Engineering cellular immunotherapies using lipid-tailed antigen and adjuvant delivery

Abstract

The immune system is the best long-term defense mechanism against prevalent diseases such as cancer. Novel immunotherapies are emerging as frontline treatments for previously incurable diseases by awakening suppressed or reinvigorating dysregulated immune responses in patients. These treatments include cancer vaccines, adoptive T-cell transfer (ACT), and T-cell adjuvanting drugs. Each immunotherapy strategy also has notable drawbacks that can slow or stop continued clinical development due to lack of efficacy or dose-limited toxicities. For example, therapeutic cancer vaccines elicit marginal anti-cancer responses in patients due to challenges in delivering vaccines to antigen-presenting cells (APCs) for activating T cells. ACT and T-cell adjuvant therapies have demonstrated tremendous therapeutic potential in treating cancers, but are burdened with safety concerns caused by dose-related toxicity and adverse responses in patients. Engineered biomaterials may address efficacy and safety concerns by providing a delivery strategy to selective immune cells that enhances potency per dose while minimizing systemic off-target toxicities. However, many promising biomaterial-based strategies are either highly complex to implement or manufacture, or they are not versatile for use with diverse immune cells, limiting their potential for broad utilization in immunotherapy applications.In this thesis, we developed a novel delivery system using phospholipid-based biomaterials to expand therapeutic potential of immunomodulatory applications while avoiding strategies that greatly induce toxicities. Lipid biomaterials were engineered to enable rapid delivery of antigens and adjuvants to cell surface and intracellular compartments of diverse immune cells for controlled immune activation. This simple delivery platform can non-genetically engineer immune cells and activate immunological pathways not accessible by systemic drug formulations to enhance T-cell functions. In chapter 2, peptide antigens conjugated to either lipid or polymeric biomaterials were delivered to diverse APCs for activating antigen-specific CD4+ and CD8+ T cells. Rational biomaterial selection provided a simple approach to control antigen delivery to APCs with varying capabilities of non-specific antigen endocytosis. In chapter 3, lipid-conjugated Toll-like receptor (TLR) adjuvants were rapidly inserted into T-cell plasma membranes, directly co-stimulating and expanding T cells in vitro. Rationally delivering lipid-conjugated adjuvants signaled immune pathways initiated from either cell surface or intracellular compartments, controlling desired immune cell activation for cellular immunotherapies. Chapter 4 focused on targeting the co-stimulatory 4-1BB T-cell pathway with an engineered peptide signaling domain without needing genetic engineering or 4-1BB ligands that are associated with systemic toxicities. The 4-1BB signaling peptide increased T-cell co-stimulation and expansion compared to co-stimulatory ligands in vitro. A simple, non-genetic delivery approach can modularly pair antigen and adjuvant delivery to advance cell-based cancer vaccine designs, or can engineer T cells for ACT and T-cell adjuvant immunotherapies. This drastically broadens the repertoire of combinations immunotherapies, which may increase the long-term therapeutic potential for immunotherapy in human diseases such as cancer.