Heat shock protein peptide complex-96 vaccination for newly diagnosed glioblastoma: a phase I, single-arm trial

BACKGROUND. Heat shock protein peptide complex-96 (HSPPC-96) triggers adaptive and innate antitumor immune responses. The safety and efficacy of HSPPC-96 vaccination was examined in patients with newly diagnosed glioblastoma multiforme (GBM). METHODS. In this open-label, single-arm, phase I study, adult patients were vaccinated with HSPPC-96 in combination with the standard treatment for newly diagnosed GBM after surgical resection. Primary endpoints were frequency of adverse events and progression-free survival (PFS) at 6 months. Secondary endpoints included overall survival (OS), PFS, and tumor-specific immune response (TSIR). RESULTS. A total of 20 patients with newly diagnosed GBM were enrolled from September 2013 to February 2015. No grade 3 or 4 vaccine-related adverse events were noted. After a median follow-up of 42.3 months, PFS was 89.5% (95% CI, 66.9%-98.7%) at 6 months, median PFS was 11.0 months (95% CI, 8.2-13.8), and median OS was 31.4 months (95% CI, 14.9-47.9). TSIR was significantly increased by 2.3-fold (95% CI, 1.7-3.2) after vaccination. Median OS for patients with high TSIR after vaccination was > 40.5 months (95% CI, incalculable) as compared with 14.6 months (95% CI, 7.0-22.2) for patients with low TSIR after vaccination (hazard ratio, 0.25; 95% CI, 0.071-0.90; P = 0.034). A multivariate Cox regression model revealed TSIR after vaccination as a primary independent predicator for survival. CONCLUSION. The HSPPC-96 vaccination, combined with the standard therapy, is a safe and effective strategy for treatment of newly diagnosed GBM patients. TSIR after vaccination would be a good indicator predicting the vaccine efficacy.