Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023473 (chronic myeloid leukemia)
 18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

High doses of cytosine arabinoside (ara-C) were administered by continuous infusion to 24 patients with acute leukemia in relapse or blast phase of chronic myelogenous leukemia (CML). Ara-C was infused at a dose rate of 250 mg/M2/hr for 36 to 72 hr. The major toxicities were myelosuppression, diarrhea, and abdominal pain. Other toxicities included pulmonary edema, neurotoxicity, and liver function abnormalities. The gastrointestinal toxicity was dose-limiting and a phase II dose was established at 250 mg/M2/hr for 60-72 hr. Four patients treated with this dose schedule had objective responses. Two patients with CML in blast phase returned to chronic phase and have remained stable without maintenance therapy for 12 and 18 months. Two patients with acute myelogenous leukemia in relapse entered complete remissions which continued unmaintained for 4 and 6 months. Steady-state plasma ara-C levels ranged between 7 and 24 x 10(-6) M, while ara-U levels were as high as 4.5 x 10(-4) M. There was no detectable accumulation of ara-C or ara-U during the infusion period. These findings would suggest that the continuous infusion of high dose ara-C may be useful in the treatment of acute leukemia and CML in blast crisis.
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PMID:Prolonged high dose ARA-C infusions in acute leukemia. 328 17

Twenty-one patients with chronic myelogenous leukemia (CML) in blastic transformation underwent 22 remission induction attempts with high-dose cytosine arabinoside (ara-C), administered as a two-hour infusion of 3 g/m2 for six to 12 doses. Ara-C doses were administered every 12 hours in 15 patients and every six to ten hours in six patients. Median patient age was 35 years (range, 20 to 62). The median duration of benign phase was 25 months (range, 0 to 167). Morphology of blast crisis blast cells was myeloid in 15 patients and lymphoid in six. Five patients achieved complete remission (CR), three had partial remission (PR), and one had hematologic improvement, for an overall response rate of 41%. Median remission duration was 2.5 months (range, 0.5 to 6 months). Survival duration was 6 months for responding patients and 1.5 months for those with resistant disease. The response rate was similar for patients with myeloid and lymphoid blast crisis (31% v 50%, respectively). The response rate was significantly higher for patients whose benign phase was less than 1 year (75% v 21%, P = .05) and who had prolonged marrow aplasia after ara-C (86% v 27%, P = .05). Myelosuppression was the major dose-limiting toxicity, and cerebellar toxicity occurred in two patients. Intracellular ara-C 5'-triphosphate (ara-CTP) levels were similar in blood and bone marrow leukemic cells and were slightly greater in the cells of responding patients compared to those with resistant disease. We conclude that high-dose ara-C is an effective regimen for CML blast crisis, resulting in a substantial response rate but modest remission duration. Its combination with other agents may further improve the prognosis of patients with this resistant disease.
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PMID:High-dose cytosine arabinoside: treatment and cellular pharmacology of chronic myelogenous leukemia blast crisis. 345 11

Considering the good penetration of systemic high-dose ara-C (HDara-C) into the CNS, we used this approach for treating overt meningeal leukemia, either isolated or with concurrent extraneurologic disease, in 15 adults with high-risk acute lymphoblastic leukemia (ALL), one adult with lymphoid blast crisis of chronic granulocytic leukemia (LBC-CGL), and four adults with poor-prognosis non-Hodgkin's lymphoma (NHL). Treatment consisted of ara-C, 3 g/m2 every 12 hours by three-hour infusion for eight doses followed by a second course of four doses on day 21. Remitters received consolidation with monthly courses of HDara-C for four doses. Additional systemic multi-drug reinduction therapy and direct CNS treatment with intrathecal methotrexate (IT MTX) and cranial irradiation (CRT) was administered to the three remitters last treated. Thirteen of 20 patients (65%) achieved complete remission (CR): seven of seven patients with isolated meningeal leukemia and six of 13 patients with concurrent CNS and bone marrow disease. Of the remaining seven patients, five had a complete CSF clearing with persistent marrow disease. In all cases there was prompt resolution of neurologic signs and symptoms. The median duration of CR was 5 months (range 2 to 8 months). The most significant toxicity seen was myelosuppression, which was predictable and manageable. Nonhematologic toxicity was generally acceptable and included moderate nausea and vomiting, diarrhea, drug fever, transient liver dysfunction, and dermatitis. No cases of CNS toxicity occurred. There were no treatment-related deaths. Disease-free survival was limited by marrow relapse, either isolated or with concurrent CNS disease. No instances of isolated meningeal relapse occurred. These results obtained in a poor-risk subset of patients indicate that HDara-C is an effective treatment for the induction of remission in ALL and NHL with meningeal leukemia. Therefore, HDara-C should be considered for inclusion in multiagent consolidation programs for patients at high risk for CNS disease.
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PMID:Systemic high-dose ara-C for the treatment of meningeal leukemia in adult acute lymphoblastic leukemia and non-Hodgkin's lymphoma. 346 Nov 34

A Phase II study of high dose cytosine arabinoside (ara-C) with different schedules in patients with recurrent acute myelogenous leukaemia (AML) and myeloid blast crisis of chronic myeloid leukaemia has been conducted at St. Bartholomew's Hospital. Ara-C was infused continuously for seven days at a dose of 100-200 mgs/m2 daily from day 1 with 1-2 g/m2 (3 h infusions) twice daily from day 2 for six days. Nineteen patients with acute myelogenous leukaemia and four patients with myeloid blast crisis of chronic myeloid leukaemia (CML) were treated. Complete remission was achieved in 4/19 patients with AML and in a further four patients an antileukaemic effect was observed. There were eight early deaths and three patients failed to show any response to therapy. All four patients with myeloid blast crisis of CML failed to respond to the treatment. Toxicity was considerable with gastro-intestinal and hepatotoxicity being the most serious problems. Pharmacokinetic studies revealed that mean basal levels achieved with continuous infusion prior to high-dose ara-C were 10(2) ng/ml and peak levels were of the order of 10(4) ng/ml. The considerable toxicity of the regimen, without clinical advantage over less intensive programmes, resulted in its termination.
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PMID:Cytosine arabinoside in the management of recurrent leukaemia. 347 99

Twenty-seven patients with acute leukemia have been treated by sequential 6-day courses of thymidine (30 g/m2 by i.v. continuous infusion, days 1 and 4) and 1-beta-D-arabinofuranosylcytosine (ara-C) (200 mg/m2 by i.v. continuous infusion, days 2,3,5, and 6). Of 25 evaluable patients 4 achieved a complete remission: one of 9 for acute myelogenous leukemia; and 3 of 14 in the blastic crisis of chronic myelocytic leukemia. Six minor responses were also observed. Toxicity was mainly hematological and did not appear to be higher than that expected from ara-C alone. However, thymidine infusions gave rise to headache and somnolence. The clinical benefit of such treatment seems to be limited to the blastic crisis of chronic myelocytic leukemia. Parallel cytokinetic and biochemical studies were performed in order to assess the cytokinetic and metabolic changes induced by both drugs and to correlate them with the clinical response. Recruitment of cells into the S-phase fraction was observed following the first thymidine infusion in the two complete responders and in three of the five nonresponders studied. In contrast to this high pretherapeutic levels of S-phase fraction were observed in most minor responders and in some nonresponders with further decrease following the thymidine infusion. Recruitment of cells into S phase therefore appeared to be an important but not sufficient factor for prediction of complete response to ara-C. Responders in contrast to most nonresponders were characterized by a higher intracellular level of ara-C and its metabolites following the first 24-h infusion of the drug. Deoxythymidine triphosphate and deoxycytidine triphosphate pools were also measured before and during treatment in order to assess if nucleotide pool variations induced by the administration of thymidine can in fact correlate with the intracellular alteration in ara-C metabolism and with clinical response. The level of deoxycytidine triphosphate pools before treatment showed marked interpatient variations but did not correlate with response. As expected, thymidine infusion induced a rise in the deoxythymidine triphosphate pool and a decrease in deoxycytidine triphosphate. The pools, however, generally returned promptly to the pretherapeutic level 24 h after the end of the infusion of thymidine. There were no significant differences between responders and nonresponders in the modulation of these pools.
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PMID:Modulation of 1-beta-D-arabinofuranosylcytosine metabolism by thymidine in human acute leukemia. 402 95

Cytidine deaminase, an enzyme that catalyses the deamination of both cytidine and its nucleoside analogues including the antineoplastic agents cytosine arabinoside (ara-C) and 5-azacytidine (5-azaC), has been partially purified from normal and leukemic human granulocytes. The purification procedure included heat precipitation at 70 degrees C, ammonium sulfate precipitation, calcium phosphate gel ion exchange, and Sephadex G-150 gel filtration. The enzyme has mol wt 51,000, isoelectric pH of 4.8, and maximum activity over a broad pH range of 5-9.5. The enzyme is stabilized by the presence of the sulfhydryl reagent, dithiothreitol. Cytidine deaminase from normal human granulocytes has a greater affinity for its physiologic substrate cytidine (K(m) = 1.1 x 10(-5) M) than for ara-C (8.8 x 10(-5) M) or 5-azaC (4.3 x 10(-4) M). Halogenated analogues such as 5-fluorocytidine and 5-bromo-2'-deoxycytidine also exhibited substrate activity, with maximum velocities greater than that of the physiologic substrates cytidine and deoxycytidine. No activity was observed with nucleotides or deoxynucleotides. The relative maximum velocity of the enzyme for cytidine and its nucleoside analogues remained constant during purification, indicating that a single enzyme was responsible for deamination of these substrates. Tetrahydrouridine (THU) was found to be a strong competitive inhibitor of partially purified deaminase with a K(i) of 5.4 x 10(-8) M. The biochemical properties of partially purified preparations of cytidine deaminase from normal and leukemic cells were compared with respect to isoelectric pH, molecular weight, and substrate and inhibitor kinetic parameters, and no differences were observed. However, normal circulating granulocytes contained a significantly greater concentration of cytidine deaminase (3.52+/-1.86 x 10(3)/mg protein) than chronic myelocytic leukemia (CML) cells (1.40+/-0.70 x 10(3) U/mg protein) or acute myelocytic leukemia (AML) cells (0.19+/-0.17 x 10(3) U/mg protein). To explain these differences in enzyme levels in leukemic versus normal cells, the changes in cytidine deaminase levels associated with maturation of normal granulocytes were studied in normal human bone marrow. Myeloid precursors obtained from bone marrow aspirates were separated into mature and immature fractions by Ficoll density centrifugation. Deaminase activity in lysates of mature granulocytes was 3.55-14.2 times greater than the activity found in the lysates of immature cells. Decreased enzyme activity was also found in immature myeloid cells from a patient with CML as compared to mature granulocytes from the same patient. These observations support the conclusion that the greater specific activity of cytidine deaminase in normal mature granulocytes as compared to leukemic cells is related to the process of granulocyte maturation rather than a specific enzymatic defect in leukemic cells.
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PMID:Purification and properties of cytidine deaminase from normal and leukemic granulocytes. 452 17

Twenty-six patients with acute leukaemia and 14 with high-grade lymphoma received cytosine arabinoside (ara-C) at a twice daily dose of 2 g/m2 administered as a 3-h infusion. Thirty-four patients received 12 doses and six electively received four doses only. Complete remission was achieved in six of seven patients with acute myelogenous leukaemia (AML), one of two evaluable patients with blast crisis of chronic myeloid leukaemia and three of eight patients with acute lymphoblastic leukaemia (ALL). Three further patients with ALL had only minimal bone marrow infiltration after one cycle, toxicity precluding administration of a second. Three patients with AML who received four doses only showed no evidence of response. Four of 14 patients with lymphoma who received 12 doses, entered complete remission. Five additional patients died with minimal residual disease whilst severely neutropenic. A complete and a partial response were seen in two patients with immunoblastic and centrocytic lymphoma respectively who received four doses. These results confirm the activity of high-dose ara-C in patients with AML and suggest that it may also be a potentially useful agent in ALL and high-grade lymphoma, especially as the incidence of CNS toxicity is lower than that reported at higher doses.
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PMID:High-dose cytosine arabinoside: response to therapy in acute leukaemia and non-Hodgkin's lymphoma. 669 29

Deoxycytidine kinase (dCK) is important in the 5'-phosphorylation of deoxynucleoside analogs. Like dCK, thymidine kinase 2 (TK2) catalyzes the initial step of the phosphorylation of dcyd to dCTP. Thymidine is a strong inhibitor of the dCK activity of TK2. We examined the ratio of the dcyd phosphorylation carried out by dCK and by TK2 (dCK/TK2-dcyd) in lymphocytes from CLL patients and from donors. In the CLL lymphocytes we found a 3.5-fold average increase. Therefore, we conclude that addition of thymidine in the treatment of CLL with deoxynucleoside analogs will not be of any advantage. Furthermore, our results can explain earlier findings in CML and AML lymphocytes where the ara-C phosphorylation was twice the dcyd phosphorylation.
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PMID:Increased ratio between deoxycytidine kinase and thymidine kinase 2 in CLL lymphocytes compared to normal lymphocytes. 763 89

Twenty-five patients with CML (chronic phase (CP): 15 patients; accelerated phase (AP): 10 patients) at a median of 40 months after diagnosis and ineligible for allogeneic BMT, received an intensive chemotherapy regimen consisting of idarubicin, intermediate-dose ara-C and etoposide (ICE protocol). All patients had previously received alpha-interferon and only two patients had had partial cytogenetic response. During recovery from chemotherapy-induced aplasia, blood progenitors cells (BPC) were harvested by leukapheresis. All metaphases were found to be Ph-negative in the collection of 12 of 25 (48%) patients (CP: 9 of 15 (60%), AP: 3 of 10 (30%)) and a decrease of < 50% Ph-positive metaphases was seen in an additional five (CP: 4 patients; AP: 1 patient). The percentage of complete Ph-disappearance was 66% in patients receiving this procedure within the first 2 years of diagnosis and 30% in those treated after the second year of diagnosis. So far, the Ph-negative collections have been used in 9 patients (CP: 8 patients; AP: 1 patient) as autograft after conditioning with total body irradiation/etoposide/CY. Seven of 9 patients engrafted and 5 are alive and well, Ph-negative at 2+, 3+, 6+, 10+ and 18+ months.
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PMID:Collection of 'normal' blood repopulating cells during early hemopoietic recovery after intensive conventional chemotherapy in chronic myelogenous leukemia. 769 24

P-glycoprotein (P-gp) expression in mononuclear bone marrow cells was analyzed in 119 patients, including 60 with chronic myelogenous leukemia (CML), 48 with myelodysplastic syndromes (MDS), and 11 with acute myelogenous leukemia (AML). For P-gp measurement an immunocytological method using monoclonal antibodies C219, 4E3, and MRK 16 and the reverse transcription-polymerase chain reaction technique were applied. According to our results obtained in healthy volunteers using the immunocytological method, the limit for P-gp overexpression was set at > or = 10% P-gp-positive mononuclear bone marrow cells and at > or = 30% P-gp-positive mononuclear peripheral blood cells. All 42 CML patients in chronic phase had normal P-gp expression. P-gp overexpression was demonstrated in four of six patients in accelerated myelogenous blast cell phase and in four of 12 CML-BC patients. Of eight CML patients in blast crisis (BC) with normal P-gp expression, partial remission was achieved in three and minor response in five after prednisone/vindesine therapy. All four of the 12 CML-BC patients with P-gp overexpression did not respond to this therapy. Normal P-gp expression was seen in 41 (85.4%) of 48 untreated MDS patients. While P-gp overexpression did not develop during therapy in any of the myelodysplastic syndrome patients treated with low-dose ara-C alone, four of eight treated with low-dose ara-C plus GM-CSF and four of 11 treated with low-dose ara-C and IL-3 developed P-gp overexpression after therapy. Furthermore, 11 AML patients at primary diagnosis, including five AML patients with P-gp overexpression, who were treated with idarubicin, vepesid, and cytarabine V (ara-C) showed a complete remission. Additionally, one daunorubicin-cytarabine-pretreated refractory AML patient was treated with the oral form of the P-gp modulator drug dexniguldipine and achieved complete remission for a duration of 7 months. Our results suggest that in CML patients in BC, P-gp expression influences outcome after therapy. Further more, studies in a larger series of patients are necessary to prove the efficacy and toxicity of idarubicin/vepesid and cytardbine--or dexniguldipine-containing--therapy in relation to P-gp expression of AML patients.
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PMID:Clinical importance of P-glycoprotein-related resistance in leukemia and myelodysplastic syndromes--first experience with their reversal. 791 49


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