The pharmacokinetics of the quinazoline antifolate ICID 1694 in mice and rats

Summary N-(5-[N-(3,4-Dihydro-2-methyl-4-oxoquinazolin-6-ylmethyl)-N-methylamino]-2-thenoyl)-l-glutamic acid (ICI D1694) is an analogue of the thymidylate synthase inhibitorN ¹⁰-propargyl-5,8-dideazafolic acid (CB3717). CB3717 was found to be an active anticancer agent in early clinical studies, but its use was limited by its relative insolubility at physiological pH. ICI D1694 has been shown to be a more active anticancer agent than CB 3717 in model systems, and it is devoid of the acute renal toxicity associated with the administration of the latter drug to mice. In the present study, the pharmacokinetics of ICI D1694 were studied in both mice and rats using reverse-phase HPLC. In rats, ICI D1694 clearance (CL) conformed to a two-compartment open model and was rapid (CL=10.7 ml min^–1 kg^–1,t1/2=30 min). Excretion was mainly biliary (65% of the delivered dose in 4 h vs 12% in urine) in the rat following a 100-mg/kg i.v. bolus. A high degree of protein binding was seen in rat plasma (90% over the range of 20–100 m). In mice, ICI D1694CL=27 ml min^–1 kg^–1 andt1/2=30 min following 100 mg/kg i.v., which was significantly faster than CB3717 clearance (CL=6 ml min^–1 kg^–1,t1/2=93 min). ICI D1694 was fully bioavailable following i.p. administration (AUC=3.73 mg ml^–1 min i.v. 4.03 mg ml^–1 min i.p.), but its bioavailability following oral administration appeared to be low (approximately 10%–20%). Tissue distribution and excretion studies in mice suggested that biliary excretion predominated, confirming the results obtained in rats. Following an i.v. dose of 500 mg/kg ICI D1694 in mice, drug was detectable at 24h, suggesting the presence of a third phase of plasma clearance. The initial HPLC assay could not detect this third phase following a dose of 100 mg/kg; hence, a more sensitive assay was developed that includes a solid-phase extraction step. The latter assay was used to define the third phase of ICI D1694 clearance in mice, and preliminary studies demonstrated a terminal half-life of 6.5±2.7 h.These studies were supported by the UK Cancer Research Campaign and the British Technology Group     

Peripheral Neuropathy Due to Biweekly Paclitaxel,Epirubicin and Cisplatin in Patients with Advanced Ovarian Cancer

We assessed the peripheral neuropathic changes induced by biweekly combination chemotherapy including paclitaxel 100–165mg/m² (in a 3-h infusion), epirubicin 75mg/m² and cisplatin 50mg/m² (TEC) in patients with advanced ovarian cancer.Neurologic evaluation, including a standardized questionnaire, bed-side neurological examination, and quantitative determination of vibratory perception thresholds (VPT) and grip strength took place before therapy, after 3 and 6 cycles, and thereafter whenever possible. During chemotherapy all patients received granulocyte colony-stimulating factor from days 2 to 12. Pretreated patients received amifostine two times, before epirubicin and before cisplatin administration.Neuropathic symptoms developed in 11/13 non-pretreated patients and in 7/9 chemotherapy-pretreated patients. Neuropathic signs developed in all patients. Neuropathic symptoms and signs were predominantly sensory in character. VPT changes developed primarily in the feet. According to National Cancer Institute of Canada Common Toxicity Criteria, grade 3 peripheral neuropathy after 6 cycles developed in 1/6 and 2/4 non-pretreated patients who received TEC containing paclitaxel 150 and 165mg/m², respectively.We conclude that peripheral neuropathy is dose-limiting in chemonaïve patients treated with biweekly TEC combination chemotherapy, at paclitaxel dose level 165mg/m² in a 3-h intravenous administration.     

Plasma and cerebrospinal fluid pharmacokinetics of cytosine arabinoside in dogs

Summary Cytosine arabinoside (ara-C) is a component of many protocols for the treatment of CNS (central nervous system) leukemia and lymphoma in humans and dogs. It is also used for the prophylaxis of CNS metastasis in acute lymphoblastic leukemia. Although ara-C enters the cerebrospinal fluid (CSF) of human cancer patients after i.v. administration, it is unclear whether a similar CNS distribution occurs in humans whose blood-brain barrier has not been compromised by invasive disease. No information on the penetration of ara-C into the CSF in dogs is available. We studied the plasma and CSF pharmacokinetics of 600 mg/m² ara-C in ten healthy male dogs after its administration as a rapid i.v. bolus (six dogs) or as a 12-h i.v. infusion (four dogs). Ara-C concentration in blood and CSF samples was determined by high-performance liquid chromatography (HPLC). After an i.v. bolus of ara-C, the mean plasma distribution half-life was 7.1±4.5 min and the mean elimination half-life was 69±28 min. The mean plasma clearance was 227±125 ml min^–1 m^–2. The peak concentration of ara-C in the CSF was 29±11 m, which occurred at 57±13 min after the ara-C bolus. The CSF elimination half-life was 113±26 min. During a 12-h infusion of ara-C (50 mg m^–2 h^–1), the plasma steady-state concentration was 14.1±4.2 m, the CSF steady-state concentration was 8.3±1.1 m, and the CSF: plasma ratio was 0.62±0.14. The plasma eleimination half-life was 64±19 min and the plasma clearance was 214±69 ml min^–1 m^–2. The CSF elimination half-life was 165±28 min. No clinically significant toxicity was observed over a 21-day period following drug administration in either of the treatment groups. Our data indicate that ara-C crosses the blood-brain barrier in normal dogs and that i.v. administration of this drug has potential as a treatment modality for neoplasia involving the CNS.Supported by the Canine Disease Research Fund and in part by the Elsa U. Pardee Foundation     

A model for ultrafilterable plasma platinum disposition in patients treated with cisplatin

Summary A model incorporating recent information regarding the specificity of a high-performance liquid chromatographic assay for active platinum in plasma ultrafiltrate, and the concept of mobile and fixed metabolites, was developed for cancer patients treated with cisplatin. Model parameters were determined using plasma and urinary platinum data obtained in 20 patients. It was assumed in the model that parent drug accounted for essentially all the platinum measured in plasma ultrafiltrate in the 2 h period immediately post infusion. At times greater than 4 h post infusion, platinum concentrations in plasma ultrafiltrate were assumed to be due entirely to reactive, mobile metabolites with possible cytotoxicity. The model accurately simulated platinum concentrations in plasma ultrafiltrate over a 24-h period following a 2-h infusion of 80 mg/m² of cisplatin to seven patients, 100 mg/m² to ten patients and 120 mg/m² to three patients.This work was supported by a grant-in-aid from the Anti-Cancer Foundation of the Universities of South Australia.     

Alteration of dacarbazine pharmacokinetics after interleukin-2 administration in melanoma patients

Summary In an effort to improve the treatment of metastatic malignant melanoma, we evaluated the sequential administration of the chemotherapeutic agent dacarbazine (DTIC) and the biological response modifier interleukin-2 (rIL-2) in a phase I–II study. Since the combination of biological response modifiers and chemotherapeutic agents could alter drug disposition, we evaluated the pharmacokinetics of DTIC and its major metabolite, 5-aminoimidazole 4-carboxamide (AIC), before and after rIL-2 administration. DTIC (1 g/m², 24-h i.v. infusion) was given on day 1 and rIL-2 (2–4 million Cetus units/m², 30-min i.v. injection), on days 15–19 and 22–26 of each course of therapy. The second DTIC dose was given on day 29, i.e., 3 days after the last rIL-2 administration. DTIC and AIC were assayed by reversed-phase HPLC. DTIC plasma levels showed a significant decrease after rIL-2 administration as compared with DTIC values obtained in the same patients before rIL-2 administration. DTIC area under the curve (AUC) values obtained after rIL-2 were lower than those obtained on day 1 before rIL-2 administration (P=0.02). After rIL-2, the total body clearance (Cl_T) was increased (P=0.04), as was the volume of distribution at steady state (V_ss;P=0.02). The decrease in AUC after rIL-2 administration became more pronounced as the rIL-2 dose was increased (P=0.03). No significant difference was detected in the elimination phase of DTIC when halflives obtained before and after rIL-2 administration were compared; the mean half-lives were 0.7 and 2.8 h for the - and -phases, respectively. The model-independent mean residence time was 3.4 h. The plasma AUC for the metabolite AIC did not charge after rIL-2 administration. AIC biphasic plasma elimination was also similar after rIL-2 administration, with - and -half-lives of 0.7 and 11.4 h, respectively. Urinary excretion of DTIC and AIC did not differ after rIL-2 administration; the overall DTIC excretion was 39% of the dose over 48 h, and AIC urinary excretion was 25% of the DTIC dose. The observed decrease in the DTIC plasma AUC after rIL-2 administration appears to be due to an increase in the volume of distribution, since other factors such as half-lives, urinary excretion, and metabolism were not significantly altered. The clinical consequences of the rIL-2-DTIC interaction remain difficult to assess based on presently available data, but this drug interaction should be taken into consideration in the development of future chemo-immunotherapy regimens that include high-dose rIL-2.This study was supported by a contract from Cetus Corporation (Emeryville, California) and by Wayne State University Ben Kasle Trust Fund for Cancer Research     

Human pharmacokinetics of marcellomycin

Summary In conjunction with two phase I clinical trials, we have investigated the pharmacokinetics of marcellomycin (MCM), a new class II anthracycline antibiotic, in nine patients with normal renal and hepatic functions and no third-space fluid accumulation. MCM was infused IV over 15 min at a dosage of 27.5, 40, or 50 mg/m². Plasma and urine samples were collected up to 72 h. MCM and metabolites were assayed by thin-layer chromatography and quantified by specific fluorescence. The disappearance of total MCM-derived fluorescence from plasma followed first-order kinetics and lacked the rebound in total fluorescence that has been described for the structurally similar agent, aclacinomycin A. After 40–50 mg/m², the peak MCM concentration in plasma was 1.67±0.61 M; MCM disappeared from plasma in a triexponential fashion and was undetectabel by 48 h after infusion. The area under the plasma concentration-time plot (AUC), including the infusion time, was 1.11±0.39 Mxh; plasma clearance of MCM was 1.50±0.88 l/min/m². Five other fluorescent compounds were consistently observed in plasma. M2 was a contaminant present in the parent drug. P1 and P2 were conjugates of MCM and M2, respectively. G1 and G2 were aglycones. The peak concentrations of the metabolites were 25% or less or the peak concentration for MCM, but their persistence resulted in higher AUCs than that for MCM. For the dosage of 27.5 mg/m², fewer data were available; but the pharmacokinetics of MCM and metabolites appeared to be similar to that at higher dosage. Urinary excretion of total fluorescence amounted to 8.0%±1.6% of the total dose at 40–50 mg/m², and to 7.0%±2.3% at 27.5 mg/m². No correlation was detected among the various pharmacokinetic parameters and toxicities encountered in these patients.This work was presented in part at the Annual Meeting of the American Society of Clinical Oncology, San Diego, CA, May 1983     

Pharmacokinetic study of VM26 given as a prolonged IV infusion to ovarian cancer patients

Summary Plasma levels of VM26 were assayed by HPLC in six ovarian cancer patients with normal renal and liver function who received the drugs as an initial 1-h IV infusion of 80 mg/m² followed by a 24-h IV infusion of 120 mg/m². These doses and infusion rates were chosen on the basis of mean VM26 clearance values found in a previous study, with the aim of reaching plasma steady-state levels of approximately 6 g/ml in a short time.Plasma steady-state levels of 4–10 g/ml, close to those predicted theoretically, were in fact attained at 4–9 h during the second, slower infusion. Mean half-lives and clearance values were 8.6±1.1 h and 0.78±0.08 l/h/m². Six percent of the VM26 dose was recovered as unchanged drug in the urines collected up to 24 h after the end of infusion. The glucuronide of VM26 aglycone (4-demethylepipodophyllotoxin) was identified in the urine of all patients, in amounts corresponding to about 8% of the drug dose.     

A Randomized Phase II and Pharmacokinetic Study of Dacarbazine in Patients with Recurrent Glioma

We conducted a randomized phase II study to determine the efficacy of dacarbazine (DTIC) in recurrent gliomas. Patients were randomly assigned to receive either DTIC 750mg/m²IV day 1 every 28 days (Arm A) or DTIC 200mg/m²IV days 1–5 every 28 days (Arm B). Pharmacokinetics were studied in 6 patients on each arm using HPLC analysis. Thirty-nine patients (30 male, 9 female), ages 27–67 years (median 53) were entered on the study (20 on Arm A, 19 on Arm B). No objective responses were seen. Median time to progression was 3 months. Median survival was 8 months. Treatment was generally well tolerated. Major toxicities were grade 1–2 nausea (33%), lethargy (28%), diarrhea (15%), alopecia (15%), and grade 3 neutropenia (8%). Four patients on Arm A had mild self-limited episodes of intravascular hemolysis occurring immediately after drug infusion, the mechanism of which is unknown. Mean AUC for DTIC, HMMTIC (5-[3-hydroxymethyl-3-methyl-1-triazeno] imidazole-4-carboxamide), and MTIC (5-[3-methyl-1-triazeno] imidazole-4-carboxamide), in Arm A were 14.8, 0.17, and 1.15mMmin, respectively. Corresponding values for Arm B (on day 1 of 5) were 1.7, 0.06, and 0.29mMmin, respectively. The predicted HMMTIC and MTIC exposure over 5 days for Arm B, based on the day 1 data, is higher than with Arm A. We conclude that DTIC is well tolerated but does not have activity in patients with recurrent gliomas. The 5-day schedule appears less toxic, and pharmacokinetic studies show that it provides greater exposure to MTIC and HMMTIC compared to the one-day schedule.     

Pharmacokinetics of Amonafide in dogs

Summary Amonafide, one of a series of imide derivatives of 1,8-naphthalic acid synthesized by Brana et al. [2] has shown significant antitumor activity against a variety of experimental tumors, including L1210 leukemia and P388 leukemia. Along with the clinical trial at our institute, we have studied the disposition of Amonafide in dogs by HPLC and fluorometry. Six dogs received Amonafide i.v. at 5 mg/kg (100 mg/m²) over 15 min; three were sacrificed at 6 h, and three at 24 h. The initial plasma t_1/2, of Amonofide was 2.4±0.4 min, the intermediate t_1/2, 26.8±3.7 min, and the terminal t_1/2, 21.7±4.0 h. the peak plasma concentration achieved was 6.3±1.7 g/ml. The average apparent volume of distribution was 12.84±0.541/kg, and the total clearance was 0.56±0.161/kg/h. In 24 h, 9.5%±0.2% of the administered dose was excreted in the urine as the parent drug, and 7.4%±1.4% in the bile in 6 h. Amonafide penetrated the CSF readily and achieved the highest concentration 20–25 min after administration, which was 30% of the concurrent plasma level. Amonafide underwent extensive metabolism to at least three major metabolites and two or more minor metabolites. The and plasma t_1/2 of the major metabolite, an N-oxide derivative, were 24.8 min and 28.6 h, respectively. The 24-h cumulative urinary excretion was 1.4% of the injected dose, and the cumulative biliary excretion was 16.7% in 6 h. At autopsy 6 h after dosing, the liver contained the highest percentage (0.23% of administered dose) of unchanged Amonafide, followed by the stomach (0.11%), lung (0.04%), kidney (0.04%), and pancreas (0.03%). The rest of the major organs retained less than 0.02% of the Amonafide dose. One day after dosing, no detectable amount of Amonafide was found in any of these tissues, indicating that Amonafide appears to be extensively metabolized and not significantly retained in the dog.     

Adrenal steroids stimulate growth and progesterone receptor levels in rat uterus and DMBA-induced mammary tumors

We have studied the effect of treatment with the adrenal steroids androst-5-ene-3,17-diol (⁵-diol) and dehydroepiandrosterone (DHEA) on the growth and progesterone receptor levels of dimethylbenz-(a)anthracene (DMBA)-induced mammary tumors in the rat.While the total number of tumors in ovariectomized animals was 0.60 ± 0.19 tumor per rat after 24 days, it increased to 2.54 ± 0.50 (p<0.01) and 1.42 ± 0.26 (p<0.01) in the ⁵-diol and DHEA (2 mg, twice daily) treated animals, respectively. While very few new tumors developed during a 24-day period in ovariectomized animals (0.07 ± 0.07/rat), an average of 0.47 ± 0.19 (p<0.05) new tumor per animal appeared in intact rats. In ovariectomized animals treated with ⁵-diol or DHEA, the numbers of new tumors were 0.77 ± 0.26 (p<0.05) and 0.42 ± 0.15 (p<0.05), respectively. An even more striking effect was observed on average total tumor area, which decreased from 4.70 ± 0.95 cm² in intact animals to 0.75 ± 0.27 cm² (p<0.01) following ovariectomy. Values of 9.79 ± 2.25 (p<0.01) and 3.93 ± 0.86 cm² (p<0.01) were found in the ⁵-diol- and DHEA-treated ovariectomized animals, respectively.Treatment of ovariectomized animals with ⁵-diol and DHEA caused a marked increase (p<0.01) in progesterone receptor levels in both the uteri and DMBA-induced mammary tumors. Uterine weight was also stimulated (p<0.01) by treatment with the two adrenal steroids.The present data show that two adrenal C₁₉-⁵ steroids, ⁵-diol and DHEA, possess stimulatory effects analogous to those of estrogens on DMBA-induced mammary tumor growth and progesterone receptor levels in the rat, thus supporting the suggestion of an important role of these adrenal steroids in breast cancer and other estrogen-sensitive diseases in the human.     

The pharmacokinetics of vincristine in man:

Summary A radioimmunoassay has been used to investigate the pharmacokinetics of vincristine in 39 cancer patients who received between 0.4 and 1.54 mg vincristine/m² as part of standard treatment protocols. There was wide interindividual variation in both the terminal elimination half-life of vincristine (t_1/2) and the associated volume of distribution (Vd), resulting in an 11-fold range of dose-corrected area under the plasma concentration versus time curve values (AUC_0–). Elevated vincristine AUC_0– values were observed in those patients with raised serum alkaline phosphatase at the time of vincristine estimation. The t_1/2 was significantly longer in these patients than in those with serum alkaline phosphatase within normal limits, suggesting that biochemical evidence of cholestasis is associated with reduced clearance of vincristine. Evidence is also presented to suggest that the clearance of vincristine is dose-dependent within the therapeutic dose range. We observed a disproportionate rise in vincristine plasma concentration at doses exceeding 1 mg/m², due primarily to a lengthening of mean t_1/2 compared with that observed for patients receiving 1 mg vincristine/m² or less.     

Pharmacokinetics of etoposide: correlation of pharmacokinetic parameters with clinical conditions

Summary The pharmacokinetic parameters of etoposide were established in 35 patients receiving the drug parenterally within the framework of different polychemotherapy protocols. A total of 62 data for 24-h kinetics were analysed. After sample extraction and high-performance liquid chromatography (HPLC) or thin-layer cromatographic (TLC) separation, etoposide was measured by means of [²⁵²Cf]-plasma desorption mass spectrometry (PDMS). This highly specific detection system proved to be very practicable and reproducible. The present study comprised two parts that were absolutely comparable in terms of clinical and pharmacokinetic parameters. In part II of the study, sensitivity was improved by modifying the analytical technique. After the exclusion of patients who had previously been given cisplatin or who exhibited renal impairment and of one patient who showed extremely high levels of alkaline phosphatase, -GT and SGPT, the mean values calculated for the pharmacokinetic parameters evaluated were: beta-elimination half-life (t _1/2), 4.9±1.2 h; mean residence time (MRT), 6.7±1.4 h; area under the concentration-time curve (AUC), 5.43±1.74 mg min ml^–1; volume of distribution at steady state (Vd_ss), 6.8±2.7 l/m²; and clearance (Cl), 18.8±5.3 ml min^–1 m^–2. The pharmacokinetic parameters were correlated with 12 different demographic or biochemical conditions. Impaired renal function, previous application of cisplatin and the age of patients were found to influence etoposide disposition to a statistically significant extent. We suggest that the dose of etoposide should be reduced in elderly patients and/or in individuals with impaired renal function, especially in those exhibiting general risk factors such as reduced liver function with regard to the polychemotherapy.     

Are medical oncologists biased in their treatment of the large woman with breast cancer?

Purpose. Obesity and breast cancer are common conditions that often coexist. Concerns of relative overdosing of chemotherapy in the large cancer patient have led clinicians to apply empiric dose reductions, cap the body surface area (BSA) at 2m², or use ideal rather than actual body weight to calculate BSA. There are no data supporting or refuting these practices and their prevalence is unknown. We sought to determine the distribution of body size and prevalence of obesity in the breast cancer population of our cancer centre, and to determine clinician chemotherapy dosing practices in the era of modern adjuvant chemotherapy. Patients and methods. Women with invasive breast cancer receiving systemic therapy at our institution between 1980 and 1998 were identified and their recorded height and weight were used to calculate BSA and body mass index (BMI). We reviewed the first cycle adjuvant chemotherapy dosing practices from 1990–1998. The ideal dose of chemotherapy was calculated based on calculated BSA, and then contrasted with the actual dose received at cycle one. Discrepancies were recorded and categorized, using the largest single drug reduction if more than one drug was reduced. Results. Mean BMI in the systemic therapy population was 26.4±5.3kg/m², 54% were overweight, 2% severely obese and 18% moderately so. Their mean BSA was 1.7±0.2m² and only 5% had a BSA2m². In the adjuvant chemotherapy subgroup, most patients received >85% of their ideal dose. The mean dose reduction was 5.3±11.3% versus 9.9±11.3% in the BSA <2 and >2m² groups, respectively (p=0.02), and 4.3±8.2% versus 6.7±13.1% in the BMI <25 and 25kg/m² groups, respectively (p=0.008). While only 24% of chemotherapy dose reductions of 15% were in the BSA 2m² group, 76% were in the BMI 25kg/m² group. Conclusions. Obesity is prevalent in this breast cancer population. BSA is not a sensitive index of large body size. We consistently detected more frequent empiric dose reductions at cycle one of adjuvant chemotherapy, with reductions of greater magnitude in the largest women (BSA 2m²) and those who were overweight (BMI 25kg/m²).     

Pharmacokinetics of high-dose etoposide after short-term infusion

Summary The pharmacokinetics of high-dose etoposide (total dose, 2100 mg/m² divided into three doses given as 30-min infusions on 3 consecutive days) were studied in ten patients receiving high-dose combination chemotherapy followed by autologous bone marrow transplantation. In addition to etoposide, all subjects received 2×60 mg/kg cyclophosphamide and either 6×1,000 mg/m² cytosine arabinoside (ara-C), 300 mg/m² carmustine (BCNU), or 1,200 mg/m² carboplatin. Plasma etoposide concentrations were determined by²⁵²Cf plasma desorption mass spectrometry. In all, 27 measurements of kinetics in 10 patients were analyzed. According to graphic analysis, the plasma concentration versus time data for all postinfusion plasma ctoposide values were fitted to a biexponential equation. The mean values for the calculated pharmacokinetic parameters were:t1/2, 256±38 min; mean residence time (MRT), 346±47 min; AUC, 4,972±629g min ml^–1 (normalized to a dose of 100 mg/m²); volume of distribution at steady state (Vd_ss), 6.6±1.2l/m²; and clearance (CL), 20.4±2.4 ml min^–1 m^–2. A comparison of these values with standard-dose etoposide pharmacokinetics revealed that the distribution and elimination processes were not influenced by the dose over the range tested (70–700 mg/m²). Also, the coadministration of carboplatin did not lead to significant pharmacokinetic alterations. Although plasma etoposide concentrations at the time of bone marrow reinfusion (generally at 30 h after the last etoposide infusion) ranged between 0.57 and 2.39 g/ml, all patients exhibited undelayed hematopoietic reconstitution.     

Phase II study of carboplatin,cisplatin, and vindesine in advanced non-small-cell lung cancer

Cisplatin in combination with vindesine has been widely used for the treatment of advanced non-small-cell lung cancer (NSCLC), producing an overall response rate of 32%. We conducted a phase II study to examine whether the addition of carboplatin to the combination of cisplatin and vindesine would improve the antitumor activity of the two platinum agents in advanced NSCLC without increasing their toxicity. Carboplatin (240 mg/m²) and vindesine (3 mg/m²) were given intravenously on day 1 and cisplatin (60 mg/m²) and vindesine (3 mg/m²), on day 8. Of the 40 evaluable patients with advanced NSCLC, 12 showed a partial response, for an overall response rate of 30% (95% confidence interval, 17%–47%). The median duration of response was 12 weeks, and the median survival duration for all patients was 38 weeks. The major toxicity was hematologic: leukopenia (WHO grade3) was observed in 21 patients (53%) and anemia (WHO grade3), in 13 patients (33%). However, thrombocytopenia was mild and WHO grade 3 toxicity was observed in only 4 patients (10%). Nonhematologic toxicities consisted mainly of WHO grade2 nausea and vomiting in 16 patients (40%) and WHO grade2 alopecia in 11 patients (28%). No significant nephrotoxicity or neurotoxicity was seen. Our findings indicate that the addition of carboplatin to the combination of cisplatin and vindesine does not improve antitumor activity in patients with advanced NSCLC.     

In vitro evaluation of a novel chemotherapeutic agent,adozelesin, in gynecologic-cancer cell lines

Summary Adozelesin is a derivative of an extremely cytotoxic compound, CC1065. This entirely new class of drug binds preferentially to DNA and facilitates alkylation reaction. In the present study, we used the adenosine triphosphate (ATP) chemosensitivity assay to compare the cytotoxic potency of Adozelesin with that of common chemotherapeutic agents in ten gynecologic-cancer cell lines. Flow cytometry was also used to study its effects on cell-cycle kinetics. The mean drug concentrations required to produce a 50% reduction in ATP levels as compared with controls [IC₅₀] were: Adriamycin, 0.17±0.06 m; 4OH-Cytoxan, 18±3 m; cisplatin, 17±7 m; 5-fluorouracil, 183±116 m; and Adozelesin, 11.0±5.4pm. Thus, Adozelesin was 10⁴–10⁷ times more potent than Adriamycin, cisplatin, 5-fluorouracil, and Cytoxan. Cell kinetics studies revealed significant S and G2 blocks such as those previously reported for other alkylating agents.Supported in part by an American Cancer Society Clinical Oncology Fellowship and an American Cancer Society/Florida Division Startup Grant (both awarded to H. N. N.)     

Epirubicin metabolism and pharmacokinetics after conventional- and high-dose intravenous administration: a cross-over study

In a pharmacokinetics study, six patients were treated i.v. with epirubicin (EPI) at the two dose levels of 60 and 120 mg/m², whereas a further six patients were treated at 75 and 150 mg/m². Both groups were studied according to a balanced cross-over design; the aim of the study was to assess the pharmacokinetic linearity of epirubicin given at high doses. Both the absolute goodness of fit and the Akaike Information Criterion (AIC) point to a linear, tricompartmental open model as the choice framework for discussing EPI plasma disposition after 16/24 administrations, independent of the delivered dose. After 8 treatments, the minimal AIC value corresponded to a nonlinear tissue-binding model. However, even in these cases, second-order effects were present only during the early minutes following treatment. In a model-independent framework, mean EPI plasma clearance was identical at the two dose levels of 60 and 120 mg/m² (65.4±8.0 vs 65.3±13.4 l/h,P=0.92). Both the mean residence time (MRT) and the volume of distribution at steady-state (V_ss) were similar as well (MRT: 22.6±2.9 vs 24.2±3.7 h;P=0.46; V_ss: 21.3±1.5 vs 22.6±6.5 l/kg,P=0.46). No statistically significant difference could be found in mean statistical-moment-theory parameters determined after 75- and 150-mg/m² EPI doses (plasma clearance, PICI: 83.4±13.5 vs 68.5±12.8 l/h,P=0.12; MRT: 22.6±4.8 vs 21.9±3.9 h,P=0.60; V_ss: 26.7±10.5 vs 21.2±7.0 l/kg,P=0.17). Analysis of variance also failed to reveal any significant correlation between dose and plasma clearance. However, when data relative to single patients were examined, a trend toward nonlinear drug distribution as well as a consequent increase in peripheral bioavailability could be observed in 4/6 patients of the 75-mg/m² vs the 150-mg/m² group. No significant dose-dependent variation was observed in the ratio between the molecular-weight-corrected areas under the concentration-time curve for the metabolites and those for EPI [60 vs 120 mg/m²: epirubicinol (EPIol), 0.23±0.10 vs 0.22±0.06,P=0.20; epirubicin glucoronide (G1), 0.46±0.14 vs 0.62±0.40,P=0.26; epirubicinol glucuronide (G2), 0.21±0.05 vs 0.30±0.16,P=0.06; and 75 vs 150 mg/m²: EPIol, 0.33±0.22 vs 0.32±0.19,P=0.42; G1, 0.51±0.23 vs 0.46±0.17,P=0.53; G2, 0.18±0.10 vs 0.22±0.10,P=0.34]. In conclusion, all the metabolic pathways seemed well preserved when the dose was doubled, and no evident sign of saturation kinetics could be found.     

Phase I and pharmacokinetic trial of liposome-encapsulated doxorubicin

A total of 21 patients with advanced cancer were entered into a phase I study to determine the maximum tolerable dose (MTD) of liposome-encapsulated doxorubicin (LED) given weekly for 3 consecutive weeks at doses of 20, 30, or 37.5 mg/m² per week. For a comparison of the pharmacokinetic behavior of LED with that of standard-formulation doxorubicin, 13 patients received a dose of standard-formulation doxorubicin 2 weeks prior to the first dose of LED. All doses were given by 1-h infusion through a central vein. Toxicity was evaluated in 22 courses delivered to 17 patients. The MTD with this schedule was 30 mg/m² per week×3. The single patient treated at 37.5 mg/m² weekly could not complete the entire course due to myelosuppression. At the dose of 30 mg/m² per week, three of eight patients had grade 3 leukopenia. Other toxicities included mild to moderate thrombocytopenia, nausea, vomiting, fever, alopecia, diarrhea, fatigue, stomatitis, and infection. At the dose of 30 mg/m² per week, the total doxorubicin AUC and peak total doxorubicin concentrations in plasma were 8.75±8.80 M h (mean±SD) and 3.07±1.45 M, respectively, after LED administration. The total doxorubicin AUC and peak total doxorubicin concentrations in plasma were 3.92±2.47 M h and 2.75±2.70 M, respectively, after the infusion of standard-formulation doxorubicin. The total body clearance of doxorubicin was 18.42±11.23 l/h after the infusion of LED and 31.21±15.48 l/h after the infusion of standard-formulation doxorubicin. The mean elimination half-lives of doxorubicin were similar: 8.65±5.16 h for LED and 7.46±5.16 h for standard-formulation doxorubicin. Interpatient variability in pharmacokinetic parameters as demonstrated by the percentage of coefficients of variation was 33%–105%. There was no relationship between the percentage of WBC decrease or the duration of WBC suppression and the total doxorubicin or doxorubicinol AUC. There was no correlation between the duration of leukopenia and drug exposure as reflected by the AUC of liposome-associated doxorubicin. LED can be given in doses similar to those of standard-formulation doxorubicin and produces acute toxicities similar to those caused by standard doxorubicin.Abbreviations MTD maximum tolerable dose - LED liposome-encapsulated doxorubicin - AUC area under the plasma concentration x time curve - WBC white blood cell count - PLT platelet count - ECOG Eastern Cooperative Oncology Group - EKG electrocardiogram - MUGA multigated nuclide scan - CLTB total body clearance - PC phosphatidylcholine: PG, phosphatidylglycerol - PEG-DSPE polyethylene glycol conjugated to distearoyl phosphatidylethanolamine - HSPC hydrogenated soy phosphatidylcholine - chol cholesterol This work was supported by DHHS, NCl NO-l-CM 07 303 and by a Career Development Award from the American Cancer Society (to B. A. C.)     

Pharmacokinetics of VP16-213 given by different administration methods

Summary Plasma pharmacokinetics of VP16-213 were investigated after a 30–60 min infusion in 14 adult patients and six children. In adults the elimination half-life (T_1/2 ), plasma clearance (Cl_p) and volume of distribution (Vd) were respectively 7.05±0.67 h, 26.8±2.4 ml/min/m², and 15.7±1.8 l/m²; in children 3.37±0.5 h, 39.34±6.6 ml/min/m², and 9.97±3.7 l/m². After repeated daily doses no accumulation of VP16-213 was found in plasma. The unchanged drug found in the 24 h urine after administration amounted to 20–30% of the dose.In eight choriocarcinoma patients plasma levels of VP16-213 were measured after oral capsules and drinkable ampoules. The bioavailability compared to the i.v. route was variable, mean values being 57% for capsules and 91% for ampoules. In one further patient, with abnormal d-Xylose absorption results, VP16-213 was not detectable in plasma after the oral ampoule dose.Steady state levels investigated in three patients after 72 h continuous VP16-213 infusion (100 mg/m²/24 h) were around 2–5 g/ml. Levels of VP16-213 were undetectable in CSF after i.v. or oral administration.     

Pharmacokinetics of acridine-4-carboxamide in the rat,with extrapolation to humans

Summary The pharmacokinetics ofN-[2-(dimethylamino)ethyl]acridine-4-carboxamide (AC) were investigated in rats after i. v. administration of 18, 55 and 81 mol/kg [³H]-AC. The plasma concentration-time profiles of AC (as measured by high-performance liquid chromatography) typically exhibited biphasic elimination kinetics over the 8-h post-administration period. Over this dose range, AC's kinetics were first-order. The mean (±SD) model-independent pharmacokinetic parameters were; clearance (Cl), 5.3±1.1 1 h^–1 kg^–1; steady-state volume of distribution (Vss), 7.8±3.0 l/kg; mean residence time (MRT), 1.5±0.4 h; and terminal elimination half-life (t _1/2Z), 2.1±0.7 h (n=10). The radioactivity levels (expressed as AC equivalents) in plasma were 1.3 times the AC concentrations recorded at 2 min (the first time point) and remained relatively constant for 1–8 h after AC administration. By 6 h, plasma radioactivity concentrations were 20 times greater than AC levels. Taking into account the species differences in the unbound AC fraction in plasma (mouse, 16.3%; rat, 14.8%; human, 3.4%), allometric equations were developed from rat and mouse pharmacokinetic data that predicted a Cl value of 0.075 (range, 0.05–0.10; 95% confidence limits) 1 h^–1 kg^–1 and a V_ss value of 0.63 (range, 0.2–1.1) l/kg for total drug concentrations in humans.