Supplementary Material for: Defying the Odds in Recurrent Glioblastoma: Complete Response Following Salvage Therapy with Bevacizumab and Irinotecan

Introduction: The most formidable primary tumor in the central nervous system is glioblastoma multiforme (GBM), distinguished by a median survival duration of just 12 months and recurrence likelihoods above 90% in less than 6 months following therapy. In spite of the implementation of multimodal treatment strategies, recurrent GBM (r-GBM) presents substantial therapeutic dilemmas, with the absence of a universally recognized standard of care. Case Presentation: In this discourse, we delineate the case of a 42-year-old male patient diagnosed with IDH-wildtype, MGMT-unmethylated, TERT promoter mutated, and EGFR amplified GBM, who manifested an early recurrence during adjuvant temozolomide therapy. Subsequent to maximal safe surgical resection and chemoradiation (60 Gy in conjunction with temozolomide), recurrence was identified through magnetic resonance imaging (MRI), necessitating the initiation of fractionated stereotactic re-irradiation (27 Gy over 5 fractions) in combination with bevacizumab and temozolomide. Due to transient ischemic complications requiring dose adjustment, subsequent disease progression prompted a transition to irinotecan-bevacizumab therapy. Conclusions: Our findings, contextualized within contemporary evidence on re-irradiation (SRS/FSRT) and combinatorial strategies (bevacizumab with lomustine or irinotecan), underscore the need for further empirical investigation to optimize treatment sequencing in r-GBM. This case emphasizes the necessity for individualized multimodal approaches to improve outcomes in this refractory patient population.