Novel strategies for relapsed and refractory acute myeloid leukemia

Chemotherapy or Allogeneic Stem Cell Transplantation as Salvage Therapy for Patients with Refractory Acute Myeloid Leukemia: A Multicenter Analysis

Introduction

The overall outcome of patients with refractory AML (rAML) remains poor. Though allogeneic hematopoietic stem cell transplantation (allo-HSCT) is considered as the only curative therapy, it is routinely recommended only for patients after remission with salvage chemotherapy.

Objective

In this study, we evaluated the impact of salvage chemotherapy or allo-HSCT on the overall outcome in rAML.

Methods

We collected the clinical data of 220 patients from 4 medical centers and performed retrospective analysis of prognosis factors, including salvage chemotherapy, intensity of chemotherapy, and allo-HSCT.

Results

A total of 29 patients received allo-HSCT directly without salvage chemotherapy, 26 patients achieved complete remission (CR) or complete remission with incomplete hematological recovery (CRi) after transplantation and 4-year leukemia-free survival (LFS) and overall survival (OS) were 45.0 ± 10.7 and 51.0 ± 10.6%, respectively. Another 191 patients received salvage chemotherapy and 81 (42.2%) achieved CR or CRi. Thirty-four patients among them underwent subsequent allo-HSCT with 4-year LFS and OS of 46.0 ± 8.8 and 46.2 ± 9.0%. The 4-year LFS and OS in 26 patients who failed to obtain CR or CRi but received allo-HSCT with active disease were 32.9 ± 10.0 and 36.9 ± 10.8%, respectively. For patients who received salvage chemotherapy but not allo-HSCT, few of them became long-term survivors. In multivariate analysis, salvage chemotherapy and the intensity of chemotherapy failed to have significant impact on both OS and LFS. Allo-HSCT was the only prognostic factor for improved OS and LFS in multivariate analysis.

Conclusions

These results indicate the benefit of allo-HSCT in patients with rAML and direct allo-HSCT without salvage chemotherapy could be treatment option.

The effect of granulocyte colony-stimulating factor dose and administration interval after allogeneic hematopoietic cell transplantation on early engraftment of neutrophil and platelet

BACKGROUND

Hematopoietic stem cell transplantation (HSCT) is one of the treatments for hematologic malignancies. Numerous factors affect the HSCT outcome. The purpose of this study was to investigate the effect of post-HSCT administration of granulocyte colony-stimulating factor (post-G-CSF) on early neutrophil and platelet engraftment in allogeneic HSCT (allo-HSCT).

MATERIAL & METHODS

The study was performed on 76 patients diagnosed with AML and ALL. All patients underwent allo-HSCT at Taleghani stem cell transplantation center, Tehran, Iran, from February 2016 to December 2018. Chemotherapy regimens based on patients' conditions were selected between myeloablative and reduced-intensity regimens.

RESULTS

Statistical analysis revealed that the number of administered G-CSF units after HSCT was a time-dependent variable. Statistical analysis before day +11 reported that patients who received G-CSF <14 units had three times better early neutrophil engraftment than those with G-CSF ≥14 (CI 95%, AHR = 3.03, p:0.002). CD3+ cells count <318.5 × 10⁶ /kg was associated with fast platelet engraftment (CI 95%, AHR 2.28, p:0.01).

CONCLUSION

In this study, post-G-CSF stimulation was associated with early engraftment in a time- and dose-dependent manner. Administration of G-CSF beyond 14 units resulted in adverse effects on neutrophil early engraftment. It also appeared that with a reduction in CD3+ cell counts, the likelihood of GVHD decreases, and platelet engraftment occurs earlier. Further investigations in the future are required to determine the factors affecting the process of early engraftment.

Cellular Metabolomics Profiles Associated With Drug Chemosensitivity in AML

Background

Acute myeloid leukemia (AML) is a hematological malignancy with a dismal prognosis. For over four decades, AML has primarily been treated by cytarabine combined with an anthracycline. Although a significant proportion of patients achieve remission with this regimen, roughly 40% of children and 70% of adults relapse. Over 90% of patients with resistant or relapsed AML die within 3 years. Thus, relapsed and resistant disease following treatment with standard therapy are the most common clinical failures that occur in treating this disease. In this study, we evaluated the relationship between AML cell line global metabolomes and variation in chemosensitivity.

Methods

We performed global metabolomics on seven AML cell lines with varying chemosensitivity to cytarabine and the anthracycline doxorubicin (MV4.11, KG-1, HL-60, Kasumi-1, AML-193, ME1, THP-1) using ultra-high performance liquid chromatography - mass spectrometry (UHPLC-MS). Univariate and multivariate analyses were performed on the metabolite peak intensity values from UHPLC-MS using MetaboAnalyst to identify cellular metabolites associated with drug chemosensitivity.

Results

A total of 1,624 metabolic features were detected across the leukemic cell lines. Of these, 187 were annotated to known metabolites. With respect to doxorubicin, we observed significantly greater abundance of a carboxylic acid (1-aminocyclopropane-1-carboxylate) and several amino acids in resistant cell lines. Pathway analysis found enrichment of several amino acid biosynthesis and metabolic pathways. For cytarabine resistance, nine annotated metabolites were significantly different in resistance vs. sensitive cell lines, including D-raffinose, guanosine, inosine, guanine, aldopentose, two xenobiotics (allopurinol and 4-hydroxy-L-phenylglycine) and glucosamine/mannosamine. Pathway analysis associated these metabolites with the purine metabolic pathway.

Conclusion

Overall, our results demonstrate that metabolomics differences contribute toward drug resistance. In addition, it could potentially identify predictive biomarkers for chemosensitivity to various anti-leukemic drugs. Our results provide opportunity to further explore these metabolites in patient samples for association with clinical response.

Sequential intensified conditioning followed by prophylactic DLI could reduce relapse of refractory acute leukemia after allo-HSCT

The major obstacle is leukemia relapse for refractory leukemia undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). We previously introduced a strategy of sequential intensified conditioning and early rapid immunosupressant withdrawal for refractory leukemia undergoing allo-HSCT, with 5-year overall survival (OS) and 3-year relapse rate of 44.6% and 33.3%. To reduce leukemia relapse, prophylactic donor lymphocyte infusion (DLI) was administered based on our historical strategy. A total of 153 refractory advanced acute leukemia patients were enrolled in this prospective study. According to the availability of donor lymphocytes and the criteria for DLI, 144 patients surviving day +60 were divided into two groups (80 DLI versus 64 non-DLI). The relapse rate was less and OS was better in patients receiving DLI than in those not receiving DLI (22.7% vs 33.9%, P=0.048; 58.1% vs 54.9%, P=0.043). The non-relapse mortality (NRM) was similar between DLI and non-DLI groups (P=0.104). Overall, the 5-year overall and disease-free survival post-transplantation were 51.1%±5.7% and 49.2%±5.3%. The 5-year relapse rate and NRM were 27.3%±4.4% and 29.7%±5.3%. Multivariate analysis revealed that lower bone marrow blasts on day 0, DLI and chronic graft-versus-host disease were associated with less relapse and better OS. The strategy of sequential intensified conditioning followed by early immunosupressant withdrawal and DLI could reduce relapse of refractory acute leukemia after allo-HSCT and improve survival.

Durable graft-versus-leukaemia effects without donor lymphocyte infusions - results of a phase II study of sequential T-replete allogeneic transplantation for high-risk acute myeloid leukaemia and myelodysplasia

Allogeneic haematopoietic stem-cell transplantation remains the only curative treatment for relapsed/refractory acute myeloid leukaemia (AML) and high-risk myelodysplasia but has previously been limited to patients who achieve remission before transplant. New sequential approaches employing T-cell depleted transplantation directly after chemotherapy show promise but are burdened by viral infection and require donor lymphocyte infusions (DLI) to augment donor chimerism and graft-versus-leukaemia effects. T-replete transplantation in sequential approaches could reduce both viral infection and DLI usage. We therefore performed a single-arm prospective Phase II clinical trial of sequential chemotherapy and T-replete transplantation using reduced-intensity conditioning without planned DLI. The primary endpoint was overall survival. Forty-seven patients with relapsed/refractory AML or high-risk myelodysplasia were enrolled; 43 proceeded to transplantation. High levels of donor chimerism were achieved spontaneously with no DLI. Overall survival of transplanted patients was 45% and 33% at 1 and 3 years. Only one patient developed cytomegalovirus disease. Cumulative incidences of treatment-related mortality and relapse were 35% and 20% at 1 year. Patients with relapsed AML and myelodysplasia had the most favourable outcomes. Late-onset graft-versus-host disease protected against relapse. In conclusion, a T-replete sequential transplantation using reduced-intensity conditioning is feasible for relapsed/refractory AML and myelodysplasia and can deliver graft-versus-leukaemia effects without DLI.

Busulfan and fludarabine conditioning regimen given at hematological nadir of cytoreduction fludarabine, cytarabine, and idarubicin chemotherapy in patients with refractory acute myeloid leukemia undergoing allogeneic stem cell transplantation: a single arm pilot consort study

To improve the outcome of allogeneic stem cell transplantation in refractory acute myeloid leukemia (AML), we conducted a single-arm phase II clinical trial to evaluate the efficacy and feasibility of conditioning regimen following cytoreduction chemotherapy with 7-day interval. Adult patients with refractory AML were enrolled in the study and received fludarabine, cytarabine, and idarubicin (FLAG-IDA) as cytoreductive chemotherapy followed by busulfan and fludarabine (Flu-BU) conditioning regimen and transfusion of mobilized peripheral stem cells from human leukocyte antigen-matched sibling or unrelated donor. The primary endpoint of the study was 2-year leukemia-free survival (LFS) and secondary endpoints included complete-remission rate, 2-year overall survival (OS), nonrelapse mortality (NRM), and relapse rate. A total of 16 patients were enrolled with median age of 36 (16-60), which included 9 primary induction failure, 2 early relapse, and 5 with relapse/refractory disease. The median cycles of previous chemotherapy were 4 (3-10) with a median of 55% (1%-90%) blasts in bone marrow. Six patients received transplantation from matched sibling and 10 from matched unrelated donors. After transplantation, 15 patients achieved bone marrow remission (11 complete remissions [CRs] and 4 bone marrow remissions without platelet recovery) at day +28. A total of 8 patients remained alive in CR with median LFS of 29.5 months (9.5-40.5 months). Four patients relapsed and 3 of them died of disease and another 4 patients died because of transplantation-related toxicity. The 2-year NRM and relapse rates were 25.0% ± 10.8% and 33.4% ± 13.8%, respectively with 2-year OS at 53.5% ± 13.1% and LFS at 50.0% ± 12.5%. Based on the Simon 2-stage design, 5 out of first eligible 14 patients remained leukemia-free for more than 2 years after allogeneic hematopoietic stem cell transplantation; thus, the null hypothesis of the study will be rejected and the study protocol is accepted as being warranted for further study. Based on the above data, our phase II study demonstrated that the sequential FLAG-IDA cytoreduction chemotherapy followed by Flu-BU conditioning regimen given at the hematological nadir was feasible and has sufficient activity to warrant further investigation prospectively with a larger patient sample (clinicaltrials.gov identifier: NCT01496547).

Treatment of Acute Myeloid Leukemia in Adolescent and Young Adult Patients

The objectives of this review were to discuss standard and investigational treatment strategies for adolescent and young adult with acute myeloid leukemia, excluding acute promyelocytic leukemia. Acute myeloid leukemia (AML) in adolescent and young adult patients (AYAs) may need a different type of therapy than those currently used in children and older patients. As soon as AML is diagnosed, AYA patient should be offered to participate in well-designed clinical trials. The standard treatment approach for AYAs with AML is remission induction chemotherapy with an anthracycline/cytarabine combination, followed by either consolidation chemotherapy or stem cell transplantation, depending on the ability of the patient to tolerate intensive treatment and cytogenetic features. Presently, continuing progress of novel drugs targeting specific pathways in acute leukemia may bring AML treatment into a new era.

Harnessing the power of alloreactivity without triggering graft-versus-host disease: how non-engrafting alloreactive cellular therapy might change the landscape of acute myeloid leukemia treatment

Human leukocyte antigen-mismatched leukocyte infusions outside of the context of transplantation are a promising strategy for acute myeloid leukemia. Recent studies using such non-engrafting alloreactive cellular therapy (NEACT) revealed that survival of elderly patients increased from 10% to 39% when NEACT was given following chemotherapy, and that durable complete remissions were achieved in about a third of patients with relapsed or chemorefractory disease. We review the clinical reports of different NEACT approaches to date and describe how although T-cell and NK alloreactivity could generate immediate anti-leukemic effects, long-term disease control may be achieved by stimulating recipient-derived T-cell responses against tumor-associated antigens. Other variables likely impacting NEACT such as the release of pro-inflammatory cytokines from donor-host bidirectional alloreactivity and the choice of chemotherapeutics as well as future avenues for improving NEACT, such as optimizing the cell dose and potential synergies with adjuvant pharmacologic immune checkpoint blockade, are discussed.

Distribution and clonality of the vα and vβ T-cell receptor repertoire of regulatory T cells in leukemia patients with and without graft versus host disease

Graft versus host disease (GVHD) is the main complication following allogeneic hematopoietic stem cell transplantation (allo-HSCT). Recent data indicated that regulatory T (Treg) cells might relate to GVHD, and such functions might be mediated by certain T-cell receptor (TCR) subfamily of Treg cells. Thus, we analyzed the distribution and clonality of the TCR Vα and Vβ repertoire of Treg cells from leukemia patients with and without GVHD after allo-HSCT. Numerous TCR Vα subfamilies, including Vα1, Vα9, Vα13, Vα16-19, and Vα24-29, were absent in Treg cells after allo-HSCT. The usage numbers for the TCR Vα and Vβ subfamilies in Treg cells from patients without GVHD appeared more widely. The expression frequencies of Vα10 or Vα20 between both groups were significantly different. Moreover, the expression frequency of TCR Vβ2 subfamily in patients without GVHD was significantly higher than that in patients with GVHD. Oligoclonally expanded TCR Vα and Vβ Treg cells were identified in a few samples in both groups. Restricted utilization of the Vα and Vβ subfamilies and the absence of some important TCR rearrangements in Treg cells may be related to GVHD due to a lower regulating function of Treg subfamilies.

BMP4 is involved in the chemoresistance of myeloid leukemia cells through regulating autophagy-apoptosis balance

This study showed that silencing BMP4 expression significantly activated caspase-2, 3, and 9, while decreasing Matrigel colony formation in Cytarabine (Ara-C)-treated leukemia HL-60 cells. In contrast, Ara-C significantly upregulated Atg5 and Beclin-1 expression, the ratio of LC3-II/LC3-I, and CDK1 and cyclin B1 expression in leukemia cells expressing BMP4. BafA significantly sensitized the apoptotic effect of Ara-C in leukemia cells. Injection of Ara-C significantly inhibited tumor growth in mice inoculated with leukemia cells with BMP4 silenced. In conclusion, BMP4 plays a crucial role in the chemoresistance of leukemia cells through the activation of autophagy and subsequent inhibition of apoptosis.

Molecular monitoring and stepwise preemptive therapy for Epstein-Barr virus viremia after allogeneic stem cell transplantation

The optimal preemptive therapy for Epstein-Barr virus (EBV)-associated diseases remains under discussion. We developed a stepwise preemptive therapy (antiviral agents and reduction of immunosuppressants [RI] followed by rituximab) for EBV viremia, based on duration of EBV viremia and changes of viral loads. The blood EBV-DNA loads were regularly monitored by quantitative real-time polymerase chain reaction in 251 recipients undergoing allogeneic stem cell transplantation. The 3-year cumulative incidence of EBV viremia and EBV-associated diseases were 31.1% ± 3.1% and 15.6% ± 2.5%, which rose steeply with greater numbers of major risk factors. Of the 64 patients undergoing first-step preemption, 24 achieved complete response (CR) and 40 showed no response, including 25 progressing to EBV-associated diseases. The effective rates of antiviral agents and RI plus antiviral agents were 2/16 and 22/48 (P = 0.017). Fourteen achieved CR and one progressed to lymphoproliferative disease in the 15 patients undergoing rituximab preemption. Of the 26 patients progressing to EBV-associated diseases during preemptive therapy, 20 obtained CR in the 23 cases with rituximab-based treatments. The preemptive efficacy of RI plus antiviral agents was correlated with the numbers of major risk factors (rs  = -0.298; P = 0.04). B-cell reconstitution was significantly delayed for at least 6 months in patients with rituximab preemption. The risk of herpesvirus infection was similar in patients who showed effective progress to first-step and rituximab preemption (P = 0.094). RI plus antiviral agents could be given priority to low-risk patients, whereas more frequent monitoring of blood EBV-DNA and earlier preemptive rituximab should be advocated in high-risk patients.

Effects of intensified conditioning on Epstein-Barr virus and cytomegalovirus infections in allogeneic hematopoietic stem cell transplantation for hematological malignancies

BACKGROUND

Intensified conditioning regimens (increasing the intensity of standard myeloablative conditioning) for hematological malignancies in allogeneic hematopoietic stem cell transplantation (allo-HSCT) could reduce the relapse rate of the underlying disease, but it might simultaneously increase the transplant-related mortality including the mortality of infections. To explore whether intensified conditioning affected Epstein-Barr virus (EBV) and cytomegalovirus (CMV) infections, 185 patients undergoing allo-HSCT were enrolled.

METHODS

A total of 104 cases received standard and 81 intensified conditioning. Cyclosporine A (CsA) withdrawal and/or donor lymphocyte infusion (DLI) were conducted in high-risk patients. The EBV-DNA and CMV-DNA levels of blood were monitored regularly by quantitative real-time polymerase chain reaction (RQ-PCR) and immune reconstitution of recipients were analyzed by flow cytometry.

RESULTS

The 3-year cumulative incidence of EBV viremia, EBV-associated diseases and mortality of EBV-associated diseases were 25.3% ± 4.6%, 10.5% ± 3.4% and 0.0% ± 0.0% in the standard group, compared with 45.6% ± 6.5%, 26.0% ±5.3% and 7.3% ± 3.1% in the intensified group (P = 0.002, P = 0.002, P = 0.008). The 3-year cumulative incidence of CMV viremia and CMV-associated diseases, mortality of CMV-associated diseases and incidence of bacterial and fungal infections were similar between the two groups (P = 0.855, P = 0.581, P = 0.933, P = 0.142, P = 0.182, respectively). Multivariate analysis showed that intensified conditioning was one of the risk factors for EBV viremia and EBV-associated diseases (P = 0.037, P = 0.037), but it had no effects on CMV infections. The percentage of CD4+ T cells and CD4+/CD8+ ratio at 3 months post-transplantation were lower in the intensified group (P = 0.032, P = 0.022). The 3-year OS and DFS in the standard group were 62.2% ± 5.8% and 60.6% ± 5.6%, compared with 51.6% ± 6.2% and 51.1% ± 5.9% in the intensified group (P = 0.029, P = 0.063).

CONCLUSIONS

Intensified conditioning represents a promising approach for high-risk hematological malignancies, although it affects early immune reconstitution of recipients and increases the incidence and mortality of EBV infections.

Temsirolimus, an mTOR inhibitor, in combination with lower-dose clofarabine as salvage therapy for older patients with acute myeloid leukaemia: results of a phase II GIMEMA study (AML-1107)

The mammalian target of rapamycin (mTOR) signalling pathway has emerged as an important therapeutic target for acute myeloid leukaemia (AML). This study assessed the combination of temsirolimus, an mTOR inhibitor, and lower-dose clofarabine as salvage therapy in older patients with AML. Induction consisted of clofarabine 20mg/m(2) on days 1-5 and temsirolimus 25mg (flat dose) on days 1, 8 and 15. Patients achieving complete remission with (CR) or without (CRi) full haematological recovery could receive monthly temsirolimus maintenance. In 53 evaluable patients, the overall remission rate (ORR) was 21% (8% CR, 13% CRi). Median disease-free survival was 3·5months, and median overall survival was 4months (9·1months for responders). The most common non-haematological severe adverse events included infection (48%), febrile neutropenia (34%) and transaminitis (11%). The 30-d all-cause induction mortality was 13%. Laboratory data from 25 patients demonstrated that a >50%in vivo inhibition of S6 ribosomal protein phosphorylation was highly correlated with response rate (75% with inhibition versus 0% without inhibition; P=0·0001), suggesting that targeting the mTOR pathway is clinically relevant. The acceptable safety profile and the predictive value of target inhibition encourage further investigation of this novel regimen.

High dose cytarabine plus gemtuzumab ozogamicin for patients with relapsed or refractory acute myeloid leukemia: Cancer and Leukemia Group B study 19902

Gemtuzumab ozogamicin (GO), an anti-CD33 immunoconjugate, was combined with high dose cytarabine (HiDAC; cytarabine 3g/m(2) over 3h daily for 5 days) for adults with relapsed or refractory AML. HiDAC plus GO 9mg/m(2) on day 7 and 4.5mg/m(2) on day 14 was not tolerated, but HiDAC followed by GO 9mg/m(2) on day 7 was safe: 12/37 (32%) patients with relapsed AML achieved complete remission. Median overall survival was 8.9 months. No grade 4 hepatic veno-occlusive disease was observed. This regimen merits further study, both in this setting and as a remission consolidation therapy.

Salvage chemotherapy with low-dose cytarabine and aclarubicin in combination with granulocyte colony-stimulating factor priming in patients with refractory or relapsed acute myeloid leukemia with translocation (8;21)

High expression levels of granulocyte colony stimulating factor (G-CSF) receptor were found in the leukemic cells of acute myeloid leukemia (AML) patients with t(8;21). Therapeutic significance of G-CSF receptor on chemotherapy remains to be defined. We evaluate the efficacy and tolerability of CAG regimen, consisting of concurrent use of G-CSF with low-dose cytarabine and aclarubicin, in 36 refractory/relapsed AML patients with t(8;21). The overall complete remission (CR) rate was 75% and median CR duration was 12 months. No significant treatment-related adverse events were observed. These data demonstrate that CAG regimen might be an alternative option in the treatment of AML with t(8;21), especially in older patients or patients with co-morbidities.

Sequential intensified conditioning and tapering of prophylactic immunosuppressants for graft-versus-host disease in allogeneic hematopoietic stem cell transplantation for refractory leukemia

For patients with advanced leukemia undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT), a major obstacle to success, especially in those with a high leukemia cell burden, is relapse of the underlying disease. To improve the outcome of allo-HSCT for refractory leukemia, we investigated the strategy of sequential intensified conditioning and early rapid tapering of prophylactic immunosuppressants therapy for graft-versus-host disease (GVHD) during the early stage after transplantation. A total of 51 patients with refractory leukemia (median age, 30.0 years; unfavorable karyotypes, 49%) received fludarabine (Flu) 30 mg/m(2)/day and cytarabine 2 g/m(2)/day (on days -10 to -6), 4.5 Gy total body irradiation (TBI)/day (on days -5 and -4), and cyclophosphamide (Cy) 60 mg/kg/day and etoposide 600 mg/day (on days -3 and -2) for conditioning. Cyclosporine A (CsA) was withdrawn rapidly in a stepwise fashion to avoid overwhelming GVHD reactions if acute GVHD (aGVHD) did not develop at day +30. All 51 patients developed regimen-related toxicities (13 with grade III-IV); 93.9% of them achieved complete remission by day +30. Median follow-up was 41 months (range, 6.6 to 92.2 months); 5-year overall survival (OS) and disease-free survival (DFS) were 44.6% +/- 8.1% and 38.2% +/- 7.7%, respectively. Thirteen patients relapsed; the 3-year cumulative incidence of leukemia relapse was 33.3%. On multivariate analysis, cytogenetic status was the only significant pretransplantation factor. Survival was better in patients with grade I or II aGVHD than in those without aGVHD. Our data indicate that the sequential strategy of cytoreductive chemotherapy followed immediately by intensified myeloablative (MA) conditioning for allo-HSCT and rapid tapering of prophylactic immunosuppressants for GVHD in the early stage after transplantation has an acceptable toxicity profile and may be a better approach to treating refractory leukemia.

Current and emerging therapies for acute myeloid leukemia

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The efficient generation of immunocompetent dendritic cells from leukemic blasts in acute myeloid leukemia: a local experience

Dendritic cells (DCs) are the most important antigen presenting cells with potentially useful applications in cancer immunotherapy. Leukemic cells of patients with acute myeloid leukemia (AML) could be differentiated to DC-like cells possessing the ability of stimulating anti-leukemic immune response. Despite obvious progress in DC-based immunotherapy, some discrepancies were reported in differentiation potential of AML blasts from all patients toward DC like cells. The present study, as a local experience, was set up to generate DCs from AML blasts of various subtypes. Leukemic Blasts from 16 Iranian AML patients were differentiated into functional DCs by culturing in the presence of rhGM-CSF, rhIL-4 and TNF-alpha for 8 days. The morphology, expression of key surface molecules and allostimulatory activity of resultant DCs were compared with primary blasts and cultured but cytokine untreated control groups. The pattern of angiotensin-converting enzyme (ACE) expression was used to approve the leukemic origin of generated DCs. Neo-expression or upregulation of DC-associated markers were occurred during culturing period in cytokine treated cells compared with primary blasts and cultured but cytokine untreated control groups: CD1a (63.22% vs. 3.22% and 11.79%), CD83 (41.27% vs. 0.11% and 0.70%), CD40 (15.17% vs. 0.00% and 0.04%), CD80 (49.96 vs. 0.02% and 0.32%), CD86 (56.49% vs. 0.50% and 5.71%) and HLA-DR (52.52% vs. 14.32% and 2.49%) respectively. The potency of generated DCs to induce allogeneic T cell proliferation increased significantly compared to pre and post culture control groups (27,533.4 +/- 2,548.3, 8,820.4 +/- 1,639.4 and 3,200.35 +/- 976 respectively). The expression pattern of ACE in AML-DCs, blast cells and DCs derived from normal monocytes (7.93%, 1.28% and 74.97% respectively) confirmed the leukemic origin of DCs. Our data confirmed the generation of sufficient AML-derived cells with the properties of DCs in all cases. This potency of AML blasts, offers a useful route for active immunotherapy of AML patients.