MicroRNA profiling can classify acute leukemias of ambiguous lineage as either acute myeloid leukemia or acute lymphoid leukemia

PURPOSE

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

EXPERIMENTAL DESIGN

Here, we compared the microRNA (miRNA) expression profiles of 17 cases with acute leukemia of ambiguous lineage and 16 cases of AML, B-cell acute lymphoid leukemia (B-ALL), and T-cell acute lymphoid leukemia (T-ALL).

RESULTS

We show that leukemias of ambiguous lineage do not segregate as a separate entity but exhibit miRNA expression profiles similar to AML, B-ALL, or T-ALL. We show that by using only 5 of the most lineage-discriminative miRNAs, we are able to define acute leukemia of ambiguous lineage as either AML or ALL.

CONCLUSION

Our results indicate the presence of a myeloid or lymphoid lineage-specific genotype, as reflected by miRNA expression, in these acute leukemias despite their ambiguous immunophenotype. miRNA-based classification of acute leukemia of ambiguous lineage might be of additional value in therapeutic decision making.

Deregulated expression of EVI1 defines a poor prognostic subset of MLL-rearranged acute myeloid leukemias: a study of the German-Austrian Acute Myeloid Leukemia Study Group and the Dutch-Belgian-Swiss HOVON/SAKK Cooperative Group

PURPOSE

To evaluate the prognostic value of ecotropic viral integration 1 gene (EVI1) overexpression in acute myeloid leukemia (AML) with MLL gene rearrangements.

PATIENTS AND METHODS

We identified 286 patients with AML with t(11q23) enrolled onto German-Austrian Acute Myeloid Leukemia Study Group and Dutch-Belgian-Swiss Hemato-Oncology Cooperative Group prospective treatment trials. Material was available from 177 AML patients for EVI1 expression analysis.

RESULTS

We divided 286 MLL-rearranged AMLs into three subgroups: t(9;11)(p22;q23) (44.8%), t(6;11)(q27;q23) (14.7%), and t(v;11q23) (40.5%). EVI1 overexpression (EVI1(+)) was found in 45.8% of all patients with t(11q23), with t(6;11) showing the highest frequency (83.9%), followed by t(9;11) at 40.0%, and t(v;11q23) at 34.8%. Concurrent gene mutations were rare or absent in all three subgroups. Within all t(11q23) AMLs, EVI1(+) was the sole prognostic factor, predicting for inferior overall survival (OS; hazard ratio [HR], 2.06; P = .003), relapse-free survival (HR, 2.28; P = .002), and event-free survival (HR, 1.79; P = .009). EVI1(+) AMLs with t(11q23) in first complete remission (CR) had a significantly better outcome after allogeneic transplantation compared with other consolidation therapies (5-year OS, 54.7% v 0%; Mantel-Byar, P = .0006). EVI1(-) t(9;11) AMLs had lower WBC counts, more commonly FAB M5 morphology, and frequently had additional trisomy 8 (39.6%; P < .001). Among t(9;11) AMLs, EVI1(+) again was the sole independent adverse prognostic factor for survival.

CONCLUSION

Deregulated EVI1 expression defines poor prognostic subsets among AML with t(11q23) and AML with t(9;11)(p22;q23). Patients with EVI1(+) MLL-rearranged AML seem to benefit from allogeneic transplantation in first CR.

Rationale for the clinical application of flow cytometry in patients with myelodysplastic syndromes: position paper of an International Consortium and the European LeukemiaNet Working Group

An international working group within the European LeukemiaNet gathered, aiming to determine the role of flow cytometry (FC) in myelodysplastic syndromes (MDS). It was agreed that FC has a substantial application in disease characterization, diagnosis and prognosis. FC may also be useful in predicting treatment responses and monitoring novel and standard therapeutic regimens. In this article the rationale is discussed that flow cytometry should be integrated as a part of diagnostic and prognostic scoring systems in MDS.

Plerixafor and granulocyte colony-stimulating factor for first-line steady-state autologous peripheral blood stem cell mobilization in lymphoma and multiple myeloma: results of the prospective PREDICT trial

In Europe, the combination of plerixafor + granulocyte colony-stimulating factor is approved for the mobilization of hematopoietic stem cells for autologous transplantation in patients with lymphoma and myeloma whose cells mobilize poorly. The purpose of this study was to further assess the safety and efficacy of plerixafor + granulocyte colony-stimulating factor for front-line mobilization in European patients with lymphoma or myeloma. In this multicenter, open label, single-arm study, patients received granulocyte colony-stimulating factor (10 μg/kg/day) subcutaneously for 4 days; on the evening of day 4 they were given plerixafor (0.24 mg/kg) subcutaneously. Patients underwent apheresis on day 5 after a morning dose of granulocyte colony-stimulating factor. The primary study objective was to confirm the safety of mobilization with plerixafor. Secondary objectives included assessment of efficacy (apheresis yield, time to engraftment). The combination of plerixafor + granulocyte colony-stimulating factor was used to mobilize hematopoietic stem cells in 118 patients (90 with myeloma, 25 with non-Hodgkin's lymphoma, 3 with Hodgkin's disease). Treatment-emergent plerixafor-related adverse events were reported in 24 patients. Most adverse events occurred within 1 hour after injection, were grade 1 or 2 in severity and included gastrointestinal disorders or injection-site reactions. The minimum cell yield (≥ 2 × 10(6) CD34(+) cells/kg) was harvested in 98% of patients with myeloma and in 80% of those with non-Hodgkin's lymphoma in a median of one apheresis. The optimum cell dose (≥ 5 × 10(6) CD34(+) cells/kg for non-Hodgkin's lymphoma or ≥ 6 × 10(6) CD34(+) cells/kg for myeloma) was harvested in 89% of myeloma patients and 48% of non-Hodgkin's lymphoma patients. In this prospective, multicenter European study, mobilization with plerixafor + granulocyte colony-stimulating factor allowed the majority of patients with myeloma or non-Hodgkin's lymphoma to undergo transplantation with minimal toxicity, providing further data supporting the safety and efficacy of plerixafor + granulocyte colony-stimulating factor for front-line mobilization of hematopoietic stem cells in patients with non-Hodgkin's lymphoma or myeloma.

The European LeukemiaNet AML Working Party consensus statement on allogeneic HSCT for patients with AML in remission: an integrated-risk adapted approach

Allogeneic haematopoietic stem-cell transplantation (HSCT) is frequently applied as part of the treatment in patients with acute myeloid leukaemia (AML) in their first or subsequent remission. Allogeneic HSCT reduces relapse, but nonrelapse mortality and morbidity might counterbalance this beneficial effect. Here, we review recent studies reporting new disease-specific prognostic markers, in addition to allogeneic-HSCT-related risk factors, which can be assessed at specific time points during treatment. We propose risk assessment as a dynamic process during treatment, incorporating both disease-related and transplant-related factors for the decision to proceed either to allogeneic HSCT or to apply a nontransplant strategy. We suggest that allogeneic HSCT might be favoured if the projected disease-free survival is expected to improve by at least 10% based on an individual's risk assessment. The approach requires initial disease risk assessment, identifying a sibling or unrelated donor soon after diagnosis and the incorporation of time-dependent risk factors, all within the context of an integrated therapeutic management approach.

Comparative analysis of the value of allogeneic hematopoietic stem-cell transplantation in acute myeloid leukemia with monosomal karyotype versus other cytogenetic risk categories

PURPOSE

To determine to what extent allogeneic hematopoietic stem-cell transplantation (alloHSCT) quantitatively reduces relapse in acute myeloid leukemia with monosomal karyotype (MK-AML) compared with alternative postremission therapy and how it compares with other cytogenetic subcategories.

PATIENTS AND METHODS

Of 2,560 patients (younger than age 61 years) without core-binding factor abnormalities including 305 patients with MK-AML receiving first-line induction treatment, 1,975 patients (77%) achieved remission, and 1,588 received consolidation in the first complete remission (CR1) after two induction cycles. Consolidation treatment of 107 patients with MK-AML consisted of alloHSCT (n = 45), chemotherapy (n = 48), or autologous HSCT (n = 14).

RESULTS

The 5-year overall survival after start of consolidation was 19% for patients with MK-AML who received alloHSCT and 9% for those who received chemotherapy or autoHSCT (P = .02). Relapse-free survival (RFS) at 5 years was 17% versus 7% (P = .003). Cox regression analysis was performed with alloHSCT as a time-dependent covariate. Hazard ratios (HRs) associated with alloHSCT for relapse and RFS were 0.30 (95% CI, 0.24 to 0.37; P < .001), and 0.52 (95% CI, 0.43 to 0.62; P < .001), respectively. HRs were similar in MK-AML and the other cytogenetic subgroups.

CONCLUSION

AlloHSCT, applied as consolidation in CR1, is associated with a significant reduction of relapse and improvement of survival in MK-AML, with the same relative reduction of relapse or death as in other cytogenetic risk categories.

Promiscuous binding of invariant chain-derived CLIP peptide to distinct HLA-I molecules revealed in leukemic cells

Antigen presentation by HLA class I (HLA-I) and HLA class II (HLA-II) complexes is achieved by proteins that are specific for their respective processing pathway. The invariant chain (Ii)-derived peptide CLIP is required for HLA-II-mediated antigen presentation by stabilizing HLA-II molecules before antigen loading through transient and promiscuous binding to different HLA-II peptide grooves. Here, we demonstrate alternative binding of CLIP to surface HLA-I molecules on leukemic cells. In HLA-II-negative AML cells, we found plasma membrane display of the CLIP peptide. Silencing Ii in AML cells resulted in reduced HLA-I cell surface display, which indicated a direct role of CLIP in the HLA-I antigen presentation pathway. In HLA-I-specific peptide eluates from B-LCLs, five Ii-derived peptides were identified, of which two were from the CLIP region. In vitro peptide binding assays strikingly revealed that the eluted CLIP peptide RMATPLLMQALPM efficiently bound to four distinct HLA-I supertypes (-A2, -B7, -A3, -B40). Furthermore, shorter length variants of this CLIP peptide also bound to these four supertypes, although in silico algorithms only predicted binding to HLA-A2 or -B7. Immunization of HLA-A2 transgenic mice with these peptides did not induce CTL responses. Together these data show a remarkable promiscuity of CLIP for binding to a wide variety of HLA-I molecules. The found participation of CLIP in the HLA-I antigen presentation pathway could reflect an aberrant mechanism in leukemic cells, but might also lead to elucidation of novel processing pathways or immune escape mechanisms.

Minimal residual disease detection defined as the malignant fraction of the total primitive stem cell compartment offers additional prognostic information in acute myeloid leukaemia

INTRODUCTION

Immunophenotypic detection of minimal residual disease (MRD) in bone marrow (BM) of acute myeloid leukaemia (AML) patients is of high prognostic relevance. Standard MRD percentage is assessed as a percentage of total white blood cells (WBCs) and is therefore highly dependent on WBC count. Peripheral blood (PB) contains more than five times lower MRD percentages. Therefore, PB in BM aspirates cause dilution of the MRD cells, possibly leading to false-negative results for BM MRD. The latter is avoided when relating the fraction of malignant primitive cells, identified by aberrant marker expression [aberrant primitive cells (aPC)], to the total population of primitive cells. Such a fraction may in addition reflect an important biological parameter.

METHODS

As this approach is thus independent of WBC count and the total size of the primitive compartment, we investigated the role of aPC fractions on overall and relapse-free survival (RFS) in 98 patients with AML under the age of 60.

RESULTS

We show that this approach identifies MRD-negative (as defined by % of WBC) but aPC-positive (as defined by % of primitive cells) patients with poor outcome after both first and second induction cycle of chemotherapy.

CONCLUSION

As a result, in cases with a primitive marker present, RFS is best predicted when combining standard MRD percentage with aPC fractions.

Residual normal stem cells can be detected in newly diagnosed chronic myeloid leukemia patients by a new flow cytometric approach and predict for optimal response to imatinib

Insensitivity of chronic myeloid leukemia (CML) hematopoietic stem cells to tyrosine kinase inhibitors (TKIs) prevents eradication of the disease and may be involved in clinical resistance. For improved treatment results more knowledge about CML stem cells is needed. We here present a new flow cytometric approach enabling prospective discrimination of CML stem cells from their normal counterparts within single-patient samples. In 24 of 40 newly diagnosed CML patients residual normal CD34(+)CD38(-) stem cells could be identified by lower CD34 and CD45 expression, lower forward/sideward light scatter and by differences of lineage marker expression (CD7, CD11b and CD56) and of CD90. fluorescent in situ hybridization (FISH) analysis on Fluorescence-activated cell sorting sorted cells proved that populations were BCR-ABL positive or negative and long-term liquid culture assays with subsequent colony forming unit assays and FISH analysis proved their stem cell character. Patients with residual non-leukemic stem cells had lower clinical risk scores (Sokal, Euro), lower hematological toxicity of imatinib (IM) and better molecular responses to IM than patients without. This new approach will expand our possibilities to separate CML and normal stem cells, present in a single bone marrow or peripheral blood sample, thereby offering opportunities to better identify new CML stem-cell-specific targets. Moreover, it may guide optimal clinical CML management.

Abstract LB-45: High aldehyde dehydrogenase activity is a marker for normal hematopoietic stem cells but not leukemic stem cells in acute myeloid leukemia: novel therapeutic implications

Only a minority of cells, the leukemic stem cells (LSC), within AML are responsible for tumor growth and maintenance. Many patients experience relapse after therapy which originates from outgrowth of therapy resistant LSC. Therefore, eradication of LSC is necessary to cure AML. Both the normal hematopoietic stem cells (HSC) and LSC co-exist in the bone marrow (BM) of AML patients and success of anti-LSC strategies relies on specific elimination of LSC while sparing HSC. LSC are contained within the CD34+CD38-, the side population (SP) and the high aldehyde dehydrogenase (ALDH) activity compartments.

ALDH is a detoxifying enzyme responsible for oxidation of intracellular aldehydes and high ALDH activity results in resistance to alkylating agents such as cyclophosphamide. It has been shown that ALDH is highly expressed in both normal progenitor and stem cells and in AML blasts. In view of applicability of LSC specific therapies the detoxification by ALDH is clinically very important. A difference in ALDH activity between HSC and LSC might be used to preferentially kill LSC while sparing HSC.

To establish ALDH activity differences between HSC and LSC it should be possible to discriminate between them. We have shown that LSC can be identified and discriminated from HSC using stem cell-associated cell surface markers, such as CLL-1, lineage markers (CD7, CD19, CD56) and recently CD34/CD45 expression and cell size characteristics (Terwijn, Blood 111: 487, 2008). This offers the opportunity to identify co-existing LSC and HSC in the AML BM.

We now show that, although malignant AML blasts have varying ALDH activity, a common feature of all AML cases is that HSC that co-exist with LSC in BM of AML patients have a higher ALDH activity as compared to their malignant counterparts. We have analyzed ALDH activity in HSC and LSC, both present in the BM from 18 AML patients. In nine BM AML samples, defined as CD34negative (&lt;1%CD34+ blasts), the CD34+ compartment contained only normal CD34+CD38− HSC. The ALDH activity in these CD34+ HSC, is a factor 4,4 (range 1,7–18,9) higher than in LSC. In nine BM AML samples, defined as CD34positive AML, the CD34+CD38- HSC have a 7,7 fold (range 1,73–29,2 fold) higher ALDH activity as compared to putative LSC. In both CD34-positive and CD34-negative AML, we confirmed the identity of HSC and LSC by screening for molecular aberrancies present in AML blasts. The level of the ALDH activity of HSC within the AML BM is similar to that of HSC in NBM of healthy donors.

In conclusion, high ALDH activity is an unique marker of normal HSC within the AML BM (irrespective of AML phenotype) at diagnosis. Consequently, AML patients with high ALDH activity in HSC might benefit from treatment with agents that will be converted by ALDH enzymes, such as cyclophosphamide, whereby the difference between the activity in LSC and HSC will define the therapeutic window.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-45. doi:10.1158/1538-7445.AM2011-LB-45

Chronic myeloid leukemia lysate-loaded dendritic cells induce T-cell responses towards leukemia progenitor cells

Treatment of chronic myeloid leukemia with tyrosine kinase inhibitors, such as imatinib mesylate, dasatinib and nilotinib, results in high rates of cytogenetic and molecular responses. However, in many patients, minimal residual disease is detected by molecular techniques. Since chronic myeloid leukemia cells are particularly good targets for immune surveillance mechanisms, we explored active specific immunotherapy using leukemia lysate-loaded dendritic cells in vitro. Our data show the potency of dendritic cell-based vaccination strategies for the induction of T cell-mediated responses to eradicate minimal residual disease.

Cytarabine dose for acute myeloid leukemia

BACKGROUND

Cytarabine (ara-C) is an important drug in the treatment of acute myeloid leukemia (AML). High-dose cytarabine (2000 to 3000 mg per square meter of body-surface area) is toxic but results in higher rates of relapse-free survival than does the conventional dose of 100 to 400 mg per square meter. Intermediate dose levels have not been thoroughly evaluated.

METHODS

We compared two induction regimens in patients 18 to 60 years of age (median, 49) who had newly diagnosed AML. The intermediate-dose group, totaling 431 patients, received cytarabine at a dose of 200 mg per square meter given by continuous intravenous infusion for 24 hours during cycle 1 of induction therapy and 1000 mg per square meter by infusion for 3 hours twice daily during cycle 2 of induction therapy. The high-dose group, totaling 429 patients, received a dose-escalated regimen of 1000 mg of cytarabine per square meter every 12 hours in cycle 1 and 2000 mg per square meter twice daily in cycle 2. Patients with a complete response did not receive additional cytarabine but received consolidation therapy in a third cycle of chemotherapy (mitoxantrone-etoposide) or underwent autologous or allogeneic stem-cell transplantation. Complete remission rates, survival rates, and toxic effects were assessed for each treatment group.

RESULTS

At a median follow-up of 5 years, no significant differences were noted between the intermediate-dose group and the high-dose group with respect to complete remission rates (80% and 82%, respectively), probability of relapse, event-free survival at 5 years (34% and 35%), or overall survival (40% and 42%). High-dose cytarabine provided no clear advantage in any prognostic subgroup. The high-dose treatment resulted in higher incidences of grade 3 and grade 4 toxic effects (in cycle 1), prolonged hospitalization, and delayed neutrophil recovery (in cycle 2) and platelet recovery (in cycles 2 and 3).

CONCLUSIONS

Induction therapy with cytarabine at the lower dose already produced maximal antileukemic effects for all response end points, suggesting a plateau in the dose-response relationship above this dose level. High-dose cytarabine results in excessive toxic effects without therapeutic benefit. (Netherlands Trial Register number, NTR230.).

Review of the relevance of aberrant antigen expression by flow cytometry in myeloid neoplasms

This article reviews the use of aberrant antigen expression detected by flow cytometry in the diagnosis and clinical handling of acute myeloid leukaemia (AML) and the myelodysplastic syndromes (MDS). Such aberrancies offer a valuable tool for the proper classification of these myeloid malignancies according the World Health Organization 2008 classification. Aberrant antigen expression by flow cytometry is also important for prognostification. This review supports the view, that minimal residual disease detection methods that make use of such aberrancies should be part of the routine management of AML patients to guide therapy, but also suggests the introduction of flow cytometry in MDS for diagnosis and treatment decisions in the near future.

Allogeneic stem-cell transplantation as salvage therapy for patients with diffuse large B-cell non-Hodgkin's lymphoma relapsing after an autologous stem-cell transplantation: an analysis of the European Group for Blood and Marrow Transplantation Registry

PURPOSE

To analyze the outcome, including nonrelapse mortality (NRM), relapse rate (RR), progression-free survival (PFS), and overall survival (OS), of patients with diffuse large B-cell non-Hodgkin's lymphoma (DLBCL) relapsed after an autologous stem-cell transplantation (ASCT) and treated with an allogeneic stem-cell transplantation (allo-SCT).

PATIENTS AND METHODS

The European Group for Blood and Marrow Transplantation database was scanned for a first allo-SCT in relapsed DLBCL after a previous ASCT between 1997 and 2006. Other inclusion criteria were age at allo-SCT ≥ 18 years and availability of an HLA-identical sibling or a matched unrelated donor. A total of 101 patients (57 males; median age, 46 years) were included. Median follow-up for survivors was 36 months.

RESULTS

Myeloablative conditioning regimen was used in 37 patients and reduced intensity conditioning (RIC) was used in 64 patients. Three-year NRM was 28.2% (95% CI, 20% to 39%), RR was 30.1% (95% CI, 22% to 41%), PFS was 41.7% (95% CI, 32% to 52%), and OS was 53.8% (95% CI, 44% to 64%). NRM was significantly increased in patients ≥ 45 years (P = .01) and in those with an early relapse (< 12 months) after ASCT (P = .01). RR was significantly higher in refractory patients (P = .03). A time interval to relapse after ASCT of < 12 months was associated with lower PFS (P = .03). The use of RIC regimens was followed by a trend to a lower NRM (P = .1) and a trend to a higher RR (P = .1), with no differences in PFS and OS. No differences were seen between HLA-identical siblings and matched unrelated donors.

CONCLUSION

Allo-SCT in relapsed DLBCL after ASCT is a promising therapeutic modality. Patients with a long remission after ASCT and with sensitive disease at allo-SCT are the best candidates for this approach.