Immunotherapy Proves Effective in Subtypes of Advanced Sarcoma

10/23/17

A recent study demonstrated meaningful clinical activity with limited toxicity in patients with soft-tissue and bone sarcoma after treatment with an immuno-agent.

Patients with advanced sarcomas are faced with a poor prognosis and have limited treatment options available. Chemotherapies offer only minimal and short-lived disease control. The effects of immunotherapy in patients with soft-tissue or bone sarcoma are not well documented.

Hussein A Tawbi, MD, University of Texas MD Anderson Cancer Center, and colleagues conducted a two-cohort, single-arm, open-label, phase II study to assess pembrolizumab for safety and efficacy in patients with advanced soft-tissue or bone sarcoma. A total of 84 patients—42 of whom with soft-tissue disease, while the remaining 42 had bone disease—were enrolled from 12 US academic centers in the Sarcoma Alliance for Research through Collaboration from 2015 to 2016. All patients were treated with 200 mg every 3 weeks of pembrolizumab.

Enrollment criteria included metastatic or unresectable locally advanced disease, up to three previous lines of systemic therapy, and at least on measurable lesion on Response Evaluation Criteria in Solid Tumors version 1.1. The primary endpoint was investigator-assessed objective response.

Results of the study were published in The Lancet Oncology (online October 4, 2017; doi:10.1016/S1470-2045(17)30624-1).

After a median follow-up of 17.8 months, researchers reported observable responses in 7 of 40 evaluable patients (18%) with soft-tissue sarcoma, including 4 of 10 (40%) with undifferentiated pleomorphic sarcoma, 2 of 10 (20%) with liposarcoma, 1 of 10 (10%) with synovial sarcoma, and 0 of 10 with leiomyosarcoma. Among the evaluable patients with bone disease, 2 of 40 (5%) demonstrated responses, including 1 of 22 (5%) with osteosarcoma and 1 of 5 (20%) with chondrosarcoma.

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Researchers noted that no responses were observed in the 13 patients presenting with Ewing’s sarcoma.

Additionally, researchers reported that serious adverse events occurred in only 11% of patients, including 10% with soft-tissue sarcoma and 12% with bone sarcoma.

In their concluding remarks, authors of the study wrote that “Pembrolizumab has meaningful clinical activity in patients with undifferentiated pleomorphic sarcoma or dedifferentiated liposarcoma.” Expanded cohorts of these subtypes is ongoing in order to confirm and characterize the activity of pembrolizumab, they noted.—Zachary Bessette