PURPOSE We sought to determine the tolerance of estramustine phosphate (EMP) combined with a 3-hour paclitaxel infusion in women with solid paclitaxel-pretreated solid tumors. Paclitaxel pharmacology was to be studied at the recommended phase II dose. PATIENTS AND METHODS Paclitaxel was administered to cohorts of at least three assessable patients at doses of 150, 180, 210, and 225 mg/m2, while EMP was given at 900 and 1,200 mg/m2/d in divided doses orally for 2 days preceding and on the day of paclitaxel. The pharmacologic study was performed at 225 mg/m2 paclitaxel given in the absence and 3 weeks later in the presence of EMP 900 mg/m2/d. RESULTS Thirty-eight patients received a total of 178 courses. Grade 3 nausea, vomiting, and diarrhea were common at EMP 1,200 mg/m2 and paclitaxel 225 mg/ m2; this was considered the maximum-tolerated dose. Since these toxicities appeared related to EMP, the pharmacologic study used a dose of 900 mg/m2 of this agent with 225 mg/m2 paclitaxel. Antitumor activity was documented against breast and ovarian cancers at all levels. Paclitaxel pharmacokinetics without and with EMP did not differ. CONCLUSION EMP 900 mg/m2 for 3 days and 225 mg/m2 paclitaxel by 3-hour infusion are well tolerated; antitumor activity was seen in women with paclitaxel-pretreated solid tumors. This apparent enhancement of antitumor effects is unlikely to be mediated by P-glycoprotein.
Pharmacokinetic and pharmacodynamic study of tariquidar (XR9576), a P-glycoprotein inhibitor, in combination with doxorubicin, vinorelbine, or docetaxel in children and adolescents with refractory solid tumors
