Purpose: To determine the maximum-tolerated dose (MTD) and acceptable dose level of a cytotoxic regimen of CPT-11, a new camptothecin derivative, in combination with etoposide (VP-16) and to describe the principal toxicities associated with it.
Patients and methods: Patients with refractory solid tumors received VP-16 and CPT-11 daily for 3 consecutive days (days 1 through 3) every 3 or 4 weeks. Groups entered the trial at escalating CPT-11/VP-16 dose levels of 40/60, 60/60, 60/80, and 80/60 mg/m2. Thirty-four patients entered this study, of whom 33 were assessable for toxicity and 22 for therapeutic efficacy.
Results: Granulocytopenia was so severe that this regimen required supportive therapy with recombinant human granulocyte colony-stimulating factor (G-CSF). The majority of the patients experienced a 5% weight loss and diarrhea was the dose-limiting toxicity. The MTDs were 60/80 and 80/60 mg/m2 administered on days 1 through 3. Five of seven previously untreated patients with non-small-cell lung cancer (NSCLC) achieved partial responses (PRs) to this therapy, as did two with NSCLC who had received prior chemotherapy, two with head and neck cancer, and one with an adenocarcinoma (primary tumor unknown).
Conclusion: The recommended dose of CPT-11/VP-16 for this regimen with G-CSF is 60/60 mg/m2 on days 1 through 3 every 3 to 4 weeks. We suggest that the combination of topoisomerase I and II inhibitors is likely to be an effective treatment strategy. The activity of this regimen against NSCLC is particularly encouraging and should be evaluated in a phase II trial.