Intrasubject variation in children of ifosfamide pharmacokinetics and metabolism during repeated administration

 The aim of this study was to investigate intrasubject variability in ifosfamide (IFO) pharmacokinetics and metabolism which may influence clinical effect, since the pharmacology of this drug is dependent on metabolism. A group of 11 patients (ages 1–16 years) were studied on at least two occasions. IFO, 9 gm^-2, was administered as a continuous infusion over 72 h. Plasma and urine samples were collected and concentrations of IFO and its metabolites were determined. Comparisons were made between courses in the same subject, allowing for differences in age and prior IFO treatment. There was a wide variation in drug (twofold) and metabolite (up to tenfold) AUCs between courses in the same patient. Although some patients did show an increase in clearance between courses (up to threefold), there was no significant consistent change in overall pharmacokinetics among the different courses studied in the same patient. There was a significant decrease (up to 63%) in the AUC of the inactive metabolite 3-dechloroethylifosfamide (3-DCI) in later courses compared with the first course studied (P=0.032, paired t-test). This was matched by an increase in the AUC of the total dechloroethylated metabolites with course (P=0.015, paired t-test). None of the other metabolites measured showed any consistent change in plasma or urine levels between courses. Overall, the AUC of parent drug correlated with age (r ²=0.86, P=0.011), and postinfusion half-life correlated with plasma bilirubin (r ²=0.89, P=0.007). This study demonstrated large and seemingly unpredictable intrasubject variability in IFO pharmacokinetics and metabolism during repeated administrations. Investigations relating the clinical effects of IFO to pharmacokinetics and metabolism must take this variation into account. Received: 13 January 1995/Accepted: 9 October 1995     

A combination of ifosfamide and mitoxantrone as salvage therapy in patients with advanced ovarian cancer

 Ifosfamide (IFX) and mitoxantrone (MXN) have been found to be effective against advanced epithelial ovarian cancer. The combination of these two agents has not yet been tested in this setting but seems to be rational, given the different action mechanisms of these drugs and their not completely overlapping side effects. Between June 1987 and November 1991, 37 patients with advanced ovarian carcinoma recurrent or refractory to primary cisplatin-based chemotherapy entered the study. Therapy consisted of MXN, given i.v. at 10 mg/m² on day 1 and IFX given i.v. at 2,000 mg/m² per day on days 1–3 with mesna. The cycles were repeated every 3 weeks. Four patients achieved a complete remission and three achieved a partial remission, for response rates of 18.9% [95% confidence interval (CI) 6.3–31.5%] in the whole sample and 38.8% (95% Cl 16.3–61.3%) in the subset of 18 patients responding to first-line cisplatin. No response was obtained in the remaining patients, whose disease was refractory to primary platinum-based chemotherapy. Clinically significant toxicity (WHO grades 3–4) included leukopenia in 46% of the patients and anemia in 32.5%. The non-hematologic toxicity was mild, except for reversible alopecia (57%) and nausea and vomiting (48.5%). This regimen seems attractive for patients who have either failed or not received platinum retreatment, especially when limiting neurotoxicity occurs. Further studies are warranted to establish the relative impact of both of these agents. Received: 9 September 1995/Accepted: 15 December 1995     

Effect of ifosfamide on intracellular glutathione levels in peripheral blood lymphocytes and its correlation with therapeutic response in patients with advanced ovarian cancer

 The successful outcome of ovarian cancer therapy with alkylating agents and cisplatin is seriously hampered by the development of acquired drug resistance. An increase in intracellular glutathione (GSH) levels in cancer cells is one of the major mechanisms involved. Depletion of GSH overcomes drug resistance and restores the chemosensitivity of malignant cells. Ifosfamide (IFEX), an alkylating agent, has been demonstrated to decrease intracellular GSH levels in vitro in malignant cell lines and in vivo in peripheral blood lymphocytes (PBL) obtained from patients with cancer. We studied the effect of IFEX on intracellular GSH levels in PBL isolated from patients with advanced ovarian cancer who were receiving chemotherapy. A total of 14 patients received IFEX plus mesna as a continuous infusion (1 g/m² per day) for 6 consecutive days and cisplatin (100 mg/m²) as a 24-h continuous infusion on the 6th day. PBL were isolated prior to the initiation of chemotherapy and on the 3rd and 6th days of IFEX infusion. Intracellular GSH levels were determined by a modification of Tietze’s method. IFEX caused a 20% or greater suppression of intracellular GSH levels in nine patients, eight of whom achieved complete remission of their disease. Six patients responded poorly to this chemotherapeutic regimen, five of whom showed no significant suppression of GSH levels. These data suggest that IFEX suppresses intracellular GSH levels in PBL from patients with ovarian cancer and that this suppression correlates closely with the subsequent clinical outcome. Received: 16 March 1996 / Accepted: 25 July 1996     

Pharmacokinetics of trofosfamide and its dechloroethylated metabolites

 To contribute to effective and safe outpatient treatment, we investigated the metabolism of trofosfamide (Trofo) after oral administration. We analyzed Trofo metabolism in 15 patients aged from 3 to 73 years who were treated with 150 or 250 mg/m² Trofo in combination with etoposide. Serum samples were collected with 13 patients after oral administration, and Trofo and its dechloroethylated metabolites were quantified by gas chromatography. Urine samples were collected from five patients and analyzed by same method. Ifosfamide (Ifo) was the main metabolite in serum and urine (AUC_Trofo:AUC_Ifo 1:13), whereas cyclophosphamide (Cyclo) was formed in smaller amounts (AUC_Ifo:AUC_Cyclo 18:1). Ifo and Cyclo were further oxidized in the chloroethyl side chains to form 2- and 3-dechloroethylifosfamide in varying quantities. The urinary excretion of Trofo and its dechloroethylated metabolites amounted to about 10% of the total dose. Our results confirm former in vitro observations about the metabolism of Trofo. The main side-chain metabolites Ifo and Cyclo can be further activated by oxidation and formation of their respective phosphoramide mustards. Hence, Trofo is an interesting agent for oral chemotherapy. Received 21 July 1996 / Accepted: 11 November 1996     

Urinary excretion of ifosfamide, 4-hydroxyifosfamide, 3- and 2-dechloroethylifosfamide, mesna, and dimesna in patients on fractionated intravenous ifosfamide and concomitant mesna therapy

 The oxazaphosphorine antineoplastic ifosfamide (IF) is metabolized by two different initial pathways: ring oxidation (“activation”), forming 4-OH-IF (“activated IF”), and side-chain oxidation with liberation of chloroacetaldehyde (CAA), forming the inactive metabolites 3-dechloroethylifosfamide or 2-dechloroethylifosfamide (3-DCE-IF, 2-DCE-IF). 4-OH-IF and 4-OH-IF-derived acrolein are thought to be responsible for IF-induced urotoxicity (hemorrhagic cystitis), whereas CAA may be involved in IF-associated nephrotoxicity (renal tubular damage). The thiol compound 2-mercaptoethane sulfonate sodium (mesna) has proved to inactivate sufficiently the urotoxic metabolites of oxazaphosphorine cytostatics and is therefore routinely given to patients receiving IF chemotherapy. The cumulative urinary excretion of IF, 4-OH-IF, 3-DCE-IF, 2-DCE-IF, mesna, and its disulfide dimesna was studied in 11 patients with bronchogenic carcinoma receiving IF on a 5-day divided-dose schedule (1.5 g/m² daily) with concomitant application of mesna (0.3 g/m² at 0, 4, and 8 h after IF infusion). On day 1 the mean cumulative 24-h urinary recoveries (percentage of the IF dose) recorded for IF, 4-OH-IF, 3-DCE-IF, and 2-DCE-IF were 13.9%, 0.52%, 4.8%, and 1.5%, respectively. On day 5 the corresponding values were 12.2%, 0.74%, 9.9%, and 3.6%, respectively. This time-dependent increase in urinary excretion of IF metabolites, which is caused by rapid autoinduction of hepatic oxidative metabolism, may result in a higher probability for the development of urotoxic and nephrotoxic side effects during prolonged IF application. The mean 24-h urinary recoveries (percentage of the daily mesna dose) recorded for mesna/dimesna on day 1 (day 5) were 23.8%/45.2% (21.2%/39.8%), respectively. The mean molar excess of urinary reduced (“free”) mesna over 4-OH-IF ranged from 11 to 72 on day 1 and from 6 to 40 on day 5. This indicates that although urinary excretion of 4-OH-IF rises with repeated IF application, mesna in standard doses should sufficiently inactivate the urotoxic IF metabolites. Received: 8 March 1995 / Accepted: 14 August 1996     

Phase I study of ifosfamide plus high-dose epirubicin in advanced non-small-cell lung cancer

 The present phase I study was designed to determine the maximum tolerated dose (MTD) of epirubicin given in combination with ifosfamide at a dose of 3 g/m², recycled every 4 weeks, in patients with advanced non-small-cell lung cancer (NSCLC). A total of 18 patients entered the study; they received the following four dose levels of epirubicin (i. v., day 1): 75 (6 patients), 90 (3 patients), 105 (3 patients), and 120 mg/m² (6 patients). The MTD of epirubicin was 120 mg/m², neutropenia being the dose-limiting toxicity. We observed 1/6, 1/3 1/3, and 2/6 partial responses (PRs) at epirubicin dose levels of 75, 90, 104, and 120 mg/m², respectively. A phase II study of epirubicin given at a dose of 120 mg/m² in association with conventional-dose ifosfamide in advanced NSCLC is in order. Received: 27 March 1995 / Accepted: 14 September 1995     

Bioavailability of 50- and 75-mg oral etoposide in lung cancer patients

 This study was designed to determine the bioavailability of etoposide capsules administered orally at doses of 50 and 75 mg. Patients with inoperable or relapsed lung cancer, who had an Eastern Cooperative Oncology Group (ECOG) performance status of 0–2 and adequate organ function, were eligible. A group of 17 patients were evaluable, all of whom were 75 years old or less, with an ECOG performance status of 0 or 1. The bioavailability of oral etoposide was determined by measuring the area under the etoposide plasma concentration versus time curve (AUC) on days 1, 10 and 21 during a once-daily regimen of oral administration for 21 consecutive days and comparing the value with the AUC achieved following intravenous administration 1 or 2 weeks after the last oral dose. The bioavailability of 50, 75 and 100 mg oral etoposide was determined in six, nine and two patients, respectively. The mean etoposide bioavailabilities (±SD) of the 50-mg and 75-mg doses were 47±11% and 59±18%, respectively, and of the 100-mg dose in two patients were 51% and 33%, respectively. There was no statistically significant difference in bioavailability between the 50-mg and 75-mg doses. The bioavailability of low-dose oral etoposide was the same as that reported in previous higher dose oral etoposide bioavailability studies and that shown on the package insert supplied by the manufacturer. Improved bioavailability of low-dose oral etoposide was therefore not observed in a population of Japanese patients. Received: 12 January 1995/Accepted: 14 May 1995     

Toxicity, pharmacokinetics, and in vitro hemodialysis clearance of ifosfamide and metabolites in an anephric pediatric patient with Wilms' tumor

Purpose: We evaluated the in vitro hemodialysis ratio and subsequent toxicity and pharmacokinetics of ifosfamide in an anephric patient with Wilms' tumor. Methods: An in vitro model was used to determine the extraction ratio of ifosfamide by dialysis. The toxicity and plasma concentrations of ifosfamide, chloroacetaldehyde, and 4-hydroxyifosfamide were then determined over 24?h after a single 1.6?g/m² dose of ifosfamide. Plasma concentrations were also measured before and after ten dialysis sessions during four courses of ifosfamide therapy. Results: The in vitro hemodialysis model showed that ifosfamide was cleared with an extraction ratio of 86.7?±?0.5% and remained constant even at low concentrations of drug. The mean decrease in vivo following hemodialysis for ifosfamide, chloroacetaldehyde, and 4-hydroxyifosfamide were 86.9%, 77.2%, and 36.2%, respectively. The pharmacokinetic parameters for ifosfamide using model-independent methods were calculated: Vd?=?0.23 l/kg, t_½?=?4.8?h, and Cl_T?=?3.30 l/h per?m². Ifosfamide-associated neurotoxicity was noted within hours of drug administration and improved rapidly following hemodialysis. Conclusions: The results of our study suggest that the pharmacokinetics of parent ifosfamide may not be substantially altered in patients with renal failure. Hemodialysis was shown to remove ifosfamide, chloroacetaldehyde, and 4-hydroxyifosfamide from the blood stream. Hemodialysis was also shown to reverse ifosfamide-related neurotoxicity.     

Phenytoin-induced alteration in the N-dechloroethylation of ifosfamide stereoisomers

 Case: A suspected alteration in ifosfamide (IFF) metabolism and pharmacokinetics was observed in a pediatric patient receiving phenytoin. Methods: Sequential plasma samples were obtained and analyzed for the concentrations of the enantiomers of IFF and their N-dechloroethylated metabolites (DCE-IFF) using a validated enantioselective gas chromatographic-mass spectrometric method. Results: In the phenytoin-treated patient, the metabolic formation of IFF enantiomers was increased and the metabolic pattern of the N-dechloroethylation altered from non-phenytoin-treated patients: (R)-3-DCE IFF*(S)-3-DCE-IFF = (S)-2-DCE-IFF>(R)-2-DCE-IFF (control) vs (S)-3-DCE-IFF = (S)-2-DCE-IFF>(R)-3-DCE-IFF*(R)-2-DCE-IFF (patient). Conclusions: Previous studies have attributed the production of the (S)-2-DCE-IFF and (S)-3-DCE-IFF metabolites to the activity of CYP2B6 and (R)-2-DCE-IFF and (R)-3-DCE-IFF to the activity of CYP3A4. The results suggest that phenytoin induced the activity of CYP2B6 to a greater extent than CYP3A4. In addition, the patient, who was at least partially refractory to several other treatments, went into remission after IFF treatment suggesting that phenytoin pretreatment might increase IFF therapeutic efficacy. Received: 4 December 1996 / Accepted: 3 April 1997     

A phase II study of CI-973 [SP-4-3(R)]- [1, 1-cyclobutane-dicarboxylato (2-)] (2-methyl-1,4-butanediamine-N,N′) platinum in patients with refractory advanced breast cancer

 CI-973 is a water-soluble platinum diamine complex whose antitumor activity is greater than that of cisplatin in some murine tumors. It has shown activity against cisplatin-resistant tumors. This phase II trial had the objectives of determining the therapeutic efficacy of CI-973 in patients with metastatic breast cancer who had been treated with one prior chemotherapy regimen, and of further defining the toxicity of the agent and the reversibility of its toxicity. CI-973 was administered as an intravenous infusion over 30 min with no prehydration or antiemetic programs. Treatment cycles were repeated at 21-day intervals. Patients with histologically confirmed metastatic breast cancer, measurable disease, and good performance status who had received only one prior chemotherapy regimen for metastatic disease were eligible for treatment. Adequate hematologic, renal, and hepatic function were required. A total of 26 patients received a median of two courses of CI-973 (range, 1–18 courses). Hematologic toxicity was severe: nearly all patients experienced granulocytopenia with granulocyte counts of 0 at all dose levels. Nevertheless, neutropenic fever and documented systemic infection were uncommon, and there were no hospitalizations for neutropenic fever or infection. Visceral disease dominated in this patient group. Of the 26 patients, 14 had visceral disease, 6 had bone or bone marrow disease, and 6 had skin, soft-tissue, or lymph-node disease. Of the 26 patients treated, 25 were evaluable for response. There were two partial remissions, one in liver and one in bone, and three minor responses, for a response rate of 8%. Nonhematologic toxic effects were mild and consisted of nausea and vomiting, fatigue, minimum peripheral paresthesia, and hypomagnesemia. Further study of CI-973 at the dose and schedule used in this study is not warranted. Because this agent had no significant extramedullary toxicity, intensification of the dose of CI-973 with concomitant administration of colony-stimulating factors has the potential to improve response in this patient population. Received: 12 February 1995/Accepted: 12 October 1995     

Epirubicin and ifosfamide in relapsed or refractory small cell lung cancer patients

Introduction

In small cell lung cancer (SCLC), despite the high response rates induced by platinum-based first line chemotherapies, relapse happens in 85% of the first-line responding tumors. Since 1992 we used a combination of epirubicin and ifosfamide (EI) as a non-cross-resistant regimen in relapsed or refractory SCLC. With the topotecan approval in second line treatment, this combination has been moved from the second line to the third line setting.

Methods

Patients presenting with a relapsed or refractory, histologically proven, SCLC were considered for this combination associating ifosfamide 3 g/m² day 1-2 with uroprotection using mesna, and epirubicin 90 mg/m² day 1 given every four weeks until progression or unacceptable toxicity.

Results

Seventy patients were accrued between September 1992 and August 2010 (seven women). Median age was 56 years. Performance Status was 0, 1, 2 and 3 for 16 (23%), 25 (35%), 20 (29%) and 9 (13%) patients respectively. Proportion of refractory, resistant and sensitive tumors was 20, 21 and 59% respectively. Median time from first line chemotherapy until progression was 90 days (range 5-1720 days). Forty-four patients were treated in second line setting whereas the 26 others have had received two lines at time of accrual. A total of 203 cycles were delivered (median 2 cycles, range: 1-6). Fifteen patients (21.4%) achieved an objective response (including one complete), and 10% had a stable disease. Median overall survival was 3.9 months (95% confidence interval: 3.3-5.1). Overall NCI-CTC grade 3 and 4 toxicity was mainly hematological: neutropenia (71% of the patients, febrile neutropenia 9.4% of the cycles), thrombocytopenia (23%), and anemia (22%). In univariate analysis, previous anthracyclines treatment was associated with a trend towards shorter survival (median overall survival 3.9 versus 4.6 months, p = 0.12). In multivariate analysis, only a high serum NSE level and presence of brain metastases were independent prognostic variables.

Conclusion

The EI combination is an active regimen in relapsed or refractory SCLC. The trend towards a greater activity of this regimen in patients not pretreated using anthracyclines suggests that class of agents should be tested in SCLC relapsing after the etoposide-platinum standard regimen.     

A Phase I and pharmacokinetics study of 2-chlorodeoxyadenosine in patients with solid tumors

 Preclinical studies of 2-chlorodeoxyadenosine (2-CdA) against solid tumors in the human tumor cloning assay and evidence that 2-CdA is active against slow-growing or resting tumor cells have stimulated interest in the clinical activity of this agent against solid tumors. This study sought to estimate the maximum tolerated dose, dose-limiting toxicity, and plasma and urine pharmacokinetics accompanying the intravenous administration of 2-CdA by 120-h continuous infusion in patients with solid tumors. Treated patients were also assessed for other toxicities of therapy and for antitumor response. A total of 23 patients received 35 courses of treatment given at doses of 3.5, 5.3, 6.5 and 8.1 mg/m² per day by continuous intravenous infusion for 5 days and repeated every 28 days. Blood and urine specimens were collected before, during, and after drug infusion. The dose-limiting toxicity at 8.1 mg/m² per day manifested as granulocytopenia in 2 of 5 patients (3 of 7 courses of treatment) and as thrombocytopenia in 3 of 5 patients (3 of 7 courses of treatment). At the dose levels of 6.5 and 8.1 mg/m² per day, recovery from thrombocytopenia was often delayed. Severe lymphocytopenia (<1,000/μl) was observed at all dose levels of 2-CdA. Dose-related anemia and leukopenia were observed and were infrequently severe. Nonhematological toxicities were confined to mild-to-moderate nausea, vomiting, fatigue, and anorexia. Fever of 37^°–40^°C was induced during drug infusion in 19 patients. No antitumor response was observed. Average plasma concentrations at steady-state (Cp_ss) ranged from 3 ng/ml at the initial dose level to 13 ng/ml at the dose level of 8.1 mg/m² per day. Both the Cp_ss and the area under the plasma concentration-time curve (AUC) were proportional to the dose. A relationship was observed between the percentage of change in absolute neutrophil count and the AUC. Renal excretion accounted for only 18% of the elimination of 2-CdA over the 5-day infusion period. The maximum tolerated dose for 2-CdA given by 5-day continuous infusion was 8.1 mg/m² per day in this study. The recommended dose on this schedule for phase II studies is 6.5 mg/m² per day. Granulocytopenia and thrombocytopenia were dose-limiting. No antitumor activity was observed during this study. On the basis of the plasma concentrations of 2-CdA observed, it is unlikely that this schedule of drug administration will permit achievement of the concentrations consistent with antitumor activity observed in preclinical studies. Received: 14 March 1994/Accepted: 22 July 1994     

Phase I and pharmacologic study of 7- and 21-day continuous etoposide infusion in patients with advanced cancer

 Purpose. This phase I study was undertaken to evaluate the safety and tolerability of prolonged infusional etoposide, and to evaluate its pharmacokinetic/pharmacodynamic profile in patients with advanced cancer. Methods. A group of 17 patients received a 7-day infusion of etoposide (schedule A) every 21 days at doses from 30 to 75 mg/m² per day, and a second group of 37 patients a 21-day infusion (schedule B) every 28 days at doses from 18 to 40 mg/m² per day. Patients had a median Karnofsky performance status (PS) of 80%, and 34 patients had no prior chemotherapy. Etoposide concentrations at steady state (Css) and other pharmacokinetic parameters (plasma clearance, CLp; area under the curve, AUC) were determined during the first treatment cycle. Correlation coefficients were calculated to measure the relationship between variables. Results. Myelosuppression was the major toxicity, and was associated with three deaths. The maximum tolerated dose due to neutropenia was 75 mg/m² per day for schedule A and 40 mg/m² per day for schedule B. There was significant interpatient pharmacokinetic variability in both infusional schedules. Even though etoposide dose levels did not significantly correlate with plasma levels, the Css was ≥1 μg/ml in the majority of the patients. A significant correlation between AUC and neutrophil absolute decrease was noted only in schedule B (r=0.56,  P=0.003). There were several marginal relationships in schedule B: PS versus Css (r=0.31,  P=0.058), PS versus AUC (r=−0.38; P= 0.058) and age versus CLp (r=−0.31, P=0.057). Conclusion. Overall, significant correlations were found for several hematologic variables and etoposide dose levels, but not with the Css values. One major problem with the application of pharmacodynamic models to predict hematologic toxicity in clinical practice is the presence of significant interpatient variability. Received: 3 April 1995/Accepted: 6 December 1995     

In vitro studies of the hyperthermic enhancement of activated ifosfamide (4-hydroperoxy-ifosfamide) and glucose isophosphoramide mustard

Purpose: To study the effect of hyperthermia on the cytotoxicity of glucose isophosphoramide mustard (D-19575), a derivative of ifosfamide, which does not require activation and preclinically demonstrates less nephrotoxicity and myelosuppression than ifosfamide.Methods: In vitro studies (using a crystal violet cell survival assay) of the interaction of hyperthermia with D-19575, as well as the activated form of ifosfamide (4-hydroperoxy-ifosfamide, D-18851), were performed using L929 and OVCAR-3 cell lines held at various temperatures (i.e. 37 °C (control), 40.5 °C, 41.8 °C, 42.5 °C, and 43 °C) for 65 min.Results: The following thermal enhancement ratios (TER) were demonstrated: D-19575 in L929 1.2, 2.0 and 2.3 at 40.5, 41.8 and 42.5 °C, respectively; for D-18851 in L929 1.7 at 41.8 °C; for D-19575 in OVCAR-3 2.1, 3.2 and 3.3 at 40.5, 41.8 and 42.5 °C, respectively; for D-18851 in OVCAR-3 4.6 at 41.8 °C. Conclusion: The significant observed increase in cytotoxicity of D-19575 caused by hyperthermia taken together with its known preclinical toxicity profile, encourage its further preclinical and ultimately clinical testing, including its use with whole body and regional hyperthermia. Received: 9 May 1996 / Accepted: 2 October 1996     

Variations in schedules of ifosfamide administration: a better understanding of its implications on pharmacokinetics through a randomized cross-over study

Feline soft tissue sarcomas are spontaneous, rapidly growing, and aggressive neoplasms that mimic their human counterpart. The purpose of this study was to evaluate the feasibility and efficacy of electrochemotherapy (ECT) in an adjuvant fashion for the treatment of feline sarcomas, and the possibility of repeated treatments in the case of recurrence. Cats with fibrosarcoma (FSA) were assigned to receive surgery or surgery plus ECT. Feline patients recruited in the ECT study were enrolled in a microscopic arm (39 patients) or a macroscopic arm (19 patients) on the basis of their tumor status (absence or presence of gross disease). Patients received local injection of bleomycin followed by bursts of eight biphasic pulses at a voltage of 1,300 V/cm for postoperative and of 800 V/cm for intraoperative treatments. The median time to recurrence was 4 months for cats treated with surgery alone, 19 months for the postoperative cohort, and 12 months for the intraoperative group. Moreover, ten patients with recurring neoplasms were retreated and experienced responses lasting 6 to 28+ months. Side effects were minimal. Of interest, the metastatic rate (1.7%) in our patients was negligible: only one cat had distant spread. The results suggest that ECT is a well tolerated and potentially useful addition to surgery in controlling high-grade sarcomas. On the basis of these results, additional evaluations are warranted in pets and in humans.     

Effect of tamoxifen pretreatment on the pharmacokinetics, metabolism and cardiotoxicity of doxorubicin in female rats

The purpose of this study was to examine the effect of tamoxifen pretreatment on the metabolism and pharmacokinetics of doxorubicin. We tested the hypothesis that the pretreatment would counteract the side effects of doxorubicin and modify the disposition of the drug. The concentration-time profiles of doxorubicin in plasma and blood cells were determined in conjunction with the cumulative amount of renal and hepatobiliary elimination of unchanged drug and metabolites following a 10-day tamoxifen pretreatment at a dose of 1 mg/kg per day. Furthermore, under the same experimental protocol the serum concentration-time profile of endothelin was determined as a biomarker of toxicity. Methods: Female Sprague Dawley rats (225–275 g), pretreated orally for 10 days with corn oil or tamoxifen in corn oil (1 mg/kg per day), received ¹⁴C-doxorubicin (specific activity 0.4 μCi/mg, 10 mg/kg) intravenously. Plasma, blood cells, bile and urine were collected periodically and analyzed for doxorubicin and its metabolites. Four other groups of animals received the same pretreatment and non-labeled doxorubicin. Their serum samples were analyzed for endothelin. Two additional groups were also used to examine the effect of tamoxifen on the in vitro metabolism of doxorubicin by the cytosolic enzyme aldo-keto reductase. Results: Tamoxifen pretreatment reduced the total protein of the cytosolic fraction by 50% and reduced the formation of doxorubicinol both in vitro and in vivo. The pretreatment resulted in a notable increase in the area under plasma and blood cells concentration-time curves of doxorubicin and a significant reduction in mean residence time, apparent volume of distribution and serum endothelin levels. Conclusions: We attributed the increase in the area under the curves of plasma and blood cells following tamoxifen pretreatment to a reduction in the uptake of doxorubicin by peripheral tissues. This conclusion was consistent with the reduction in the volume of distribution of plasma, mean residence time and higher availability of the parent compound for excretion. An interesting observation was that the increase in concentration of doxorubicin in plasma was not concomitant with an increase in concentration of doxorubicinol. The levels of this toxic metabolite and its corresponding biliary rate constant were reduced by approximately 50%. The results demonstrate that tamoxifen, in addition to being a modulator of P-glycoprotein and counteracting the effects of doxorubicin at the cellular level, also alters the metabolic profile of doxorubicin either by inhibiting the formation of the toxic metabolite doxorubicinol or by reducing the enzyme responsible for the biotransformation. The change in metabolism may well be a contributing factor to reduction of serum endothelin levels. Received: 2 September 1999 / Accepted: 14 April 2000     

Biotransformation of the platinum drug JM216 following oral administration to cancer patients

 This study evaluates the metabolic profile of JM216 [bis(acetato)ammine-dichloro(cyclohexylamine) platinum(IV)], the first orally administrable platinum complex, in plasma ultrafiltrates of 12 patients (n=2–4 time points per patient) following different doses of drug (120, 200, 340, 420, 560 mg/m²). The biotransformation profile was evaluated by high-performance liquid chromatography (HPLC) followed by atomic absorption spectrophotometry (AA). The AA profiles were compared with those previously identified by HPLC on line with mass spectrometry (HPLC-MS) in plasma incubated with JM216. A total of six platinum peaks (Rt=5.5, 7.2, 10.6, 12.4, 15.6, and 21.6 min, respectively) were observed in patients’ plasma ultrafiltrate samples, of which only four appeared during the first 6 h post-treatment. Four of these coeluted with those observed and identified previously in plasma incubation medium. No parent JM216 was detected. The major metabolite seen in patients was the Pt II complex JM118 [cis-amminedichloro-(cyclohexylamine)platinum (II)] and was observed in all the patients. Interestingly, the second metabolite was shown to coelute with the Pt IV species JM383 [bis-acetatoammine(cyclohexylamine)dihydroxoplatinum (IV)]. Both JM118 and JM383 were identified by HPLC-MS in a clinical sample. Peak C, which was a minor product (less than 5% of the free platinum), coeluted with JM559 [bis-acetatoammine-chloro(cyclohexylalamine)hydroxoplatinum (IV)]. The cytotoxicity profile of all three metabolites in a panel of cisplatin-sensitive and -resistant human ovarian carcinoma cell lines was very close to that of the parent drug. In addition, the concentrations of JM118 reached in patients’ plasma ultrafiltrate were comparable with the cytotoxic levels of the compound determined in the ovarian carcinoma panel of cell lines. Two metabolites were seen in patients but not in the in vitro incubation medium, suggesting the involvement of a possible enzyatic reaction. Thus, the biotransformation profile following oral administration of JM216 shows a variety of Pt(IV) and Pt(II) metabolites in plasma that differ significantly from other systemically applied platinum drugs. Received: 8 May 1995/Accepted: 6 October 1995     

周剂量紫杉醇联合异环磷酰胺治疗晚期非小细胞肺癌23例

目的　评价周剂量紫杉醇与异环磷酰胺联合化疗治疗晚期非小细胞肺癌的疗效和安全性。方法　紫杉醇 5 0～ 65mg/m2 静脉滴注 ,第 1、8、15天 ,异环磷酰胺 1.3 g/m2 静脉注射 ,第 2～ 4天。每 2 8天重复 ,2～ 3周期为一疗程。使用紫杉醇前常规给予抗过敏等处理 ,异环磷酰胺使用后第 0、4、8小时给予美安解毒。结果　本组完全缓解 1例 ,部分缓解 8例 ,稳定 11例 ,进展 3例 ,总有效率为 3 9.1% ( 9/2 3 ) ,临床受益率为 87.0 % ( 2 0 /2 3 )。化疗后KPS评分显著提高 (P <0 .0 1)。随防 2 0例 ,中位生存期为 8.9月 ,1年生存率为40 % ( 8/2 0 )。全组毒性反应主要为血液学毒性和消化道反应 ,其中白细胞降低发生率为 69.6% ( 16/2 3 ) ,恶心呕吐发生率为 47.8% ( 11/2 3 )。结论　周剂量紫杉醇 +异环磷酰胺联合化疗对晚期非小细胞肺癌有较好的疗效 ,不良反应可耐受 ,安全性高 ,可在临床上推广应用。     

Relationship between pharmacokinetics of unchanged cisplatin and nephrotoxicity after intravenous infusions of cisplatin to cancer patients

 Purpose: The relationships between pharmacokinetic parameters of unchanged cisplatin (CDDP) and several markers for nephrotoxicity after CDDP infusion (80 mg/m²) over 2 and 4 h were quantitated in patients with various cancers (lung, stomach and colon cancers and mediastinal tumor). Methods: Plasma and urinary levels of unchanged CDDP were measured using a specific high-performance liquid chromatography method. Pharmacokinetic parameters were calculated according to the model-independent method. The nephrotoxicity markers, blood urea nitrogen (BUN), serum creatinine (SCr), plasma and urinary β₂-microglobulin (BMG_p and BMG_u), urinary N-acetyl-β-D-glucosaminidase (NAG) and creatinine clearance (CCR) were monitored for 30 days following CDDP administration. Results: The maximum plasma concentration (C_max), maximum urinary excretion rate (dAe/dt_max), area under the plasma concentration-time curve from time zero to infinity (AUC), cumulative amount excreted in urine from time zero to infinity (Ae), total clearance (Clt), renal clearance (Clr) and plasma half-life (t_1/2) of unchanged CDDP were not significantly different between the 2-h and 4-h infusion schedules. The values of the nephrotoxicity markers changed significantly following CDDP administration, suggesting that CDDP chemotherapy (80 mg/m²) caused nephrotoxicity. The C_max of unchanged CDDP was the most informative pharmacokinetic parameter for nephrotoxicity. C_max was related to maximum BUN, maximum SCr and minimum CCR levels in 27 CDDP treatments according to an exponential model. Conclusion: In order to attain more effective CDDP chemotherapy with minimum nephrotoxicity, the present pharmacokinetic and pharmacodynamic studies suggest that the C_max or steady-state plasma level of unchanged CDDP should be maintained between 1.5 and 2 μg/ml in a standard continuous infusion schedule over 2 h and 4 h. Received: 2 May 1995/Accepted: 25 March 1996