New Therapeutic for Treating Certain Soft Tissue Sarcomas

The U.S. Food and Drug Administration approval provides a new option for patients with liposarcoma and leiomyosarcoma that is no longer responding to other treatments

The U.S. Food and Drug Administration (FDA) has approved trabectedin (Yondelis) for the treatment of certain patients with two types of soft tissue sarcoma, liposarcoma and leiomyosarcoma.

Trabectedin is intended for patients who have either liposarcoma or leiomyosarcoma that cannot be removed by surgery or that is advanced, and whose cancer has progressed despite treatment with a chemotherapy regimen that includes an anthracycline, such as doxorubicin.

The new chemotherapeutic was shown to extend the time before disease progressed for patients in a randomized phase III clinical trial. The approval is welcome because patients with advanced soft tissue sarcoma have a poor prognosis; median survival is estimated to be just 12 to 15 months.

Soft tissue sarcomas are a group of cancers that arise in soft tissues of the body, such as the muscles, tendons, fat, blood vessels, lymph vessels, nerves, and tissues around joints.

Liposarcomas, which arise in fat cells in any part of the body, but most commonly fat cells in the muscles of the limbs or in the abdomen, and leiomyosarcomas, which arise in smooth muscle cells, most frequently those in the uterus or abdomen, are among the most common forms of soft tissue sarcoma.

Trabectedin has an unusual origin. It was first isolated from the sea squirt Ecteinascidia turbinata in the 1960s, but it wasn’t until 1996 that chemists developed a way to synthetically produce it. This breakthrough allowed the production of sufficient quantities of trabectedin to test its potential as an anticancer therapeutic. How it exerts its anticancer effects is still not completely clear, although it is thought to interfere with the “reading” of genes, which disrupts several key cellular processes, and to affect cells in the tumor microenvironment.

The FDA approval of trabectedin was based on results from a phase III clinical trial that were published in the Journal of Clinical Oncology. Trabectedin extended the time before disease progressed compared with the chemotherapeutic agent dacarbazine: The median progression-free survival time for those patients assigned trabectedin was 4.2 months compared with 1.5 months for those assigned dacarbazine.

The FDA approval was rendered on Oct. 23, 2015.