Multinational randomized trial of addition of pembrolizumab to preoperative radiotherapy for stage III soft tissue sarcoma of the extremity

Approximately half of patients with localized, high-risk soft tissue sarcoma (STS) of the extremity develop metastases. The randomized SU2C-SARC032 trial, at 20 centers in four countries, evaluated addition of pembrolizumab to preoperative radiotherapy for patients with stage III STS of the extremity or limb girdle. Patients were randomized to radiotherapy followed by surgery (control group) or pembrolizumab and radiotherapy followed by surgery (experimental group). In modified intention-to-treat analysis after median 43 months of follow-up, the experimental group had significantly longer disease free survival than the control group (HR 0.61; p=0.035) with 2-year DFS rate 67% versus 52%. Grade 3 or higher adverse events occurred more frequently in the experimental group than in the control group (56% versus 31%). The authors conclude that addition of pembrolizumab to preoperative radiotherapy improved disease-free survival among patients with stage III soft tissue sarcoma of the extremity.