A phase I study of dose-dense topotecan given upfront to standard therapy in patients with small cell lung cancer

To determine the feasibility and maximum tolerated dose of dose-dense topotecan as induction chemotherapy before standard therapy (carboplatin plus etoposide alone or in combination with radiotherapy) in patients with small cell lung cancer (SCLC).

Chemotherapy-naive patients with SCLC and good performance status were eligible. Three 2-week cycles of dose-dense topotecan administered on days 1-3 with granulocyte colony-stimulating factor support were followed by four cycles of standard carboplatin plus etoposide therapy alone (extensive-stage SCLC) or with radiotherapy (limited-stage SCLC). The dose of topotecan was escalated from 1.5 mg/m2/day to 2.5 mg/m2/day in increments of 0.25 mg/m2/day within cohorts of 3-5 patients each. Dose-limiting toxicity was defined as any grade 3 or 4 toxicity resulting in a treatment reduction or a delay of >3 days.

Twenty-two patients with SCLC (5 limited-stage, 17 extensive-stage) were enrolled. Treatment was well tolerated. The dose-limiting toxicities were thrombocytopenia and neutropenia, and the maximum tolerated dose of dose-dense topotecan induction therapy was 2.25 mg/m2/day. Overall, topotecan-related grade 3/4 haematological toxicities included neutropenia (n = 4), thrombocytopenia (n = 3) and febrile neutropenia (n = 1). No grade 4 non-haematological toxicities occurred. Grade 3 adverse events included nausea (n = 2), renal toxicity (n = 1) and anorexia (n = 1). Toxicity during the carboplatin plus etoposide +/- radiotherapy phase of therapy was consistent with that reported in previous trials. The overall response rate was 80% for limited-stage and 76% for extensive-stage SCLC. Median survival was 8 months in patients with limited-stage SCLC and 13.5 months for patients with extensive-stage SCLC.

The results of this phase I study suggest that a regimen of sequential dose-dense topotecan and carboplatin plus etoposide is feasible, and the preliminary activity observed in patients with SCLC warrants further investigation at a starting dose of topotecan 2.25 mg/m2/day.