Tawbi HA et al. - The safety and activity of pembrolizumab in patients with advanced soft-tissue sarcoma or bone sarcoma have not been established. In the current study, pembrolizumab was shown to have significant clinical activity in patients with undifferentiated pleomorphic sarcoma or dedifferentiated liposarcoma.

Methods

• Patients > 18 years of agewith soft-tissue sarcoma or bone sarcoma from 12 academic centres were enrolled.
• Inclusion criteria included histologic evidence of metastatic or surgically unresectable locally advanced sarcoma, up to three previous lines of systemic anticancer therapy, at least one measurable lesion, and at least one lesion accessible for biopsy.
• The patients were treated with 200 mg of intravenous pembrolizumab every 3 weeks.
• The primary endpoint was objective response.

Results

• 80 patients were evaluable for response.
• The median follow-up was 17·8 months.
• 7 of 40 patients had an objective response, including 4 of 10 with undifferentiated pleomorphic sarcoma, 2 of 10 with liposarcoma, and 1 of 10 with synovial sarcoma.
• No patients with leiomyosarcoma had an objective response.
• 2 of 40 patients with bone sarcoma had an objective response, including 1 of 22 patients with osteosarcoma and 1 of 5 patients with chondrosarcoma.
• None of 13 patients with Ewing's sarcoma had an objective response.