Paclitaxel and docetaxel are the two presently clinically available representatives of the new class of taxane drugs. They share major parts of their structures and mechanisms of action, but differ in several other aspects. For instance, there is a difference in their tubulin polymer generation, and docetaxel appears twice as active in depolymerization inhibition. In vitro docetaxel also tends to be more potent in different cell lines and investigational models. While in vitro and in vivo studies suggest that prolonged exposure to paclitaxel is better than a brief exposure, no such tendency is seen for docetaxel, indicating it to be a schedule-independent drug. Clinical studies have not confirmed an advantage for prolonged exposure to paclitaxel; but do show differences in the toxicity profiles of the two drugs. These topics will be addressed in detail.

Subgroups with different survival expectancy can be identified among patients who are eligible for phase I clinical trials. If confirmed, the proposed prognostic model may be useful for therapeutic decision making in palliative oncology.

We conclude that the CF regimen has no advantage over the CABO regimen, which in fact showed a higher complete response rate. Both combinations showed improved response rates but also more toxicity and no improvement in overall survival in comparison with cisplatin alone.

Docetaxel is an active drug in patients with advanced squamous cell carcinoma of the head and neck.

168 pharmacokinetic data sets were obtained in 107 patients (97 first courses, 43 second courses, 23 third courses, 4 fourth courses, and 1 fifth course). Rebound concentrations of CPT-11 were frequently observed at about 0.5 to 1 h following the end of the i.v. infusion, which is suggestive of enterohepatic recycling of the drug. Model-independent analysis yielded the following mean population pharmacokinetic parameters for CPT-11: a terminal half-life of 10.8 h, a mean residence time (MRT) of 10.7 h, a volume of distribution at steady state (Vdss) of 150 L/m2, and a total body clearance of 14.3 L/m2/h. Model-dependent analysis disclosed a CPT-11 plasma disposition as either biphasic or triphasic with a mean terminal half-life of 12.0 h. The volume of distribution Vdss (150 L/m2) and total body clearance (14.8 L/m2/h) yielded almost identical values to the above model-independent analysis. The active metabolite SN-38 presented rebound concentrations in many courses at about 1 h following the end of the i.v. infusion which is suggestive of enterohepatic recycling. The mean time at which SN-38 maximum concentrations was reached was at 1 h since the beginning of the 0.5 h infusion (i.e., 0.5 h post i.v.). SN-38 plasma decay followed closely that of the parent compound with a mean apparent terminal half-life of 10.6 h. Mean 24 h CPT-11 urinary excretion represented 16.7% of the administered dose, whereas metabolite SN-38 recovery in urine was minimal (0.23% of the CPT-11 dose). The number of CPT-11 treatments did not influence pharmacokinetic parameters of either the parent compound or metabolite SN-38. Although CPT-11 pharmacokinetics presented an important interpatient variability, both CPT-11 maximum concentrations (Cmax) and the CPT-11 area under the plasma concentration versus time curves (AUC) increased proportionally and linearly with dosage (Cmax, r = 0.78, p < 0.001); CPT-11 AUC, r = 0.88, p < 0.001). An increase in half-life and MRT was observed at higher dosages, although this did not influence the linear increase in AUC as a function of dose. The volume of distribution at steady state (Vdss) and the total body clearance (CL) were not affected by the CPT-11 dose. Metabolite SN-38 AUC increased proportionally to the CPT-11 dose (r = 0.67, p < 0.001) and also with the parent compound AUC (r = 0.75, p < 0.001) (ABSTRACT TRUNCATED)