Outcomes of Salvage Fractionated Reirradiation Combined With Bevacizumab for Recurrent High-grade Gliomas That Progressed After Treatment With Bevacizumab

Background: This study evaluated the outcomes of reirradiation combined with bevacizumab (Bev) for patients with recurrent high-grade gliomas that progressed after treatment with Bev.Methods: Between January 2015 and September 2019, 14 patients who experienced progression after Bev treatment were treated with reirradiation consisting of 25 Gy in five fractions combined with Bev (ReRT/Bev). The isocitrate dehydrogenase (IDH) 1/2 mutation status was analysed by pyrosequencing. Results: The diagnoses of 14 patients at the time of reirradiation included six cases of glioblastoma (GBM) with IDH-wildtype, four cases of GBM with IDH-mutant, one case of anaplastic astrocytoma (AA) with IDH-wildtype, one case of AA with IDH-mutant, and one case of GBM not otherwise specified (NOS), and one case of radiologically diagnosed brainstem glioma. The median overall survival (OS) and progression-free survival (PFS) times with ReRT/Bev were 6.1 months and 3.8 months, respectively. The 6-month OS and PFS rates were 54.5% and 15.7%, respectively. The median OS and PFS did not differ significantly between patients with IDH-wildtype (N=7) and IDH-mutant (N=5) (OS: 7.3 [wildtype] vs 6.0 [mutant] months, p = 0.64; PFS: 3.8 [wildtype] vs 3.7 [mutant] months, p = 0.56). The median OS and PFS did not differ significantly between patients with a diagnosis of GBM (N=6) and those with a diagnosis of non-GBM (N=7) (OS: 9.3 [GBM] vs 6.0 [non-GBM] months, p = 0.19; PFS: 4.0 [GBM] vs 3.8 [non-GBM] months, p = 0.31). Four patients (28.6%) achieved a complete or partial radiological response and three patients (21.4%) experienced improvement after ReRT/Bev. Tumor recurrences were observed in 12 patients, including 3 (21.4%) in-field recurrence; 5 (35.7%) marginal recurrence, 3 (21.4%) out-field recurrence, and 1 (7.1%) had in-field and out-field recurrence. Grade 3/4 toxicities included leukopenia in four patients (28.6%), hypertension in three (21.4%), proteinuria in one (7.1%), and gastrointestinal haemorrhage in one (7.1%) with ReRT/Bev. Conclusions: ReRT/Bev for patients with high-grade glioma who experienced progression after Bev was effective and involved acceptable toxicities.