Reduced-Dose Regorafenib for Recurrent Glioblastoma: A Safety and Outcome Analysis

Background/Objectives: Recurrent glioblastoma has a poor prognosis and no universally accepted standard of care. Regorafenib has been investigated in this setting, but its use may be limited by treatment-related toxicity. This study evaluated the feasibility, safety, and clinical outcomes of reduced-dose regorafenib in patients with recurrent IDH-wildtype glioblastoma. Methods: We retrospectively analyzed 21 patients with recurrent IDH-wildtype glioblastoma (WHO 2021) treated at a single center after progression according to the Stupp protocol. Regorafenib was started at 80 mg/day on the standard 3-weeks-on/1-week-off schedule. We assessed overall survival from diagnosis (OS1) and from first progression (OS2), progression-free survival from diagnosis (PFS1) and from first progression (PFS2), treatment exposure, dose modifications, and treatment-related adverse events (CTCAE v5.0). Results: Median PFS2 was 5 months (95% CI, 3–8), median OS2 was 6 months (95% CI, 5–10), and median OS1 was 21 months (95% CI, 15–27). No grade ≥ 3 adverse events occurred, and no patient discontinued treatment permanently because of toxicity. Conclusions: In this retrospective single-center cohort, reduced-dose regorafenib was feasible and well tolerated in selected patients. These descriptive, hypothesis-generating findings warrant prospective studies to define the role of individualized regorafenib dosing in recurrent glioblastoma.