Proof-of-Concept in Developing a 45% Drug Loaded Amorphous Nanoparticle Formulation

Amorphous solid dispersion (ASD) is an enabling approach utilized to deliver poorly soluble compounds. ASDs can spontaneously generate drug-rich amorphous nanoparticles upon dissolution, which can act as a reservoir for maintaining supersaturation during oral absorption. But, conventional ASDs are often limited in drug loadings to < 20 %. For indications where the dose is high, this can translate into a significant pill burden. The aim of this research was to develop a high drug loading (DL) amorphous nanoparticle (ANP) formulation that can release the drug-rich nanoparticles into solution upon contact with aqueous environment. Nanoparticles were directly engineered using solvent/anti-solvent precipitation. The obtained nanoparticle suspension was then concentrated followed by solidification to a re-dispersible amorphous dosage form using spray drying or lyophilization. The impact of process variables was studied using dynamic light scattering (DLS), scanning electron microscopy (SEM), high performance liquid chromatography (HPLC), nuclear magnetic resonance (NMR) and differential scanning calorimetry (DSC). It was observed that spray drying led to a non-re-dispersible formulation. Sucrose and trehalose containing lyocakes resulted in re-dispersible formulations. The trehalose containing lyocakes, in a dog study, gave comparable performance to the reference tablet in the fasted state but lower area under the curve (AUC) in fed state.

Toroidal-spiral particles as a CAR-T cell delivery device for solid tumor immunotherapy

Chimeric antigen receptor (CAR) T cell therapy has resulted in positive effects on patients with hematologic malignancy but shows limited efficacy in solid tumor treatments due to insufficient trafficking and tumor infiltration, intensive CAR-T-related toxicities, and antigen escape. In this work, we developed and investigated a biodegradable and biocompatible polymeric toroidal-spiral particle (TSP) as a in vivo cell incubator and delivery device that can be implanted near tumor through a minimally invasive procedure or injected near or into solid tumors by using a biopsy needle. The main matrix structure of the millimeter-sized TSP is made from crosslinking of gelatin methacrylamine (GelMA) and poly (ethylene glycol) diacrylate (PEGDA) with a tunable degradation rate from a few days to months, providing appropriate mechanical properties and sustained release of co-encapsulated drugs and/or stimulation compounds. The toroidal-spiral layer of the particles, presenting an internal void volume for high-capacity cell loading and flexibility of co-encapsulating small and large molecular compounds with individually manipulated release schedules, is filled with collagen and suspended T cells. The TSPs promote cell proliferation, activation, and migration in the tumor micro-environment in a prolonged and sustained manner. In this study, the efficacy of mesothelin (MSLN) CAR-T cells released from the TSPs was tested in preclinical mouse tumor models. Compared to systemic and intratumoral injection, peritumoral delivery of MSLN CAR-T cells using the TSPs resulted in a superior antitumor effect. The TSPs made of FDA approved materials as an in vivo reactor may provide an option for efficiently local delivery of CAR-T cells to solid tumors for higher efficacy and lower toxicity, with a minimally invasive administration procedure.

Heterogeneous toroidal spiral particles for islet encapsulation

Transplantable cell encapsulation systems present a promising approach to deliver a therapeutic solution from hormone-producing cells for the treatment of endocrine diseases like type 1 diabetes. However, the development of a broadly effective and safe transplantation system has been challenging. While some current micro-sized capsules have been optimized for adequate nutrient and metabolic transport, they lack the robustness and retrievability for the clinical safety translation that macro-devices may offer. An existing challenge to be addressed in the current macro-devices is their configuration which may lead to unsatisfactory mass transfer. Here, we design and characterize a millimeter-size particle system of poly-ethylene glycol (PEG) featuring internal toroidal spiral channels, called toroidal spiral particles (TSPs). The characteristic internal structure of the TSPs allows for large encapsulation capacity and large surface area available to all the encapsulated cell mass for effective molecular diffusion. The polymeric matrix renders the particle flexible yet robust for safe transplantation and retrieval. We demonstrate the feasibility of fabricating these particles with various polymer compositions, while optimizing their mechanical properties as well as glucose and insulin permeability. Encapsulation of islets of Langerhans is achieved with high loading capacity (∼160 IEQ per TSP) and excellent cell viability. TSP-encapsulated islets showed similar glucose-stimulated insulin secretion to the naked islets. Preliminary biocompatibility of the TSPs on naïve C57BL/6 mice shows minimal inflammatory response after 4-week transplantation into the intraperitoneal (IP) space. Long-term therapeutic efficacy of encapsulated islets needs to be confirmed in diabetic rodent models in the future, while determining minimal mass required to reverse diabetes. However, we believe from the in vitro favorable results and the TSPs' unique design that TSPs may provide a safe, effective method to transplant and retrieve therapeutic cells for type 1 diabetes treatment and may also be applicable for other cell therapies.

Heterogeneous Polymeric Particles Encapsulating Human T cells for Controlled Activation, Proliferation, and Delivery

We report a particulate cell delivery platform, toroidal spiral particles (TSPs), for continuous cell activation, expansion, and local sustained release. Biocompatible TSPs, generated by a self-assembly process of polymeric droplet sedimentation in an aqueous solution and subsequent polymer solidification, possess many engineering design flexibilities to manipulate the microenvironment of the cells to control cell proliferation, migration, and release kinetics. These millimeter-size particles with desired mechanical and physicochemical properties may be potentially used for adoptive cellular therapy (ACT) delivery by a minimally invasive procedure to the tumor mass.