Avelumab and Trabectedin in Treating Patients With Liposarcoma or Leiomyosarcoma That is Metastatic or Cannot Be Removed by Surgery

This phase I/II studies the side effects of avelumab and trabectedin and how well they work in treating patients with leiomyosarcoma or liposarcoma that has spread to other places in the body (metastatic) or cannot be removed by surgery. Immunotherapy with monoclonal antibodies, such as avelumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Drugs used in chemotherapy, such as trabectedin, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Giving avelumab and trabectedin may work better in treating patients with liposarcoma or leiomyosarcoma.

PRIMARY OBJECTIVES: I. To assess the safety and tolerability of the combination of trabectedin and avelumab in subjects with advanced leiomyosarcoma and liposarcoma. II. To assess the objective response rate of advanced L-type sarcoma patients receiving the combination regimen of avelumab and trabectedin. SECONDARY OBJECTIVE: I. To further explore the clinical activity and safety profile of avelumab and trabectedin as a combination therapy. OUTLINE: Avelumab will be administered every 2 weeks. Trabectedin will be administered every 3 weeks for the first two doses (Week 1 and Week 4), and then every four weeks (Week 7, Week 11,…) moving forward. After Cycle 2 of trabectedin, dosing may extend to every 5 weeks at investigator discretion, for management of trabectedin-associated toxicity only. Delays of trabectedin beyond 5 weeks may be allowed but require written approval from the Sponsor-Investigator. On days where both drugs are scheduled to be administered, avelumab will be administered first. This will continue until unacceptable toxicity or confirmed disease progression. After completion of study treatment, patients are followed up at 30 and 90 days, then every 12 weeks for 2 years.