Efficacy Study on Trabectedin in Retroperitoneal Leiomyosarcoma and Well Differentiated/Dedifferentiated Liposarcoma

Overview

This is an Italian, multicentre, single arm, phase II study, with an intra-patient comparison end point. This study aims at confirming the activity of the drug trabectedin as second/further line treatment in retroperitoneal leiomyosarcoma and well differentiated/dedifferentiated liposarcoma expressed in terms of slowing down tumour growth. Another objective is to investigate this peculiar benefit of trabectedin in typical retroperitoneal sarcomas may be exploited to help multidisciplinary clinical decision-making in the management of retroperitoneal sarcomas

Retroperitoneal soft-tissue sarcomas (R-STSs) are rare neoplasms, accounting for 10% to 15% of Soft Tissue Sarcomas (STSs), which represent 1-3% of all cancers. They may show different histological types, but the predominant ones in the retroperitoneal region are: leiomyosarcoma, liposarcoma. The most commonly encountered in the retroperitoneum is the well differentiated/dedifferentiated liposarcoma. First-line chemotherapy usually consists of doxorubicin and/or ifosfamide. These two drugs are the most active agents in adult STSs, with a dose-response relationship and response rates between 20% and 50%. However, the sarcoma community is currently doubtful as to the activity of ifosfamide in the subgroup of leiomyosarcomas. Trabectedin has been found to be mainly active in leiomyosarcoma and liposarcoma and is approved by European Medicines Agency (EMA) as second-line chemotherapy for STSs. Although the response rate observed in pre-registration studies did not exceed 10%, trabectedin provided disease control, with progression arrest rates exceeding 50% and Progression Free Survival (PFS) rates exceeding 20% at 6 months. Since so far no phase II studies tested the activity of trabectedin in retroperitoneal sarcomas, this is the specific aim of this study. Target population: Patients with previously treated, histologically confirmed, retroperitoneal leiomyosarcoma and well differentiated/dedifferentiated liposarcoma. Patients may be either unamenable to surgery or amenable but in whom the addition of medical treatment is considered clinically advisable. Translational studies will be performed, with the aim of characterising the tumour biological features associated with different response patterns to trabectedin. These assessments will be done in 15-20 patients who will undergo surgery after trabectedin, comparing tumour tissue specimens collected before and after treatment.