The FDA approved eribulin for treatment of advanced liposarcoma based on data from a phase III study showing that it increased overall survival by about 7 months compared with a commonly used chemotherapy, dacarbazine.

The FDA approved the chemotherapeutic eribulin mesylate (Halaven; Eisai) for the treatment of inoperable or advanced cases of liposarcoma, a type of soft-tissue sarcoma (STS) that affects fat tissue, on January 28. Patients with liposarcoma who have received prior chemotherapy containing an anthracycline are now eligible for eribulin therapy.

Eribulin, a synthetic analog of a sea sponge compound called halichondrin B, exerts its cytotoxic effect by inhibiting microtubule dynamics. The drug has also been approved for the treatment of late-stage breast cancer.

In a phase III study conducted at 119 global sites, 452 patients with the STSs liposarcoma and leiomyosarcoma were randomly assigned to receive eribulin or the alkylating agent dacarbazine, a chemotherapeutic. Patients in the eribulin arm had a relatively small but statistically significant improvement in overall survival: 13.5 months versus 11.5 months for those who received dacarbazine.

However, when the researchers examined eribulin's efficacy in a subset of 143 trial participants with previously treated liposarcoma that could not be surgically removed or had begun to metastasize, the difference in overall survival was significantly greater: Patients who received eribulin lived 15.6 months compared with 8.4 months for those receiving dacarbazine. The 7.2-month improvement was enough to consider eribulin “a clinically meaningful drug,” says Richard Pazdur, MD, director of the Office of Hematology and Oncology Products in the FDA's Center for Drug Evaluation and Research.

Notably, eribulin did not prolong overall survival in the subset of participants with leiomyosarcoma and did not improve progression-free survival in the overall study population. Other potential treatments are available for STSs, though none clearly outperforms the rest. While this could be seen as bad news, it fuels continuing discussion about combination therapy for STSs.

Which drugs to use first, or in combination, “remains to be defined by ongoing clinical trials and future clinical trials,” said Robin L. Jones, MD, MRCP, a medical consultant at Royal Marsden Hospital in London, UK, during a recent panel discussion. “I think this is an evolving field. It's good to have a choice of different drugs that are showing promise in these rare diseases.” –Esther Landhuis