Genomic amplification of MYC as double minutes in a patient with APL-like leukemia

BACKGROUND

Acute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia (AML) characterized by a PML-RARA fusion due to a translocation t(15;17). Its sensitivity to treatment with all-trans retinoic acid (ATRA), which causes differentiation of the abnormal promyelocytes, combined with anthracycline based chemotherapy makes it the best curable subtype of acute myeloid leukemia. A rapid and accurate diagnosis is needed in the first place to prevent (more) bleeding problems. Here we present a patient with a leukemia with an APL-like morphology but no detectable PML-RARA fusion, as demonstrated by RT-PCR and cytogenetic analysis.

RESULTS

Unexpectedly, karyotyping revealed numerous double minutes (dmins). Fluorescence in situ hybridization (FISH) with DNA probes specific for the MYC-region showed the presence of multiple MYC amplicons. SNP-array analysis uncovered amplification of the 8q24.13-q24.21 region, including the MYC-gene, flanked by deletions in 8q24.13 and 8q24.21-q24.22, and a homozygous deletion in 9p21.3, flanked by heterozygous deletions in the same chromosome region.

CONCLUSIONS

The diagnosis was revised to AML, not otherwise specified (AML, NOS) and therefore therapy with ATRA was discontinued.

Abstract 3890: MicroRNA-551b is highly expressed in hematopoietic stem cells and expression in acute myeloid leukemia is associated with relapse and poor survival

Despite high remission rates after chemotherapy, only 30-40% of acute myeloid leukemia (AML) patients survive five years after diagnosis. The main cause for this treatment failure is insufficient eradication of a subpopulation of chemotherapy resistant leukemic cells with a stem cell-like character. These so-called leukemic stem cells (LSC) are thought to be responsible for relapse.

We hypothesized that success of novel anti-AML therapies relies on functional manipulation of genes including microRNAs, resulting in elimination of leukemic (stem) cells while sparing residual co-existing normal hematopoietic stem cells (HSC). We aimed at identification of microRNAs differentially expressed between HSC, LSC and the AML bulk obtained from the same AML bone marrow, taking into account the effects of the leukemic microenvironment.

To that end, we described immunophenotypic markers that can distinguish LSC from HSC. Moreover, we identified that HSC have higher aldehyde dehydrogenase activity than LSC (Schuurhuis et al. Plos One 2013). Comparing the microRNA expression profile of LSC with that of HSC showed that microRNA-551b (miR-551b) is highly expressed in residual HSC in the AML bone marrow. To determine whether miR-551b is a HSC specific microRNA we purified stem and progenitor cell subsets from normal bone marrow and showed that miR-551b is the highest expressed in the two most primitive CD34+CD38- populations i.e. CD90+CD45RA- HSC and CD90-CD45RA- multipotent progenitors.

To investigate whether the expression of miR-551b is of clinical importance in AML we determined its expression in AML bone marrow samples (n=154) and showed that high miR-551b is associated with lower complete remission (CR) rates after the first cycle of induction chemotherapy, shorter relapse free survival and a worse overall survival. In line with miR-551b being a stem cell miRNA, high expression in AML was associated with an undifferentiated morphology (FAB M0).

To shed more light on the functional role of miR-551b in AML we correlated the expression of miR-551b with overall gene expression in a large panel of AML patients. Many of the genes that highly correlated with miR-551b like; MLLT3, INPP4B, HTR1F, HOPX, PROM1 and others, are also present in published HSC signatures. In conclusion, miR-551b is specifically expressed in normal stem and multipotent progenitor cells and high expression in AML is associated with poor prognosis. Currently, our research focuses on the function of miR-551b in AML.

Citation Format: David C. de leeuw, Fedor Denkers, Peter Valk, Iris de Rink, Ron Kerkhoven, Gerrit Jan Schuurhuis, Gert J. Ossenkoppele, Linda Smit. MicroRNA-551b is highly expressed in hematopoietic stem cells and expression in acute myeloid leukemia is associated with relapse and poor survival. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3890. doi:10.1158/1538-7445.AM2014-3890

Leukemic stem cell frequency: a strong biomarker for clinical outcome in acute myeloid leukemia

INTRODUCTION

Treatment failure in acute myeloid leukemia is probably caused by the presence of leukemia initiating cells, also referred to as leukemic stem cells, at diagnosis and their persistence after therapy. Specific identification of leukemia stem cells and their discrimination from normal hematopoietic stem cells would greatly contribute to risk stratification and could predict possible relapses.

RESULTS

For identification of leukemic stem cells, we developed flow cytometric methods using leukemic stem cell associated markers and newly-defined (light scatter) aberrancies. The nature of the putative leukemic stem cells and normal hematopoietic stem cells, present in the same patient's bone marrow, was demonstrated in eight patients by the presence or absence of molecular aberrancies and/or leukemic engraftment in NOD-SCID IL-2Rγ-/- mice. At diagnosis (n=88), the frequency of the thus defined neoplastic part of CD34+CD38- putative stem cell compartment had a strong prognostic impact, while the neoplastic parts of the CD34+CD38+ and CD34- putative stem cell compartments had no prognostic impact at all. After different courses of therapy, higher percentages of neoplastic CD34+CD38- cells in complete remission strongly correlated with shorter patient survival (n=91). Moreover, combining neoplastic CD34+CD38- frequencies with frequencies of minimal residual disease cells (n=91), which reflect the total neoplastic burden, revealed four patient groups with different survival.

CONCLUSION AND PERSPECTIVE

Discrimination between putative leukemia stem cells and normal hematopoietic stem cells in this large-scale study allowed to demonstrate the clinical importance of putative CD34+CD38- leukemia stem cells in AML. Moreover, it offers new opportunities for the development of therapies directed against leukemia stem cells, that would spare normal hematopoietic stem cells, and, moreover, enables in vivo and ex vivo screening for potential efficacy and toxicity of new therapies.

BCR-ABL1 compound mutations combining key kinase domain positions confer clinical resistance to ponatinib in Ph chromosome-positive leukemia

Ponatinib is the only currently approved tyrosine kinase inhibitor (TKI) that suppresses all BCR-ABL1 single mutants in Philadelphia chromosome-positive (Ph(+)) leukemia, including the recalcitrant BCR-ABL1(T315I) mutant. However, emergence of compound mutations in a BCR-ABL1 allele may confer ponatinib resistance. We found that clinically reported BCR-ABL1 compound mutants center on 12 key positions and confer varying resistance to imatinib, nilotinib, dasatinib, ponatinib, rebastinib, and bosutinib. T315I-inclusive compound mutants confer high-level resistance to TKIs, including ponatinib. In vitro resistance profiling was predictive of treatment outcomes in Ph(+) leukemia patients. Structural explanations for compound mutation-based resistance were obtained through molecular dynamics simulations. Our findings demonstrate that BCR-ABL1 compound mutants confer different levels of TKI resistance, necessitating rational treatment selection to optimize clinical outcome.

Resistance prediction in AML: analysis of 4601 patients from MRC/NCRI, HOVON/SAKK, SWOG and MD Anderson Cancer Center

Therapeutic resistance remains the principal problem in acute myeloid leukemia (AML). We used area under receiver-operating characteristic curves (AUCs) to quantify our ability to predict therapeutic resistance in individual patients, where AUC=1.0 denotes perfect prediction and AUC=0.5 denotes a coin flip, using data from 4601 patients with newly diagnosed AML given induction therapy with 3+7 or more intense standard regimens in UK Medical Research Council/National Cancer Research Institute, Dutch-Belgian Cooperative Trial Group for Hematology/Oncology/Swiss Group for Clinical Cancer Research, US cooperative group SWOG and MD Anderson Cancer Center studies. Age, performance status, white blood cell count, secondary disease, cytogenetic risk and FLT3-ITD/NPM1 mutation status were each independently associated with failure to achieve complete remission despite no early death ('primary refractoriness'). However, the AUC of a bootstrap-corrected multivariable model predicting this outcome was only 0.78, indicating only fair predictive ability. Removal of FLT3-ITD and NPM1 information only slightly decreased the AUC (0.76). Prediction of resistance, defined as primary refractoriness or short relapse-free survival, was even more difficult. Our limited ability to forecast resistance based on routinely available pretreatment covariates provides a rationale for continued randomization between standard and new therapies and supports further examination of genetic and posttreatment data to optimize resistance prediction in AML.

In situ loading of skin dendritic cells with apoptotic bleb-derived antigens for the induction of tumor-directed immunity

The generation and loading of dendritic cells (DC) ex-vivo for tumor vaccination purposes is laborious and costly. Direct intradermal (i.d.) administration of tumor-associated antigens could be an attractive alternative approach, provided that efficient uptake and cross-presentation by appropriately activated skin DCs can be achieved. Here, we compare the efficiency of i.d. delivery of relatively small apoptotic blebs (diameter ∼0.1-1 μm) derived from MART-1 transduced acute myeloid leukemia (AML) HL60 cells, to that of larger apoptotic cell remnants (ACR; 2-10 μm) in a physiologically highly relevant human skin explant model. Injection of either fluorescently-labelled ACRs or blebs alone did not affect the number or distribution of migrated DC subsets from skin biopsies after 48 hours, but resulted in a general up-regulation of the co-stimulatory molecules CD83 and CD86 on skin DCs that had ingested apoptotic material. We have previously shown that i.d. administration of GM-CSF and IL-4 resulted in preferential migration of a mature and highly T cell-stimulatory CD11^hiCD1a⁺CD14^- dermal DC subset. Here, we found that co-injection of GM-CSF and IL-4 together with either ACRs or blebs resulted in uptake efficiencies within this dermal DC subset of 7.6% (±6.1%) and 19.1% (±15.9%), respectively, thus revealing a significantly higher uptake frequency of blebs (P < 0.02). Intradermal delivery of tumor-derived blebs did not affect the T-cell priming and T_H-skewing abilities of migratory skin DC. Nevertheless, in contrast to i.d. administration of ACR, the injection of blebs lead to effective cross-presentation of MART-1 to specific CD8⁺ effector T cells. We conclude that apoptotic bleb-based vaccines delivered through the skin may offer an attractive, and broadly applicable, cancer immunotherapy.

Procedures for the expansion of CD14(+) precursors from acute myeloid leukemic cells to facilitate dendritic cell-based immunotherapy

AIMS

Vaccination with acute myeloid leukemia (AML)-derived dendritic cells (DCs) is a promising immunotherapeutic approach to prevent relapse of AML. However, in clinical practice AML-derived DC culture is unfeasible in 40% of cases. Here, we demonstrate that AML cells can be expanded in vitro prior to differentiation with cocktails of cytokines with known myeloid growth-promoting effects.

RESULTS

Nine out of 13 initially CD14(-) samples gain de novo CD14 (>10%) expression (69% increment; p = 0.01) after in vitro expansion. These expanded CD14(+) leukemic cells displayed a high probability (six out of six initially CD14(-) samples tested) to differentiate into DCs upon culture with GM-CSF, TNF-α and IL-4.

CONCLUSION

Induction of CD14 on initially CD14(-) AML cells potentially increases the number of patients eligible for DC-based immunotherapy.

Apoptotic blebs from leukemic cells as a preferred source of tumor-associated antigen for dendritic cell-based vaccines

Since few leukemia-associated antigens (LAA) are characterized for acute myeloid leukemia (AML), apoptotic tumor cells constitute an attractive LAA source for DC-based vaccines, as they contain both characterized and unknown LAA. However, loading DC with apoptotic tumor cells may interfere with DC function. Previously, it was shown in mice that apoptotic blebs induce DC maturation, whereas apoptotic cell remnants (ACR) do not. Here, we analyzed human monocyte-derived DC (MoDC) functionality in vitro, after ingesting either allogeneic AML-derived ACR or blebs. We show that MoDC ingest blebs to a higher extent and are superior in migrating toward CCL19, as compared to ACR-loaded MoDC. Although MoDC cytokine production was unaffected, co-culturing bleb-loaded MoDC with T cells led to an increased T cell proliferation and IFNγ production. Moreover, antigen-specific CD8(+) T cells frequencies increased to 0.63 % by priming with bleb-loaded MoDC, compared to 0.16 % when primed with ACR-loaded MoDC. Importantly, CD8(+) T cells primed by bleb-loaded MoDC recognized their specific epitope at one to two orders of magnitude lower concentrations compared to ACR-loaded MoDC. In conclusion, superior ingestion efficiency and migration, combined with favorable T cell cytokine release and CD8(+) T cell priming ability and avidity, point to blebs as the preferred component of apoptotic leukemic cells for LAA loading of DC for the immunotherapy of AML.

Comorbidity and treatment decision-making in elderly non-Hodgkin's lymphoma patients: a survey among haematologists

BACKGROUND

Elderly patients with non-Hodgkin's lymphoma (NHL) are often not treated with standard immunochemotherapy and this might have a negative impact on their survival. Little is known about the determinants that play a role in treatment decision-making of clinicians regarding elderly patients with NHL. The objective of this study was to gain more insight into these determinants.

METHODS

A survey was conducted amongst haematologists in the Netherlands. The survey contained questions about comorbidity, polypharmacy, social setting, nutritional status, depression, mild cognitive impairment, dementia, activities of daily living (ADL) and instrumental activities of daily living (IADL) in relation to treatment decisions in elderly NHL patients.

RESULTS

Of all comorbidities, respondents designated cognitive disorders and cardiovascular comorbidity as the most important factors when assessing whether an older patient with NHL is eligible for curative treatment. Also in decreasing degree of importance ADL, IADL and depressive disorder are frequently included in treatment decision-making. Almost half of the respondents feel that treatment of the elderly person is complicated as a result of a lack of scientific evidence.

CONCLUSION

Haematologists are aware of coexisting problems in elderly patients and they frequently take comorbidities, cognitive disorders and functional status into consideration in treatment decision-making. Future studies are needed to determine the exact role that these factors should play in the treatment of elderly patients. Furthermore, haematologists feel that treatment of the elderly is complicated and there is a lack of scientific evidence, and therefore older adults should be better represented in clinical trials.

Attenuation of microRNA-126 expression that drives CD34+38- stem/progenitor cells in acute myeloid leukemia leads to tumor eradication

Despite high remission rates after therapy, 60% to 70% of patients with acute myeloid leukemia (AML) do not survive 5 years after their initial diagnosis. The main cause of treatment failures may be insufficient eradication of a subpopulation of leukemic stem-like cells (LSC), which are thought to be responsible for relapse by giving rise to more differentiated leukemic progenitors (LP). To address the need for therapeutic targets in LSCs, we compared microRNA (miRNA) expression patterns in highly enriched healthy CD34(+)CD38(-) hematopoietic stem cells (HSC), CD34(+)CD38(-) LSCs, and CD34(+)CD38(+) LPs, all derived from the same patients' bone marrow (BM) specimens. In this manner, we identified multiple differentially expressed miRNAs, in particular miR-126, which was highly expressed in HSCs and increased in LSCs compared with LPs, consistent with a stem-like cell function. High miR-126 expression in AML was associated with poor survival, higher chance of relapse, and expression of genes present in LSC/HSC signatures. Notably, attenuating miR-126 expression in AML cells reduced in vitro cell growth by inducing apoptosis, but did not affect the survival of normal BM in which it instead enhanced expansion of HSCs. Furthermore, targeting miR-126 in LSCs and LPs reduced their clonogenic capacity and eliminated leukemic cells, again in the absence of similar inhibitory effects on normal BM cells. Our results define miR-126 as a therapeutic focus to specifically eradicate LSCs and improve AML outcome.

Absence of aberrant myeloid progenitors by flow cytometry is associated with favorable response to azacitidine in higher risk myelodysplastic syndromes

BACKGROUND

In intermediate-2 (Int-2) and high risk patients with myelodysplastic syndromes (MDS), treatment with azacitidine is associated with hematological improvement and prolonged overall survival (OS) in patients who respond to therapy. However, only half of the patients who are treated will benefit from this treatment. It is a major challenge to predict which patients are likely to respond to treatment. The aim of this study was to investigate the predictive value of immunophenotyping for response to treatment with azacitidine of Int-2 and high risk MDS patients.

METHODS

Bone marrow aspirates were analyzed by flow cytometry in 42 patients with Int-2 and high risk MDS, chronic myelomonocytic leukemia, or low blast count acute myeloid leukemia before treatment and after every third cycle of azacitidine. A flow score was calculated using the flow cytometric scoring system (FCSS).

RESULTS

The presence of myeloid progenitors with an aberrant immunophenotype was significantly associated with lack of response (p = 0.02). A low pretreatment FCSS was associated with significantly better OS compared with a high pretreatment FCSS (p = 0.03). A significant decrease in FCSS was observed in patients with complete response after three cycles azacitidine compared to patients with progressive disease (p = 0.006).

CONCLUSIONS

Absence of aberrant myeloid progenitor cells at baseline and/or a decrease in the FCSS during treatment identified Int-2 and high risk MDS patients who are likely to respond to treatment with azacitidine.

Absence of aberrant myeloid progenitors by flow cytometry is associated with favorable response to azacitidine in higher risk myelodysplastic syndromes

Background: In intermediate-2 and high risk patients with myelodysplastic syndromes (MDS), treatment with azacitidine is associated with hematological responses and prolonged overall survival in patients who respond to therapy. However, only half of the patients that are treated will benefit from this treatment. It is a major challenge to predict which patients are likely to respond to treatment. The aim of this study was to investigate the predictive value of immunophenotyping for response to treatment with azacitidine of Int-2 and high risk MDS patients. Methods: Bone marrow aspirates were analyzed by flow cytometry in 42 patients with Int-2 and high risk MDS, chronic myelomonocytic leukemia or low blast count acute myeloid leukemia before treatment and after every third cycle of azacitidine. A flow score was calculated using the flow cytometric scoring system (FCSS). Results: The presence of myeloid progenitors with an aberrant immunophenotype was significantly associated with lack of response (p=0.02). A low pretreatment FCSS was associated with significantly better overall survival compared with a high pretreatment FCSS (p=0.03). A significant decrease in FCSS was observed in patients with complete response after three cycles azacitidine compared to patients with progressive disease (p=0.006). Conclusions: Absence of aberrant myeloid progenitor cells at baseline and/or a decrease in the FCSS during treatment identified Int-2 and high risk MDS patients who are likely to respond to treatment with azacitidine. © 2014 Clinical Cytometry Society.

Normal hematopoietic stem cells within the AML bone marrow have a distinct and higher ALDH activity level than co-existing leukemic stem cells

Persistence of leukemic stem cells (LSC) after chemotherapy is thought to be responsible for relapse and prevents the curative treatment of acute myeloid leukemia (AML) patients. LSC and normal hematopoietic stem cells (HSC) share many characteristics and co-exist in the bone marrow of AML patients. For the development of successful LSC-targeted therapy, enabling eradication of LSC while sparing HSC, the identification of differences between LSC and HSC residing within the AML bone marrow is crucial. For identification of these LSC targets, as well as for AML LSC characterization, discrimination between LSC and HSC within the AML bone marrow is imperative. Here we show that normal CD34+CD38– HSC present in AML bone marrow, identified by their lack of aberrant immunophenotypic and molecular marker expression and low scatter properties, are a distinct sub-population of cells with high ALDH activity (ALDH^bright). The ALDH^bright compartment contains, besides normal HSC, more differentiated, normal CD34+CD38+ progenitors. Furthermore, we show that in CD34-negative AML, containing solely normal CD34+ cells, LSC are CD34– and ALDH^low. In CD34-positive AML, LSC are also ALDH^low but can be either CD34+ or CD34–. In conclusion, although malignant AML blasts have varying ALDH activity, a common feature of all AML cases is that LSC have lower ALDH activity than the CD34+CD38– HSC that co-exist with these LSC in the AML bone marrow. Our findings form the basis for combined functionally and immunophenotypically based identification and purification of LSC and HSC within the AML bone marrow, aiming at development of highly specific anti-LSC therapy.

High prognostic impact of flow cytometric minimal residual disease detection in acute myeloid leukemia: data from the HOVON/SAKK AML 42A study

PURPOSE

Half the patients with acute myeloid leukemia (AML) who achieve complete remission (CR), ultimately relapse. Residual treatment-surviving leukemia is considered responsible for the outgrowth of AML. In many retrospective studies, detection of minimal residual disease (MRD) has been shown to enable identification of these poor-outcome patients by showing its independent prognostic impact. Most studies focus on molecular markers or analyze data in retrospect. This study establishes the value of immunophenotypically assessed MRD in the context of a multicenter clinical trial in adult AML with sample collection and analysis performed in a few specialized centers.

PATIENTS AND METHODS

In adults (younger than age 60 years) with AML enrolled onto the Dutch-Belgian Hemato-Oncology Cooperative Group/Swiss Group for Clinical Cancer Research Acute Myeloid Leukemia 42A study, MRD was evaluated in bone marrow samples in CR (164 after induction cycle 1, 183 after cycle 2, 124 after consolidation therapy).

RESULTS

After all courses of therapy, low MRD values distinguished patients with relatively favorable outcome from those with high relapse rate and adverse relapse-free and overall survival. In the whole patient group and in the subgroup with intermediate-risk cytogenetics, MRD was an independent prognostic factor. Multivariate analysis after cycle 2, when decisions about consolidation treatment have to be made, confirmed that high MRD values (> 0.1% of WBC) were associated with a higher risk of relapse after adjustment for consolidation treatment time-dependent covariate risk score and early or later CR.

CONCLUSION

In future treatment studies, risk stratification should be based not only on risk estimation assessed at diagnosis but also on MRD as a therapy-dependent prognostic factor.

Targeting the acute myeloid leukemic stem cell compartment by enhancing tumor cell-based vaccines

Harvesting the potential of the immune system in order to eradicate (residual) acute myeloid leukemia (AML) cells is the long pursued goal of immunotherapy in AML. Strategies using apoptotic tumor cell vaccines have been explored for many years, without significant clinical improvements. In recent years insight has been gained into the mechanisms activating and interfering with tumor-directed immunity. With the arrival of novel immune-modulating agents allowing for the interference with regulatory molecules and interaction with immune-propelling mechanisms, new doors are opening for increasing vaccination efficacy. Combined with advances in the design of apoptotic tumor-based vaccines, we are on the verge of creating an effective AML vaccine strategy, offering a much needed novel therapeutic option for this devastating disease.

Allogeneic dendritic cell (DC) vaccination as an “off the shelf” treatment to prevent or delay relapse in elderly acute myeloid leukemia patients: Results of phase I study

3029

Background: Vaccines against tumor-associated antigens represent an appealing strategy for preventing tumor recurrence. A novel immunotherapy platform is represented by the DCOne cell line, which originates from a human myeloid leukemia cell line, endogenously expresses a range of tumor associated antigens and can be differentiated into mature dendritic cells. Methods: A phase I study enrolled 12 AML patients (age range 58-71) who were either in CR1/CR2 (n=5) or had smouldering disease (n=7), at high risk of relapse and ineligible for available post-remission therapies, in a 3+3 design, starting with 4 bi-weekly intradermal DCOne DC vaccinations of 10E6 cells (n=3), 25E6 (n=3) or 50E6 (n=6). Patients were monitored for clinical and immunological responses for 126 days and surviving patients were followed up after study completion. Results: Treatment was well tolerated in all patients, with expected toxicities of injection site reactions (< grade 2). During the study 3 patients died: 2 from infections and 1 from leukemia. Patients who survived more than 6 months post-vaccination showed remarkable survival (22 mo after the first patient was recruited, 3 patients have been alive for 22, 20 and 16 months respectively). One patient with smouldering AML at entry achieved CR2 after vaccination; one patient who was in CR2 at entry, relapsed 8 mo after vaccination and entered CR3 following a single low dose of 5-AZA. Remarkably, 1/5 patients that were evaluable by IFNg ELIPOTs showed vaccination-induced specific T cell responses to WT-1 and PRAME, antigens present in DCOne DC. In addition, increased post vaccination delayed type hypersensitivity reactions were observed in all cohorts. Furthermore, induction of systemic immune responses, with increases in CD4+ and CD8+ T cell proliferative responses and/or seroconversion to DCOne DC and/or AML blasts was seen in 5 out of 9 patients. Conclusions: Vaccination with DCOne derived DC is feasible in AML, generated cellular and humoral immune responses, and interesting clinical responses. The hypothesis that immune responses correlate with clinical benefit will be investigated in a randomised phase II trial. Clinical trial information: NCT01373515.

A phase I first-in-human study with tefinostat - a monocyte/macrophage targeted histone deacetylase inhibitor - in patients with advanced haematological malignancies

Tefinostat (CHR-2845) is a monocyte/macrophage targeted histone deacetylase inhibitor (HDACi). This first-in-human, standard 3 + 3 dose escalating trial of oral, once daily tefinostat was conducted to determine the safety, tolerability, pharmacokinetic and pharmacodynamic profile of tefinostat in relapsed/refractory haematological diseases. Eighteen patients were enrolled at doses of 20-640 mg. Plasma concentrations of tefinostat exceeded those demonstrated to give in vitro anti-proliferative activity. Flow cytometric pharmacodynamic assays demonstrated monocyte-targeted increases in protein acetylation, without corresponding changes in lymphocytes. Dose-limiting toxicities (DLTs) were not observed and dose escalation was halted at 640 mg without identification of the maximum tolerated dose. Drug-related toxicities were largely Common Toxicity Criteria for Adverse Events grade 1/2 and included nausea, anorexia, fatigue, constipation, rash and increased blood creatinine. A patient with chronic monomyelocytic leukaemia achieved a bone marrow response, with no change in peripheral monocytes. An acute myeloid leukaemia type M2 patient showed a >50% decrease in bone marrow blasts and clearance of peripheral blasts. In conclusion, tefinostat produces monocyte-targeted HDACi activity and is well tolerated, without the DLTs, e.g. fatigue, diarrhoea, thrombocytopenia, commonly seen with non-targeted HDACi. The early signs of efficacy and absence of significant toxicity warrant further evaluation of tefinostat in larger studies. (clinicaltrials.gov identifier: NCT00820508).

Abstract LB-246: MicroRNA profiling can classify acute leukemias of ambiguous lineage as either acute myeloid leukemia or acute lymphoid leukemia

Classification of acute leukemia (AL) is based on commitment of the leukemic cells to either the myeloid or the lymphoid lineage. However, a small percentage of AL cases display features of both hematopoietic lineages and lacks immunophenotypical lineage commitment. These leukemias of ambiguous lineage represent a heterogeneous category of AL that cannot be classified as either myeloid AL (AML) or lymphoid AL (ALL). The lack of a clear classification of acute leukemias of ambiguous lineage as either AML or ALL is a hurdle in treatment choice for these patients.

MicroRNAs are small single stranded RNA molecules which regulate gene expression by promoting degradation of mRNAs or repressing their translation. MicroRNA expression profiles have shown to be able to accurately discriminate AL of the lymphoid lineage from those of the myeloid lineage. Here, we compared the microRNA expression profiles of acute leukemias of ambiguous lineage with those of B-ALL, T-ALL and AML.

MicroRNA expression profiles of nine patients with leukemia of ambiguous lineage and eleven patients with AML, B-ALL or T-ALL were analyzed. Unsupervised clustering analysis of the AML, B-ALL and T-ALL samples resulted in a clear separation between cases of the myeloid and lymphoid lineages. The top differentially expressed microRNAs between AML and ALL were miR-199b, miR-27a/b, miR-223, miR-23a, miR-221 and miR-150. Subsequently, we compared the general miRNA expression profiles of AL of ambiguous lineage with those of the AML, B-ALL and T-ALL cases thereby showing that these leukemias of ambiguous lineage do not segregate as a separate entity. Moreover, unsupervised clustering of all the AL samples using the top 10 percent of most variable microRNAs resulted in clustering of leukemias of ambiguous lineage with either AML, B-ALL or T-ALL. Furthermor, qRT-PCR expression analysis of the five most discriminative microRNAs between ALL and AML was able to define AL of ambiguous lineage as either AML or ALL.

Thus, our results indicate the presence of a lymphoid or myeloid lineage specific microRNA expression profile in AL cases of ambiguous lineage, despite their mixed immunophenotype. At diagnosis, the classification of AL of ambiguous lineage by microRNA expression analysis might be of additional value in therapeutic decision making.

Citation Format: Dave C. de Leeuw, Willemijn van den Ancker, Fedor Denkers, Rene X. Menezes, Theresia M. Westers, Gert J. Ossenkoppele, Arjan A. van de Loosdrecht, Linda Smit. MicroRNA profiling can classify acute leukemias of ambiguous lineage as either acute myeloid leukemia or acute lymphoid leukemia. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr LB-246. doi:10.1158/1538-7445.AM2013-LB-246

High-dose imatinib versus high-dose imatinib in combination with intermediate-dose cytarabine in patients with first chronic phase myeloid leukemia: a randomized phase III trial of the Dutch-Belgian HOVON study group

Despite the revolutionary change in the prognosis of chronic myeloid leukemia (CML) patients with the introduction of imatinib, patients with resistant disease still pose a considerable problem. In this multicenter, randomized phase III trial, we investigate whether the combination of high-dose imatinib and intermediate-dose cytarabine compared to high-dose imatinib alone, improves the rate of major molecular response (MMR) in newly diagnosed CML patients. This study was closed prematurely because of declining inclusion due to the introduction of second generation tyrosine kinase inhibitors and only one third of the initially required patients were accrued. One hundred nine patients aged 18-65 years were randomly assigned to either imatinib 800 mg (n = 55) or to imatinib 800 mg in combination with two successive cycles of cytarabine 200 mg/m(2) for 7 days (n = 54). After a median follow-up of 41 months, 67 % of patients were still on protocol treatment. The MMR rate at 12 months was 56 % in the imatinib arm and 48 % in the combination arm (p = 0.39). Progression-free survival was 96 % after 1 year and 89 % after 4 years. Four-year overall survival was 97 %. Adverse events grades 3 and 4 were more common in the combination arm. The addition of intermediate-dose of cytarabine to imatinib did not improve the MMR rate at 12 months. However, the underpowering of the study precludes any definitive conclusions. This trial is registered at www.trialregister.nl (NTR674).