(209e) Immunomodulatory Therapy of Layer-By-Layer Nanoparticles for Targeted Delivery to Cancer-Associated Immune Cells

Ovarian cancer is an aggressive disease that is difficult to treat due to its propensity to metastasize and develop resistance to platinum and taxane chemotherapy—the current standard of care. Immunotherapy offers an alternative approach to prime a patient’s immune system to attack cancer cells and develop long-lived immune memory; however, immune checkpoint blockade has had limited success in ovarian cancer due to the cancer’s immune-suppressive tumor environment so alternative strategies are needed to transform the tumors to an inflamed, immune-infiltrated phenotype. Nanoparticles that facilitate the targeted delivery of potent immune modulating agents to specific cells in the tumor environment have the potential to address this need and improve disease outcomes.

To design drug carriers that direct therapeutics to specific cells, we elucidated how the surface chemistry and core composition of Layer-by-Layer nanoparticles (LbL NPs) influences association of particles with ovarian cancer and antigen-presenting cells (APCs). To evaluate the effectiveness of our targeted NP properties, we developed a LbL NP loaded with Poly(I:C) which is a potent TLR-3 immune agonist that has poor half-life and toxicity profiles as a free drug, necessitating the use of a drug carrier. The Poly(I:C)-loaded NPs were formulated with the optimal physiochemical properties that were identified to demonstrate the targeted delivery of this immune agonist to APCs in the tumor environment for an anti-cancer immunomodulatory therapy. We hypothesize that the delivery of the immune agonist poly(I:C) to macrophages and dendritic cells in the ovarian tumor environment can synergize with chemotherapy to lead to the production of inflammatory cytokines, increased antigen presentation and effector T cell infiltration in the tumor to promote long-lasting anti-tumor immunity.

Due to the modular nature of LbL, we optimized the 1) cell-targeting surface chemistry by varying the negatively-charged terminal layer, 2) the stiffness of the core to promote NP internalization, and 3) drug loading of poly(I:C). LbL NPs formulated with varying surface chemistries—including glycan-decorated polymers and native polysaccharide polymers—were screened on ovarian cancer, RAW264.7 macrophage-like cells and primary dendritic cells (DCs) to identify candidates with high NP-cell association. This revealed that dextran sulfate enhanced NP association with macrophages (Figure 1a). Contrarily, our novel galactose-decorated polymer enhanced targeting to DCs, likely due to interactions with galactose-binding lectins expressed on DCs (Figure 1b). LbL NPs with softer liposomal cores showed enhanced intracellular accumulation in APCs compared to rigid cores. Loading of poly(I:C)—an immunomodulatory dsRNA analog—was optimized to yield LbL NPs with weight loading of ~41%. Targeted Poly(I:C) LbL NPs facilitated greater poly(I:C) delivery to macrophages and DCs, resulting in nearly a 4-fold upregulation of CD86 expression and 2-fold TNF-a cytokine production compared to free poly(I:C) (Figure 2a-c). Ongoing studies are elucidating the immunomodulatory effects and efficacy of this therapy in mouse models of ovarian cancer. This work demonstrates the targeted delivery of immunotherapeutic agents using LbL NPs with optimized physiochemical properties can dramatically improve the delivery of an immune agonist to APCs for a more specific and effective immunotherapeutic treatment strategy.