NIMG-07RADIOGRAPHIC PATTERNS OF PROGRESSION WITH ASSOCIATED OUTCOMES AFTER BEVACIZUMAB THERAPY IN GLIOBLASTOMA PATIENTS

INTRODUCTION: Patterns of progression following bevacizumab (bev) treatment and associated outcomes remain poorly characterized. In patients (pts) with glioblastoma (GB) treated with bev, we describe radiographic patterns of progression and their association with outcome. METHODS: 64 pts treated at MD Anderson matched the predetermined inclusion criteria. Tumor progression after bev treatment was assessed according to the RANO criteria and pts categorized into groups based on previously published data: Group1:exclusively T2-diffuse hyperintense tumor (T2-diffuse), Group2:initial decrease and subsequent flare-up of contrast enhancement (CE) at progression (cT1 Flare-up), Group3:no decrease in CE or development of new lesions at first follow-up imaging (non- responders), Group4:exclusively T2-circumscribed hyperintense tumor progression (T2-circumscribed). In addition, we screened for new diffusion-restricted lesions or pre-contrast T1-hyperintense lesions or both (double-positive). RESULTS: Pts were categorized into Group1:11%, Group2: 33%, Group3: 45%, Group4: 11%. 16 pts had T1-hyperintense lesions and 37 had restricted diffusion;10 pts had double-positive lesions. There was no significant difference in time-to-initiation of bev treatment in the 4 groups. After starting bev, median OS and PFS (months) was Group1:8.6, 4.2 Group2:12.3,3.9 Group3:5.6,1.4 and Group4:7.0,3.2 respectively. Comparing non-responders vs the rest of the groups (responders), OS from initiation of bev was 5.6 vs 10 months (p =