Project description:Autologous tumor lysate-pulsed dendritic cell (ATL-DC) vaccination is a promising immunotherapy for patients with high grade gliomas, but responses have not been demonstrated in all patients. Pre-clinical studies demonstrate that toll-like receptor (TLR) agonists can enhance the anti-tumor immune response from cancer vaccines. To determine the most effective combination of autologous tumor lysate-pulsed DC vaccination, with or without the adjuvant toll-like receptor (TLR) agonists poly-ICLC or resiquimod, we conducted a randomized, open-label multi-arm Phase 2 clinical trial to evaluate immune responses and survival in 23 patients with newly diagnosed or recurrent WHO Grade III-IV malignant gliomas. Patients were randomized to receive ATL-DC vaccination with either a placebo, a TLR-7/8 agonist (resiquimod, topical 0.2%), or a TLR-3 agonist (poly-ICLC, 20 mcg/kg intramuscular). Peripheral blood was obtained at baseline and following the vaccination cycle for immune monitoring. Mass cytometry, bulk and single-cell RNA sequencing analyses were performed. Analysis of the bulk RNAseq data (pre-treatment vs. post-treatment) demonstrated highly significant upregulation of type 1 and type 2 interferon gene expression selectively in patients who received adjuvant TLR agonist (either poly-ICLC or resiquimod) together with ATL-DC. CyTOF analysis of patient peripheral blood mononuclear cells (PBMCs) showed increased levels of memory PD-1+ T-cell and monocyte populations after ATL-DC + TLR agonist administration. In addition, scRNA-seq demonstrated a higher expression fold change of IFN-induced genes with poly-ICLC treatment in both peripheral blood monocytes and T lymphocytes. Median progression-free survival (PFS) was 8.1 months (5.5 placebo vs. 8.1 resiquimod vs. 31.4 poly-ICLC), and median overall survival (OS) was 26.6 months (7.7 placebo vs. 16.7 resiquimod vs. 52.5 poly-ICLC). Patients who had higher expression of interferon response genes lived significantly longer and had longer time to progression compared to those with lower expression. The results suggest that ATL-DC in conjunction with adjuvant poly-ICLCTL induces a polarized interferon response in circulating monocytes and specific activation of a CD8+ T cell population. This combination was associated with extended survival in this patient population. This interferon response signature may represent an important blood biomarker for immunotherapy in patients with malignant glioma.

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