Effectiveness of Pucotenlimab Combined With Standard Chemotherapy Regimen

This study comprises both Phase I and Phase II research. This phase focuses on safety, tolerability, and pharmacokinetics using a "3+3" dose escalation design with three dose groups: 1 mg/kg, 3 mg/kg, and 6 mg/kg. The drug will be administered in combination with the standard regimen for intermediate/high-risk rhabdomyosarcoma once every three weeks (Q3W). In phase II study, all subjects will receive Pucotenlimab combined with the standard regimen for intermediate/high-risk rhabdomyosarcoma for 2-4 cycles of neoadjuvant therapy every 3 weeks (Q3W), followed by surgery.