mRNA levels of G250/CA9 and longer overall survival (P = .022), a similar trend with high mRNA levels of PRAME (P = .103), and a hint for RHAMM/HMMR. In contrast, for other TAAs like WT1, TERT, PRTN3, BCL2, and LAMR1, we found no correlation with clinical outcome. High expression of at least 1 of the 3 TAAs, RHAMM/HMMR, PRAME, or G250/CA9, provided the strongest favorable prognostic effect (P = .005). Specific T-cell responses were detected in 8 (47%) of 17 patients with AML in complete remission for RHAMM/HMMR-R3 peptide, in 7 (70%) of 10 for PRAME-P3 peptide, and in 6 (60%) of 10 for newly characterized G250/CA9-G2 peptide, a significant increased immune response compared with patients with AML patients who had refractory disease (P < .001). Furthermore, we could demonstrate specific lysis of T2 cells presenting these epitope peptides. In conclusion, expression of the TAAs RHAMM/HMMR, PRAME, and G250/CA9 can induce strong antileukemic immune responses, possibly enabling MRD control. Thus, these TAAs represent interesting targets for polyvalent immunotherapeutic approaches in AML.

Flow cytometric assessment of autologous gammadelta T cells in patients with acute myeloid leukemia: potential effector cells for immunotherapy?

BACKGROUND

Gammadelta T cells are a rare component of the circulating innate immune system capable of exerting anti-neoplastic activity. This population may be suitable for the adoptive immunotherapy of acute myeloid leukemia (AML). Little is known however, about the frequency and function of circulating gammadelta T cells in AML. The aim of the study was to enumerate peripheral blood gammadelta T cells in patients with AML and explore the feasibility of their use clinically.

METHODS

We compared the absolute circulating gammadelta T cell levels in 33 AML patients before and after treatment versus 20 healthy volunteers using flow cytometry. The function of gammadelta T cells was assessed by detection of intracelluar interferon-gamma (IFN-gamma) and cytotoxicity against leukemic blasts.

RESULTS

AML patients with high blast counts prior to induction chemotherapy had marginally decreased gammadelta T cell levels compared with healthy controls: median 38/microL versus 83/microL; P = 0.051. Sequential gammadelta T cell enumeration after induction showed significantly decreased counts in patients with a persistently high blast burden compared to patients with reduced but detectable residual disease (molecular maker or borderline bone marrow infiltration): median 7/microL versus 105/microL; P = 0.008. Patients with residual disease had significantly higher gammadelta T cell counts compared to those retested after they had achieved complete remission (CR); P = 0.0025. In CR, gammadelta T cell counts remained lower than those of healthy individuals: median 33/microL versus 83/microL, P = 0.030. We detected a sharp increase (on average, four-fold higher than values in CR) of gammadelta T cells in patients in very early morphologic or molecular relapse. We also tested the functional properties of gammadelta T cells from patients with AML in CR. Flow cytometric assessment of IFN-gamma revealed similar numbers of gammadelta T cells expressing the T1 cytokine compared with healthy controls. We also showed that gammadelta T cells were able to kill leukemic target cells in vitro.

CONCLUSION

Flow cytometric assessment of gammadelta T cells in patients with AML revealed quantitative shifts with respect to disease status. Our data suggest that gammadelta T cells warrant further investigation as potential therapeutic agents.

Constitutive c-jun N-terminal kinase activity in acute myeloid leukemia derives from Flt3 and affects survival and proliferation

OBJECTIVE

c-jun N-terminal kinase (JNK) has been implicated in proliferation and survival downstream from the tyrosine kinase oncogene, p210 BCR-ABL, in chronic myeloid leukemia. We studied whether a similar relationship between JNK and FMS-like tyrosine kinase 3 (Flt3) describes acute myeloid leukemia (AML).

METHODS

By immunoprecipitation, Flt3 was found to be activated and identified as the potential origin of JNK activity in a heavy majority of JNK+ve AML blasts tested. Often, Flt3 activity is associated with activating mutation of the gene locus. However, statistical linkage tied JNK activity with Flt3 expression levels rather than with mutation. An adaptor network to describe the signal cascade Flt3-to-JNK was uncovered.

RESULTS

Active Flt3 was linked to p85 phosphoinositide-3 (PI-3) kinase, and p85 with cbl and CrkII/CrkL by co-immunoprecipitaton assays from lysates of model cell lines and primary AML blasts. JNK1 co-immunoprecipitated from such lysates with p85-cbl-crkII/L and bound to Crk species SH3 domain in pull-down assay. siRNA-mediated depletion of Flt3 or of cbl, the adaptor at the nexus of this signaling group, inhibited JNK activity on substrate c-jun. Within AML blast cells influenced by Flt3 signaling, selective inhibition of JNK by a small molecule inhibitor, led to proliferative inhibition, apoptosis, and sensitizing cells to the anthracycline, daunorubicin. These effects occurred upon JNK inhibition without off-target inhibition of extracellular signal-regulated kinase or AKT pathways, and p38-kinase activation, an effector in the p53/p14 arf tumor suppressor pathway, was also maintained or augmented.

CONCLUSION

JNK is a bonafide signaling pathway from Flt3 in AML whose function for proliferation and survival is required in a significant AML cohort with active Flt3 signaling, by mutation or overexpression of Flt3.

Identification and characterization of leukemia stem cells in murine MLL-AF9 acute myeloid leukemia

Using a mouse model of human acute myeloid leukemia (AML) induced by the MLL-AF9 oncogene, we demonstrate that colony-forming cells (CFCs) in the bone marrow and spleen of leukemic mice are also leukemia stem cells (LSCs). These self-renewing cells (1) are frequent, accounting for 25%-30% of myeloid lineage cells at late-stage disease; (2) generate a phenotypic, morphologic, and functional leukemia cell hierarchy; (3) express mature myeloid lineage-specific antigens; and (4) exhibit altered microenvironmental interactions by comparison with the oncogene-immortalized CFCs that initiated the disease. Therefore, the LSCs responsible for sustaining, expanding, and regenerating MLL-AF9 AML are downstream myeloid lineage cells, which have acquired an aberrant Hox-associated self-renewal program as well as other biologic features of hematopoietic stem cells.

Validation of the European Prognostic Index for younger adult patients with acute myeloid leukaemia in first relapse

In order to validate the European Prognostic Index (EPI) for patients <or=60 years with acute myeloid leukaemia in first relapse, a cohort of 599 such patients, treated between 1980 and 2004 at the MD Anderson Cancer Center, were assessed using this prognostic index. Three risk groups were defined: favourable, 76 patients (13%) [Overall survival (OS), 64% at 1 year, 22% at 5 years]; intermediate, 137 patients (23%) (OS, 38% at 1 year, 12% at 5 years); and poor, 386 patients (64%) (OS, 17% at 1 year 6% at 5 years). The EPI is reproducible and useful.

CXCR4 is a prognostic marker in acute myelogenous leukemia

CXCR4 chemokine receptors retain hematopoietic progenitors and leukemia cells within the marrow microenvironment. We prospectively evaluated the prognostic implication of CXCR4 in 90 consecutive patients with acute myelogenous leukemia (AML) by flow cytometry. Patients were divided into groups with low (n=32), intermediate (n=26), or high (n=32) CXCR4 expression, as defined by CXCR4 mean fluorescence intensity ratio thresholds of less than 5, 5 to 10, or more than 10, respectively. We found that low CXCR4 expression on AML cells correlated with a better prognosis, resulting in a longer relapse-free and overall survival of 24.3+/-2.9 months for low CXCR4-expressing patients, compared with 17.4+/-3.4 months for intermediate and 12.8+/-2 months (mean+/-SEM) for patients with high expression. In univariate analyses, CXCR4 expression, cytogenetics, white blood cell count, and serum lactate dehydrogenase (LDH) predicted for shorter survival. Multivariate analysis revealed CXCR4 expression and unfavorable cytogenetics as independent prognostic factors. We conclude that CXCR4 expression in AML is an independent prognostic predictor for disease relapse and survival that can rapidly and easily be determined at disease presentation. These findings warrant further investigation into the role of CXCR4 in AML and suggest that CXCR4 should be incorporated into the risk assessment of AML patients.

An approach to the management of leukemia in the developing world

Management of leukemia is expensive. In the developing world where there are significant resource constraints, how does the physician manage leukemia? Government health budgets need to put their money into areas where a small investment is likely to benefit a large proportion of its people and these would include immunization, sanitation, family planning and treatment of communicable diseases and the cost of expensive treatments would have to be borne by the patient and family. However, in many of the emerging economies in the developing world, society is three-tiered in terms of resources with a small proportion being able to afford the best treatment, the middle class with the ability to meet a significant proportion of the healthcare costs on their own and the poor who depend wholly on what the Government health budget can afford. Providing an accurate diagnosis is possible even with limited resources and this must be made available to all. Sometimes a precise diagnosis even at the molecular level is more important in the developing world so that resources are not wasted on inappropriate treatments. Choosing a protocol for management based on resources available for the individual patient would appear ethically unacceptable, but is probably the only solution when wealth is unevenly distributed in society. This paper illustrates an approach to the management of leukemia in the developing world that has evolved with experience over two decades in a tertiary referral hospital in India.

Phase I study of cloretazine (VNP40101M), a novel sulfonylhydrazine alkylating agent, combined with cytarabine in patients with refractory leukemia

PURPOSE

Cloretazine (VNP40101M) is a novel sulfonylhydrazine alkylating agent with significant antileukemia activity. A phase I study of cloretazine combined with cytarabine (1-beta-d-arabinofuranosylcytosine, ara-C) was conducted in patients with refractory disease.

DESIGN

Ara-C was given i.v. at a fixed dose of 1.5 gm/m(2)/d by continuous infusion for 4 days (patients ages <65 years at time of diagnosis) or 3 days (patients ages > or =65 years). Cloretazine was given i.v. over 15 to 60 minutes on day 2 at a starting dose of 200 mg/m(2), with escalation in 100 mg/m(2) increments in cohorts of three to six patients until a maximum tolerated dose was established. The DNA repair enzyme O(6)-alkylguanine DNA alkyltransferase (AGT) was measured at baseline.

RESULTS

Forty patients, including 32 with acute myeloid leukemia, received 47 courses of treatment. Complete responses were seen at cloretazine dose levels of > or =400 mg/m(2) in 10 of 37 (27%) evaluable patients, and in this patient subset, AGT activity was significantly lower in patients that responded to treatment than in patients who did not (P < or = 0.027). Dose-limiting toxicities (gastrointestinal and myelosuppression) were seen with 500 and 600 mg/m(2) of cloretazine combined with the 4-day ara-C schedule but not seen with the 3-day schedule.

CONCLUSION

The recommended cloretazine dose schedule for future studies is 600 mg/m(2) combined with 1.5 gm/m(2)/d continuous infusion of ara-C for 3 days. The cloretazine and ara-C regimen has significant antileukemic activity. AGT activity may be a predictor of response to cloretazine.

A phase II study of cloretazine (VNP40101M), a novel sulfonylhydrazine alkylating agent, in patients with very high risk relapsed acute myeloid leukemia

Cloretazine (VNP40101M) is a sulfonylhydrazine alkylating agent with significant anti-leukemia activity. A multicenter phase II study of cloretazine was conducted in patients with first relapse of acute myeloid leukemia (AML) following an initial complete remission (CR) of less than 12 months. Cloretazine was given as a single intravenous infusion at a dose of 600 mg/m(2). Fifty-three patients (median age 62 years (18-84), 41 of 44 (93%) evaluable with intermediate or high risk cytogenetics, 32 (60%) with initial CR durations < or =6 months) were treated on study. Two patients (4%) achieved a second CR. Five (9%) patients died within 30 days of receiving cloretazine therapy. Median overall survival (2.3 months) in the study cohort was directly comparable to that of 233 matched patients treated with other single agents. The study cloretazine regimen had minimal activity in a very high risk subset of patients with relapsed AML.

Advances in the pathologic diagnosis and biology of acute myeloid leukemia

In a general surgical pathology practice, cases of acute myeloid leukemia (AML), including myeloid sarcoma, are relatively rare; the diagnosis is very often difficult, however, and consequences of a missed or improper diagnosis compromise patient care. Currently, accurate diagnosis of every case of AML requires integration of the morphological features and results of cytochemical and immunohistochemical stains, flow cytometric immunophenotyping, cytogenetics, and molecular studies. This review focuses on a practical approach to diagnosis of AML according to current standard of practice and discusses some of recent changes in the field of AML.

Serum-free generation and quantification of functionally active Leukemia-derived DC is possible from malignant blasts in acute myeloid leukemia and myelodysplastic syndromes

Functional dendritic cells (DC) are professional antigen presenting cells (APC) and can be generated in vitro from leukemic cells from acute myeloid leukemia AML patients, giving rise to APC of leukemic origin presenting leukemic antigens (DC(leu)). We have already shown that DC can be successfully generated from AML and myeloplastic syndromes (MDS) cells in serum-free 'standard' medium (X-vivo + GM-CSF + IL-4 +TNFalpha + FL) in 10-14 days. In this study, we present that DC counts generated from mononuclear cells (MNC) varied between 20% (from 55 MDS samples), 34% (from 100 AML samples) and 25% (from 38 healthy MNC samples) medium. Between 53% and 58% of DC are mature CD83+ DC. DC harvests were highest in monocytoid FAB types (AML-M4/M5, MDS-CMML) and independent from cytogenetic risk groups, demonstrating that DC-based strategies can be applied for patients with all cytogenetic risk groups. Proof of the clonal derivation of DC generated was obtained in five AML and four MDS cases with a combined FISH/immunophenotype analysis (FISH-IPA): The clonal numerical chromosome aberrations of the diseases were regularly codetectable with DC markers; however, not with all clonal cells being convertible to leukemia-derived DC(leu) (on average, 53% of blasts in AML or MDS). To the contrary, not all DC generated carried the clonal aberration (on average, 51% of DC). In 41 AML and 13 MDS cases with a suitable antigen expression, we could confirm FISH-IPA data by Flow cytometry: although DC(leu) are regularly detectable, on average only 57% of blasts in AML and 64% of blasts in MDS were converted to DC(leu). After coculture with DC in mixed lymphocyte reactions (MLR), autologous T cells from AML and MDS patients proliferate and upregulate costimulatory receptors. The specific lysis of leukemic cells by autologous T cells could be demonstrated in three cases with AML in a Fluorolysis assay. In six cases with only few DC(leu) or few vital T cells available after the DC/MLR procedure, no lysis of allogeneic or autologous leukemic cells was seen, pointing to the crucial role of both partners in the lysis process. We conclude: (1) the generation of DC is regularly possible in AML and also in MDS under serum-free conditions. (2) Clonal/leukemia-derived DC(leu) can be regularly generated from MDS and AML-MNC; however, not with all blasts being converted to DC(leu) and not all DC generated carrying leukemic markers. We recommend to select DC(leu) for vaccinations or ex vivo T-cell activations to avoid contaminations with non-converted blasts and non-leukemia-derived DC and to improve the harvest of specific, anti-leukemic T cells. DC and DC-primed T cells could provide a practical strategy for the immunotherapy of AML and MDS.

Leukemia-Derived Dendritic Cells can be Generated from Blood or Bone Marrow Cells from Patients with Acute Myeloid Leukaemia: A Methodological Approach under Serum-Free Culture Conditions

Functional dendritic cells (DC) are professional antigen-presenting cells (APC) and can be generated in vitro from healthy as well as from leukaemic cells from acute myeloid leukemia (AML) patients giving rise to APC of leukaemic origin-presenting leukaemic antigens. We describe the generation and characterization of DC from different mononuclear cell (MNC) fractions from 50 AML patients under different serum-free culture conditions, determine the optimal culture conditions and compare the results with that from 23 healthy donors. In parallel cultures, we compared DC harvests after 7- or 14-day culture, with total or adherent MNC or T-cell depleted MNC or peripheral blood (PB) or bone marrow-MNC (BM-MNC), thawn or fresh MNC, in Xvivo or CellGro serum-free media, +/-10% autologous plasma or +/-FL. In detail, we could show that AML-DC harvests were higher after 10-14 days culture (healthy DC: 7 days); total or adherent PB or BM-MNC fractions yield comparable DC counts, however, from magnetic cell sorting (MACS)-depleted MNC fractions or thawn MNC lower DC counts can be generated. Whereas the addition of FL increases the DC harvest, the addition of autologous plasma in many cases has inhibitory influence on DC maturation. CellGro and Xvivo media yield comparable DC counts. Optimal harvest of vital and mature DC from AML samples was obtained with a granulocyte/macrophage-colony stimulating factor, interleukin-4, FL and tumour necrosis factor-alpha-containing serum-free Xvivo medium after 10-14 days of culture (36/26% DC; 38/64% vital DC; 46/51% mature DC were generated from AML/healthy MNC samples). Surface marker profiles (e.g. costimulatory antigen expressing) of DC obtained from AML samples were comparable with that of healthy DC. The leukaemic derivation of AML-DC was demonstrated by the persistence of the clonal cytogenetic aberration in the DC or by coexpression of leukaemic antigens on DC. Autologous T-cell activation of leukaemia-derived DC was demonstrated in cases with AML. Autologous T cells proliferate and upregulate DC-contact-relevant antigens. We demonstrate that the generation of leukaemia-derived DC is feasable in AML under serum-free culture conditions giving rise to DC with comparable characteristics as healthy DC and offering an anti-leukaemia-directed immunotherapeutical vaccination strategy in AML.

IL-2/B7.1 (CD80) fusagene transduction of AML blasts by a self-inactivating lentiviral vector stimulates T cell responses in vitro: a strategy to generate whole cell vaccines for AML

Combined expression of costimulatory factors and proinflammatory cytokines stimulate effective immune-mediated tumor rejection in a variety of murine tumor models. Specifically, syngeneic tumor cells genetically modified to express B7.1 (CD80) have been shown to induce rejection of previously established murine solid tumors, and transduction with IL-2 can further increase survival. However, poor rates of gene transfer and inefficient expression of multiple transgenes encoded by single vectors have hampered the development of such autologous tumor cell vaccines for clinical trials in acute myeloid leukemia (AML) patients. Here we describe the development of a self-inactivating lentiviral vector encoding B7.1 and IL-2 as a single fusion protein postsynthetically cleaved to generate biologically active membrane-anchored B7.1 and secreted IL-2. This enables the efficient transduction of both established and primary AML blasts, resulting in expression of the transgenes in up to 98% of the cells following a single round of infection at an m.o.i. of 10. The combined expression of IL-2 and B7.1 in AML blasts enables increased stimulation of both allogeneic and autologous T cells. The stimulated lymphocytes secrete greater levels of Th1 cytokines and show evidence of specificity, as indicated by their increased proliferation in the presence of autologous AML compared to remission bone marrow cells.

Adaptive randomized study of idarubicin and cytarabine alone or with interleukin-11 as induction therapy in patients aged 50 or above with acute myeloid leukemia or high-risk myelodysplastic syndromes

A higher complete remission (CR) rate was observed in patients with acute myeloid leukemia (AML) who, on a prior randomized study of induction therapy, received gemtuzumab ozogamicin (GO) plus interleukin-11 (IL-11) rather than GO alone. An adaptive randomized phase III study of the addition of IL-11 to idarubicin and cytarabine (IA) induction in 100 patients >/=50 years of age with AML or high-risk myelodysplastic syndrome (MDS) was conducted. Median patient age was 67 years (range 50-82). Twenty-four of the 45 (53%) patients randomized to IA plus IL-11 achieved CR. Eight (33%) subsequently relapsed, 4 (17%) died in CR; median time to treatment failure (TTF) was 37 weeks. Twenty-nine of the 55 (53%) patients treated without IL-11 achieved CR. Eight (28%) subsequently relapsed, 2 (7%) died in CR; median TTF was 46 weeks. Median overall survivals were 21 and 59 weeks for the IA plus IL-11 and IA cohorts, respectively (p=0.271, log rank test; 0.435, Gehan-Breslow test). Ten episodes of the following grade 3 or 4 cardiopulmonary toxicities were observed in patients receiving IA plus IL-11, 12 such episodes in those receiving IA alone: atrial fibrillation, pleural effusions, myocardial infarction, bradycardia or hypotension. Two patients in each arm experienced grade 3 peripheral edema. There was no significant difference in incidence of any grade 3 or 4 adverse event, including thrombocytopenia, between treatment arms. There was no significant impact on CR rates, TTF, survival, or toxicity of adding an IL-11 regimen to IA induction in patients >/=50 years of age with AML.