A phase I clinical trial of weekly oral topotecan for relapsed small cell lung cancer

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 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.

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.

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.