Abstract
BACKGROUND: Trabectedin is a novel anticancer agent used to treat soft tissue sarcoma (STS). This phase I study of trabectedin was performed to determine the recommended dose for phase II studies in Japanese patients with STS. METHODS: Patients who had STS refractory to, or who could not tolerate, anthracycline-based chemotherapy were enrolled. The starting dose of trabectedin was 0.9 mg/m(2), given as a 24-h continuous infusion every 21 days. The dose was escalated to 1.2 mg/m(2) and then to 1.5 mg/m(2), using a "3 + 3" cohort expansion design. Plasma samples were collected for pharmacokinetic analysis. RESULTS: Fifteen patients received 1 of 3 dose levels of trabectedin. Dose-limiting toxicity occurred in two of three patients at 1.5 mg/m(2): 1 had a grade 3 increase in creatine phosphokinase and grade 3 anorexia, and the other had grade 4 platelet count decreased. Frequent grade 3 or 4 adverse events (AEs) included elevations of alanine aminotransferase and aspartate aminotransferase and decrease in neutrophil count. The frequency and severity of AEs were clearly greater at 1.5 mg/m(2) than at the lower doses. Pharmacokinetic analysis showed that the area under the concentration-time curve at a dose of 1.2 mg/m(2) was adequate to produce antitumor activity. A partial response was obtained in three patients with translocation-related sarcomas (1 each with myxoid liposarcoma, synovial sarcoma, and extraskeletal Ewing sarcoma). CONCLUSIONS: The recommended dose of trabectedin for phase II studies is 1.2 mg/m(2) in Japanese patients with STS. Trabectedin may be especially effective against translocation-related sarcomas.