Pharmacokinetics and efficacy of i.v. and i.p. VM26 chemotherapy in mice bearing Krebs II ascitic tumors

Efficacy of i.v. or i.p. injected cytotoxic drugs on proliferating and non-proliferating hair follicles of the mouse

A range of drug doses of Adriamycin (ADR), Actinomycin-D (ACT-D), and Mitomycin-C (MMC) were given i.v. or i.p. to mice 1 day after a priming dose of radiation to elicit epilation response. The hair follicles were stimulated through plucking 11 days before irradiation or were unstimulated to represent proliferating and nonproliferating populations. The maximum epilation that appears at 8 days or at 8.5 weeks for proliferating and nonproliferating follicles was quantified using a subjective scale. In general, the i.v. route of administration was more effective than i.p. for all three drugs. Proliferating follicles were more susceptible than non-proliferating follicles to the action of drugs, especially ADR (p = .0001). Radiation doses which would give the same effect as ADR were calculated for proliferating follicles: 8 mg/kg given i.v. was equivalent to 4.6 (3.9, 5.2) Gy. For i.p. administration, 8 mg/kg was equivalent to only 0.6 (-0.1, 1.3) Gy. The in vivo assay of drug effect on hair follicles has advantages over LD10 as a model for toxicological investigation of new drugs: it can assess response of proliferating or non-proliferating cells of the same histotype and, in the case of proliferating follicles, it is quicker, thus enabling the use of doses higher than LD50 for bone marrow deaths.

Teniposide and cisplatin given by intraperitoneal administration: preclinical and phase I/pharmacokinetic studies

Cisplatin and teniposide given by intraperitoneal (IP) route exert a synergistic therapeutic effect against ascitic P388 leukemia in mice. As single agents, they display different dose-limiting toxicities and favourable pharmacokinetic characteristics in IP phase I trials. We administered cisplatin (fixed dose: 200 mg/m2) and teniposide (escalating doses) by IP route without dwell-time to investigate the toxicity, pharmacokinetics and clinical activity of this 2-drug combination. Nine patients received a total of 14 courses. Myelosuppression, nausea and vomiting were the most frequent toxicities. Leukopenia was the dose-limiting toxicity. The maximum tolerated dose of teniposide was 100 mg/m2 when administered with a fixed dose of 200 mg/m2 cisplatin. Pharmacokinetic analysis showed that the main parameters of both cisplatin and teniposide in the peritoneum and in the plasma were not modified when the drugs were combined. It appears that a pharmacodynamic interaction exists between cisplatin and teniposide which results in increased hematologic toxicity. Although an objective response has been observed in one patient with refractory ovarian cancer, such association should not be applicable for further clinical development due to marked toxicity and the low dose of teniposide recommended.

Phase I/pharmacokinetic study of intraperitoneal teniposide (VM 26)

A phase I/pharmacokinetic study of the i.p. administration of teniposide (VM 26) was undertaken. Eighteen patients with various malignancies and refractory malignant ascites consented to enter this trial. The dose escalation was made according to the modified Fibonacci scheme. Twenty-four courses were evaluable for toxicity, response and pharmacokinetics. The maximum tolerated dose was reached at 450 mg/m2 and the limiting toxicity was myelosuppression, principally leukopenia. Abdominal pain occurred in one half of the courses but was not limiting. No partial remission, but two 'no change' were achieved for more than 2 months. A reduction or disappearance of ascites was seen in two patients. Pharmacokinetic studies, carried out in all courses, showed that the total exposure for peritoneal cavity averaged 10-fold greater than that of plasma. Based on the outcome of this phase I study, we could recommend phase II studies at a dose of 390 mg/m2 i.p. repeated every 4 weeks with a 4 h dwell-time.

Uptake and binding of teniposide (VM26) in Krebs II ascites cells

With [3H] VM26 as marker, the uptake and binding of teniposide have been made in cells of Krebs II ascitic tumors. The intracellular accumulation of drug displayed a passive diffusion and a saturation kinetics with an apparent Michaelis-Menten constant of 37.54 10(-6) M and a flux of 13.4 nM/min/mg of protein. VM26 was rapidly taken and an equilibrium was established with the extracellular drug in about 30 min. The steady-state accumulation was diminished by Na+ and Ca2+ absence and VP16-213, whereas, K+ and Mg2+ have no effect. Energy dependence of the system was characterized by a Q10 of 1.75 +/- 0.2 and the uptake was reduced by ouabain and iodoacetamide, when 2-4-dinitrophenol and glucose absence were without appreciable change. The study of the efflux showed that about 87% of the uptaken drug was removed, the residual amount being probably irreversibly bound. The intracellular accumulation of the drug was associated with various cell organelles, however, only the nuclear fraction demonstrated a high affinity binding.