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PubMed1989

Horner's syndrome and demyelinating peripheral neuropathy caused by high-dose cytosine arabinoside.

High-dose cytosine arabinoside may benefit patients with refractory acute leukemia. Peripheral nervous system disturbances caused by cytosine arabinoside have rarely been reported. We describe a patient with acute leukemia who developed Horner's syndrome and a severe demyelinating peripheral neuropathy leading to death after receiving high-dose cytosine arabinoside. Peripheral nerve dysfunction is a potentially serious complication of high-dose cytosine arabinoside.

Adult↗
PubMed1975

Combinations of arabinosyl cytosine and 6-thioguanine for treatment of adults with acute leukemia.

The combination of arabinosyl cytosine and 6-thioguanine has been effective for the treatment of acute leukemia. Three schedules of this combination were studied to determine which was most effective, especially in patients who had prior exposure to either or both of these drugs. Sequential and simultaneous 5-day courses of the combination were ineffective. A regimen consisting of a 5-day course of arabinosyl cytosine followed by a 5-day course of 6-thioguanine and another 5-day course of arabinosyl cytosine produced responses in 36% of 25 patients. Seven of the nine patients who responded were refractory to prior therapy with arabinosyl cytosine and 5 were refractory tp prior therapy with 6-mercaptopurine. However, the median duration of response was only six weeks. Four patients developed central nervous system complications and three of these patients died while in complete remission. Major toxicity from all three regiments was myelosuppression. This regimen was about as effective as most other regimens used as secondary therapy in patients with acute myelogenous leukemia, but its toxicity was too great for routine usage.

Adolescent↗
PubMed1998

Drug resistance to 5-aza-2'-deoxycytidine, 2',2'-difluorodeoxycytidine, and cytosine arabinoside conferred by retroviral-mediated transfer of human cytidine deaminase cDNA into murine cells.

PURPOSE: The hematopoietic toxicity produced by the cytosine nucleoside analogs is a critical problem that limits their effectiveness in cancer therapy. One strategy to prevent this dose-limiting toxicity would be to insert a gene for drug resistance to these analogs into normal bone marrow cells. Cytidine (CR) deaminase can deaminate and thus inactivate 5-aza-2'-deoxycytidine (5-AZA-CdR), 2',2'-difluorodeoxycytidine (dFdC) and cytosine arabinoside (ARA-C). The aim of this study was to determine if gene transfer of CR deaminase into murine fibroblast cells confers drug resistance to these cytosine nucleoside analogs and if this resistance can be prevented by the CR deaminase inhibitor, 3,4,5,6-tetrahydrouridine (THU). METHODS: NIH 3T3 murine fibroblast cells were transduced with retroviral particles containing the human CR deaminase cDNA. Assays measuring CR deaminase activity as well as the inhibitory action of 5-AZA-CdR, dFdC and ARA-C on colony formation, were performed in the presence of different concentrations of THU. RESULTS: Retroviral-mediated transfer of the CR deaminase gene into 3T3 fibroblasts produced a considerable increase in CR deaminase activity. The transduced cells also showed significant drug resistance to 5-AZA-CdR, dFdC and ARA-C, as demonstrated by a clonogenic assay. This drug resistance phenotype and elevated CR deaminase activity were reversed by THU. CONCLUSIONS: These findings indicate that the CR deaminase gene can potentially be used in cancer gene therapy for protecting normal cells against the cytotoxic actions of different cytosine nucleoside analogs. In addition, the CR deaminase-transduced cells can be used as a model for screening different CR deaminase inhibitors in an intact cellular system.

3T3 Cells↗
PubMed1988

Differential inhibition of mitogen induced T cell proliferation by 5-azacytidine and cytosine-arabinoside.

The cytotoxic drugs 5-azacytidine and cytosine-arabinoside influence the enzymatic methylation of DNA in opposite ways (1,2). The in vitro effects of these two drugs on Con A induced proliferation of thymic and splenic rat lymphocytes were investigated. Cytosine-arabinoside was found to inhibit mitogen induced proliferation already at a concentration of 0.001 microM, whereas 5-azacytidine was inhibitory only above concentrations of 1 microM. A stimulation of mitogen induced T cell proliferation was consistently seen with 5-azacytidine, but not with cytosine-arabinoside, at concentrations lower than the cytotoxic concentration. The results show that 5-azacytidine and cytosine-arabinoside interfere with mitogen stimulated lymphocyte proliferation by different mechanisms and suggest that hypomethylated DNA plays a role in the proliferation of T cells.

Animals↗
PubMed1992

Influence of denervation on smooth muscle response to repeated administration of cyclophosphamide, cytosine arabinoside, or their combination.

Cyclophosphamide, 40 mg.kg-1, cytosine arabinoside, 2 mg.kg-1 or their combination, were all given once weekly to chicks for 5 weeks. The expansor secundariorum muscle of the left wing of each chick was then surgically denervated leaving that of the right wing to serve as the control. Drug administrations continued for a further 5 weeks before the responses of normal and denervated expansor muscles were determined pharmacologically. Cyclophosphamide depressed the response of the expansor muscle to noradrenergic nerve stimulation but enhanced the response to noradrenaline and potassium chloride. Cytosine arabinoside enhanced responses of expansor muscles to noradrenergic nerve stimulation and noradrenaline, but depressed responses evoked by potassium chloride. The combination enhanced responses to nerve stimulation, noradrenaline, and potassium chloride. Expansor muscles were unresponsive to acetylcholine and anticancer drugs failed to restore the responsiveness to acetylcholine except the combination. Denervation depressed responses to noradrenergic nerve stimulation but caused supersensitivity to noradrenaline; this was more marked in the combination and cyclophosphamide groups, with no change in sensitivity seen in the cytosine arabinoside group. The denervated expansor muscle responded to acetylcholine in the order, combination much greater than cyclophosphamide greater than control greater than cytosine group. Denervated expansor muscles from anticancer groups were supersensitive to potassium chloride, with the combination group having the most pronounced effect. It is suggested that denervation influences smooth muscle sensitivity to agonist drugs which can modify the effects of anticancer drugs on smooth muscle.

Adrenergic Fibers↗
PubMed1984

[(IgG)2 protein A]2 complex stimulates cytosine arabinoside incorporation into DNA and inhibits L cell proliferation.

A Mr = 716 000 complex, [(IgG)2 Protein A]2, formed when Protein A is mixed with a molar excess of IgG anti-L cell antibody, augmented [3H]thymidine incorporation in DNA and growth of a murine transformed L cell line. It was also possible to augment the incorporation of [3H]cytosine arabinoside (2.3-fold) in DNA by the binding of this complex to L cells. A synergistic inhibition of L cell proliferation was produced using the complex and certain concentrations of cytosine arabinoside. By binding the complex to L cells, a 5-fold lower concentration of cytosine arabinoside (0.050 microgram/ml) was as effective in inhibiting cell replication as the higher dose of the drug (0.25 microgram/ml) with cells bound by IgG antibody alone, and a 20-fold lower concentration compared to the effects of the drug itself (1.0 microgram/ml). Addition of 10 microM thymidine to the complex permitted the use of an even lower dose of cytosine arabinoside (0.004 microgram/ml) for inhibition of cell growth. Thymidine caused this effect by producing an even greater incorporation of drug into the DNA of complex-stimulated cells. Thus, by stimulating the cell with the immune [(IgG)2 Protein A]2 complex it was possible to stimulate uptake of a chemotherapeutic nucleoside and selectively inhibit cell replication at non-toxic doses of nucleoside.

Animals↗
PubMed1989

Determination of 3H-labelled cytosine arabinoside and eight metabolites in cell extracts by high-performance liquid chromatography and scintillation spectrometry.

We have developed a method for the separation and quantitation of radiolabeled cytosine arabinoside and its eight metabolites in cell extracts by anion-exchange gradient high-performance liquid chromatography. Baseline separation of cytosine arabinoside and uracil arabinoside and their respective 5'-mono-, di- and triphosphates, as well as cytosine arabinoside diphosphocholine was obtained with the shortest interval between peaks being 3 min. This degree of separation was found to be essential for quantitation of 3H-labeled metabolites by scintillation counting of 1-min fractions. Application of this procedure to the quantitation of [3H] cytosine arabinoside and its metabolites from HL60 human leukemia cells is demonstrated.

Arabinofuranosyluracil↗
PubMed1997

Functional analysis of mutated purine-cytosine permease from Saccharomyces cerevisiae. A possible role of the hydrophilic segment 371-377 in the active carrier conformation.

The purine-cytosine permease (PCP) is an active transporter located in the plasma membrane of the yeast Saccharomyces cerevisiae. This protein mediates purine (adenine, guanine, and hypoxanthine) and cytosine accumulation in the cell by using an electrochemical potential difference in proton as the energy source. Various mutant strains, with altered Kt(app) (apparent Michaelis constant of transport) of uptake for one or several bases, have already been selected. Their cloning and sequencing revealed that three of them presented substitutions in the same region of the putative sequence of the PCP: this region might correspond to the hydrophilic segment 371-377 (I-A-N-N-I-P-N). Two mutants displayed single mutations, resulting in only one amino acid residue change (N377I and N374I, respectively), and the other displayed three amino acid substitutions (I371V, I375V, and N377G). Therefore, to analyze the contribution of individual amino acid changes to the phenotype of the complex mutant, single (N377G) and double (I371V,I375V) mutants were constructed by site-directed mutagenesis. The influence of single mutations in this region was studied by measuring, for adenine, hypoxanthine, and cytosine, the uptake constants on cells and equilibrium binding parameters on plasma membrane-enriched fractions. Uptake and binding constant determinations showed that all the variations observed for the Kt(app) of uptake were correlated with variations of the binding Kd(app) for the corresponding solutes. Thus, our results emphasize the role of the two asparagine residues, located at positions 374 and 377, respectively, in the binding of the bases. In addition, the sole substitution of the 377 asparagine residue by glycine is responsible for the phenotype of the triple mutant. The effect of pH on the apparent hypoxanthine binding dissociation constant showed that the effects of N377G and N377I changes were, at least partially, due to a shift of the pKa of an ionizable amino acid residue of the unliganded permease. These two amino acid residue changes induced a shift of the pKa of this group in the unliganded, deprotonated permease about two units toward acidic pH. This result suggests that the 371-377 segment might play a key role in the proper three-dimensional structure of the active purine-cytosine permease.

Alleles↗
PubMed2001

Treatment of non-AIDS progressive multifocal leukoencephalopathy with cytosine arabinoside.

This open label study determined the outcome of non-AIDS progressive multifocal leukoencephalopathy patients treated with a standard dose of intravenous cytosine arabinoside. Nineteen patients with PML proven by brain biopsy or spinal fluid polymerase chain reaction were treated with intravenous cytosine arabinoside 2 mg/kg per day for 5 days and followed for neurologic outcome by neurologic examination and MRI scanning. Seven of 19 PML patients treated with cytosine arabinoside intravenously improved neurologically. The range of follow-up for these patients was 2.0 to 4.5 years. All were left with neurologic deficits but were functionally improved, and 6 of 7 were able to independently carry out the activities of daily living. Twelve PML patients showed no evidence of response and died rapidly of their disease after treatment (range, 8 days to 6 months). All who survived their neurologic disease recovered from treatment-induced pancytopenia. Cytosine arabinoside given intravenously to non-AIDS PML patients in this small study was associated with a 36% chance of developing stabilization at 1 year. Treatment was associated with significant bone marrow toxicity. The improvement in MRI scan changes in those patients who responded took 6 weeks or longer.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Idarubicin and cytosine arabinoside reinduction therapy for children with multiple recurrent or refractory acute lymphoblastic leukemia: a Pediatric Oncology Group study.

PURPOSE: This study was designed to determine the toxicity of and response to idarubicin and cytosine arabinoside in children and adolescents with acute lymphoblastic leukemia (ALL) who had refractory or recurrent bone marrow disease. PATIENTS AND METHODS: Patients <21 years of age with ALL in second or later bone marrow relapse or refractory to induction therapy were eligible. Some patients also had concurrent central nervous system (CNS) relapse. Therapy consisted of cytosine arabinoside, 1 g/m2/day given as a 6-h infusion, followed by bolus idarubicin, 5 mg/m2/day, both daily for 6 days. Children achieving remission received maintenance therapy with 3 days of etoposide, 100 mg/m2/day, followed by ifosfamide, 2.8 g/m2/day, alternating every 3 weeks with 3 days of cytosine arabinoside and idarubicin in the dosages described earlier. All courses of therapy were followed by granulocyte colony-stimulating factor (G-CSF). Removal from study to undergo bone marrow transplantation (BMT) was encouraged. RESULTS: Eighty-two patients were entered. There were 14 deaths (nine early), mostly from documented or presumed bacterial or fungal sepsis. Overall, 30 patients achieved complete remission (37%). These were mostly of brief duration--only one patient was still alive at 600+ days after BMT. CONCLUSIONS: Cytosine arabinoside and idarubicin showed moderate activity in heavily pretreated children with ALL.

Administration, Oral↗
PubMed1995

Membrane topology analysis of the Escherichia coli cytosine permease.

The Escherichia coli codBA operon encodes cytosine permease (CodB) and cytosine deaminase (CodA). CodB mediates uptake of exogenously supplied cytosine, and CodA catalyses the hydrolytic deamination of cytosine to uracil and ammonia. The hydropathic profile of CodB indicates that it is an integral cytoplasmic membrane protein possessing several transmembrane-spanning domains. The membrane topology of CodB was investigated by using gene fusions containing varying lengths of the amino-terminus of CodB fused to either alkaline phosphatase (AP) or beta-galactosidase (BG). The AP activities expressed by the CodB-AP fusions are consistent with a topological model in which the amino- and the carboxy-termini of CodB are located in the cytoplasm, and in which CodB possesses 12 membrane-spanning segments. The enzyme activities of most of the CodB-BG fusions support the model. However, the results obtained with some of the CodB-BG fusions illustrate the limitations of using BG as a reporter protein in studies of membrane protein topology.

Alkaline Phosphatase↗
PubMed1998

Human leukemic K562 cells treated with cytosine arabinoside: enhancement of erythroid differentiation by retinoic acid and retinol.

Human leukemia K562 cells can be induced to erythroid differentiation when treated with a variety of compounds, including hemin, cytosine arabinoside and 5-azacytidine. Following erythroid induction, K562 cells express at high level gamma-globin and accumulate both Hb Portland and Hb Gower 1. In this paper we determined whether a combination treatment of K562 cells with suboptimal concentrations of cytosine arabinoside and retinoids lead to full expression of differentiated functions. Cell growth kinetics studies, intracellular detection of hemoglobin by benzidine staining and hemoglobin analysis by cellulose acetate were performed. The results obtained show that (a) retinoic acid and retinol are not able to induce differentiation of K562 cells and (b) cytosine arabinoside induces differentiation only when used at 100-300 nmol/l concentrations. In addition, our data demonstrate that erythroid differentiation of K562 occurs when 40 micromol/l of retinoic acid or retinol are added together with 75 nmol/l cytosine arabinoside.

Antimetabolites, Antineoplastic↗
PubMed1987

Evaluation of intensive postremission chemotherapy for adults with acute nonlymphocytic leukemia using high-dose cytosine arabinoside with L-asparaginase and amsacrine with etoposide.

In order to test the toxicity and efficacy of intensive postremission therapy with high-dose cytosine arabinoside with L-asparaginase and amsacrine with etoposide in adults with acute nonlymphocytic leukemia (ANL), 100 adults (ages 19 to 75) with previously untreated ANL were entered into a study using six sequential cycles of chemotherapy. Cycles 1 (induction), 3, and 5 included conventional doses of daunomycin, cytosine arabinoside, 6-thioguanine, vincristine (VCR), and prednisone. Cycle 2 was cytosine arabinoside 3 g/m2 intravenously (IV) every 12 hours for four doses, followed by L-asparaginase 10,000 U intramuscularly (IM) at hour 42; this combination was repeated 1 week later. Cycle 4 included amsacrine 120 mg/m2/d and etoposide 100 mg/m2/d, both IV for five days, and cycle 6 was three monthly courses of VCR on day 1, and prednisone, mercaptopurine, and methotrexate each for five days. Seventy-four patients (74%) achieved complete remission (CR) (51 with cycle 1 and 23 after cycle 2). The overall disease-free survival (DFS) for patients achieving CR is 27% at 3 years by Kaplan-Meier analysis, while for patients achieving CR with cycle 1 it is 34%. The actuarial probability of being free from relapse at 3 years for patients achieving CR is 34%. Sixteen of the 74 CR patients (22%) died in CR while continuing to receive intensive chemotherapy, including 12 (18%) who succumbed to infection (nine bacterial, three fungal). After a median follow-up of 20 months, 36 patients have relapsed and 21 remain alive in CR. Intensive consolidation with high-dose cytosine arabinoside, amsacrine, and etoposide can modestly prolong DFS compared with historical controls. However, relapse continued to be a major problem and, in addition, with more aggressive consolidation therapy, infection during marrow aplasia resulted in a significant number of deaths.

Acute Disease↗
PubMed1987

Cerebellar toxicity with high-dose cytosine arabinoside.

CNS dysfunction, especially impaired cerebellar function, is the dose-limiting toxicity associated with high-dose cytosine arabinoside, which precludes doses of greater than 48 g/m2. Four hundred eighteen patients between the ages of 2 and 74 years with leukemia or lymphoma received 36 to 48 g/m2 cytosine arabinoside either alone or with anthracycline antibiotics, 4'-(9-acridinylamino) methane sulfon-m-anisidine (m-AMSA), or total body irradiation. In only 35 of 418 patients (8%) did severe cerebellar toxicity develop; it was irreversible or fatal in four (1%) patients. The age of the patient was a critical factor in the incidence of severe cerebellar toxicity. Patients greater than 50 years old had a statistically significant greater incidence of cerebellar toxicity compared with younger patients (26/137, 19%, v 9/281, 3%; P less than .0005, chi 2). Neither the diagnosis, disease status, sex, nor the regimen altered the incidence of severe cerebellar toxicity (when corrected for age). A second course of high-dose cytosine arabinoside, administered to 62 patients, did not increase the incidence of severe cerebellar toxicity, which occurred in five (8%) of these patients. Two of the five patients had severe toxicity with the initial course. Of the 60 patients with no antecedent cerebellar dysfunction, three (5%) had severe toxicity with the second course: one of 41 patients were less than 50 years old; two of 19 patients were greater than or equal to 50 years. Since the occurrence of severe cerebellar dysfunction is greatly affected by age, reduced doses of high-dose cytosine arabinoside should be given to patients greater than 50 years old, and methods for reducing the cerebellar toxicity should be investigated in these patients.

Adolescent↗
PubMed2002

Neutropenic colitis after treatment of acute myelogenous leukemia with idarubicin and cytosine arabinoside.

OBJECTIVE: To determine the gastrointestinal toxic effects of idarubicin and cytosine arabinoside combination therapy in patients with newly diagnosed acute myelogenous leukemia (AML). PATIENTS AND METHODS: We performed a single-institution retrospective analysis of the incidence of neutropenic colitis in patients with newly diagnosed AML receiving idarubicin and cytosine arabinoside combination therapy. Using pharmacy records, we identified 78 patients who received idarubicin during the study period of January 1997 to September 1998 and who agreed to a review of their medical records. Patients with preexisting bowel conditions were excluded from this analysis. We used a strict definition of neutropenic colitis that included clinical findings (severe abdominal pain, diarrhea, hematochezia, and/or peritoneal signs) plus radiographic evidence of bowel inflammation in the absence of an identified bacterial pathogen. RESULTS: Of the 78 patients receiving idarubicin and cytosine arabinoside for treatment of AML, 65 were included in this study. We observed neutropenic colitis in 10 of these 65 AML patients. This complication was followed by sepsis in 3 patients and was the major cause of death in 4 of the 8 patients who died. CONCLUSION: This analysis suggests that neutropenic colitis is a frequent and serious complication of idarubicin and cytosine arabinoside treatment.

Adult↗
PubMedDate not supplied

Microbiologic assay for cytosine arabinoside (NSC-63878): the use of a mutant of streptococcus faecium var. durans resistant to methotrexate (NSC-740) and 6-mercaptopurine (NSC-755).

Cytosine arabinoside has been shown to be effective in the treatment of acute leukemias and lymphomas, especially in combination with other established anticancer agents such as methotrexate, 6-mercaptopurine, and 6-thioguanine. A microbiologic assay capable of detecting cytosine arabinoside in the presence of such anticancer agents in body fluids has been developed using a strain of Streptococcus faecium var. durans resistant to methotrexate and 6-mercaptopurine; the assay can also be used to determine cytosine arabinoside concentrations in the presence of l-thioguanine. In view of the present trend toward drug combinations, including those using tetrahydrouridine, in the chemotherapy for human neoplasms, the proposed assay method will be valuable in cytosine arabinoside distribution studies.

Biological Assay↗
PubMed1975

Effect and toxicity of combination treatment including cyclocytidine or cytosine arabinoside in L-1210 and sarcoma-180 systems.

Combination effect of antitumor agents, including cyclocytidine and cytosine arabinoside, was evaluated on the conception of pharmacological synergism and not of therapeutic synergism. Ascites sarcoma-180 and L-1210 leukemia were used as tumor systems. In sarcoma-180 system, combinations of cyclophosphamide plus cyclocytidine or cytosine arabinoside by simultaneous administration and cyclocytidine plus Daunorubicin or Vinblastine by alternate administration provided synergism. In L-1210 system, many compounds in combination with cyclocytidine or cytosine arabinoside in both simultaneous and alternate administrations provided synergism. Combination effect of agents was affected by the schedule of drug administration. It was found that the combination effect of drugs in one tumor system cannot be generalized to that in other tumor systems, even though equally effective doses of agents were administered in both tumor systems. Toxicity of cytosine arabinoside in combination with other drugs was affected by the schedule of administration. Compounds which provided synergism in simultaneous administration provided antagonism in alternate one. As a result, it was found that alternate administration of drugs is advantageous for the activity and diminution of toxicity of the host animal.

Animals↗
PubMed2005

GM-CSF and low-dose cytosine arabinoside in high-risk, elderly patients with AML or MDS.

Priming of leukemic cells with cytokines may enhance the efficacy of cell-cycle chemotherapy. In this study, we utilized these synergistic effects of granulocyte-macrophage colony-stimulating factor (GM-CSF, sargramostim [Leukine]), hydroxyurea, and low-dose cytosine arabinoside to treat elderly patients with acute myelogenous leukemia (AML) or myelodysplastic syndrome (MDS). In a single-institution, retrospective study, we evaluated 94 treatments with concomitant hydroxyurea, cytosine arabinoside, and GM-CSF between the years of 1997 and 2003 in high-risk elderly patients with AML or MDS. A total of 80% of patients received all of the GM-CSF doses; 78% of patients received all of the cytosine arabinoside doses. Adverse events were minimal. No patient developed mucositis or alopecia. The most common adverse event was neutropenic fever, which was noted in 57% of patients. Twenty-one percent of patients remained neutropenic after treatment until death or relapse. Sixty-eight percent of patients reached an absolute neutrophil count of greater than 1000 microL in a median of 33.5 days. Our data show an overall response rate of 52%, with a complete response rate of 39% and a partial response rate of 13%. Overall, our study showed that low-dose cytosine arabinoside given by continuous infusion together with continuous infusion GM-CSF and hydroxyurea was well-tolerated and effective in treating elderly AML and MDS patients who were not eligible for standard induction therapy.

Adult↗