Key point. For better or worse, Avastin is SOC, the only approved therapy for rGBM... everything else is experimental.
VBLT has data with spider plots showing that high dose VB-111 has attenuated tumor growth compared to low dose VB-111. It stands to reason they a also might have data on rate of tumor growth--in aggregate--for VB-111 plus avastin compared to high dose VB-111 alone although that's not published, but they must have this data from the phase II trial. This data set probably informed them on the phase III trial design.