Pharmacokinetics of cytosine arabinoside in patients with acute myeloid leukaemia.

1 The pharmacokinetics of cytosine arabinoside were studied after a single i.v. bolus of 2 mg/kg ara-C in patients with newly diagnosed untreated AML, using a bioassay and GC-MS method to measure the plasma concentrations. 2 Most patients showed a bi- or tri-phasic decline in plasma concentrations with time. Plasma clearance was 3.9 to 18.1 l/min as measured by the GC-MS method, and terminal half-lives varied from 7--107 min. 3 There was poor correlation of the GC-MS assay with the bioassay, probably because the latter was interfered with by the release of endogenous nucleosides from blasts after after ara-C. 4 Plasma concentrations were measured by GC-MS during continuous infusions in 14 patients. Plasma clearances were much lower than after a bolus, 0.39 to 5.25 l/min. 5 There was no correlation of response (remission or fall in peripheral blast count) with exposure to ara-C calculated from infusion dose, clearance and duration of infusion. 6 This study shows that ara-C pharmacokinetics varies markedly from patient to patient and that there is a wide range in the plasma concentrations associated with therapeutic response.     

Pharmacokinetics of nimustine, cytosine arabinoside, and methotrexate in cerebrospinal fluid during cerebrospinal fluid perfusion chemotherapy

This report investigates the pharmacokinetics of nimustine (ACNU), cytosine arabinoside (Ara-C), and methotrexate (MTX) in cerebrospinal fluid (CSF) during CSF perfusion chemotherapy. A 47-year-old Japanese man with spinal cord, cerebellum and brain stem dissemination of oligo-astrocytoma received nine courses of CSF perfusion chemotherapy with ACNU, Ara-C, and MTX. A CSF perfusion chemotherapy solution was perfused via an Ommaya reservoir in the ventricle, and was discharged by drainage though another Ommaya reservoir in the lumbar spinal canal. CSF samples via Ommaya reservoirs in the lumbar spinal canal were obtained during the fifth and eighth courses of treatment. The concentrations of ACNU and Ara-C in CSF were measured by HPLC, and the MTX concentrations by fluorescence polarization immunoassay. In the fifth course of treatment, a CSF injection chemotherapy solution, consisting of 5 mg of ACNU dissolved in 20 ml of artificial CSF, was injected over a few minutes using the Ommaya reservoir. Next, a CSF perfusion chemotherapy solution, consisting of 10 mg of Ara-C and 5 mg of MTX dissolved in 100 ml of artificial CSF, was perfused over 2 h. In the eighth course of treatment, a CSF perfusion chemotherapy solution, consisting of 5 mg of ACNU, 10 mg of Ara-C and 5 mg of MTX dissolved in 100 ml of artificial CSF, was perfused over 2 h. In both treatments, the highest concentrations of Ara-C and MTX in CSF were observed 1 or 2 h after the end of perfusion, with the values of each drug being similar. The CSF AUCs of Ara-C and MTX in each treatment were of similar values. Although the highest concentration of ACNU in CSF was observed in the fifth treatment 1 h after injection (an injection chemotherapy of ACNU plus a perfusion chemotherapy of Ara-C and MTX), the concentration of ACNU in CSF was undetectable in the eighth treatment (a perfusion chemotherapy of ACNU, Ara-C and MTX). We were successful in administering all anticancer drugs, and reaching a level of over 1.0 microg/ml concentration in CSF of the lumbar spinal canal, using an injection chemotherapy of ACNU plus a perfusion chemotherapy of Ara-C and MTX; this was done even though the drugs, in particular ACNU, underwent some perfusion-period dependent decomposition.     

Pharmacokinetics of nimustine, methotrexate, and cytosine arabinoside during cerebrospinal fluid perfusion chemotherapy in patients with disseminated brain tumors

Objective: This study was conducted to evaluate the pharmacokinetics of anticancer drugs in cerebrospinal fluid (CSF) perfusion chemotherapy. Methods: We administered CSF perfusion chemotherapy with nimustine (ACNU), methotrexate (MTX), and cytosine arabinoside (Ara-C) to three patients with disseminated malignant brain disease. The drugs were infused via Ommaya's reservoirs to the lateral ventricle and removed by drainage from the temporal lobe or lumbar spine. CSF and plasma concentrations of the anticancer drugs were determined by high-performance liquid chromatography and fluorescence polarization immunoassay. Results: The concentrations of anticancer drugs in the discharged CSF peaked about 40 min after the start of a 1-h CSF perfusion. After the perfusion, the drug level in CSF decreased exponentially in a monophasic manner. ACNU and Ara-C were not detectable in the discharged CSF in the temporal lobe at 6 h and 48 h after perfusion, respectively, but MTX was detectable at 48 h. The maximum concentration ratio of anticancer drugs and the duration of perfusion were inversely correlated. The plasma concentrations of anticancer drugs were much lower than those in CSF. The half-life of ACNU was very short (0.2–1.1 h), whereas the half-lives of MTX and Ara-C were relatively long (2.81–13.5 h and 1.84–6.25 h, respectively). The half-lives of the anticancer drugs in CSF tended to decrease with repeated CSF perfusion chemotherapy. Conclusion: Results suggest that CSF perfusion chemotherapy enables a high concentration of anticancer drug to be administered for dissemination in the spinal cord within a short period of time, with minimal adverse effects. Received: 17 September 1996 / Accepted in revised form: 21 April 1998     

Pharmacokinetics of cytosine arabinoside, methotrexate, nimustine and valproic acid in cerebrospinal fluid during cerebrospinal fluid perfusion chemotherapy

This report investigates the pharmacokinetics of cytosine arabinoside (Ara-C), methotrexate (MTX), nimustine (ACNU) and valproic acid (VPA) in cerebrospinal fluid (CSF) during CSF perfusion chemotherapy. A 28-year-old Japanese woman with disseminated glioblastoma was, on admission, on a stable oral regimen of prolonged-release VPA tablets (Depakene-R), 400 mg twice a day, for seizure control. Twelve courses of CSF perfusion chemotherapy with Ara-C, MTX, and ACNU were administered. Plasma samples and CSF samples via Ommaya reservoirs were obtained during the eleventh course of treatment. The Ara-C and ACNU concentrations were measured by HPLC. The MTX and VPA concentrations were measured by fluorescence polarization immunoassay. During CSF perfusion chemotherapy, the highest CSF concentrations of Ara-C, MTX, and ACNU were observed at the end of the perfusion and decreased in a monoexponential pattern. The half-lives of Ara-C, MTX, and ACNU were 2.65, 3.52, and 0.71 h, respectively. No anticancer drugs were detectable in plasma during CSF perfusion chemotherapy. Before CSF perfusion chemotherapy, the free VPA concentration in plasma was 14.4% of the total VPA concentration. The mean total and free VPA concentrations in plasma were 78.0+/-0.8 and 10.9-0.3 microg/ml, respectively. The free VPA concentrations in plasma and in CSF were of similar values. At the end of perfusion, the lowest free VPA concentration in CSF was 30.3% of that at the initiation of perfusion. The free VPA concentrations in CSF at 3, 7, 23, and 47 h after the end of perfusion were 79.8, 94.5, 100.9, and 100.9% respectively of that at the initiation of perfusion. During CSF perfusion chemotherapy, the ratio of free VPA concentrations to the total VPA in CSF was 86.3+/-6.9%. The VPA concentrations in CSF rapidly decreased during the CSF perfusion but recovered to pre-treatment levels within 7 h.     

（—）表没食子儿茶素没食子酸酯增强阿糖胞苷对HL—60细胞的抗肿瘤活性

AIM: To study the potentiation of anti-tumor effect induced by cytosine arabinoside (AraC) with (-)-epigallocatechin-3-gallate (EGCG). METHODS: Growth curve method and MTT assay were used to measure the cytotoxic effect of AraC alone or in combination with EGCG on HL-60 cells. Flow cytometry was used to study the cell cycle distribution of HL-60 cells. Nullification assay was used to examine whether EGCG would nullify the rescue effect of deoxycytidine (dCdR) to AraC. Western blot analysis was employed to investigate bcl-2 expression. Intracellular Ca2+ assay was evaluated. RESULTS: Inhibition of HL-60 cell proliferation induced by AraC was enhanced by EGCG, with multiplication time prolonging from 48 h to 70 h and growth saturation density decreasing from 5.78 to 5.54. The MTT results indicated that IC50 was decreased from (0.34+/-0.29) micromol/L (AraC alone) to (0.11+/-0.09) micromol/L (P<0.05) (in combination with EGCG). Cell cycle analysis indicated that AraC blocked HL-60 cells in G1 phase, inhibited cells in S phase. EGCG had no effect on cell cycle at the current concentration, but enhanced the cell arrest by AraC. Nullification assay indicated that IC50 was 0.03 micromol/L (AraC alone), increased to 0.02 mmol/L when rescued with dCdR, and finally decreased to 4.8 micromol/L when addition with EGCG. The expression of bcl-2 protein was down-regulated after treatment with AraC in combination with EGCG. The intracellular Ca2+ was increased after treatment by AraC in combination with EGCG. CONCLUSION: The combination with EGCG could enhance the anti-tumor effect of AraC on HL-60 cells.     

Carboplatinum and cytosine arabinoside in patients with disseminated malignant melanoma

Summary Eighteen patients with disseminated malignant melanoma were treated with a combination of carboplatinum and cytosine arabinoside. There were 14 males and 4 females with median age of 51 years (range 36–68 years). We observed 4 complete responses (CR) and 3 partial responses (PR). Lung metastases, cutaneous and subcutaneous metastases responded more often, while liver and lymph node metastases did not respond. Two groups of toxicities were observed: gastrointestinal and hematological. Only nine grade 3 toxicities were observed. Response rates and low toxicity we observed during this study warrant its use for patients with disseminated malignant melanoma comparing it in a future studies with DTIC containing regimens.     

Recent and remote spatial memory in mice treated with cytosine arabinoside

Clinical studies suggest that chemotherapy is associated with long-term cognitive impairment in some patients. A number of underlying mechanisms have been proposed, however, the etiology of chemotherapy-related cognitive dysfunction remains relatively unknown. As part of a multifaceted approach, animal models of chemotherapy-induced cognitive impairment are being developed. Thus far, the majority of animal studies have utilized a rat model, however, mice may prove particularly beneficial in studying genetic risk factors for developing chemotherapy-induced cognitive impairment. Various chemotherapy agents, including cytosine arabinoside (Ara-C), have been found to impair remote spatial memory in rats in the Morris water maze. The present study evaluated the effects of Ara-C on remote (30 d) spatial memory in mice. In addition, the possibility that time relative to chemotherapy treatment may modulate the effect of chemotherapy on spatial learning and/or recent (1 d) memory was explored. Male C57BL/6J mice received either Ara-C (275 mg/kg i.p. daily for 5 days) or saline. Spatial learning and memory was assessed using the Morris water maze. Half the mice performed a remote (30 d) memory version of the task and the other half performed a recent (1 d) memory version of the task. The experiment was designed such that the probe trial for the recent memory version occurred on the same day relative to chemotherapy treatment as the remote memory version. Despite significant toxic effects as assessed by weight loss, Ara-C treated mice performed as well as control mice during acquisition, recent memory, and remote memory portions of the task. As are some humans, C57BL/6J mice may be resistant to at least some aspects of chemotherapy induced cognitive decline.     

Involvement of tryptophan residues of lysozyme in its binding with cytosine arabinoside

Cytosine-1-β-d-arabinofuronaside, an antileukemic drug and hen egg white lysozyme (E.C. 3.2.1.17) form a 1:1 complex with K_a 1.2 × 10⁴ M^?1 at low drug concentrations. However, association was cooperative in nature at high concentrations with values of K_a = 1.8 × 10⁴ M^?1 and N = 2. Involvement of tryptophan in the drug protein complex was evident from fluorescence quenching and from the association of the drug with free tryptophan with a K_a = 1.5 × 10⁴ M^?1. Modification of tryptophan 108 reduced the binding by 89% suggesting a major role for this residue in the binding process. Oxidation of tryptophan 62 and acetylation of lysine residues also decreased the affinity of the drug to the protein by 55 and 66% respectively. Binding improved with increase in temperature and positive values for change in enthalpy and entropy were obtained. Ara-C inhibited lysozyme activity noncompetitively.     

Targeting of daunomycin using biotinylated immunoliposomes: Pharmacokinetics,tissue distribution and in vitro pharmacological effects

Biotinylated immunoliposomes were prepared by a non-covalent (biotin-streptavidin) coupling procedure and conjugated to the OX26 monoclonal antibody directed against the rat transferrin receptor. In vitro, these biotinylated immunoliposomes were used to by-pass P-glycoprotein in multidrug-resistant RBE4 brain capillary endothelial cells and thereby to achieve 2- to 3-fold higher intracellular accumulation of liposomal daunomycin as compared to free drug. The extent of cellular uptake of liposomal daunomycin was dose- and time-dependent, was inhibited by competition with unbound OX26 and was associated with a pharmacological (i.e. cytotoxic) effect. Cytotoxic effects of liposomal formulations of daunomycin, in contrast to the free drug, were apparent only after prolonged incubation periods being indicative of a slow intracellular unpacking and release of liposomal daunomycin. Pharmacokinetics and tissue distribution studies in the rat revealed brain accumulation of daunomycin in OX26-immunoliposomes to higher levels as compared to brain uptake of free daunomycin, or daunomycin incorporated within pegylated liposomes or within unspecific IgG_2a isotype control immunoliposomes. Such OX26-mediated effects were not observed in other tissues such as spleen, liver, muscle or kidney.     

The pharmacokinetics of subcutaneous cytosine arabinoside in patients with acute myelogenous leukaemia.

1 The pharmacokinetics of subcutaneous cytosine arabinoside were compared with bolus intravenous injection and intravenous infusion in five patients with acute myelogenous leukaemia. 2 Subcutaneous cytosine arabinoside was rapidly absorbed and then declined biexponentially with initial and terminal half-lives similar to intravenous bolus injection. 3 Cytosine arabinoside levels declined rapidly after intravenous bolus and subcutaneous bolus injection, and fell below steady state infusion levels after a mean time of 40 min (intravenous bolus) and 100 min (subcutaneous injection).     

Studies on the relationship between therapeutic schedule and antitumor effect of etoposide and cytosine arabinoside in murine L1210 leukemia

The sequence dependency of the antitumor effect of etoposide and ara-C was investigated against the L1210 ascites tumor in BDF1 mice. Etoposide (7.5 mg/kg or 15 mg/kg) and ara-C (25 mg/kg or 500 mg/kg) were administered intraperitoneally on days 1, 4 and 7 after inoculation of L1210 with or without time interval of 3 or 6 h. Antitumor effect was decided for cure rate and post inoculation survival time of the mice died of tumor. Six hours pretreatment with 15 mg/kg of etoposide followed by 500 mg/kg of ara-C yielded 100% of cure rate, but only 20% of cure rate was obtained with the reverse sequence. Simultaneous administration of etoposide and ara-C produced 70% of cure rate. At every dosage examined, pretreatment with etoposide given 6 hr before ara-C was the most effective antitumor schedule in L1210 leukemia.     

Effect of organic isothiocyanates on the P-glycoprotein- and MRP1-mediated transport of daunomycin and vinblastine

Purpose. Organic isothiocyanates (ITCs), or mustard oils, are non-nutrient components present in the diet, especially in cruciferous vegetables. The purpose of this investigation was to examine the effect of ITCs on P-glycoprotein (P-gp)- and multidrug resistance-associated Protein (MRP1)-mediated transport in multidrug resistant (MDR) human cancer cell lines. Methods. The direct effect of ITCs on the 2-h cellular accumulation of daunomycin (DNM) and vinblastine (VBL), substrates for both P-gp and MRP1, were measured in sensitive and resistant MCF-7 cells and in PANC-1 cells. Resistant MCF-7 cells (MCF-7/ADR) overexpress P-gp whereas PANC-1 cells overexpress MRP1. The following compounds were evaluated: allyl-, benzyl-(BITC), hexyl-, phenethyl-(PEITC), phenyl-, 1-naphthyl-(NITC), phenylhexyl-, phenylpropyl-, and phenylbutyl-ITC, sulforaphane, erucin, and erysolin. Results. NITC significantly increased the accumulation of DNM and VBL in both resistant cell lines, but had no effect on DNM accumulation in sensitive MCF-7 cells. VBL accumulation in resistant MCF-7 cells was increased 40-fold by NITC whereas that in PANC-1 cells was increased 5.5-fold. Significant effects on the accumulation of DNM and VBL in resistant MCF-7 cells were also observed with benzyl-isothiocyanate whereas PEITC, erysolin, phenylhexyl-ITC, and phenylbutyl-ITC increased the accumulation of DNM and/or VBL in PANC-1 cells. Overall, the inhibitory activities of these compounds in MCF-7 cells and PANC-1 cells were significantly correlated (r²= 0.77 and 0.86 for DNM and VBL, respectively). Significant effects on accumulation were generally observed with the ITCs at 50 M concentrations, but not at 10 M concentrations. Conclusions. One strategy to enhance the effectiveness of cancer chemotherapy is to reverse the MDR phenomena. Our results indicate that certain dietary ITCs inhibit the P-gp- and the MRP1-mediated efflux of DNM and VBL in MDR cancer cells and suggest the potential for diet-drug interactions.