A phase I study of the safety and pharmacokinetics of trabectedin in combination with pegylated liposomal doxorubicin in patients with advanced malignancies

Background: To determine the maximum tolerated dose (MTD), safety, potential pharmacokinetic (PK) interactions, and effect on liver histology of trabectedin in combination with pegylated liposomal doxorubicin (PLD) for advanced malignancies. Patients and methods: Entry criteria for the 36 patients included normal liver function, prior doxorubicin exposure <250 mg/m2, and normal cardiac function. A 1-h PLD (30 mg/m2) infusion was followed immediately by one of six trabectedin doses (0.4, 0.6, 0.75, 0.9, 1.1, and 1.3 mg/m2) infused over 3 h, repeated every 21 days until evidence of complete response (CR), disease progression, or unacceptable toxicity. Plasma samples were obtained to assess PK profiles. Results: The MTD of trabectedin was 1.1 mg/m2. Drug-related grade 3 and 4 toxic effects were neutropenia (31%) and elevated transaminases (31%). Six patients responded (one CR, five partial responses), with an overall response rate of 16.7%, and 14 had stable disease (less than a 50% reduction and less than a 25% increase in the sum of the products of two perpendicular diameters of all measured lesions and the appearance of no new lesions) >4 months (39%). Neither drug had its PK affected significantly by concomitant administration compared with trabectedin and PLD each given as a single agent. Conclusion: Trabectedin combined with PLD is generally well tolerated at therapeutic doses of both drugs in pretreated patients with diverse tumor types and appears to provide clinical benefit. These results support the need for additional studies of this combination in appropriate cancer types.