Imaging Biomarkers Of Ramucirumab And Olaratumab In Patients With Recurrent Glioblastoma

2044 Background: VEGF and PDGF receptors are overexpressed in glioblastoma (GBM). Both receptor families may be important therapeutic targets. We explored early biologic markers of VEGFR-2 or PDGFRa inhibition with functional MRI. Methods: A subset of patients (pts) from a multicenter phase II study of monoclonal antibodies to VEGFR-2 (ramucirumab 8mg/kg IV q2wks) or PDGFRa (olaratumab 20mg/kg IV q2wks) in adult patients with recurrent GBM underwent a standardized MRI brain protocol with dynamic contrast enhanced (CE); diffusion tensor; perfusion weighted and routine sequences at -1d, +1d, +28d and every +56d from treatment initiation. ACRIN performed site qualification and imaging QA. Regions of CE and T2w hyperintensity were manually defined; percent change in volumes and change in normalized image intensities was calculated. Results: 28 patients were evaluable. Pts receiving ramucirumab (n=11; 7 male) had a median age of 54 (43-67), KPS 90 (70-100) and Dex dose 2mg (0-8). Pts receiving olaratumab (n=17...