STMO-21 The Outcome of tumor resection followed by photodynamic therapy for recurrent glioblastoma

Abstract Recurrent glioblastoma remains a clinical problem with no standard treatment and quite a few effective treatment options. We evaluated the efficacy of photodynamic therapy (PDT) using talaporfin sodium (TS) as a treatment for recurrent glioblastoma in a retrospective analysis of 70 patients who underwent PDT with surgery (PDT group) between 2014 and 2018, and 38 patients who underwent surgery alone (control group) during the same period. The median overall survival (OS) of the PDT and control groups were 16.03 and 12.75 months, respectively (P=0.0311). The median progression-free survival (PFS) of these two groups were 5.67 and 2.2 months, respectively (P=0.00428). Univariate and multivariate analyses showed PDT with surgery and preoperative Karnofsky Performance Scale as significant independent prognostic factors for both PFS and OS.On the other hand, IDH mutation and previous pathology before recurrence were not significant prognostic factors in this study. In the PDT group, there was no significant difference in PFS and OS between patients with GBM from the previous pathology before recurrence and those with malignant transformation to GBM from lower-grade glioma. Furthermore, there was also no significant difference in TS accumulation in the tumor between these two groups. These results suggest that additional PDT treatment for recurrent glioblastoma can have potential survival benefits and that its efficacy is independent of the pathology before recurrence or IDH status.