Standard treatment for newly diagnosed glioblastoma consists of maximal safe resection followed by chemoradiation and maintenance chemotherapy [1,2]. Nevertheless, prognosis remains poor, with median time to tumor recurrence of 7–10 months [3]. Recurrence occurs locally in 70–90 % of cases while 10–30 % of relapses occur in a marginal, distant or multifocal fashion. In the recurrent setting, no standard-of-care is established; repeat surgery, re-irradiation (re-RT), clinical trials, systemic therapy (e.g., lomustine, temozolomide (TMZ) re-challenge), tumor-treating fields (TTF), bevacizumab (BEV) or best supportive care can be considered [4,5].