REACT: A phase II study of rindopepimut (CDX-110) plus bevacizumab (BV) in relapsed glioblastoma (GB).

TPS2103 Background: EGFRvIII is a constitutively active tumorigenic deletion mutation of EGFR. It is expressed in ~30% of primary GB where it is linked to poor long-term survival (Pelloski 2007). The investigational vaccine rindopepimut consists of the unique EGFRvIII peptide sequence conjugated to keyhole limpet hemocyanin (KLH), delivered intradermally (500ug with 150ug GM-CSF as an adjuvant). Remarkably consistent and promising results across 3 phase II studies in newly diagnosed, resected EGFRvIII+ GB (Lai 2011) represent a statistically significant improvement over a historical control cohort matched for major eligibility criteria (median overall survival [OS] = 24.4 - 24.6 vs. 15.2 months from diagnosis [m] and median progression-free survival [PFS] = 12.3 - 15.3 vs. 6.4 m). ACT IV, a phase III trial in this population, is ongoing. The immunosuppressive influence of residual/advanced GB presents a challenge to activation of efficacious antitumor immune responses. Anecdotal evidence (compassionate us...