NI-60 * RECURRENT PATTERNS OF BEVACIZUMAB MONOTHERAPY FOR RECURRENT PRIMARY GLIOBLASTOMA AND PERSPECTIVES ON BEVACIZUMAB-BASED THERAPIES

Abstract

BACKGROUND. Prognosis of patients with recurrent glioblastoma (GBM) remains dismal, their median overall survival (mOS) ranging from 7 to 10 months. Currently, bevacizumab (BEV), a monoclonal antibody against VEGF, has been widely used since it prolonged progression-free survival (PFS) accompanied with symptom relief in BEV trials. However, improvement of OS seems modest at most, and issues regarding short survival after BEV failure, invasive relapse, and difficulty in determining true progression remain unsolved. Here we examined the patterns of radiological BEV failure in relationship with survival of several post-treatment periods. METHODS. Twenty-five patients with primary GBM who were treated with BEV monotherapy at recurrence in Kyorin University hospital since August 2009 were included in this study. Mean age was 53 yo, 13 males/12 females, median KPS was 60 (30-100), and mOS from the initial surgery was 23.2 months. MRI patterns at BEV progression were determined using modified classification by Nowosielsky et al. (Neurology 2014) as follows: 1) T2-diffuse, 2) cT1-flare up, 3) Primary non-responders, 4) T2-circumscribed, and 5) Remote metastasis. RESULTS. mPFS and mOS of BEV monotherapy were 3.4 and 7.6 months, respectively, and post-BEV mOS was 4.7 months. Frequency and BEV-PFS/post-BEV OS were 1) 20%, 3.8/0.8 months; 2) 40%, 3.4/7.1 months, 3) 24%, 0.9/3.3 months, 4) 8%, 3.7/3.9 months, 5) 8%, 2.0/4.2 months. The cT1-flare up recurrent pattern was found most frequently with relatively better survivals, whereas the T2-diffuse recurrence included fatal brain stem invasion in two cases, resulting in poorer prognosis. CONCLUSIONS. BEV monotherapy showed limited survival benefit and the clinical course after BEV failure may differ by patterns of relapse. Although RANO criteria have been a standard method to determine progression, measurement of T2/FLAIR hyperintensity remains critically controversial. Efforts to improve BEV-based therapy for recurrent GBM including longitudinal and combined chemotherapy will be also discussed.