CD99-positive soft tissue sarcoma

Main purpose: To evaluate the safety and tolerability of autologous T cell injection targeting CD99 chimeric antigen receptor gene modification in the treatment of patients with relapsed/refractory CD99+ bone or soft tissue sarcoma. Secondary purpose: To evaluate the pharmacokinetic characteristics of autologous T cell injection targeting CD99 chimeric antigen receptor gene modification after administration; To evaluate the pharmacodynamic characteristics of autologous T cell injection targeting CD99 chimeric antigen receptor gene modification after administration; To evaluate the immunogenicity of autologous T cell injection targeting CD99 chimeric antigen receptor gene modification; To evaluate the preliminary efficacy of autologous T cell injection targeting CD99 chimeric antigen receptor gene modification in relapsed/refractory CD99+ bone or soft tissue sarcoma; To explore the clinically applicable dose in the phase II clinical study.