NIMG-47. VOLUMETRIC ANALYSIS OF PHASE 2 AND 3 TRIALS IN RECURRENT GLIOBLASTOMA TREATED WITH VB-111 WITH OR WITHOUT BEVACIZUMAB OR BEVACIZUMAB MONOTHERAPY

VB-111 is a non-replicating adenovirus carrying a pro-apoptotic transgene for TNFR1/Fas under the control of a modified murine promoter to pre-proendothelin 1. The transgene is expressed only in angiogenic endothelial cells, and therefore VB-111 results in targeted apoptosis of neovascular vessels. The current study characterizes the quantitative radiographic results and impact on OS in phase 2 and 3 trials of recurrent glioblastoma (GBM) patients treated with VB-111 with or without bevacizumab (BV) or BV monotherapy. MRI data from a phase 2 (NCT01260506) and randomized, double arm, controlled phase 3 (GLOBE; NCT02511405) trial of VB-111 in recurrent GBM were used in current study: Arm A) VB-111 monotherapy until progression followed by combination VB-111 and bevacizumab (BV) (“Primed Combination”; Phase 2; N=24); Arm B) VB-111 in combination with BV (“Unprimed Combination”; Phase 3; N=124); Arm C) BV monotherapy (“Control”; Phase 3; N=120). Contrast enhanced T1-weighted digital subtraction was used to quantify tumor volume at all time points. Baseline tumor volume was prognostic for OS in all treatment groups when controlling for therapy and age (Cox, P< 0.001, HR=1.02). In patients with smaller tumors (< 25mL), the “primed combination” cohort (Arm A) from the phase 2 trial had a significant OS advantage compared to both upfront combination of VB-111 and BV (Arm B; P=0.0094, HR=0.53; median OS = 7 vs. 15mo) as well as BV alone (Arm C; P=0.025, HR=0.58; median OS=8.5 vs. 15mo). Patients with a radiographic response (>65% reduction) had a significant survival difference from non-responders when controlling for age, baseline tumor volume, and treatment arm (P=0.0014, HR=0.58). Responders to VB-111 monotherapy or combination therapy after priming with VB-111 exhibited characteristic, expansive areas of necrosis in areas of initial disease.