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Abstract

BACKGROUND: Dendritic cell (DC) vaccines for glioblastoma (GBM) are promising but significant conceptual shortcomings may have limited their clinical efficacy. First, most trials have not employed optimal DC culture techniques resulting in large numbers of immature (immunosuppressive) DC's. Second, most have used autologous tumor lysate. While highly personalized, this limits vaccine availability and precludes antigen-specific response testing. Finally, GBM-mediated immunosuppression has been largely unaddressed. We have developed a novel DC vaccine protocol that addresses these issues. METHODS: The ability of standard DC culture techniques to produce mature (CD83+) DC's from healthy donors' and GBM patients' CD14+ monocytes was assessed. An optimized technique using GBM patients' monocytes was developed. A library of human Good Manufacturing Practices (GMP) GBM cell lines was established using a novel platelet lysate supplement. Immature/mature glioneuronal markers and tumor-associated antigens (TAA's) were assessed by western blot. Finally, multicolor FACS immunophenotyping of 120 leukocyte surface markers in 5mL whole blood was established. RESULTS: Standard culture techniques produce >90% mature (CD83+) DC's from healthy donor monocytes but < 60% CD83+ DC's from GBM patients' monocytes (P<0.001). A modified technique including platelet lysate produces >90% mature DC from GBM patients. Seven GMP-compatible GBM cell lines have been developed with clonigenic karyotypic abnormalities, immature (nestin) and some mature (GFAP, olig2, β-tubulin) glioneuronal marker expression, and expression of multiple TAA's. Our 120 marker panel produces comprehensive, reproducible immunophenotyping. CONCLUSION: We have developed a DC vaccination strategy that optimizes DC maturity, utilizes renewable GBM cell lines with established TAA expression profiles, and allows comprehensive immunophenotyping to identify responding/non-responding patient populations. Based on these studies, we have initiated a phase I clinical trial (MC1272; IND#15233) of autologous DC / allogeneic tumor lysate in newly diagnosed adult GBM patients that enables multiple vaccinations in most GBM patients with extensive immunophenotyping and TAA-specific response testing.

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Published by Oxford University Press on behalf of the Society for Neuro-Oncology 2014.
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Abstracts > IMMUNOTHERAPY/VACCINE THERAPY (CLINICAL AND/OR LABORATORY RESEARCH)
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