In-Hyun Lee

Conjugated chitosan as a novel platform for oral delivery of paclitaxel.

A new platform for oral delivery of paclitaxel (PTX) was developed through chemical conjugation of PTX to a low molecular weight chitosan (LMWC). The LMWC-PTX conjugate contained approximately 12 wt % PTX and showed greatly enhanced water solubility (>1 mg/mL) as compared to native PTX. The conjugate showed comparable IC 50 values to that of the parent PTX against human cancer cell lines. The pharmacokinetic data revealed approximately 42% of bioavailability after oral administration of 5 mg PTX/kg of the conjugate. When the conjugate (10 mg/kg based on PTX content) was administered orally to mice bearing xenograft or allograft tumors, the conjugate-treated group showed significant inhibition of tumor growth, which was comparable to that seen with PTX of the clinically available injected form, formulated in cremophor EL/ethanol (iv) but with much lower toxicity. Tracking I (125)-labeled conjugate showed that LMWC-PTX was likely to be absorbed mainly from the ileum and reach the blood as the intact conjugate.

Targeted chemoimmunotherapy using drug-loaded aptamer-dendrimer bioconjugates

We reported an innovative, targeted chemoimmuno drug-delivery system. Although chemoimmunotherapy, as an alternative to or in combination with conventional therapeutic systems, has been in the forefront of recent oncological research, as presently configured, such systems face several major obstacles for efficient clinical application. Here, we establish a novel nano-platform for effective chemoimmunotherapy designed to overcome the drawbacks of conventional cancer therapies, describing a delivery system based on a dendrimer and a single-strand DNA-A9 PSMA (prostate-specific membrane antigen) RNA aptamer hybrid. Employing these vehicles, we demonstrate the promising possibility of this chemoimmuno therapeutic system against prostate cancer in in vivo and in vitro models.

A Combined Chemoimmunotherapy Approach Using a Plasmid−Doxorubicin Complex

We report a combined chemoimmunotherapy vehicle consisting of plasmid loaded with doxorubicin and evaluate its efficacy in two different tumor models. A stable complex was formed with a 1300:1 ratio of doxorubicin bound to native plasmid via intercalation. Pharmacokinetics of the complex showed much slower clearance from plasma up to 3 h compared to 10 min for free doxorubicin. In mice bearing NCI-H358 xenografts, lower doses of complex (doxorubicin 0.5 mg/kg, plasmid 4 mg/kg) effectively reduced tumor growth compared to high doses (5 mg/kg) of free doxorubicin (68% versus 77%). Similar results were observed in mice bearing 4T1 murine allografts; the complex (doxorubicin 2 mg/kg, plasmid 8 mg/kg) was effective and caused similar reduction of tumor compared to free doxorubicin (4 mg/kg) (47% versus 46%). The complex showed no signs of severe systemic toxicity or cardiotoxicity compared to the free doxorubicin in mice as indicated by body weights and heart tissue histology. Elevated levels of cytokines (IL-12, IL-6, and IFN-gamma) were observed in serum as well as in tumor tissue after intravenous injection of complex when compared to plasmid or doxorubicin alone. This approach simultaneously delivers both chemotherapeutic and immunotherapeutic agents without time delay, improves pharmacokinetics of the free drug, lowers drug toxicity, upregulates a variety of cytokines, and is effective against different tumors.

Gold Nanoparticles Displaying Tumor‐Associated Self‐Antigens as a Potential Vaccine for Cancer Immunotherapy

Golden vaccine for cancers. Gold nanoparticles enable efficient antigen delivery to dendritic cells and then activate the cells to facilitate cross-presentation, inducing antigen-specific cytotoxic T-lymphocyte responses for effective cancer therapy.

Oral delivery of an anti-diabetic peptide drug via conjugation and complexation with low molecular weight chitosan

Despite the therapeutic potential of exendin-4 as a glucagon-like peptide-1 (GLP-1) mimetic for the treatment of type 2 diabetes, its utility has so far been limited because of the low level of patient compliance due to the requirement for frequent injections. In this study, an orally available exendin-4 was produced by conjugating it to low molecular weight chitosan (LMWC). Conjugation between the LMWC and cysteinylated exendin-4 was carried out using a cleavable linker system in order to maximize the availability of the active peptide. The LMWC-exendin-4 conjugate formed a nanoparticle structure with a mean particle size of 101 ± 41 nm through complexation between the positively charged LMWC backbone and the negatively charged exendin-4 of individual conjugate molecules. The biological activity of the LMWC-exendin-4 conjugate was evaluated in an INS-1 cell line. The LMWC-exendin-4 conjugate stimulated insulin secretion in a dose dependent manner as similar as that of native exendin-4. From the pharmacokinetic study after oral administration of the conjugate, a C(max) value of 344 pg/mL and a T(max) of 6 h were observed, and the bioavailability, relative to the subcutaneous counterpart, was found to be 6.4%. Furthermore, the absorbed exendin-4 demonstrated a significantly enhanced hypoglycemic effect. These results suggest that the LMWC-exendin-4 conjugate could be used as a potential oral anti-diabetic agent for the treatment of type 2 diabetes.

Aptide-conjugated liposome targeting tumor-associated fibronectin for glioma therapy

Aptides, developed by our laboratory, are a novel class of high-affinity peptides. Here, we describe the conjugation of an aptide targeting extra-domain B (EDB) of tumor-associated fibronectin to drug-containing liposomes and explore the potential of these aptide-conjugated liposomes as a robust and efficient targeted drug-delivery system for glioma therapy.

Synthesis and therapeutic evaluation of an aptide-docetaxel conjugate targeting tumor-associated fibronectin

Targeted delivery of anticancer drugs to tumors has attracted considerable research interest because of its potential to reduce adverse toxicity while improving therapeutic efficacy. In this study, we synthesized and evaluated the therapeutic efficacy of a conjugate of a high-affinity peptide (aptide) and the anticancer drug docetaxel (DTX). A fibronectin extra domain B (EDB)-specific aptide (APTEDB) was used as a cancer-specific targeting ligand. An APTEDB-DTX conjugate was synthesized from an alkyne-modified aptide and azide-modified DTX via click chemistry. A microscopy study revealed selective binding of dye-labeled APTEDB to EDB-overexpressing cancer cells. The cytotoxicity of the conjugate toward EDB-overexpressing murine lung carcinoma (LLC) and human glioblastoma (U87MG) was similar to that of free DTX. In a pharmacokinetic study, APTEDB-DTX formulated with PEG400/ethanol(5%) exhibited a circulation half-life similar to that of a Tween-80/ethanol formulation of parent DTX. Finally, an evaluation of intravenously injected APTEDB-DTX in mice bearing EDB-positive tumors showed that APTEDB-DTX inhibited the growth of both LLC allograft and U87MG xenograft tumors with an efficacy better than the parent-DTX formulation but with much lower toxicity, as evidenced by reduced body weight loss. Taken together, these results indicate that the aptide-drug conjugate system described here may hold potential as a targeted therapy regimen.

Automatic rule generation by the transformation of expert's diagram: LIFT

Abstract To enhance the efficiency of revealing and refining an experts knowledge, the Experts Diagram approach is proposed. The Experts Diagram proposed in this paper is specifically designed for rule-based consulting systems. Using the Experts Diagram approach, the knowledge acquisition system LIFT is developed, which transforms the Experts Diagram automatically to rules in the syntax of the shell SKI 2 that is developed for tax consulting-purposes. For the transformation, either the conclusion-directed approach or the condition-directed approach can be applied. The role of LIFT can be generalized to some extent to adapt to the changes in the Experts Diagram and target shells. According to our experience in the acquisition of Korean corporate tax knowledge, experts could reveal their knowledge effectively using the Experts Diagram after a short period of training. Thus the rules could be generated automatically by LIFT without the aid of knowledge engineers.

Preparation and therapeutic evaluation of paclitaxel-conjugated low-molecular-weight chitosan nanoparticles

Synthetic and natural polymers have been widely utilized as raw materials for manufacturing drug-delivery vehicles to treat diseases. This widespread use reflects several favorable features of these polymers, including facile chemical modification, ease of creating nano-sized particles through a self-assembly process, the ability to solubilize or encapsulate hydrophobic drugs within the core, and enhanced accumulation in tumors by the so-called enhance permeability and retention (EPR) effect. Among such polymeric materials, natural polymers such as dextran, chitosan, and hyaluronic acid may have advantages over synthetic polymers in the preparation of nanoparticle (NP)-based drug delivery systems in terms of biocompatibility. Because such natural polysaccharide components are water-soluble, their polymers require modification with hydrophobic components before NP formation via a self-assembly process. It has been shown that hydrophobically modified dextran, hyaluronic acid, and high-molecular-weight chitosan self-assemble into NPs that exhibit effective anticancer efficacy through EPR effectmediated, passive tumor targeting. In fact, chitosan has been widely used in the pharmaceutical field because it is known to be biocompatible and biodegradable, and increases the solubility of hydrophobic drugs. Very recently, we utilized water-soluble, low-molecular-weight chitosan (LMWC) as a carrier to achieve oral delivery of anticancer drugs, such as paclitaxel (PTX) and docetaxel, and anti-diabetic peptide drugs, such as insulin and exendin-4. All conjugates between LMWC and drugs of interest in our previous studies showed high oral bioavailability with little toxicity, suggesting the potential of LMWC as a biocompatible carrier for drug-delivery applications. In the present study, we prepared conjugates between LMWC and PTX with different drug content and evaluated the therapeutic efficacy of self-assembled NPs formed from these conjugates (Figure 1(a)).