Rindopepimut Vaccine Plus Bevacizumab Induces Immune Response and Tumour Regression in Relapsed Glioblastoma

By Brandon M. May

CHICAGO -- May 11, 2016 -- When administered with bevacizumab, the investigational vaccine rindopepimut demonstrates promising survival and safety results in patients with relapsed glioblastoma and the type III epidermal growth factor receptor mutation (EGFRvIII), according to results of a phase 2 study presented at the 84th Annual Meeting of the American Association of Neurological Surgeons (AANS).

“Giving this vaccine…generates high levels of immune response specific to the EGFRvIII mutation,” stated investigator John H. Sampson, MD, PhD, MBA, MHSc, Duke University School of Medicine, Durham, North Carolina, speaking here at a poster session.

Investigators from the ReACT trial randomised bevacisumab-naïve patients with EGFRvIII who were in a first or second relapse of glioblastoma (n = 73) in a 1:1 fashion to receive bevacizumab plus either double-blinded vaccine injection or control injection with a carrier protein (keyhole limpet haemocyanin). Clinical endpoints were 6-month progression-free survival (PFS), overall survival (OS), safety, and objective response rate.

Analyses for OS were adjusted in this study for various prognostic factors that consistently favour rindopepimut. Results showed that rindopepimut induces EGFRvIII-specific immune responses and tumour regression. The vaccine also appears to be associated with a significant prolonged OS rate in this population.

While there was a slight increase in PFS in the treatment group, it was not significant. Dr. Sampson noted that immunotherapeutics typically offer little improvement in PFS.

Follow-up continues to further assess the longer-term survival of this patient cohort.

EGFRvIII is a mutation of the EGFR gene, and is responsible for poor long-term survival in patients with glioblastoma, Dr. Sampson explained. “EGFR mutation not only negatively affects the cell in which the gene actually is encoded, but also can affect neighboring cells…We believe this is why it is associated with a negative prognosis.”

EGFR mutation is present in about one third of all patients with glioblastoma. Patients presenting with EGFRvIII and glioblastoma have typically experienced poor long-term survival.

Importantly, Dr. Sampson noted, bevacisumab may also reverse the immunosuppressive effect in these patients, which may have limited the maximum vaccine results in this trial.

[Presentation title: ReACT: A Randomized Phase II Study of Rindopepimut (CDX-110) Plus Bevacizumab in Relapsed Glioblastoma.]
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