Abstract PR13: Adjuvant TLR-3 administration enhances proinflammatory immune responses and is associated with extended survival in glioblastoma patients treated with dendritic cell vaccination

Malignant glioma, associated with a poor prognosis, is the most common primary malignant brain tumor in adults. We and others have documented immune responses following dendritic cell (DC) vaccination as an active immunotherapeutic treatment for these patients. In this phase II clinical trial, we randomized malignant glioma patients to receive autologous tumor lysate pulsed DC vaccination with and without adjuvant Toll-like receptor (TLR) agonists. TLRs are present on dendritic cells and serve to modulate immune responses. Twenty-three patients with WHO grade III or IV glioma were treated with three intradermal injections of autologous tumor lysate-pulsed DC on days 0, 14, and 28 followed by an adjuvant placebo, TLR-7 agonist (resiquimod), or TLR-3 agonist (Poly ICLC). Mass cytometry (CyTOF) was used to analyze immune cell populations of patient peripheral blood mononuclear cells (PBMC) before and following treatment. DC-vaccinated patients who received adjuvant Poly ICLC treatment had a significantly improved median survival of 54 months over placebo (11 months) and adjuvant resiquimod (17 months) groups (P This abstract is also being presented as Poster B27. Citation Format: Joseph P. Antonios, Richard G. Everson, Aaron Mochizuki, Sara Khattab, Horacio Soto, Prashant Romiyo, Matthew Z. Sun, Diana Moughon, Emma Billingslea-Yoon, Sylvia Odesa, Gang Li, Eric Kawaguchi, Alex Salazar, William Yong, Jason Schlossman, Benjamin Ellingson, Anthony C. Wang, Timothy Cloughesy, Robert M. Prins, Linda M. Liau. Adjuvant TLR-3 administration enhances proinflammatory immune responses and is associated with extended survival in glioblastoma patients treated with dendritic cell vaccination [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr PR13.