Background: Paclitaxel (Taxol) and ifosfamide are among the most active single agents for the treatment of non-small-cell lung cancer. We undertook this phase I dose escalation study to determine the maximum tolerated doses of these drugs which could be administered without growth factors to untreated patients with tumours of this type.
Patients and methods: Forty patients with advanced non-small-cell lung cancer were treated with a 3-hour infusion of paclitaxel and a 1-hour infusion of ifosfamide every 3 weeks. Groups of 3 patients were entered at escalating dose levels in traditional phase I design. Starting doses were paclitaxel, 100 mg/m2, and ifosfamide 3 g/m2, and all patients received premedication with dexamethasone, diphenhydramine and a 5-HT3 blocker. Dose escalation occurred only after full toxicity assessment for 2 cycles for all patients in the dose level.
Results: Dose escalation of paclitaxel continued to 225 mg/m2 without dose-limiting toxicity, but further escalation was not attempted because of the known likelihood of neuro-toxicity above this level. Instead, ifosfamide was increased to 4 g/m2 for the final level. At these doses, dose-limiting myelosuppression was not seen, and there was only 1 episode of febrile neutropenia in 164 treatment cycles. Drug-related toxicities of ifosfamide included gross hematuria and confusion in 1 patient each, and paclitaxel-related symptoms included flu-like syndrome in most patients, mild to moderate arthralgia and/or myalgia in 8 and 25 patients, respectively, parasthesiae in 15 patients and mild to moderate hypersensitivity reactions in 15 patients each. Partial response was seen in 20.5% of patients (CI 9.3%-36.5%).
Summary: Out-patient paclitaxel given over 3 hours and single-dose ifosfamide over 1 hour may be combined safely without the need for hematopoietic growth factors for the treatment of patients with non-small-cell lung cancer. The recommended doses for phase II study are paclitaxel, 225 mg/m2 and ifosfamide, 4 g/m2 every 3 weeks.