Polymer Nanoparticles for Immunotherapy from Encapsulated Tumor-Associated Antigens and Whole Tumor Cells

Abstract

Encapsulation of tumor-associated antigens (TAA) in polymer nanoparticles is a promising approach to increasing the efficiency of antigen (Ag) delivery for antitumor vaccines. We optimized a polymer preparation method to deliver both defined tumor-associated proteins and the complex mixtures of tumor Ags present in tumors. Tumor Ags were encapsulated in a biodegradable, 50:50 poly(D,L-lactide co-glycolide) copolymer (PLGA) by emulsification and solvent extraction. Two particular Ags were studied, gp100 (a melanoma-associated antigen) and ovalbumin (OVA), as well as mixtures of proteins and lysates of tumor cells. The efficiency of encapsulation was measured by protein assays of dissolved nanoparticles. Ag stability after release from nanoparticles was verified by SDS-acrylamide gel electrophoresis and Western blot analysis. Molecular weight and protein loading interact to define the encapsulation efficiency and release rate of nanoparticles formulated from 50:50 PLGA. A midrange molecular weight polymer had more desirable release properties at 100 mg/mL than at 50 mg/mL protein loading, indicating the need for optimization of nanoparticle formulation for preparations with different particle loadings. Mixtures of proteins derived from cell lysates were reliably encapsulated into nanoparticles, which released the spectrum of proteins contained in lysates. Antigenic proteins were co-encapsulated with cell lysate and released from nanoparticles; these Ags retained their antigenicity and functioned better than soluble Ags when tested in in vitro assays of T cell cytokine formation and in vivo tumor vaccination challenge.

Configuration-dependent Presentation of Multivalent IL-15:IL-15Rα Enhances the Antigen-specific T Cell Response and Anti-tumor Immunity

“…3c versus 2 ng/ml in Fig. 2c), indicating a stronger immune response elicited by the encapsulated antigen (38,39,77,78). We confirmed this by comparing free OVA and NP/OVA particles at the same dose (data not shown).…”

“…Perhaps one of the most explored carriers has been the polymeric poly(lactide-co-glycolide) (PLGA) system because of its significant promise and established effect in clinical settings (25)(26)(27) and well understood methods of formulation for delivery of small-molecule drugs, nucleic acids, and protein antigens (22, 28 -31). Several studies have demonstrated the promise of antigen-loaded PLGA nanoparticles as nanoparticle-based vaccines and delivery systems targeting DCs (32)(33)(34)(35)(36)(37)(38)(39).…”

Targeting human dendritic cells via DEC-205 using PLGA nanoparticles leads to enhanced cross-presentation of a melanoma-associated antigen

“…Currently, there are no human peptide-based cancer vaccines on the market, mostly because of the difficulties associated with their poor immunogenicity, stability, and delivery. Our group 15,17,[35][36][37][38] and others [39][40][41][42] have described strategies to enhance peptide/protein immunogenicity and stability by directing Ag to DCs using particulate delivery systems. The particulate nature of these delivery vehicles permits their rapid internalization by DCs and their composition can provide adjuvant properties required for immunogenicity.…”

Acetalated dextran is a chemically and biologically tunable material for particulate immunotherapy

“…Iron oxide microparticles have been successfully used for the prevention of model tumors (7), but iron oxide is completely nondegradable, which could potentially lead to toxic bioaccumulation. Another material used in particulate vaccines is poly(lactic-co-glycolic acid) (PLGA), which is biocompatible and easily processed into microparticles (8,9). However, one possible drawback to PLGA in immunotherapy is that its degradation rate is slow and not tunable on timescales relevant to antigen presentation, potentially limiting optimal behavior.…”