Purpose: To define the maximum-tolerated dose (MTD) for weekly paclitaxel administered in combination with daily vatalanib (PTK787/ZK 222584, PTK/ZK) and assess for a drug-drug interaction.
Methods: Patients were treated with escalating doses of weekly paclitaxel (75-85 mg/m(2)), and daily PTK/ZK (250-1,000 mg). During the first cycle only, paclitaxel was given on days 1 and 15, and PTK/ZK on days 3-28. Pharmacokinetic studies were conducted on cycle 1 days 1 and 15 for paclitaxel, and on cycle 1 day 15 for PTK/ZK. Therapy was given until disease progression.
Results: Twenty-seven patients were accrued to four dose levels. Two of five patients treated with paclitaxel 85 mg/m(2) and PTK/ZK 1,000 mg had Grade 3 transaminase elevation as dose-limiting toxicity. Paired PK analyses demonstrated a significant increase in paclitaxel clearance on day 15 (p = 0.006). Activity included one partial response and 11 patients with stable disease > or =4 months, including patients previously treated with paclitaxel.
Conclusions: The MTD for weekly paclitaxel plus daily PTK/ZK is 75 mg/m(2) and 750 mg. PK analysis revealed a significant drug-drug interaction, with an increase in paclitaxel clearance. This combination was well tolerated with evidence of anti-cancer activity and provides guidance for phase 2 planning.