Enhanced stability and efficacy of GEM-TOS prodrug by co-assembly with antimetastatic shell LMWH-TOS

Cancer cell membrane-modified Soluplus® micelles for gemcitabine delivery to pancreatic cancer using a prodrug approach

Pancreatic cancer (PC) is one of the most lethal malignancies worldwide and its incidence is increasing. Chemotherapy is often associated to limited efficacy, poor targeting and systemic toxicity. In this work, the hydrophilic gemcitabine (GEM), widely used in PC treatment alone or in combination, was conjugated with vitamin E succinate (VES) and encapsulated in Soluplus® micelles. This prodrug approach facilitated encapsulation of the anticancer drug into the self-assembled copolymer micelles. Soluplus®/VES-GEM micelles were optimized regarding the ratio of the components and the preparation process. The micelles were small-sized (<80 nm), monodisperse, and highly stable, efficiently retaining the conjugate drug and showing significant antiproliferative activity against BxPC3 cell line. To improve biofunctionalization and targeting properties of prepared Soluplus®/VES-GEM micelles, biomimetic modification with PC cell membrane was further attempted by co-extruding PC cell membrane (BxPC3) nanovesicles with Soluplus®/VES-GEM micelles. Several protocols were attempted to prepare the BxPC3-modified Soluplus®/VES-GEM micelles and the outcomes were analyzed in detail. Overall, the results pave the way to innovative PC-targeted nanotherapies by maximizing GEM encapsulation in hydrophobic compartments with high stability and affinity. The results also highlight the need of higher resolution techniques to characterize cell membrane coating of nanocarriers bearing highly hydrophilic shells.

Design of pH-responsive molecularly imprinted polymer as a carrier for controlled and sustainable capecitabine release

A molecularly imprinting polymer (MIP) carrier with pH-responsivity was designed to construct a drug delivery system (DDS) focusing on controlled and sustainable capecitabine (CAPE) release. The pH-responsive characteristic was achieved by the functionalization of SiO2 substrate with 4-formylphenylboronic acid, accompanied by the introduction of fluorescein isothiocyanate for the visualization of the intracellular localization of the nanocarrier. Experimental results indicated that CAPE was adsorbed onto the drug carrier with satisfactory encapsulation efficiency. The controlled release of CAPE was realized based on the break of borate ester bonds between -B(OH)2 and cis-diols in the weakly acidic environment. Density functional theory computations were conducted to investigate the adsorption/release mechanism. Moreover, in vitro experiments confirmed the good biocompatibility and ideal inhibition efficiency of the developed DDS. The MIP can act as an eligible carrier and exhibits the great potential in practical applications for tumor treatment.

Gemcitabine-Vitamin E Prodrug-Loaded Micelles for Pancreatic Cancer Therapy

Pancreatic cancer (PC) is an aggressive cancer subtype presenting unmet clinical challenges. Conventional chemotherapy, which includes antimetabolite gemcitabine (GEM), is seriously undermined by a short half-life, its lack of targeting ability, and systemic toxicity. GEM incorporation in self-assembled nanosystems is still underexplored due to GEM's hydrophilicity which hinders efficient encapsulation. We hypothesized that vitamin E succinate-GEM prodrug (VES-GEM conjugate) combines hydrophobicity and multifunctionalities that can facilitate the development of Pluronic® F68 and Pluronic® F127 micelle-based nanocarriers, improving the therapeutic potential of GEM. Pluronic® F68/VES-GEM and Pluronic® F127/VES-GEM micelles covering a wide range of molar ratios were prepared by solvent evaporation applying different purification methods, and characterized regarding size, charge, polydispersity index, morphology, and encapsulation. Moreover, the effect of sonication and ultrasonication and the influence of a co-surfactant were explored together with drug release, stability, blood compatibility, efficacy against tumour cells, and cell uptake. The VES-GEM conjugate-loaded micelles showed acceptable size and high encapsulation efficiency (>95%) following an excipient reduction rationale. Pluronic® F127/VES-GEM micelles evidenced a superior VES-GEM release profile (cumulative release > 50%, pH = 7.4), stability, cell growth inhibition (<50% cell viability for 100 µM VES-GEM), blood compatibility, and extensive cell internalization, and therefore represent a promising approach to leveraging the efficacy and safety of GEM for PC-targeted therapies.

CD44 targeting nanodrug based on chondroitin sulfate for melanoma therapy by inducing mitochondrial apoptosis pathways

Neovascularization is crucial to the occurrence and progression of tumors, and the development of antiangiogenic drugs has essential theoretical value and clinical significance. However, antiangiogenesis therapy alone cannot meet the needs of tumor therapy. Meanwhile, polysaccharides are ideal drug carriers with promising applications in drug modification and delivery. In this research, we developed a novel redox and acid sensitive nanodrug (CDDP-CS-Cys-EA, CCEA) composed of chondroitin sulfate (CS), antiangiogenic peptide (endostatin2-alft1, EA) and chemotherapeutic drug (cisplatin, CDDP). CCEA exhibited redox and acid responsiveness, better blood hemocompatibility (hemolysis rate < 5 %), the ability to target tumors (CD44-mediated endocytosis), and strong antiangiogenesis and antitumor characteristics in vitro. Moreover, CCEA showed excellent antitumor activity and low toxicity in B16 xenograft mice. It also has been confirmed that CCEA induced tumor cell apoptosis through promoting the expression of Bax, suppressing the expression of Bcl-2, decreasing mitochondrial membrane potential, releasing cytochrome C (Cyto C), and enhancing the activities of Caspase 9 and Caspase 3. The results of this paper provided a theoretical basis and insight for the development of antitumor drugs.

Hydrolysis kinetics of the prodrug myristyl nicotinate

Myristyl nicotinate is a prodrug of nicotinic acid. In this research, the kinetics of hydrolysis for myristyl nicotinate was studied in an aqueous phosphate buffer solution within a 5-10 pH range and constant ionic strength at a high temperature which was 80 °C to perform accelerated hydrolysis experiments. The effect of temperature, ionic strength, buffer concentrations, and buffer type was studied. The degradation was monitored using a validated HPLC method. The kinetics of hydrolysis of myristyl nicotinate was also studied in skin and liver homogenates. The hydrolysis was found to follow pseudo-first-order kinetics. The rate constant was calculated from the slope of a linear plot of Ln transformation (Ln) of the remaining parent prodrug concentration versus time. The hydrolysis was found pH- dependent, and a pH rate profile was constructed. Moreover, the hydrolysis rate of the prodrug was found to be buffer species dependent. Carbonate buffer has the most catalytic effect over borate and phosphate buffers. The effect of temperature on the kinetics of hydrolysis of myristyl nicotinate in phosphate buffer at pH 9 at 343, 348, 353, and 358°K was studied. The hydrolysis was found to follow the Arrhenius equation. From the Arrhenius plot, the half-life at 25 °C, and the activation energy were calculated and were found to be 466.5 days and 24.57 kcal mol^-1, respectively. The hydrolysis of the prodrug was faster in liver and skin homogenates than those in aqueous buffer solutions. The pseudo-first-order rate constants were found to be 0.012, 0.028 min^-1 for myristyl nicotinate in the liver, and skin homogenates, respectively.

An Overview of Antitumour Activity of Polysaccharides

Cancer incidence and mortality are rapidly increasing worldwide; therefore, effective therapies are required in the current scenario of increasing cancer cases. Polysaccharides are a family of natural polymers that hold unique physicochemical and biological properties, and they have become the focus of current antitumour drug research owing to their significant antitumour effects. In addition to the direct antitumour activity of some natural polysaccharides, their structures offer versatility in synthesizing multifunctional nanocomposites, which could be chemically modified to achieve high stability and bioavailability for delivering therapeutics into tumor tissues. This review aims to highlight recent advances in natural polysaccharides and polysaccharide-based nanomedicines for cancer therapy.

Emerging nanomedicine-based therapeutics for hematogenous metastatic cascade inhibition: Interfering with the crosstalk between "seed and soil"

Despite considerable progresses in cancer treatment, tumor metastasis is still a thorny issue, which leads to majority of cancer-related deaths. In hematogenous metastasis, the concept of “seed and soil” suggests that the crosstalk between cancer cells (seeds) and premetastatic niche (soil) facilitates tumor metastasis. Considerable efforts have been dedicated to inhibit the tumor metastatic cascade, which is a highly complicated process involving various pathways and biological events. Nonetheless, satisfactory therapeutic outcomes are rarely observed, since it is a great challenge to thwart this multi-phase process. Recent advances in nanotechnology-based drug delivery systems have shown great potential in the field of anti-metastasis, especially compared with conventional treatment methods, which are limited by serious side effects and poor efficacy. In this review, we summarized various factors involved in each phase of the metastatic cascade ranging from the metastasis initiation to colonization. Then we reviewed current approaches of targeting these factors to stifle the metastatic cascade, including modulating primary tumor microenvironment, targeting circulating tumor cells, regulating premetastatic niche and eliminating established metastasis. Additionally, we highlighted the multi-phase targeted drug delivery systems, which hold a better chance to inhibit metastasis. Besides, we demonstrated the limitation and future perspectives of nanomedicine-based anti-metastasis strategies.

Self-Delivery Micellar Nanoparticles Prevent Premetastatic Niche Formation by Interfering with the Early Recruitment and Vascular Destruction of Granulocytic Myeloid-Derived Suppressor Cells

Distal metastases of tumors result from the interaction between "seeds" (circulating tumor cells, CTCs) and "soil" (premetastatic niche, PMN). Various strategies focus on CTC inhibition, but only a few strategies inhibit PMN formation. The main predisposition of PMN formation in melanoma lies in the pulmonary recruitment of granulocytic myeloid-derived suppressor cells (G-MDSCs, CD11b⁺Ly6G⁺ cells) induced by tumors, which increase vascular permeability by secreting matrix metalloproteinase-9 (MMP-9) and result in immunosuppression by secreting interleukin-10 (IL-10) in premetastatic lungs. Here, a micellar hypotoxic low molecular weight heparin-tocopherol succinate nanoparticle (LMWH-TOS nanoparticle, LT NP) was established and investigated for its influence on PMN formation in this study. We first demonstrated that the hydrophilic segment LMWH in LT NPs can inhibit early pulmonary recruitment of G-MDSCs through interrupting their extravasation by inhibiting P-selectin/PSGL-1-mediated adhesion between vascular endothelial cells and G-MDSCs. In addition, the hydrophobic segment (TOS) in LT NPs significantly inhibited the expression of MMP-9 in G-MDSCs. As a result, the drug-free nanoparticles could maintain the normal microenvironment of lungs, thus effectively inhibiting implantation and colonization of CTCs. Further, phenylboronic acid (PBA)-modified and doxorubicin/immunopotentiator α-galactosylceramide (αGC)-coloaded nanoparticles (PLT/DOX/αGC NPs) were exploited. PBA modification achieved targeted chemotherapy by binding to overexpressed sialic acid residues on the tumor cell surface. This nanosystem effectively inhibited the postoperative metastasis and tumor recurrence simultaneously. Our work provides a proof of concept that the prevention of PMN formation through interfering G-MDSCs with self-delivery nanosystems is a safe and effective antimetastasis strategy.

Enhanced anti-tumor and anti-metastasis therapy for triple negative breast cancer by CD44 receptor-targeted hybrid self-delivery micelles

Tumor growth and metastasis are multistep processes regulated by multiple signaling pathways. The successful treatment of cancer largely depends on the ability to inhibit metastatic process. Multiphase inhibition of metastasis is a promising approach. Here, we described a targeting delivery system which was constructed by mixing hyaluronic acid-d-α-tocopheryl succinate (HA-TOS, HT) and low molecular weight heparin-TOS (LMWH-TOS, LT) to form a stable hybrid micelle (HT-LT), encapsulating chemotherapeutic drug doxorubicin (DOX). The prepared HT-LT NPs was about 125 nm in diameter with high drug encapsulation rate and continuous drug release behavior. We confirmed that HT-LT NPs exhibited an effective targeting ability both in vitro and in vivo using a 4T1 model that was attributed to HA binding to CD44 receptors. In addition, HT-LT NPs acted on different phases of the invasion-metastasis cascade and inhibited tumor cell migration and invasion, thus inhibiting tumor metastasis. This combinatorial strategy provided an alternative approach for triple negative breast cancer therapy.