Newly diagnosed glioblastoma patients treated with an autologous heat shock protein peptide vaccine: PD-L1 expression and response to therapy.

2011 Background: Standard therapy for glioblastoma (GBM) consists of surgical resection followed by concurrent chemo and radiotherapy with a median overall survival of 16 months. In this phase II, single arm study, addition of an autologous heat shock protein peptide vaccine was evaluated for newly diagnosed GBM. Expression of PD-L1 on peripheral monocytes has been shown to be elevated in GBM patients and was evaluated as a predictor of survival. Methods: Adult patients with GBM underwent surgical resection followed by chemoradiotherapy. Vaccine was generated from tissue obtained at surgery. Key eligibility criteria included ≥ 90% tumor resection and collection of sufficient tumor tissue to generate at least four 25 μg doses of vaccine. Within 5 weeks of completing radiotherapy, patients received weekly vaccinations, followed by adjuvant temozolomide with monthly vaccinations until depletion of vaccine or tumor progression. The primary endpoint was overall survival. Relative PD-L1 expression on circulatin...