Synthetic vaccine particles for durable cytolytic T lymphocyte responses and anti-tumor immunotherapy.

We previously reported that synthetic vaccine particles (SVP) encapsulating antigens and TLR agonists resulted in augmentation of immune responses with minimal production of systemic inflammatory cytokines. Here we evaluated two different polymer formulations of SVP-encapsulated antigens and tested their ability to induce cytolytic T lymphocytes (CTL) in combination with SVP-encapsulated adjuvants. One formulation led to efficient antigen processing and cross-presentation, rapid and sustained CTL activity, and expansion of CD8+ T cell effector memory cells locally and centrally, which persisted for at least 1-2 years after a single immunization. SVP therapeutic dosing resulted in suppression of tumor growth and a substantial delay in mortality in several syngeneic mouse cancer models. Treatment with checkpoint inhibitors and/or cytotoxic drugs, while suboptimal on their own, showed considerable synergy with SVP immunization. SVP encapsulation of endosomal TLR agonists provided superior CTL induction, therapeutic benefit and/or improved safety profile compared to free adjuvants. SVP vaccines encapsulating mutated HPV-16 E7 and E6/E7 recombinant proteins led to induction of broad CTL activity and strong inhibition of TC-1 tumor growth, even when administered therapeutically 13-14 days after tumor inoculation in animals bearing palpable tumors. A pilot study in non-human primates showed that SVP-encapsulated E7/E6 adjuvanted with SVP-encapsulated poly(I:C) led to robust induction of antigen-specific T and B cell responses.

Multifunctional polyelectrolyte microparticles for oral insulin delivery.

Multicomponent insulin-containing microparticles are prepared by layer-by-layer assembly of dextran sulfate and chitosan on the core of protein-polyanion complex with or without protease inhibitors. Oral bioavailability of the encapsulated insulin is improved due to the cumulative effect of each component. A physico-chemical study shows that the particle design allows adjustment of the pH-dependent profile of the insulin release, as well as mucoadhesive properties and Ca(2+) binding ability of the microparticles. Supplementing the microparticles with 2-3% protease inhibitors fully prevents proteolysis of human insulin. The pharmacological effect of microencapsulated insulin in doses 50-100 IU kg(-1) is demonstrated in chronic experiments after oral administration to diabetic rats fed ad libitum.