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Mahfouz RZ, Jankowska A, Ebrahem Q, Gu X, Visconte V, Tabarroki A, Terse P, Covey J, Chan K, Ling Y, Engelke KJ, Sekeres MA, Tiu R, Maciejewski J, Radivoyevitch T, Saunthararajah Y. Increased CDA expression/activity in males contributes to decreased cytidine analog half-life and likely contributes to worse outcomes with 5-azacytidine or decitabine therapy. Clin Cancer Res 2013; 19:938-48. [PMID: 23287564 PMCID: PMC3577958 DOI: 10.1158/1078-0432.ccr-12-1722] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
PURPOSE The cytidine analogs 5-azacytidine and decitabine, used to treat myelodysplastic syndromes (MDS), produce a molecular epigenetic effect, depletion of DNA-methyltransferase 1 (DNMT1). This action is S-phase dependent. Hence, genetic factors that decrease the half-lives of these drugs could impact efficacy. Documentation of such impact, and elucidation of underlying mechanisms, could lead to improved clinical application. EXPERIMENTAL DESIGN Cytidine deaminase (CDA) rapidly inactivates 5-azacytidine/decitabine. The effect of CDA SNP A79C and gender on CDA expression, enzyme activity, and drug pharmacokinetics/pharmacodynamics was examined in mice and humans, and the impact on overall survival (OS) was evaluated in 5-azacytidine/decitabine-treated patients with MDS (n = 90) and cytarabine-treated patients with acute myeloid leukemia (AML) (n = 76). RESULTS By high-performance liquid chromatography (HPLC), plasma CDA activity was decreased as expected in individuals with the SNP A79C. Interestingly and significantly, there was an even larger decrease in females than in males. Explaining this decrease, liver CDA expression was significantly lower in female versus male mice. As expected, decitabine plasma levels, measured by mass spectrometry, were significantly higher in females. In mathematical modeling, the detrimental impact of shorter drug half-life (e.g., in males) was greater in low compared with high S-phase fraction disease (e.g., MDS vs. AML), because in high S-phase fraction disease, even a short exposure treats a major portion of cells. Accordingly, in multivariate analysis, OS was significantly worse in male versus female patients with MDS treated with 5-azacytidine/decitabine. CONCLUSIONS Increased CDA expression/activity in males contributes to decreased cytidine analog half-life and likely contributes to worse outcomes with 5-azacytidine or decitabine therapy.
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Affiliation(s)
- Reda Z Mahfouz
- Department of Translational Hematology & Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio
| | - Ania Jankowska
- Department of Translational Hematology & Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio
| | - Quteba Ebrahem
- Department of Translational Hematology & Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio
| | - Xiaorong Gu
- NCTT, Division of Pre-Clinical Innovations, National Center for Advancing Translational Sciences, NIH, Bethesda, Maryland
| | - Valeria Visconte
- Department of Translational Hematology & Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio
| | - Ali Tabarroki
- Department of Translational Hematology & Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio
| | - Pramod Terse
- NCTT, Division of Pre-Clinical Innovations, National Center for Advancing Translational Sciences, NIH, Bethesda, Maryland
| | - Joseph Covey
- Toxicology and Pharmacology Branch, Developmental Therapeutics Program, Division of Cancer Treatment and diagnosis, NCI, NIH, Bethesda, Maryland
| | - Kenneth Chan
- College of Pharmacy, The Ohio State University, Columbus, Ohio
| | - Yonghua Ling
- College of Pharmacy, The Ohio State University, Columbus, Ohio
| | | | - Mikkael A. Sekeres
- Department of Hematologic Oncology and Blood Disorders, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio
| | - Ramon Tiu
- Department of Translational Hematology & Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio
- Department of Hematologic Oncology and Blood Disorders, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio
| | - Jaroslaw Maciejewski
- Department of Translational Hematology & Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio
- Department of Hematologic Oncology and Blood Disorders, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio
| | - Tomas Radivoyevitch
- Department of Epidemiology and Biostatistics, Case Western Reserve University, Cleveland, Ohio
| | - Yogen Saunthararajah
- Department of Translational Hematology & Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio
- Department of Hematologic Oncology and Blood Disorders, Taussig Cancer Institute, Cleveland Clinic, Cleveland, Ohio
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Saunthararajah Y, Triozzi P, Rini B, Singh A, Radivoyevitch T, Sekeres M, Advani A, Tiu R, Reu F, Kalaycio M, Copelan E, Hsi E, Lichtin A, Bolwell B. p53-Independent, normal stem cell sparing epigenetic differentiation therapy for myeloid and other malignancies. Semin Oncol 2012; 39:97-108. [PMID: 22289496 PMCID: PMC3655437 DOI: 10.1053/j.seminoncol.2011.11.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Cytotoxic chemotherapy for acute myeloid leukemia (AML) usually produces only temporary remissions, at the cost of significant toxicity and risk for death. One fundamental reason for treatment failure is that it is designed to activate apoptosis genes (eg, TP53) that may be unavailable because of mutation or deletion. Unlike deletion of apoptosis genes, genes that mediate cell cycle exit by differentiation are present in myelodysplastic syndrome (MDS) and AML cells but are epigenetically repressed: MDS/AML cells express high levels of key lineage-specifying transcription factors. Mutations in these transcription factors (eg, CEBPA) or their cofactors (eg., RUNX1) affect transactivation function and produce epigenetic repression of late-differentiation genes that antagonize MYC. Importantly, this aberrant epigenetic repression can be redressed clinically by depleting DNA methyltransferase 1 (DNMT1, a central component of the epigenetic network that mediates transcription repression) using the deoxycytidine analogue decitabine at non-cytotoxic concentrations. The DNMT1 depletion is sufficient to trigger upregulation of late-differentiation genes and irreversible cell cycle exit by p53-independent differentiation mechanisms. Fortuitously, the same treatment maintains or increases self-renewal of normal hematopoietic stem cells, which do not express high levels of lineage-specifying transcription factors. The biological rationale for this approach to therapy appears to apply to cancers other than MDS/AML also. Decitabine or 5-azacytidine dose and schedule can be rationalized to emphasize this mechanism of action, as an alternative or complement to conventional apoptosis-based oncotherapy.
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Affiliation(s)
- Yogen Saunthararajah
- Department of Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
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Chou W, Ngo T, Gershon PD. An overview of the vaccinia virus infectome: a survey of the proteins of the poxvirus-infected cell. J Virol 2012; 86:1487-99. [PMID: 22090131 PMCID: PMC3264349 DOI: 10.1128/jvi.06084-11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 11/08/2011] [Indexed: 11/20/2022] Open
Abstract
We have quantitatively profiled the proteins of vaccinia virus-infected HEK293T cells early and late during vaccinia virus infection. Proteins corresponding to 4,326 accessions were identified, the products of 3,798 genes. One hundred thirty-six of the proteins were vaccinia virus-encoded (∼64% of the known vaccinia virus proteome). The remaining accessions were from the host cell. A total of 3,403 of the 4,326 accessions could be confidently quantitated at the precursor peptide level. Although vaccinia virus gene products spanned the entire abundance dynamic range of the cellular proteome, nearly all of the proteome dynamics observed as a result of infection were manifest in the virus gene products with very little plasticity in the host cell proteome. The vaccinia virus gene products could be grouped into four kinetic classes (i.e., four combinations of pre- and postreplicative expression). These protein kinetic classes reflected, almost entirely, the corresponding gene classes within the recently characterized vaccinia virus transcriptome map. The few cellular gene products that showed notable changes in abundance upon vaccinia virus infection were concentrated largely in just a few functional groups. After all of the quantitated cellular gene products were assigned to Gene Ontology (GO)-specific groups, quantitation values for a number of these GO-specific groups were significantly skewed toward over- or underabundance with respect to the global distribution of quantitation values. Quantitative analysis of host cell functions reflected several known facets of virus infection, along with some novel observations.
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Affiliation(s)
- Wayne Chou
- Department of Molecular Biology and Biochemistry, University of California-Irvine, Irvine, California, USA
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Sriharsha L, Lipton JH, Pond G, Ma C, Raybardhan S, Messner HA, Seki JT. Examining the safety and efficacy of a chemotherapy dosing method in Allogeneic Stem Cell Transplant patients of extreme body size. J Oncol Pharm Pract 2009; 15:201-10. [DOI: 10.1177/1078155208101960] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background. There is no consensus on a universal dosing method for calculating high-dose chemotherapy in allogeneic Stem Cell Transplant (SCT) patients. The Metropolitan Life (Met-Life) Insurance Company’s weight—height tables have been used to determine body weight for chemotherapy dosing for SCT, however no formal study has been done to determine if the Met-Life weight— height tables can be used for chemotherapy dosing in SCT. We retrospectively studied the use of Met-Life weight—height tables for chemotherapy dosing in SCT. Our goal is to determine if patients with extremes of body size who had undergone an SCT and were dosed according to the Met-Life weight— height tables had an increase of Treatment Related Morbidity (TRM) or mortality or relapse. Patients and Methods. Patients were grouped into three different treatment regimens, cyclophosphamide/TBI, busulphan/cyclophosphamide, and AraC/cyclophosphamide/TBI. Patients in each treatment regimen were further divided into five equal groups based on weight. Treatment related morbidity and mortality was evaluated by comparing the lowest and highest quintiles to the middle quintiles within each treatment regimen. Result. Data from 262 patients was evaluated in this study. Overall, there was not an increase in TRM or mortality or in relapse in patients with extremes of body size. Conclusion. The Met-Life weight—height tables could be used to dose patients undergoing allogeneic SCTs. Additional prospective studies would need to be done comparing other chemotherapy dosing methods with the Met-Life weight—height tables to further validate this conclusion.
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Affiliation(s)
- Lakshmi Sriharsha
- Departments of Pharmacy, University of Toronto, Princess Margaret Hospital, Ontario, Canada
| | - Jeffrey H Lipton
- Medical Oncology and Hematology, University of Toronto, Princess Margaret Hospital, Ontario, Canada
| | - Greg Pond
- Department of Biostatistics University of Toronto, Princess Margaret Hospital, Ontario, Canada
| | - Clement Ma
- Department of Biostatistics University of Toronto, Princess Margaret Hospital, Ontario, Canada
| | - Sumit Raybardhan
- Departments of Pharmacy, University of Toronto, Princess Margaret Hospital, Ontario, Canada
| | - Hans A Messner
- Medical Oncology and Hematology, University of Toronto, Princess Margaret Hospital, Ontario, Canada
| | - Jack T Seki
- Departments of Pharmacy, University of Toronto, Princess Margaret Hospital, Ontario, Canada,
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Koehl U, Hollatz G, Rohrbach E, Visschedyk K, Cinatl J, Kornhuber B, Kreuter J, Mutschler E, Schwabe D. Pharmacology of intracellular cytosine-arabinoside-5'-triphosphate in malignant cells of pediatric patients with initial or relapsed leukemia and in normal lymphocytes. Cancer Chemother Pharmacol 2006; 60:467-77. [PMID: 17171362 DOI: 10.1007/s00280-006-0386-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2006] [Accepted: 10/31/2006] [Indexed: 10/23/2022]
Abstract
PURPOSE The prodrug cytosinearabinoside (ara-C) is widely used in the treatment of acute leukemias. The active drug is the intracellular metabolite cytosine-arabinoside-5'-triphosphate (ara-CTP). The purpose of the present study was to investigate the relation between sensitivity and pharmacokinetic parameters Cmax, t1/2 and AUC of ara-CTP. The obtained results were compared to previous studies. EXPERIMENTAL DESIGN Cmax, t1/2 and AUC of ara-CTP were assessed in leukemic cells of 17 pediatric patients with acute lymphoblastic leukemia (ALL) and in 6 lymphoblastic cell lines and compared with normal lymphocytes of 9 healthy donors by high pressure liquid chromatography (HPLC). The sensitivity of the cells against ara-C was determined by the MTT assay. RESULTS The intracellular accumulation of ara-CTP was significantly lower in normal lymphocytes (Cmax 47.7-60.9 pmol/10(6) cells) compared to leukemic cell lines (Cmax 11-1128 pmol/10(6) cells) and leukemic cells of our patients (Cmax 85.9-631 pmol/10(6) cells). Similar results were found for the AUC. There was no significant difference between initial and relapsed leukemias in our small cohort. A correlation between sensitivity in terms of IC50 values and the intracellular ara-CTP accumulation was observed in cell lines, but not in leukemic cells and normal lymphocytes from healthy donors. CONCLUSIONS Pharmacokinetic parameters varied tremendously in leukemic cells in contrast to normal lymphocytes without a difference in sensitivity. It is worthwhile to compare literature data to assess an optimal dosage of ara-C in pediatric patients.
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Affiliation(s)
- U Koehl
- Pediatric Hematology and Oncology, Laboratory for Stem Cell Transplantation and Immunotherapy, Johann Wolfgang Goethe-University, Theodor Stern Kai 7, 60596 Frankfurt a. M., Germany.
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Holtz MS, Forman SJ, Bhatia R. Nonproliferating CML CD34+ progenitors are resistant to apoptosis induced by a wide range of proapoptotic stimuli. Leukemia 2005; 19:1034-41. [PMID: 15815728 DOI: 10.1038/sj.leu.2403724] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Imatinib mesylate, a Bcr-Abl kinase inhibitor, has been very successful in the treatment of chronic myelogenous leukemia (CML). However, the majority of patients achieving cytogenetic remissions with imatinib treatment have molecular evidence of persistent disease, and residual BCR/ABL(+) progenitors can be detected. There is a need to develop new approaches that enhance elimination of malignant progenitors in imatinib-treated patients. Here we show that CML CD34(+) progenitors are sensitive to several apoptosis-inducing stimuli including the chemotherapeutic agents Ara-C and VP-16, radiation, arsenic trioxide, ceramide, growth factor withdrawal, and the death receptor activators TNFalpha and TRAIL. Bcr-Abl kinase inhibition by imatinib did not enhance sensitivity of CML progenitors to Ara-C, VP-16, ceramide, radiation or TRAIL-induced apoptosis but did enhance arsenic and TNFalpha-induced apoptosis. We further demonstrate that apoptosis was restricted to dividing cells, whereas nonproliferating BCR/ABL(+) CD34(+) cells were resistant to apoptosis induced by imatinib, Ara-C or arsenic, either alone or in combination. Resistance of quiescent CML progenitors to imatinib-induced apoptosis could contribute to persistence of residual malignant progenitors in imatinib-treated patients. Combination treatment with Ara-C or arsenic may not enhance targeting of nonproliferating CML progenitors. The assay described here may be useful for identifying agents targeting quiescent CML progenitors.
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MESH Headings
- Adult
- Aged
- Antigens, CD34/metabolism
- Antineoplastic Agents/pharmacology
- Apoptosis/drug effects
- Apoptosis/physiology
- Benzamides
- Cell Division/drug effects
- Cell Division/physiology
- Female
- Fusion Proteins, bcr-abl/antagonists & inhibitors
- Fusion Proteins, bcr-abl/genetics
- Gene Expression Regulation, Leukemic/drug effects
- Hematopoietic Stem Cells/cytology
- Hematopoietic Stem Cells/drug effects
- Hematopoietic Stem Cells/metabolism
- Humans
- Imatinib Mesylate
- In Vitro Techniques
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology
- Male
- Middle Aged
- Piperazines/pharmacology
- Pyrimidines/pharmacology
- Signal Transduction/drug effects
- Signal Transduction/physiology
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Affiliation(s)
- M S Holtz
- Division of Hematology and Hematopoietic Cell Transplantation, City of Hope National Medical Center, Duarte, CA 91010, USA
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Affiliation(s)
- R Pieters
- University Medical Center Rotterdam, Sophia Childrens Hospital, Pediatric Oncology/Hematology, Rotterdam, The Netherlands.
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Sreenivasan Y, Sarkar A, Manna SK. Mechanism of cytosine arabinoside-mediated apoptosis: role of Rel A (p65) dephosphorylation. Oncogene 2003; 22:4356-69. [PMID: 12853972 DOI: 10.1038/sj.onc.1206486] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Nuclear transcription factor kappa B (NF-kappaB) has been shown both to block apoptosis and to promote cell proliferation, and hence has been considered an important target for anticancer drug development. The pyrimidine analogue cytosine arabinoside (araC) is among the most effective agents used in the treatment of acute leukemia, and we demonstrate in this study that its chemotherapeutic activity may be mediated by its inhibition of NF-kappaB. We found that in Jurkat cells, although tumor necrosis factor (TNF), araC, or ceramide induced NF-kappaB, the induction was only transient in the case of araC. In both HuT-78 and serum-activated LPS-stimulated Jurkat (SA-LPS/Jkt) cells that expressed NF-kappaB, TNF or ceramide treatments did not affect the NF-kappaB expression whereas araC downregulated it. AraC, but not TNF or ceramide was able to induce apoptosis in these cells as detected by assays for lipid peroxidation, reactive oxygen intermediates generation, caspase activation, cytotoxicity, Bcl-2 degradation, and DNA fragmentation. AraC also potentiated apoptosis mediated by cis-platin, etoposide, or taxol in these cells. AraC was able to induce protein phosphatases (PP) 2A and 2B-A, and phosphorylation of p65 subunit of NF-kappaB in the HuT-78 and SA-LPS/Jkt cells was downregulated by araC treatment. Furthermore, calyculin A, a specific phospho-serine/phospho-threonine phosphatase inhibitor, protected HuT-78 and SA-LPS/Jkt cells from araC-mediated NF-kappaB downregulation and apoptosis. These observations collectively suggest that araC induces apoptosis in NF-kappaB-expressing cells by dephosphorylating the p65 subunit of NF-kappaB.
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Affiliation(s)
- Yashin Sreenivasan
- Laboratory of Immunology, Centre for DNA Fingerprinting & Diagnostics, Nacharam, Hyderabad 500 076, India
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Katagiri T, Miyazawa K, Nishimaki J, Yaguchi M, Kawanishi Y, Ohyashiki K. Combination of granulocyte colony-stimulating factor and low-dose cytosine arabinoside further enhances myeloid differentiation in leukemia cells in vitro. Leuk Lymphoma 2000; 39:173-84. [PMID: 10975397 DOI: 10.3109/10428190009053552] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We examined the differentiation-inducing effect on freshly isolated myeloid leukemia cells in liquid suspension culture by combined treatment with granulocyte colony-stimulating factor (G-CSF) plus low-dose cytosine arabinoside (Ara-C; 5-10 ng/ml) in 25 patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) in leukemic transformation. Culture with G-CSF alone showed leukemic cell growth stimulation in 15 out of the 25 cases (60%) and induction of cell differentiation in 19 out of the 25 cases (76%), respectively. In 23 cases (92%), either growth stimulation and/or differentiation induction of leukemia cells was observed in response to G-CSF. This suggests that most myeloid leukemia cells are able to respond to G-CSF stimulation. In addition, treatment of cells with low-dose Ara-C alone resulted in the enhancement of myeloid specific antigens expression in 16 cases (64%). Treatment of leukemia cells with higher concentrations of Ara-C (over 50 ng/ml) alone resulted in cytocidal effects but not in the induction of differentiation. Furthermore, 15 cases (60%) showed pronounced myeloid differentiation of leukemia cells after combined exposure to G-CSF plus low-dose Ara-C as compared with cells treated with either G-CSF or Ara-C alone. The enhanced effect of differentiation induction by combining G-CSF plus low-dose Ara-C was also observed in a murine myeloid leukemia cell line WEHI-3B in vitro. These data suggest that treatment with G-CSF plus low-dose Ara-C is capable of inducing differentiation of leukemic cells in vitro, and also appears to be useful for the differentiation-based therapy of patients with AML and MDS.
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Affiliation(s)
- T Katagiri
- First Department of Internal Medicine, Tokyo Medical University, Japan
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Braess J, Voss S, Jahns-Streubel G, Schoch C, Haferlach T, Kern W, Keye S, Schleyer E, Hiddemann W. The pharmacodynamic basis for the increased antileukaemic efficacy of cytosine arabinoside-based treatment regimens in acute myeloid leukaemia with a high proliferative activity. Br J Haematol 2000; 110:170-9. [PMID: 10930995 DOI: 10.1046/j.1365-2141.2000.02151.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The current study was initiated to explore the mechanisms underlying the previously demonstrated association between the proliferative activity of leukaemic blasts and the response to cytosine arabinoside (AraC)-based therapy in de novo acute myeloid leukaemia (AML). The activity of key enzymes of AraC metabolism-deoxycytidine kinase (DCK), cytidine deaminase (DCD) and polymerase alpha (PolyA) were determined in blast cells from 33 patients. In addition, formation and retention of intracellular levels of AraC triphosphate (AraCTP) and DNA incorporation of AraC were measured, as was the proliferative activity of leukaemic blasts by [3H]-TdR incorporation before and after stimulation with granulocyte-macrophage colony-stimulating factor (GM-CSF) or granulocyte CSF (G-CSF) for 48 h. AraC incorporation into the DNA (median 0.60 pmol/105 cells) was significantly related to the proliferative activity of AML blasts (r = 0.74, P < 0.001). Similarly, priming with GM-CSF or G-CSF increased both the proliferative activity of AML blasts by a median of 1.84- and 1.64-fold, respectively, and the incorporation of AraC into the DNA (1.29- and 1.40-fold respectively). In contrast, no relationship was found between the endogenous proliferative activity (EPA) and enzyme activities regulating AraC activation (DCK; median 4.70 pmol/min/mg protein), inactivation (DCD; median 2.92 pmol/min/mg protein) or inhibitory effects (PolyA; median 1.50 pmol/min/mg protein), nor the formation or retention of AraCTP (median 306.1 ng/107 cell and 1.6 h respectively). When samples were grouped according to EPA (more than or less than the median), slowly proliferating specimens had a higher response to cytokine priming for proliferative activity and incorporation of AraC into DNA. Clinical data of 15 patients were available. Although all eight patients with a high endogenous proliferative activity reached complete remission, only four out of seven patients with a low proliferative activity responded, whereas the other three patients were non-responders (P = 0.077).
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Affiliation(s)
- J Braess
- Department of Internal Medicine III, University Hospital Grosshadern, Ludwig-Maximilians University, Munich, Germany.
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