Envafolimab Combined With Neoadjuvant Chemotherapy Treat Stage IIb Resectable Osteosarcoma Patients

"\* PD-L1 inhibitor envafolimab Paediatric (\<18 years): 2.5 mg/kg (maximum 200 mg) by subcutaneous injection on Day 1 of every week (q1w).~Adult (≥18 years): 200 mg flat dose by subcutaneous injection on Day 1 of every week (q1w).~* Neoadjuvant chemotherapy--MAP regimen (paediatric patients) Doxorubicin 75 mg/m² intravenously on Days 1-2, administered in weeks 1 and 6 of each 6-week cycle.~Cisplatin 120 mg/m² intravenously on Days 1-3, administered in weeks 1 and 6 of each 6-week cycle.~Methotrexate 8-12 g/m² intravenously on Day 1 of weeks 3 and 4 of each 6-week cycle.~* Neoadjuvant chemotherapy--DIA regimen (adult patients) Doxorubicin 75 mg/m² intravenously on Days 1-2, administered in weeks 1 and 6 of each 6-week cycle.~Cisplatin 120 mg/m² intravenously on Days 1-3, administered in weeks 1 and 6 of each 6-week cycle.~Ifosfamide 12-15 g/m² total dose intravenously on Days 1-5 of week 3 of each 6-week cycle."