Docetaxel followed by gemcitabine and irinotecan in solid tumors

Docetaxel (Taxotere), gemcitabine (Gemzar), and irinotecan (Camptosar, CPT-11) are active single agents in a variety of solid tumors. In combination, synergism may be schedule dependent. Preclinical studies suggested synergistic interactions when docetaxel was administered 24 hours before gemcitabine or irinotecan. The objective of this phase I trial in patients with refractory solid tumors was to determine the maximum tolerated dose of docetaxel followed 24 hours later by gemcitabine and irinotecan. Two different schedules were tested: docetaxel escalated by 5 mg/m2/cohort from an initial dose of 20 mg/m2 on days 1 and 8 (schedule A) or escalated by 15 mg/m2/cohort from 45 mg/m2 on day 8 only (schedule B). In both schedules, docetaxel was given over 1 hour. Gemcitabine and irinotecan were given on days 2 and 9 (arm A) or 1 and 9 (arm B) at fixed doses of 1,000 mg/m2 over 30 minutes and 100 mg/m2 over 90 minutes, respectively. Escalation of docetaxel was planned in groups of three patients, with three additional patients added at the first indication of dose-limiting toxicity. Four dose levels in arm A and one dose level in arm B have been tested. Seventeen patients were evaluable in arm A; one died of an unrelated cause on cycle 1, and another withdrew consent before beginning treatment. Five of six patients were evaluable in arm B; one patient inadvertently received G-CSF on cycle 1. Forty-two cycles have been delivered in arm A (mean; 2.2 cycles/patient), and 25 cycles in arm B (mean, 4.2 cycles/patient); the maximum tolerated dose of docetaxel on arm A was 20 mg/m2. The dose-limiting toxicities were grade 3 diarrhea in one patient, grade 3 infection in two patients, and grade 4 neutropenia for > 4 days in one patient at the 25 mg/m2 level. The dose-limiting toxicities on arm B occurred at the first dose level and included grade 3 diarrhea in one patient, grade 4 diarrhea in one patient, and grade 4 neutropenia for 4 days in another patient. Accrual to schedule B was closed after testing the cohort 1 dose level because testing of a single deescalated docetaxel dose given on day 8 was not considered clinically relevant.