Glioblastoma: Adding Rindopepimut to Chemotherapy Is Ineffective

The addition of rindopepimut to standard maintenance chemotherapy did not improve overall survival compared with chemotherapy alone among newly diagnosed patients with EGFRvIII-expressing glioblastoma multiforme, according to a study presented 21^st Annual Scientific Meeting of the Society of Neuro-Oncology (SNO).¹

Approximately 30% of patients with glioblastoma harbor the EGFR deletion mutation, EGFRvIII. Rindopepimut, an EGFRvIII-targeted vaccine that consists of EGFRvIII peptide conjugated to keyhole limpet hemocyanin (KLH), has demonstrated a survival benefit in a randomized phase 3 trial of 73 patients with recurrent glioblastoma. Three phase 2 studies of 105 total patients with newly diagnosed, EGFRvIII-expressing glioblastoma and minimal residual disease showed a median overall survival of 20 to 22 months.

Researchers designed the international, double-blind, phase 3 ACT IV study (ClinicalTrials.gov Identifier: NCT01480479) to evaluate the efficacy and safety of rindopepimut added to standard maintenance therapy in this patient setting.

Investigators enrolled 745 newly diagnosed, resected, EGFRvIII-expressing patients with glioblastoma who received standard chemoradiation, 405 of which had minimal residual disease. Participants were randomly assigned 1:1 to receive rindopepimut or KLH (control) with standard maintenance temozolomide.

Among patients with minimal residual disease, results showed no significant difference in overall survival, the primary endpoint, between the 2 arms (hazard ratio [HR], 1.01; P = .93). Median overall survival was 20.1 months with rindopepimut vs 20.0 months with KLH.

There was no significant difference in overall survival between rindopepimut and KLH in the non-minimal residual disease cohort: median overall survival was 14.8 months and 14.1 months, respectively (HR, 0.79; P = .066). Two-year overall survival rates were 30% in the rindopepimut arm and 19% in the control arm.

Overall survival with rindopepimut treatment was comparable to prior studies, but patients in the control arm appeared to have longer survival than historical controls.

The study also demonstrated no significant differences in progression-free survival between the 2 groups in either cohort.

Reference

1. Weller M, Butowski N, Tran D, et al. ACT IV: An international, double-blind, phase 3 trial of rindopepimut in newly diagnosed, EGFRvIII-expressing glioblastoma. Neuro Oncol. 2016; 18 (suppl 6):vi17-vi18. doi: 10.1093/neuonc/now212.068