Phase I and pharmacokinetic study of XR11576, an oral topoisomerase I and II inhibitor, administered on days 1-5 of a 3-weekly cycle in patients with advanced solid tumours

XR11576 is an oral topoisomerase I and II inhibitor. The objectives of this phase I study were to assess the dose-limiting toxicities (DLTs), to determine the maximum tolerated dose (MTD) and to describe the pharmacokinetics (PKs) of XR11576 when administered orally on days 1–5 every 3 weeks to patients with advanced solid tumours. Patients were treated with escalating doses of XR11576 at doses ranging from 30 to 180 mg day⁻¹. For PK analysis, plasma sampling was performed during the first and second courses of treatment and XR11576 concentrations were assayed using a validated high-performance liquid chromatographic assay with mass spectrometric detection. In all, 21 patients received a total of 47 courses. The MTD was reached at 180 mg day⁻¹, with diarrhoea and fatigue as DLT. Nausea and vomiting, although not qualifying for DLT, was ubiquitous. Only in combination with an extensive prophylactic antiemetic regimen consisting of a combination of both dexamethasone and a 5HT3 antagonist was treatment with XR11576 at 120 mg day⁻¹ tolerable. The systemic exposure of XR11576 increased more than proportionally with increasing dose, with a large interpatient variability. No objective responses were seen; four patients experienced stable disease for periods of 12–30 weeks. In this study, the DLTs of XR11576 were diarrhoea and fatigue. The recommended dose for phase II studies of XR11576 is 120 mg administered orally, on days 1–5 every 21 days. Alternative regimens are currently being explored.

Phase I and pharmacokinetic study of continuous twice weekly intravenous administration of Cilengitide (EMD 121974), a novel inhibitor of the integrins alphavbeta3 and alphavbeta5 in patients with advanced solid tumours

A single-agent dose escalating phase I and pharmacokinetic study with Cilengitide, an inhibitor of the integrins alphavbeta3 and alphavbeta5, was performed to determine its safety and toxicity. Cilengitide was administered as a one-hour infusion twice weekly without interruption to patients with histologically- or cytologically-confirmed metastatic solid tumours. Plasma pharmacokinetics were determined at days 1 and 15. 37 patients were enrolled into the study. Dose levels studied were 30, 60, 120, 180, 240, 400, 600, 850, 1200, and 1600 mg/m(2)/infusion. There was no dose-limiting toxicity (DLT). Pharmacokinetics were dose-independent and time-invariant. Apparent terminal half-life ranged from 3 to 5 h. At 120 mg/m(2)/infusion, peak plasma concentrations were attained that optimally inhibited tumour growth in preclinical models. Cilengitide can be safely administered using a continuous twice-weekly infusion regimen. As DLT was not reached, future trials should explore Cilengitide at different doses.

Absorption kinetics after inhalation of fluticasone propionate via the Diskhaler, Diskus and metered-dose inhaler in healthy volunteers

OBJECTIVE

The aim of this analysis was to assess the rate and extent of systemic availability of inhaled fluticasone propionate (FP) from 2 dry powder systems (Diskhaler and Diskus) and a metered-dose inhaler (MDI) by deconvolution analysis.

METHODS

The inhalation devices were evaluated in 3 separate studies with identical protocols. 12 healthy male volunteers were randomised to receive FP given as a 1000 microg inhaled dose and 250 microg by intravenous infusion according to a double-blind double-dummy crossover design. The bioavailability of FP after inhalation represents absorption of the drug from the lungs, since the bioavailability of the swallowed portion of the inhaled dose is negligible.

RESULTS

When corrected for the bioavailability (of FP) achieved by each inhalation device, the rate of absorption of FP over the first 2 hours was rapid from all devices. The mean time for absorption of 50% of the bioavailable dose was 1.6, 2.4, and 2.2 hours for the Diskhaler, Diskus and MDI, respectively. Thereafter, absorption from each device was prolonged, with approximately 10% of the dose remaining in the lungs 12 hours after inhalation.

CONCLUSION

Irrespective of the inhalation device used, the prolonged absorption of FP into the systemic circulation indicates a long residence time in the lungs.

Acitretin versus etretinate in psoriasis. Clinical and pharmacokinetic results of a German multicenter study

175 patients with severe psoriasis of different types were treated with 10, 25, or 50 mg acitretin and compared with patients receiving 50 mg etretinate over a period of 8 weeks in a randomized, double-blind multicenter study in the Federal Republic of Germany. Plasma concentrations of etretinate and its metabolite acitretin were measured during therapy and also 3 weeks after cessation of treatment. After 4 weeks of treatment, a trend toward clinical improvement was shown in all groups with increasing dosage. Those groups receiving the lower acitretin doses (i.e., 10 and 25 mg/day) had more dropouts than the groups taking 50 mg acitretin or 50 mg etretinate. Complete remissions before the end of therapy occurred only among those receiving higher doses. Enlargement of psoriatic lesions, however, could be observed during treatment with both retinoids, despite improvement of other parameters, as measured by psoriasis area and severity index (PASI) and psoriasis severity index (PSI). After 8 weeks, a significant improvement was calculated by the PASI score and by a newly defined, corrected PASI score for all four dose regimens compared with baseline levels. A greater than 50% PSI score improvement was seen in 50% of patients treated with 10 mg acitretin, 40.5% with 25 mg acitretin, 53.8% with 50 mg acitretin, and 61.1% with 50 mg etretinate. No statistical differences were found among these groups at any time during the 8-week period. No new or unexpected side effects occurred during acitretin treatment. Moreover, cholesterol levels did not significantly change. Three weeks after cessation of drug administration, the plasma concentrations of acitretin were below the sensitivity level of the assay, whereas etretinate was still quantifiable. It is interesting that acitretin plasma concentrations during therapy with 50 mg acitretin were markedly lower (means = 18 ng/ml) than were acitretin levels during treatment with 50 mg etretinate (means = 36 ng/ml).

Studies of the pharmacology of N-methylformamide in mice

When 400 mg/kg of 14C-methyl-labeled N-methylformamide (NMF) was injected ip into mice, the curve for plasma concentration of radioactivity versus time was superimposable on the curve obtained by measuring unmetabolized NMF with gas-liquid chromatography during the first 24 hrs. Radioactivity in plasma was measurable for 8 days after NMF administration, but NMF was not measurable by gas chromatography beyond 24 hrs after administration. Radioactivity was eliminated from the plasma after 60 hrs, with an apparent half-life of 71.1 hrs. Of the radioactivity injected with NMF, 73.6% was recovered in the urine in 24 hrs; 26.4% of this was unchanged NMF. Three percent of the administered radioactivity was exhaled as 14CO2 in 7 hrs at a constant rate of 0.007% per min. One urinary metablite was a stable precursor of formaldehyde, which decomposed to formaldehyde only after alkaline hydrolysis and may well be N-(hydroxymethyl)-formamide. The areas under the plasma concentration versus time curve were estimated after ip, iv, and oral administration of NMF. The bioavailability of NMF was 1.01 after oral administration and 1.10 after ip administration.

Studies of the mode of action of antitumour triazenes and triazines-III. Metabolism studies on hexamethylmelamine

These is good evidence that the antitumour agent hexamethylmelamine (HMM) undergoes oxidative metabolic activation which might occur in the liver and/or extrahepatically. The hepatic microsomal N-methylmelamine metabolizing enzymes were investigated in mice and exhibited different affinities for different melamine derivatives. The apparent Km values are 0.09 mM for HMM, 0.23 mM for pentamethylmelamine, 0.91 mM for 2,2,4,6-tetramethylmelamine and 1.7 mM for trimethylmelamine. HMM inhibited its own metabolism in vitro at substrate concentrations greater than 0.05 mM. Its hepatic microsomal N-demethylation rate was reduced when the mice were pretreated with the hepatic glutathione depleting agent methyliodide. Injection of hexaethylmelamine, a derivative of HMM without antineoplastic properties against the M5076 sarcoma in mice, lead to plasma concentrations of drug and metabolite pentaethylmelamine which were only a fraction of the drug and metabolite levels achieved after a similar dose of HMM.

Trial of heparin and cyclophosphamide (NSC-26271) in the treatment of lung cancer

Preliminary reports have suggested that heparin may enhance the effectiveness of chemotherapy for lung cancer. The VALCSG initiated a study to evaluate further the efficacy and feasibility of administering a heparin and chemotherapy regimen. Treatment consisted of continuous iv heparin infusion for 48--72 hours followed by iv administration of cyclophosphamide (1100 mg/m2) and continued treatment with heparin and warfarin. Only one of the 19 patients (5%) with nonresectable or metastatic lung cancer showed evidence of objective tumor response. This indicated no benefit from the addition of heparin. The study also revealed some of the limitations and problems of such a treatment program.