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

Abstract

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 = <0.001). OS from diagnosis of GB was not significantly different between the 4 groups. Post-progression on bev, OS was: Group1:3.9,Group2:6.4, Group3: 3.8 and Group4:3.0. Pts with restricted diffusion had worse OS (23.4 vs17.4 months). There was no difference in survival based on presence/absence of T1-hyperintense or double-positive lesions. CONCLUSION: Compared to non-responders, cT1 Flare-up have better PFS/OS after bev initiation. Post-progression on bev, cT1 Flare pts lived significantly longer than T2-diffuse and non-responders. Though T2-diffuse and T2-circumscribed have a better PFS after bev initiation compared to non-responders, no OS benefit was seen. Restricted diffusion was a radiographic marker of worse outcomes.