Purpose: To determine the dose-limiting toxicities (DLTs) and the maximum tolerated dose (MTD) of oral topotecan administered weekly in patients with relapsed small cell lung cancer (SCLC).
Patients and methods: Patients were treated with oral topotecan on days 1, 8, and 15, every 28 days. The dose was escalated by 0.5 mg/m² increments from the starting dose of 3 mg/m² until the MTD was reached. DLTs were defined as grade 4 neutropenia, febrile neutropenia, grade 4 thrombocytopenia, non-hematologic toxicity ≥grade 3, any toxicity precluding the treatment on days 8 or 15 of the first cycle, or delay of the second cycle for more than 7 days.
Results: Eighteen patients were enrolled. Thirteen patients received oral topotecan as second-line and five as third- or further-line treatment. The DLT level was reached at 4.5 mg/m², and the MTD was determined to be 4 mg/m². DLTs consisted of grade 2/3 neutropenia and grade 2 thrombocytopenia precluding treatment on day 15 of the first cycle or on day 1 of the second cycle. The most frequent toxicities were grade 2-3 neutropenia (27.8 % of patients), grade 2-3 anemia (33.3 %), grade 2 thrombocytopenia (16.7 %), and grade 2-3 fatigue (44.4 %). The response rate was 11.1 %, the median progression-free survival 2.3 months, and the median overall survival 5.1 months.
Conclusion: The recommended phase II dose of weekly oral topotecan in pretreated patients with SCLC is 4 mg/m² on days 1, 8, and 15 every 28 days.