Pulmonary Resectable Osteosarcoma Treated by Metastasectomy and Pre-operative Immunotherapy and Stereotactic Body Radiotherapy (PROMIS): a Prospective Clinical Trial

participants first receive concurrent SBRT and penpulimab (PD-1 blockade) and two cycles of GP regimen (gemcitabine d1,d8 and Penpulimab d8 per a 21-day cycle), followed by complete pulmonary metastasectomy. After surgery, participant receive another 4 cycles of GP regimens followed by Penpulimab monotherapy maintenance. The rationale is that pre-operative SBRT could boost the immune microenvironment, leading to a long-term effect of immunotherapy post-metastasectomy and eventually resulting in better long-term survivorship compared to the histological control for pulmonary resectable recurrence of osteosarcoma .