The primary objective of this trial is to evaluate the safety and tolerability of the tumor neoantigen vaccine (SarcVac) in combination with a PD-1 antibody, with or without tumor-specific lymphocytes, in patients with advanced bone and soft tissue sarcoma who have failed first-line treatment. The secondary objectives are to assess the preliminary efficacy of SarcVac combined with a PD-1 antibody, with or without tumor-specific lymphocytes, in these patients and to evaluate whether the vaccine's efficacy demonstrates dose dependency.