This is a single-center, open-label, dose-escalation, multiple-dose investigator-initiated trial (IIT). The trial aims to evaluate the safety and tolerability of autologous dendritic cell injection sensitized with tumor neoantigens (YS247) in participants with recurrent or progressive glioblastoma, as well as to assess preliminary efficacy and pharmacodynamic characteristics. The study consists of four phases: screening, baseline, treatment, and follow-up. During the treatment phase, participants will be assigned to three dose groups (low, medium, and high) and enrolled following the "3+3" dose-escalation principle. YS247 will be administered subcutaneously once every 2 weeks for a total of 8 consecutive doses.