Topotecan preceded by oxaliplatin using a 3 week schedule: a phase I study in advanced cancer patients

Abstract Combinations of topoisomerase I (topo I) poisons and platinum derivatives have synergistic antitumoral effects. However, their clinical development is limited by supra-additive haematological toxicity. The aim of this study was to determine whether sustained doses of topotecan and oxaliplatin could be achieved using a synergistic sequence. 34 advanced cancer patients and 186 cycles were evaluable for toxicity over five dosing levels. Oxaliplatin at 85–110 mg/m 2 was given on day 1, followed by topotecan 0.5–1.25 mg/m 2 /day×5 from day 1 to 5, every 3 weeks. Plasma pharmacokinetics (PK) of total and ultrafiltrable platinum, total and lactone forms of topotecan were determined in the first cycle. The dose-limiting toxicity (DT) was identified as grade 4 thrombocytopenia. The occurrence of grade 4 thrombocytopenia did not correlate with topotecan PK, but it did with the patient's characteristics. Severe thrombocytopenia was seen in 1/8 of patients without clinical or biological evidence of malnutrition, with a creatinine clearance higher than 1 ml/s, and no more than two previous chemotherapy regimens, while it was seen in 8/10 patients with one of these characteristics ( P 2 and topotecan 1 mg/m 2 /day, every 3 weeks can be administered to patients with a favourable general status and pretreatment characteristics and a phase II study is worthwhile in ovarian cancer patients.