Macrophage-Hitchhiked Orally Administered ß-Glucans-Functionalized Nanoparticles as "Precision-Guided Stealth Missiles" for Targeted Pancreatic Cancer Therapy.

The prognosis in cases of pancreatic ductal adenocarcinoma (PDAC) with current treatment modalities is poor owing to the highly desmoplastic tumor microenvironment (TME). Herein, a ß-glucans-functionalized zinc-doxorubicin nanoparticle system (ßGlus-ZnD NPs) that can be orally administered, is developed for targeted PDAC therapy. Following oral administration in PDAC-bearing mice, ßGlus-ZnD NPs actively target/transpass microfold cells, overcome the intestinal epithelial barrier, and then undergo subsequent phagocytosis by endogenous macrophages (ßGlus-ZnD@Mϕ). As hitchhiking cellular vehicles, ßGlus-ZnD@Mϕ transits through the intestinal lymphatic system and enters systemic circulation, ultimately accumulating in the tumor tissue as a result of the tumor-homing and "stealth" properties that are conferred by endogenous Mϕ. Meanwhile, the Mϕ that hitchhikes ßGlus-ZnD NPs is activated to produce matrix metalloproteinases, destroying the desmoplastic stromal barrier, and differentiates toward the M1 -like phenotype, modulating the TME and recruiting effector T cells, ultimately inducing apoptosis of the tumor cells. The combination of ßGlus-ZnD@Mϕ and immune checkpoint blockade effectively inhibits the growth of the primary tumor and suppresses the development of metastasis. It thus represents an appealing approach to targeted PDAC therapy.

Ultrasound-Activated, Tumor-Specific In Situ Synthesis of a Chemotherapeutic Agent Using ZIF-8 Nanoreactors for Precision Cancer Therapy.

The in situ transformation of low-toxicity precursors into a chemotherapeutic agent at a tumor site to enhance the efficacy of its treatment has long been an elusive goal. In this work, a zinc-based zeolitic imidazolate framework that incorporates pharmaceutically acceptable precursors is prepared as a nanoreactor (NR) system for the localized synthesis of an antitumor drug. The as-prepared NRs are administered intratumorally in a tumor-bearing mouse model and then irradiated with ultrasound (US) to activate the chemical synthesis. The US promotes the penetration of the administered NRs into the tumor tissue to cover the lesion entirely, although some NRs leak into the surrounding normal tissue. Nevertheless, only the tumor tissue, where the H2O2 concentration is high, is adequately exposed to the as-synthesized antitumor drug, which markedly impedes development of the tumor. No significant chemical synthesis is detected in the surrounding normal tissue, where the local H2O2 concentration is negligible and the US irradiation is not directly applied. The as-proposed tumor-specific in situ synthesis of therapeutic molecules induces hardly any significant in vivo toxicity and, thus, is potentially a potent biocompatible approach to precision chemotherapy.

Engineering Nano- and Microparticles as Oral Delivery Vehicles to Promote Intestinal Lymphatic Drug Transport.

Targeted oral delivery of a drug via the intestinal lymphatic system (ILS) has the advantages of protecting against hepatic first-pass metabolism of the drug and improving its pharmacokinetic performance. It is also a promising route for the oral delivery of vaccines and therapeutic agents to induce mucosal immune responses and treat lymphatic diseases, respectively. This article describes the anatomical structures and physiological characteristics of the ILS, with an emphasis on enterocytes and microfold (M) cells, which are the main gateways for the transport of particulate delivery vehicles across the intestinal epithelium into the lymphatics. A comprehensive overview of recent advances in the rational engineering of particulate vehicles, along with the challenges and opportunities that they present for improving ILS drug delivery, is provided, and the mechanisms by which such vehicles target and transport through enterocytes or M cells are discussed. The use of naturally sourced materials, such as yeast microcapsules and their derived polymeric ß-glucans, as novel ILS-targeting delivery vehicles is also reviewed. Such use is the focus of an emerging field of research. Their potential use in the oral delivery of nucleic acids, such as mRNA vaccines, is proposed.

A bubble bursting-mediated oral drug delivery system that enables concurrent delivery of lipophilic and hydrophilic chemotherapeutics for treating pancreatic tumors in rats.

The therapeutic outcome of pancreatic cancer remains unsatisfactory, despite many attempts to improve it. To address this challenge, an oral drug delivery system that spontaneously initiates an effervescent reaction to form gas-bubble carriers is proposed. These carriers concurrently deliver lipophilic paclitaxel (PTX) and hydrophilic gemcitabine (GEM) in the small intestine. The bursting of the bubbles promotes the intestinal absorption of the drugs. The antitumor efficacy of this proposed oral drug delivery system is evaluated in rats with experimentally created orthotopic pancreatic tumors. The combined administration of equivalent amounts of PTX and GEM via the intravenous (i.v.) route, which is clinically used for treating pancreatic cancer, serves as a control. Following oral administration, the lipophilic PTX is initially absorbed through the intestinal lymphatic system and then enters systemic circulation, whereas the hydrophilic GEM is directly taken up into the blood circulation, ultimately accumulating in the tumorous pancreatic tissues. A pharmacokinetic study reveals that the orally delivered formulation has none of the toxic side-effects that are associated with the i.v. injected formulation; changes the pharmacokinetic profiles of the drugs; and increases the bioavailability of PTX. The oral formulation has a greater impact than the i.v. formulation on tumor-specific stromal depletion, resulting in greater inhibition of tumor growth with no evidence of metastatic spread. As well as enhancing the therapeutic efficacy, this unique approach of oral chemotherapy has potential for use on outpatients, greatly improving their quality of life.