Acute Myelogenous Leukemia Therapy Research Articles

Double Loading of Dendritic Cell MHC Class I and MHC Class II with an AML Antigen Repertoire Enhances Primary and Secondary T-Cell Responses In Vitro.

Despite improvements in therapy for acute myelogenous leukemia (AML), a significant percentage of patients still relapse and succumb to their disease. Dendritic cell immunotherapy offers the promise of potentially effective supportive therapy for a variety of neoplastic conditions; and the use of DCs loaded with tumor antigens is now recognized as an important investigational therapy. Though a variety of methods have been used to load DC vaccines, the loading of the MHC class II compartment with tumor lysate has predominated. The priming of a class II-mediated (CD4) T-cell response may be crucial to the success of DC immunotherapy as such a response is likely required for the development of memory CD8+ T-cells. DC cross-presentation is credited with the ability of lysate-loaded DCs to prime both CD4 and CD8 T-cell responses, enabling the generation of CD8+ CTLs without the loading of the MHC class I compartment (i.e. the cytoplasm). Recently, however, several reports have raised doubts as to the efficiency of cross-presentation as a mechanism for CTL priming in vivo. To examine this issue, we have loaded human DCs with both AML tumor lysate and mRNA. This technique allows the full repertoire of class I antigens to be presented without dependence upon cross-presentation; and, moreover, provides a full complement of class II antigens necessary for CD4 T-cell priming and the generation of memory responses.Methods: CD14+ precursors were isolated from normal donor PBPCs by magnetic separation. Immature DCs were then generated by culturing precursors for six days in GM-CSF and IL-4. Lysate was produced by three successive freeze/thaw cycles of blasts. mRNA was extracted from blasts using Trizol and oligo-dT separation. Immature DCs were pulsed for three hours with AML lysate and subsequently electroporated with AML mRNA. Loaded DCs were matured for 48 hours with IL-1β, TNF-α, IL-6, and PGE2 and then used to prime autologous T-cells. Short-term responses were assayed on day 5 of the 1st stimulation. Memory responses were assayed on day 10 of a tertiary stimulation.Results: Doubly-loaded DCs can prime a superior T-cell response in vitro in comparison to that of singly-loaded DCs, demonstrating a 30–70% increase in IFN-γ ELISpots over lysate-loaded DCs (p<0.001) and a 3–4 fold increase in ELISpots in comparison to mRNA loaded DCs (p<0.001). These results were verified by flow cytometry which showed 35% of CD8+ T-cells primed by doubly-loaded DCs were CD69+/IFN-γ+ vs. 14% of CD8+ T-cells primed by lysate-loaded DCs (p<0.001). This enhancement may be based upon both an upregulation of CD83 surface expression (p<0.0019) of doubly-loaded DCs and/or the upregulation of B7.1/B7.2 that accompanies elevated CD40L signaling. Memory responses were also greatly improved, with a 126% increase in total ELISpots (double loaded DCs versus lysate loaded DCs; p<0.03) and a 187% increase in total IFN-γ secretion (p<0.03). Unloaded (p<0.01) and mRNA (p<0.007) loaded DCs exhibited a virtual inability to generate memory T-cells in vitro, suggesting that the perpetuation of the memory response is reliant upon T-cell help.Conclusion: DCs doubly-loaded with lysate and mRNA are more efficient in the generation of primary and secondary immune responses than are singly-loaded DCs. The clinical administration of such doubly-loaded DCs may offer an important therapeutic option to patients with AML.

Impact of Granulocyte Colony-Stimulating Factor during Induction Therapy in Children with Acute Myelogenous Leukemia: Results from the Prospective and Randomized Trial AML-BFM 98.

Background: Treatment for acute myelogenous leukemia (AML) is one of the most intensive treatment modalities in pediatric oncology. Infection-related mortality is particularly high among these patients during chemotherapy-induced neutropenia. Granulocyte colony-stimulating factor (G-CSF) expands the circulating pool of neutrophils by stimulating proliferation and maturation of myeloid progenitor cells. Although G-CSF is widely used for the prevention of infectious complications in cancer patients, no larger randomized study has evaluated the effect of G-CSF in pediatric cancer patients undergoing treatment for AML.Patients and Methods: The impact of G-CSF on hematopoetic recovery, infectious complications and five-year event-free survival (5-EFS) was prospectively evaluated in the multicenter clinical trial AML-BFM 98. Patients (inclusion criteria: primary diagnosis of AML, age 0–18 years) were randomized to receive or not to receive G-CSF (5 μg/kg/day) after induction 1 (cytarabine, idarubicin, etoposide; AIE) and induction 2 (high-dose cytarabine and mitoxantrone; HAM). Patients who had more than 5% blasts in the bone marrow on day 15 were excluded from randomization. Patients with Down Syndrome were included in the clinical trial, but received only 60% of idarubicin in induction 1 and no second induction (HAM).Results: Between July 1998 and June 2003, 546 patients entered the clinical trial AML-BFM 98 (Down Syndome: n=45). Three-hundred-and-twenty-seven patients were eligible for randomization. Hundred-fifty eight of these patients were randomized to receive G-CSF, and 169 patients not to receive G-CSF. Both groups did not differ in their clinical characteristics. The G-CSF group had a significantly shorter duration of neutropenia (ANC<500/μl) both after induction 1 (16.3 vs 20.0 days, P=.019) and after induction 2 (12.4 vs 16.3 days, P=.0024). The time of thrombocytopenia (<20,000/μl) was similar in both groups (9.3, 9.4, 5.5, and 6.3 days, respectively). No impact of G-CSF was found on the incidence of grade II infections (fever without an identified pathogen) and grade III/IV infections (fever due to an identified pathogen/sepsis syndrome). Five-year event-free survival (5-EFS) did not significantly differ between the groups with and without G-CSF (65.6% + 3.9% vs 65.7% + 3.8%, P-logrank=.86). No significant difference was found when comparing the results of children randomized for G-CSF (intended-to treat) and of children who actually received the hematopoietic growth factor. Children with Down Syndrome showed also similar 5-EFS with and without G-CSF (P-logrank=.72).Conclusion: G-CSF significantly shortens the duration of neutropenia in children undergoing induction therapy for AML, but does not influence the incidence of infectious complications nor outcome (5-EFS probability). Whether there is a subgroup of children with AML who benefit from the administration of the hematopoetic growth factor has to be evaluated.

Suppression of leukemia expressing wild-type or ITD-mutant FLT3 receptor by a fully human anti-FLT3 neutralizing antibody

AbstractFMS-like tyrosine kinase 3 (FLT3), a class III receptor tyrosine kinase, is expressed at high levels in the blasts of approximately 90% of patients with acute myelogenous leukemia (AML). Internal tandem duplications (ITDs) in the juxtamembrane domain and point mutations in the kinase domain of FLT3 are found in approximately 37% of AML patients and are associated with a poor prognosis. We report here the development and characterization of a fully human anti-FLT3 neutralizing antibody (IMC-EB10) isolated from a human Fab phage display library. IMCEB10 (immunoglobulin G1 [IgG1], κ) binds with high affinity (KD = 158 pM) to soluble FLT3 in enzyme-linked immunosorbent assay (ELISA) and to FLT3 receptor expressed on the surfaces of human leukemia cell lines. IMC-EB10 blocks the binding of FLT3 ligand (FL) to soluble FLT3 in ELISA and competes with FL for binding to cell-surface FLT3 receptor. IMC-EB10 treatment inhibits FL-induced phosphorylation of FLT3 in EOL-1 and EM3 leukemia cells and FL-independent constitutive activation of ITD-mutant FLT3 in BaF3-ITD and MV4;11 cells. Activation of the downstream signaling proteins mitogen-activated protein kinase (MAPK) and AKT is also inhibited in these cell lines by antibody treatment. The antibody inhibits FL-stimulated proliferation of EOL-1 cells and ligand-independent proliferation of BaF3-ITD cells. In both EOL-1 xenograft and BaF3-ITD leukemia models, treatment with IMC-EB10 significantly prolongs the survival of leukemia-bearing mice. No overt toxicity is observed with IMC-EB10 treatment. Taken together, these data demonstrate that IMC-EB10 is a specific and potent inhibitor of wild-type and ITD-mutant FLT3 and that it deserves further study for targeted therapy of human AML. (Blood. 2004;104:1137-1144)

A phase II study of timed sequential therapy of acute myelogenous leukemia (AML) for patients over the age of 60: two cycle timed sequential therapy with topotecan, ara-C and mitoxantrone in adults with poor-risk AML

Acute myeloid leukemia (AML) in the elderly is a serious problem characterized by poor response to therapy and short survival. To improve response to therapy, a timed sequential therapy (TST) approach was designed utilizing topotecan, cytosine arabinoside (ara-C) and mitoxantrone based on multiple studies suggesting that topotecan and mitoxantrone are effective in older patients. Thirty-two adults, ≥60-year-old (median age 69) were included. None had favorable cytogenetics and 44% had and antecedent myelodysplastic syndrome (MDS) or 2° AML. Fifty-nine percent achieved a complete response (CR). Median overall survival (OS) was 6.5 months (95% confidence interval (CI): 3.1–12.0 months; range, 15 days to 25.3 months). Disease-free survival (DFS) for the 19 patients achieving a CR was 7.7 months (95% CI: 6.1–13.7 months; range, 2.9–25.3 months). There were no differences in OS or DFS between cytogenetic or disease etiology groups. Although TST was well tolerated, long-term results in this group of patients are not satisfactory and new approaches are needed.

An in vitro study on the mechanisms of coagulation activation in acute myelogenous leukemia (AML): role of tissue factor regulation by cytotoxic drugs and GM-CSF

AML patients may suffer from a disseminated coagulopathy, which can aggravate a pre-existing bleeding tendency due to thrombocytopenia and platelet dysfunction. The cellular and molecular mechanisms underlying this coagulopathy, however, are not completely understood. Indeed, the broad and increasing therapeutic use of cytotoxic drugs and growth factors is likely to contribute to the complexity of hemostatic abnormalities encountered in this hematologic malignancy. The nature of coagulation activation in AML was therefore investigated in vitro using the human leukemic cell line, HL60. Tissue factor (TF) was almost entirely located on the cell surface and bound factor VIIa, but only 15-25% of this TF was primarily functionally active. Treatment with increasing concentrations of daunorubicin or cytosine-beta-D-arabinofuranoside, two cytotoxic drugs commonly used in AML therapy, induced apoptosis and secondary necrosis of HL60 cells and resulted in marked decryption of TF PCA independent of de novo protein synthesis. This PCA-modulating effect was concomitant with and functionally dependent on the exposure of phosphatidylserine on the outer membrane leaflet. Similar observations were made in analogous ex vivo studies on patient-derived myeloblasts. Incubation of HL60 cells with GM-CSF, a cytokine expressed in the bone marrow microenvironment and used as an adjunct to AML treatment, evoked a cellular response, which included both enhanced TF production and release of VEGF-A and uPA into the culture medium. We conclude that both decryption of pre-formed TF PCA by chemotherapeutic drugs and de novo induction of TF by cytokines such as GM-CSF can regulate the pro-coagulant phenotype of HL60 cells in vitro.

Mylotarg, fludarabine, cytarabine (ara-C), and cyclosporine (MFAC) regimen as post-remission therapy in acute myelogenous leukemia.

Mylotarg, a humanized anti-CD33 antibody linked to an antitumor antibiotic, is approved for the treatment of patients with relapsed acute myeloid leukemia (AML). Its role as a component of post-remission therapy in AML has not been established. The Mylotarg, fludarabine, cytarabine, and cyclosporine (MFAC) regimen was evaluated in patients in complete remission following Mylotarg-containing regimens. The MFAC regimen comprised: Mylotarg 4.5 mg/m2 intravenously (i.v.) over 2 h after a loading dose of cyclosporine A (CSA) on day 1; fludarabine 15 mg/m2 i.v. over 30 min every 12 h for six doses on days 2 through 4; ara-C 0.5 g/m2 over 2 h every 12 h for six doses on days 2 through 4, 4 h after fludarabine started; CSA 6 mg/kg over 2 h, followed by 16 mg/kg continuous i.v. infusion on days 1 and 2. Patients in complete remission (CR) commenced idarubicin and ara-C (IA) alternating with MFAC or vice versa for 9 months from the date of CR. Idarubicin was administered at 8 mg/m2 on days 1 and 2 and ara-C at 1.5 g/m2 on days 1 and 2. A total of 22 patients received 76 courses of MFAC (35 courses) alternating with IA (41 courses) or vice versa. The interval between courses, and degrees of myelosuppression, were equivalent in the alternating regimens. Failure-free and 12-month survival rates of were 32% and 55%, respectively. Grade 3/4 toxicities, including sepsis, neutropenic fever, and nausea/vomiting, were equivalent with MFAC and IA. Post-remission therapy with MFAC is feasible and well tolerated in patients with AML.

Systemic Candidiasis

HomeRadioGraphicsVol. 23, No. 5 PreviousNext AFIP ARCHIVESSystemic CandidiasisNicholas J. E. Moore, Johnsey L. Leef, III, Yijun PangNicholas J. E. Moore, Johnsey L. Leef, III, Yijun PangAuthor Affiliations1From the Departments of Radiology and Pathology, University of Vermont School of Medicine, 111 Colchester Ave, Burlington, VT 05401. Received November 13, 2002; revision requested January 15, 2003 and received February 28; accepted March 5. Address correspondence to N.J.E.M. (e-mail: [email protected]).Nicholas J. E. MooreJohnsey L. Leef, IIIYijun PangPublished Online:Sep 1 2003https://doi.org/10.1148/rg.235025162MoreSectionsFull textPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked In References 1 Lee GR, Foerster J, Lukens J, et al. eds. Wintrobe’s clinical hematology 10th ed. Baltimore, Md: Williams & Wilkins, 1999. Google Scholar2 Anttila VJ, Elonen E, Nordling S, Sivonen A, Ruutu T, Ruutu P. Hepatosplenic candidiasis in patients with acute leukemia: incidence and prognostic implications. Clin Infect Dis 1997; 24:375-380. Crossref, Medline, Google Scholar3 Rossetti F, Brawner DL, Bowden R, et al. Fungal liver infection in marrow transplant recipients: prevalence at autopsy, predisposing factors, and clinical features. Clin Infect Dis 1995; 20:801-811. Crossref, Medline, Google Scholar4 van Burik JH, Leisenring W, Myerson D, et al. The effect of prophylactic fluconazole on the clinical spectrum of fungal diseases in bone marrow transplant recipients with special attention to hepatic candidiasis: an autopsy study of 355 patients. Medicine (Baltimore) 1998; 77:246-254. Crossref, Medline, Google Scholar5 Schwartz RS, Mackintosh FR, Schrier SL, et al. Multivariate analysis of factors associated with invasive fungal disease during remission induction therapy for acute myelogenous leukemia. Cancer 1984; 53:411-419. Crossref, Medline, Google Scholar6 Kontoyiannis DP, Luna MA, Samuels BI, Bodey GP. Hepatosplenic candidiasis: a manifestation of chronic disseminated candidiasis. Infect Dis Clin North Am 2000; 14:721-739. Crossref, Medline, Google Scholar7 Sallah S, Semelka RC, Wehbie R, Sallah W, Nguyen NP, Vos P. Hepatosplenic candidiasis in patients with acute leukaemia. Br J Haematol 1999; 106:697-701. Crossref, Medline, Google Scholar8 Lamminen AE, Anttila VJ, Bondestam S, Ruutu T, Ruutu PJ. Infectious liver foci in leukemia: comparison of short-inversion-time inversion-recovery, T1-weighted spin-echo, and dynamic gadolinium-enhanced MR imaging. Radiology 1994; 191:539-543. Link, Google Scholar9 Semelka RC, Kelekis NL, Sallah S, Worawattanakul S, Ascher SM. Hepatosplenic fungal disease: diagnostic accuracy and spectrum of appearances on MR imaging. AJR Am J Roentgenol 1997; 169:1311-1316. Crossref, Medline, Google Scholar10 Sallah S, Semelka R, Kelekis N, Worawattanakul S, Sallah W. Diagnosis and monitoring response to treatment of hepatosplenic candidiasis in patients with acute leukemia using magnetic resonance imaging. Acta Haematol 1998; 100:77-81. Crossref, Medline, Google ScholarArticle HistoryPublished in print: Sept 2003 FiguresReferencesRelatedDetailsCited ByCurrent Problems in Diagnostic Radiology, Vol. 51, No. 1Abdominal Radiology, Vol. 46, No. 6Journal of the American Academy of Dermatology, Vol. 80, No. 4Seminars in Roentgenology, Vol. 52, No. 2Multimodality Imaging of Liver Infections: Differential Diagnosis and Potential PitfallsPablo Bächler, María José Baladron, Christine Menias, Ignacio Beddings, Ron Loch, Eugenio Zalaquett, Matías Vargas, Sarah Connolly, Sanjeev Bhalla, Álvaro Huete, 27 May 2016 | RadioGraphics, Vol. 36, No. 4Current Radiology Reports, Vol. 4, No. 1Clinical Imaging, Vol. 40, No. 4Seminars in Roentgenology, Vol. 50, No. 4Ultrasound Quarterly, Vol. 24, No. 4Radiología, Vol. 49, No. 6Fungal Liver Infection in Immunocompromised Patients: Depiction with Multiphasic Contrast-enhanced Helical CT1Ur Metser, , Masoom A. Haider, , Marcus Dill-Macky, , Mostafa Atri, , Gina Lockwood, , and Mark Minden, 1 April 2005 | Radiology, Vol. 235, No. 1Recommended Articles RSNA Education Exhibits RSNA Case Collection Vol. 23, No. 5 Metrics Downloaded 8,670 times Altmetric Score PDF download

Bone marrow purging studies in acute myelogenous leukemia using the recombinant anti-CD33 immunotoxin HuM195/rGel

This study was designed to determine the effect of immunotoxin HuM195/rGel on normal human bone marrow before clinical purging. HuM195/rGel is composed of the recombinant plant toxin gelonin (rGel) chemically coupled to the anti-CD33 human chimeric antibody HuM195. The CD33 antigen is of significant interest as a target for therapy of acute myelogenous leukemia because it is present in leukemic blasts of most patients but absent in the earliest progenitor bone marrow cells. HuM195/rGel was optimally cytotoxic to acute myelogenous leukemia HL60 cells with 24 hours of exposure. We developed an in vivo purging model by mixing mobilized peripheral blood progenitor cells with HL60 cells to simulate a remission in bone marrow. Cells were treated with 10 nmol/L of HuM195/rGel either with or without exposure to freeze/thaw procedure, which has been reported to act synergistically with HuM195/rGel to produce cytotoxic effect. When clonogenic cell recovery rates were determined, HuM195/rGel alone did not affect normal peripheral blood progenitor cells, whereas HuM195/rGel plus freeze/thaw provided 2 logs of tumor cell elimination in our purging model. We also observed similar results under conditions used in the transplantation setting. We concluded that for acute myelogenous leukemia blasts expressing CD33, HuM195/rGel could be useful as a purging reagent for autologous transplantation.

High-Dose Cytarabine for Consolidation and Relapse Therapy in Acute Myelogenous Leukemia

The increasing complexity of cancer chemotherapy makes it mandatory that pharmacists be familiar with these highly toxic agents. This column focuses on the commercially available and investigational agents used to treat malignant diseases, reviewing issues related to the preparation, dispensing, and administration of cancer chemotherapy.

Preferential induction of apoptosis for primary human leukemic stem cells.

Acute myelogenous leukemia (AML) is typically a disease of stem progenitor cell origin. Interestingly, the leukemic stem cell (LSC) shares many characteristics with normal hematopoietic stem cells (HSCs) including the ability to self-renew and a predominantly G(0) cell-cycle status. Thus, although conventional chemotherapy regimens often ablate actively cycling leukemic blast cells, the primitive LSC population is likely to be drug-resistant. Moreover, given the quiescent nature of LSCs, current drugs may not effectively distinguish between malignant stem cells and normal HSCs. Nonetheless, based on recent studies of LSC molecular biology, we hypothesized that certain unique properties of leukemic cells could be exploited to induce apoptosis in the LSC population while sparing normal stem cells. In this report we describe a strategy using treatment of primary AML cells with the proteasome inhibitor carbobenzoxyl-l-leucyl-l-leucyl-l-leucinal (MG-132) and the anthracycline idarubicin. Comparison of normal and leukemic specimens using in vitro culture and in vivo xenotransplantation assays shows that the combination of these two agents induces rapid and extensive apoptosis of the LSC population while leaving normal HSCs viable. Molecular genetic studies using a dominant-negative allele of inhibitor of nuclear factor kappaB (IkappaBalpha) demonstrate that inhibition of nuclear factor kappaB (NF-kappaB) contributes to apoptosis induction. In addition, gene-expression analyses suggest that activation of p53-regulated genes are also involved in LSC apoptosis. Collectively, these findings demonstrate that malignant stem cells can be preferentially targeted for ablation. Further, the data begin to elucidate the molecular mechanisms that underlie LSC-specific apoptosis and suggest new directions for AML therapy.

Timed sequential therapy of acute myelogenous leukemia in adults: a phase II study of retinoids in combination with the sequential administration of cytosine arabinoside, idarubicin and etoposide

Clinical outcome in acute myeloid leukemia (AML) is unsatisfactory. One strategy to augment cytotoxicity is TST. All- trans retinoic acid (ATRA) down-regulates bcl-2 expression and heightens AML sensitivity to cytosine arabinoside (ara-C)-induced apoptosis in vitro. We designed a trial of ATRA plus ara-C-based TST in an attempt to enhance drug-induced apoptosis and clinical outcome. Between January 1998 and February 2000, 63 patients received induction TST (oral ATRA days 1–6, ara-C and idarubicin days 2–4, VP-16 days 9–11) followed by consolidation TST (ATRA, ara-C and idarubicin followed by a second ara-C infusion days 11–13). Complete remission (CR) was 60%, with higher rates for patients of <60 years (79%), de novo AML (70%), and non-adverse cytogenetics (81%). Median disease-free survival (DFS) for CR patients was 11.2 months (32% at 3+ years). For patients <60 years with de novo AML and non-adverse cytogenetics who underwent two-cycle TST, DFS was 67% at 3+ years. However, patients of age equal to 60 years and those with poor-risk disease features still have poor CR and DFS, despite the addition of ATRA.

Prolonged administration of all-trans retinoic acid in combination with intensive chemotherapy and G-CSF for adult acute myelogenous leukemia: single-centre pilot study in different risk groups

An exploratory trial was conducted to evaluate toxicity and potential therapeutic role of all trans-retinoic acid (ATRA) given long-term together with chemotherapy and G-CSF to adult patients with acute myelogenous leukemia (AML). ATRA was administered orally at 45 mg/m(2)/day on days 1-14 and 25 mg/m(2)/day on days 15-28 of two standard cycles (idarubicin, etoposide, cytarabine, G-CSF) and of up to three high-dose courses (cytarabine, G-CSF). The results obtained in 19 patients enrolled in the ATRA trial were compared with those from 29 comparable cases treated with the same schedule without ATRA, according to patient risk class and an in vitro study. ATRA was administered for a median of 52 days to the patients selected for study who achieved a remission. ATRA-related toxicity was mostly non-severe apart from high incidence of headache in conjunction with high-dose cytarabine. Complete remission (CR) rate after cycle 1 (54%), kinetics of hematological recovery, postremission treatment realization, disease-free survival (DFS 37.5% at three years) and overall survival (30% at three years) were not different between ATRA-treated and untreated patients. The only significant prognostic factor was the patient risk class, as defined by cytogenetics and other clinical criteria: DFS rate was 57% at three years in standard-risk cases compared to only 19% in the high-risk group, with no influx by ATRA in either category. The in vitro study, in patients with a definite clinical response, failed to document any inhibitory or pro-apoptotic effect of ATRA on AML blast cells. As a consequence to these results, the pilot ATRA phase was closed. This study does not suggest a significant role for the present ATRA schedule as an adjunct to standard antileukemic therapy in adult AML.

The diphtheria toxin/urokinase fusion protein (DTAT) is selectively toxic to CD87 expressing leukemic cells

Diphtheria fusion proteins are a novel class of agents for the treatment of chemotherapy resistant acute myelogenous leukemia (AML). We prepared diphtheria toxin/urokinase fusion protein (DTAT) composed of the amino terminal fragment of the urokinase-type plasminogen activator (uPA) fused to the catalytic and translocation domains of diphtheria toxin (DT) and assessed its activity on leukemic cell lines. The number of uPA receptors (uPAR or CD87) was measured using a phycoerythrin conjugated monoclonal antibody to CD87 and flow cytometry. Seven of 23 cell lines (30%) showed CD87 expression (≥5000 receptors/cell). DTAT cytotoxicity (IC 50≤30 pM) was observed in all seven of these samples and none of the 16 samples with low or absent CD87 expression. There was a significant correlation between DTAT sensitivity and CD87 density ( P=0.0007). These results show that specific CD87 binding is one factor important in the sensitivity of patient’s leukemic blasts to DTAT and demonstrate for the first time that the CD87/uPAR can be used as a target for fusion protein therapy of AML.

Unique molecular and cellular features of acute myelogenous leukemia stem cells.

It is well known in the field of acute myelogenous leukemia (AML) that many different translocations and genetic aberrancies are found with the various forms of the disease. Indeed, specific translocations are often associated with disease subtypes that manifest themselves through the accumulation of immature myeloid cells at varying stages of differentiation. Moreover, the differentiation state of myeloid blast populations has been utilized as a means of categorizing different AML subtypes (French, American, British, or FAB classification system). Thus, the notion that AML is a family of related but distinct diseases is a common view. Interestingly, however, studies in recent years that have formalized the concept of a leukemic stem cell (LSC) have also begun to define shared developmental, cellular and molecular features amongst the malignant stem cells that give rise to different AML subtypes. Moreover, some of these conserved features appear to be unique to the leukemia stem/progenitor cell population, and are not found in normal hematopoietic stem cells (HSCs). This article will summarize data emerging from the study of LSCs and suggest how distinct molecular and cellular characteristics of the LSC population may provide new opportunities for AML therapy.

Long-term bone marrow culture-derived stromal fibroblasts as a potential target for gene therapy in acute myelogenous leukemia

As a part of our continuing efforts to develop gene therapy for acute myelogenous leukemia (AML), this study was undertaken to evaluate the possibility of using autologous bone marrow stromal fibroblasts (BMSFs) as a target cell population. Autologous BMSFs in AML were isolated from the stromal layers of long-term bone marrow culture (LTBMC) using immunomagnetic beads. BMSFs exhibited rapid proliferation even in the absence of growth factors. Cultures stimulated with bFGF produced significantly increased numbers of BMSFs than cultures without added growth factors. Using LNC/LacZ retroviral vector, the transduction efficiecy of BMSFs was 13±4% at a 5 multiplicity of infection (MOI). LNC/interleukin-2 (IL-2)-transduced BMSFs produced between 1200 and 4800 pg of IL-2/10 6 cells per 24 h. Using adenoviral vector AdV/LacZ, the transduction efficiency was 84±10% at 100, and 92±8% at a MOI of 1000. Although the addition of basic fibroblast growth factor, epidermal growth factor, or platelet-derived growth factor did not affect the transduction efficiency, they increased the numbers of transduced cells significantly ( P<0.01). AdV/IL-2-treated BMSFs produced high levels of IL-2 over the course of 7 days between 9820 and 22,700 pg of IL-2/10 6 cells per 24 h. Our finding that the genetically engineered autologous BMSFs of AML could be successfully established in vitro implies that BMSFs obtained from LTBMC might be considered as a target cell population for certain types of clinical gene therapy in AML.

Segmental Coecal Cytomegalovirus Colitis During Fludarabine, Cytarabine and Mitoxantrone Induction Chemotherapy for Myelodysplastic Syndrome

We report the case of a 59-year-old woman treated for a refractory anemia with excess blasts (RAEB) who developed cytomegalovirus (CMV) colitis during induction therapy combining fludarabine, cytarabine and mitoxantrone. CMV infection occurred rarely during cytarabine and anthracyclin based induction therapy for acute myelogenous leukemia or RAEB. CMV infection is usually observed in immunocompromised patients but some cases have been recently observed in patients after autologous stem-cell transplantation with or without CD34+ stem-cell selection. We discuss this case and issues arising from it in relation to the use of combination of high-dose cytarabine and fludarabine.

Therapeutic options for acute myelogenous leukemia.

General therapeutic options for patients with acute myelogenous leukemia (AML) are reviewed and specific new therapies are described. Data in this review came from the published literature and the M. D. Anderson Cancer Center's acute leukemia database. Outcome following standard therapy of AML is so variable that is best to speak of a range of outcomes determined by various prognostic factors. Therapy can (and usually does) fail because of treatment-induced mortality or (more usually) resistance to therapy. Performance status and age are the principal predictors of early death, whereas cytogenetics, a history of abnormal blood counts, and MDR1 expression are predictors of resistance. Using this information, physicians can categorize patients into those in whom 1) standard therapy is indicated, 2) either standard or investigational therapy is appropriate, and 3) investigational therapy is indicated. The majority of even newly diagnosed patients belong to Group 3. The availability of allogeneic or autologous transplantation does not alter this conclusion. Investigational therapies have been developed that are directed against the CD33 surface antigen, the multidrug-resistant MDR1 protein, and other targets. Because of the number of new therapies clinical research in AML should emphasize pilot trials rather than traditionally large Phase III studies. Most patients with newly diagnosed AML should be offered investigational regimens.

Antibody therapy of acute myelogenous leukemia.

Monoclonal antibodies (mAbs) have become an important modality for cancer therapy. A genetically engineered, humanized anti-CD33 antibody HuM195 has demonstrated activity against over relapsed acute myelogenous leukemia (AML) and against minimal residual disease in acute promyelocytic leukemia (APL). Radioimmunotherapy with beta (beta) particle-emitting isotopes has produced significant responses while minimizing radiation exposure to normal tissues in both nonmyeloablative and myeloablative regimens. Targeted alpha (alpha) particle therapy with 213Bi-labeled HuM195 offers the possibility of more selective tumor cell kill. Additionally, directed chemotherapy using an anti-CD33-calicheamicin conjugate (CMA-676) has produced remissions in patients with relapsed AML.

Bleeding risk and platelet transfusion refractoriness in patients with acute myelogenous leukemia who undergo autologous stem cell transplantation.

Therapy for acute myelogenous leukemia can be complicated by alloimmunization to histocompatibility antigens (HLA), with resultant refractoriness to platelet transfusions. Autologous peripheral blood or bone marrow stem cell transplantation (referred here collectively as 'autoBMT') is emerging as a standard consolidative strategy in acute myelogenous leukemia (AML). We had noted life-threatening bleeding associated with platelet transfusion refractoriness following autoBMT; we therefore retrospectively analyzed 39 AML patients for this complication following BMT. All patients received high-dose chemoradiotherapy, followed by infusion of allogeneic sibling donor (n = 12, alloBMT) or autologous (n = 27, autoBMT) stem cells. HLA alloimmunization was assessed if patients were suspected of immune refractoriness to random donor platelet transfusions. Within 100 days of stem cell infusion, one of three alloBMT and six of 12 autoBMT recipients tested were HLA alloimmunized (not statistically significant, NS). Five of six HLA alloimmunized autoBMT patients experienced delayed bleeding, which contributed to their demise while still in remission (P < 0.001). Increased platelet requirements in HLA alloimmunized autoBMT recipients were observed between days 61 and 100 post-BMT, at a median of 211 platelet transfusions vs 0 in non-alloimmunized autoBMT patients (P < 0.01) and 17 in alloBMT patients. Our data suggest that platelet transfusion refractoriness, when associated with HLA alloimmunization, is a risk factor for increased platelet transfusion requirements, delayed bleeding, and poor outcome following autoBMT for AML.

Differentiation therapy in acute myelogenous leukemia (non-APL).

Successful treatment of acute promyelocytic leukemia (APL) has identified several novel approaches to induce leukemic cell differentiation and selective apoptosis by overcoming the site-specific transcriptional repression by dominant fusion leukemogenic proteins characteristic of APL and other forms of acute myelogenous leukemia (AML). These therapeutic approaches include the use of site-specific ligands, receptors and cytokines, disruption of dominant fusion leukemogenic proteins, chromatin remodeling and combining the above with cytotoxic chemotherapy. With the exception of cytotoxic chemotherapy, the above therapeutic strategies do not significantly affect normal hematopoiesis and their combinations have been shown to be synergistic in inducing myeloid differentiation and apoptosis in several AML cell lines and in patients with APL. These approaches are, in general, non-cross resistant and should be well tolerated particularly in elderly patients with AML. Clinical studies which include biologic end points for differentiation induction, histone acetylation and selective apoptosis are presently in development to evaluate these strategies in the treatment of AML.