The Combination of Radiotherapy，Surufatinib and Sintilimab in High-Risk Localized Soft Tissue Sarcoma

This is a prospective, single-center, single-arm, phase Ib/II clinical trial. The study aims to evaluate the safety and efficacy of the treatment which combines radiotherapy, Sintilimab (Anti-PD1 Antibody) and Surufatinib (small-molecule Tyrosine Kinase inhibitor) in patients with high-risk localized soft tissue sarcoma. There will be 52 patients with high-risk localized extremity and trunck soft tissue sarcoma recruited. The trail is designed as a two-stage study. In safety lead-in phase (phase Ib), using 3+3 design, 6 cycles of Surufatinib (250mg, 200mg, qd) and Sintilimab (200mg, q3w) will be applied. And radiotherapy (BED=50-60Gy (α/β=10)) will begin in week 4 of the therapy. In extended phase (phase II), Surufatinib will be applied in the recommended phase 2 dose (RP2D) according to phase Ib. And 200mg Sintilimab and radiotherapy will be applied as before. The dose-limiting toxicity (DLT) in phase Ib and objective response rate (ORR) in phase Ib+Phase II will be mainly analyzed.