I am now in my first faculty position as an Assistant Professor of Neurosurgery and Pediatrics at the University of Florida. I completed a T32 NIH fellowship at Duke University in Cancer Biology and Developmental Therapeutics before accepting a junior faculty position at the University of Florida where I moved with my mentor, Dr. Duane Mitchell. Dr. Mitchell and I have selected an advisory committee to ensure accrual of my intellectual and professional growth. The non-overlapping expertise of our advisory committee will be an avenue for me to develop new knowledge in tumor immunology, molecular biology, nanotechnology and translational oncology. This proposal will leverage much of this experience as it outlines a career development plan for me to become an independent investigator exploring novel RNA-nanoparticle vaccines that can re- direct the immune system against malignant brain tumors. Background: Glioblastoma (GBM) remains almost uniformly lethal with a median survival of less than 15 months thus necessitating the development of more efficacious and targeted therapeutics. While we have shown in a randomized/blinded trial that RNA-pulsed dendritic cell (DC) vaccines elicit significant survival benefits in GBM patients, these therapies remain encumbered by cost and complexity. Alternatively, RNA- nanoparticles (RNA-NPs) can deliver total tumor RNA (TTRNA), extracted and amplified from as few as 500 biopsied tumor cells, to endogenous antigen presenting cells (APCs) inducing potent, nontoxic anti-tumor immunity. Since these nanoliposomes have been used with limited toxicity in clinical-grade medicine, are stable for several hours in solution, protect nucleic acids from degradation, and can be engineered to modulate immune responses, we have explored the use of TTRNA-loaded NPs as an attractive, ?off-the-shelf? therapeutic platform to re-direct host-immunity against intracranial tumors. While we have demonstrated that intravenous delivery of RNA-NPs mediate antigen specific T cell responses against intracranial malignancies comparable to DC vaccines, these formulations were shown to induce differential phenotypes on APCs in the spleen and liver. Hypothesis: RNA-NPs transfect distinct APCs in the spleen and liver inducing differential immune responses that can be modulated in favor of enhanced effector functions.
Specific Aims : 1) Determine critical APC subsets and evaluate their role in RNA-NP mediated immune responses. 2) Identify regulatory pathways involved in RNA-NP mediated immunity and investigate capacity to target these pathways through incorporation of immunomodulatory RNAs into vaccine formulations. 3) Evaluate the safety and efficacy of the most promising RNA-NP formulation in a malignant murine glioma model. Research Design: We propose to identify critical APCs involved in RNA-NP mediated immunity, target regulatory pathways identified after vaccination, and evaluate the safety and efficacy of RNA-NPs in an invasive preclinical murine malignant glioma model. Since this platform can deliver combinatorial therapies using a single delivery platform, we will investigate if RNA-NP co-delivery of RNAs (i.e. small interfering RNAs or RNAs encoding for monoclonal antibodies) targeting regulatory pathways (i.e. programmed death-ligand 1) can potentiate our vaccine?s already promising anti-tumor immunity. Innovation: Since RNA-NPs bypass the complexity of cellular therapeutics, are amenable to central distribution, and can be made within days of tumor resection, these formulations supplant DC vaccines providing near immediate immune induction against inciting malignancies. By employing liposomal RNA-NPs encoding for both tumor RNAs and immunomodulatory molecules, as an innovative and versatile platform for delivering combinatorial therapeutics via a single treatment modality, we can rapidly screen strategies to enhance the efficacy of our vaccine platform. Potential Impact: Despite aggressive and highly toxic multi-modal therapy, GBM remains invariably recalcitrant. RNA-NP vaccines can provide a more effective and specific therapy critical in improving clinical outcomes for patients affected by GBMs without adding further toxicity to existing treatments. This novel therapeutic platform has potential to better understand the immunologic potential of RNA-NPs and contains a wide range of clinical application for all malignancies that can be targeting using TTRNA obtained from surgical resection of solid tumors.

Public Health Relevance

Glioblastoma (GBM) remains invariably recalcitrant despite maximal surgical resection and chemoradiation thus necessitating the development of novel targeted therapeutics. This proposal will test the hypothesis that RNA-nanoparticle (RNA-NP) vaccines can safely and effectively re-direct the immune system against glioblastoma by transfecting distinct cells in the spleen and liver thereby inducing immunity that can be modulated in favor of enhanced anti-tumor effector functions. We propose to identify critical antigen presenting cells (APCs) involved in RNA-NP mediated immunity, target regulatory pathways induced after vaccination, and evaluate the safety and efficacy of the most promising modified therapeutic RNA-NPs in an invasive preclinical murine malignant glioma model.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Clinical Investigator Award (CIA) (K08)
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Subcommittee I - Transistion to Independence (NCI)
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Lim, Susan E
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University of Florida
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Hoang-Minh, Lan B; Siebzehnrubl, Florian A; Yang, Changlin et al. (2018) Infiltrative and drug-resistant slow-cycling cells support metabolic heterogeneity in glioblastoma. EMBO J 37:
Sayour, Elias J; De Leon, Gabriel; Pham, Christina et al. (2017) Systemic activation of antigen-presenting cells via RNA-loaded nanoparticles. Oncoimmunology 6:e1256527
Sayour, Elias J; Mitchell, Duane A (2017) Immunotherapy for Pediatric Brain Tumors. Brain Sci 7: