Phase I study of docetaxel and topotecan in patients with solid tumors

Both docetaxel (DOC), a promoter and stabilizer of microtubule assembly, and topotecan (TOPO), a topoisomerase I inhibitor, have shown antitumor activity in a variety of solid tumor malignancies. This phase I trial was conducted to determine the overall and dose-limiting toxicities (DLT), the maximum tolerated dose (MTD) and the pharmacokinetics of the combination of DOC and TOPO in patients with advanced solid tumor malignancies.

DOC was administered first at 60 mg/m2 without G-CSF and at 60, 70, and 80 mg/m2 with G-CSF by 1-h infusion on day 1 of the odd-numbered cycles (1, 3, 5, etc.) and on day 4 of the even-numbered cycles (2, 4, 6, etc.). TOPO 0.75 mg/m2 was administered as a 30-min infusion on days 1, 2, 3 and 4 of each cycle. G-CSF 300 micrograms was administered subcutaneously (s.c.) on days 5-14. Cycles were repeated every 21 days. All patients were premedicated with dexamethasone 8 mg orally every 12 h for a total of six doses starting on the day before DOC infusion.

A total of 22 patients were treated. Six patients were treated in cohort I with DOC and TOPO doses of 60 and 0.75 mg/m2, respectively, without G-CSF, and two patients developed DLT (febrile neutropenia). Four patients were treated in cohort II with DOC and TOPO doses of 60 and 0.75 mg/m2, respectively, with G-CSF, and no DLT was observed. Four patients were treated in cohort III with DOC and TOPO doses of 80 and 0.75 mg/m2, respectively, with G-CSF, and three developed DLT (febrile neutropenia). DOC was then de-escalated to 70 mg/m2 and delivered with TOPO 0.75 mg/m2 and G-CSF (cohort IV). Eight patients were treated at this dose level, and one DLT (febrile neutropenia) was observed. Two patients developed a severe hypersensitivity reaction shortly after the DOC infusion was started, one in cycle 1 and one in cycle 2. Both patients were removed from the study. Two patients developed severe dyspnea in the presence of progressive pulmonary metastases. Other nonhematological toxicities were mild. One patient with extensively pretreated ovarian carcinoma had a partial response, and eight patients with various solid tumor malignancies had stable disease with a median time to progression of 12 weeks (range 9-18 weeks). Administration of TOPO on days 1-4 and DOC on day 4 resulted in increased neutropenia.

DOC 80 mg/m2 given first as a 1-h infusion on day 1 with TOPO 0.75 mg/m2 given as a 0.5-h infusion on days 1, 2, 3 and 4 with G-CSF was considered the MTD. The recommended phase II dose for DOC given on day 1 is 70 mg/m2 with TOPO 0.75 mg/m2 given on days 1, 2, 3 and 4 every 21 days with G-CSF 300 micrograms s.c. on days 5-14. The alternative schedule with DOC given on day 4 and TOPO on days 1-4 is not recommended.