Preclinical and clinical studies of NK012, an SN-38-incorporating polymeric micelles, which is designed based on EPR effect

Microfluidic Manufacturing of SN-38-Loaded Polymer Nanoparticles with Shear Processing Control of Drug Delivery Properties

Two-phase gas-liquid microfluidic reactors provide shear processing control of SN-38-loaded polymer nanoparticles (SN-38-PNPs). We prepare SN-38-PNPs from the block copolymer poly(methyl caprolactone- co-caprolactone)- block-poly(ethylene oxides) (P(MCL- co-CL)- b-PEO) using bulk and microfluidic methods and at different drug-to-polymer loading ratios and on-chip flow rates. We show that, as the microfluidic flow rate ( Q) increases, encapsulation efficiency and drug loading increase and release half times increase. Slower SN-38 release is obtained at the highest Q value ( Q = 400 μL/min) than is achieved using a conventional bulk preparation method. For all SN-38-PNP formulations, we find a dominant population (by number) of nanosized particles (<50 nm) along with a small number of larger aggregates (>100 nm). As Q increases, the size of aggregates decreases through a minimum and then increases, attributed to a flow-variable competition of shear-induced particle breakup and shear-induced particle coalescence. IC₂₅ and IC₅₀ values of the various SN-38-PNPs against MCF-7 cells show strong flow rate dependencies that mirror trends in particle size. SN-38-PNPs manufactured on-chip at intermediate flow rates show both minimum particle sizes and maximum potencies with a significantly lower IC₂₅ value than the bulk-prepared sample. Compared to conventional bulk methods, microfluidic shear processing in two-phase reactors provides controlled manufacturing routes for optimizing and improving the properties of SN-38 nanomedicines.

Evaluation of Anti-Tumor Efficacy of Vorinostat Encapsulated Self-Assembled Polymeric Micelles in Solid Tumors

Vorinostat (VOR), a potent HDAC inhibitor, suffers from low solubility and poor absorption, which hinders its successful application in therapy, especially in the treatment of solid tumors. In this study, an effort to improve the physicochemical characteristics of VOR was made by encapsulating it in PEG-PLGA copolymeric micelles. VOR-loaded PEG-PLGA micelles (VOR-PEG-PLGA) were produced by thin-film hydration and physicochemically characterized. The PEG-PLGA micelles had an average size of 124.06 ± 2.6 nm, polydispersity index of 0.27 ± 0.1, and entrapment efficiency of 90 ± 2.1%. Micelles were characterized by TEM, DSC, and drug release studies. The drug release occurred in a sustained manner up to 72 h from PEG-PLGA micelles. In the in vitro cell-based studies using human breast cancer (MDA MB 231) and murine melanoma (B16F10) cell lines, VOR-PEG-PLGA micelles exhibited superior cellular internalization, enhanced cytotoxic activity, and greater apoptosis compared to free drug. Percent cell killing of 54.9% for VOR-PEG-PLGA-treated cells was observed after 24 h compared to 36% for free VOR in MDA MB 231 cell line. Further, significant tumor suppression was witnessed in B16F10 tumor-bearing mice treated with VOR-PEG-PLGA micelles with a 1.78-fold reduction in tumor volume compared to free VOR-treated animals. Overall, the VOR-PEG-PLGA micelles improved the biopharmaceutical properties of VOR, which resulted in enhanced anti-tumor efficacy. Therefore, the newly developed nano-formulation of VOR could be considered as an effective treatment option in solid tumors.

Nanomedicines for the treatment of hematological malignancies

Hematological malignancies (HM) are a collection of malignant transformations originating from cells in the primary or secondary lymphoid organs. Leukemia, lymphoma, and multiple myeloma comprise the three major types of HM. Current treatment consists of bone marrow transplantation, radiotherapy, immunotherapy and chemotherapy. Although, many chemotherapeutic drugs are clinically available for the treatment of HM, the use of these agents is limited due to dose-related toxicity and lack of specificity to tumor tissue. Moreover, the poor pharmacokinetic profile of most of the chemotherapeutics requires high dosage and frequent administration to maintain therapeutic levels at the target site, both increasing adverse effects. This underlines an urgent need for a suitable drug delivery system to improve efficacy, safety, and pharmacokinetic properties of conventional therapeutics. Nanomedicines have proven to enhance these properties for anticancer therapeutics. The most extensively studied nanomedicine systems are lipid-based nanoparticles and polymeric nanoparticles. Typically, nanomedicines are small sub-micron sized particles in the size range of 20-200 nm. The biocompatible and biodegradable nature of nanomedicines makes them attractive vehicles to improve drug delivery. Their small size allows them to extravasate and accumulate at malignant sites passively by means of the enhanced permeability and retention (EPR) effect, resulting from rapid angiogenesis and inflammation. Moreover, the specificity to the target tissue can be further enhanced by surface modification of nanoparticles. This review describes currently available therapies as well as limitations and potential advantages of nanomedicine formulations for treatment of various types of HM. Additionally, recent investigational and approved nanomedicine formulations and their limited applications in HM are discussed.

Dimeric camptothecin-loaded RGD-modified targeted cationic polypeptide-based micelles with high drug loading capacity and redox-responsive drug release capability

Camptothecin (CPT) is a broad spectrum anticancer drug, but its application is limited due to the poor water solubility, lactone ring instability, and low drug loading potential. In this study, biocompatible cationic polypeptide-based micelles were developed to deliver dimeric CPT (DCPT) with the aim of overcoming the above-mentioned obstacles and achieving favorable therapeutic effects. Cationic polypeptide poly-lysine-block-poly-leucine (PLys-b-PLeu) was fabricated via the ring-opening polymerization of N-ε-carbobenzoxy-l-lysine (ε-Lys(Z)) and l-leucine (Leu) and further grafted with polyethylene glycol (PEG) and an arginine-glycine-aspartic acid (RGD) peptide. DCPT was synthesized by reacting CPT and 2-hydroxyethyl disulfide, and micelles were prepared using a dialysis method. The obtained DCPT-loaded RGD-PEG-g-poly-l-lysine-b-poly-l-leucine (DRPPP) micelles showed a high encapsulation efficiency of 89.7% and a high drug loading capacity of 46.1%. In addition, the DRPPP micelles remained stable under physiological conditions (PBS at a pH of 7.4) but showed rapid release when triggered by a reductive environment (PBS at a pH of 7.4 with 10 mM dithiothreitol). Compared to micelles without RGD decoration, the DRPPP micelles exhibited an increased cellular uptake through RGD targeting and were internalized into cells via caveolae-mediated endocytosis and macropinocytosis. Furthermore, the DRPPP micelles exerted an enhanced cytotoxicity against MDA-MB-231 cells compared to MCF-7 cells, which expressed less α_vβ₃ receptors. Besides, the DRPPP micelles induced cell apoptosis and caused a decrease of mitochondrial membrane potential. These results indicate that dimeric camptothecin-loaded cationic polypeptide-based micelle is a promising strategy for cancer therapy.

Size-dependent endocytosis and a dynamic-release model of nanoparticles

Polymeric nanoparticles for drug delivery are attracting broad interest along with the rapid development of biomedical and healthcare research. Here, we prepared a series of nanocapsules via electrostatic precipitation of chitosan and lecithin micelles. These nanocapsules have controlled diameters (∼25-200 nm) that only slightly changed after several lyophilization-dissolving cycles, suggesting their excellent stability for long-term storage. In cell experiments, these nanocapsules obviously reduced the cytotoxicity of encapsulated small molecules, and clearly showed size-dependent endocytosis. In a dynamic release model mimicking the in vivo circulatory system, the nanocapsules demonstrated superiority over micelles as drug carriers due to their stable structures. To the best of our knowledge, this is the first dynamic model used to evaluate the drug-release behaviour, which might provide a new way to study the release profile of other potential drug carriers.

Functionalized Nanoparticles Efficiently Enhancing the Targeted Delivery, Tumor Penetration, and Anticancer Activity of 7-Ethyl-10-Hydroxycamptothecin

The enhanced permeability and retention (EPR) effect of tumors is much more complex than initially defined, and it alone is not sufficient for targeted delivery of nanosized agents. Meanwhile, poor tumor penetration is another major challenge for the treatment of solid tumors using nanoparticles. Development of delivery systems for SN38, the active metabolite of CPT-11 in human and a very potent anticancer molecule, has become an attractive research area. PEG_x -p(HEMASN38)_y (x and y are viable), a prodrug synthesized by using polyethylene glycol (PEG) as initiator and SN38 as monomer through atom transfer radical polymeration (ATRP) method, is previously reported. Using PEG_2.4K -p(HEMASN38)_3K as a model prodrug, herein an active-targeted strategy decorated with cys-arg-gly-asp-lys (CRGDK), a peptide specifically binds to neuropilin-1 overexpressed by tumor vessels and tumor cells, is successfully established to further improve the delivery and efficacy of SN38. CRGDK-functionalized PEG_2.4K -p(HEMASN38)_3K (C-SN38) nanoparticles and nonfunctionalized control (B-SN38) are prepared with two distinct sizes, 30 and 100 nm. Their physiochemical and biological characteristics are investigated in vitro and in vivo with multiple tumor models. It is demonstrated for the first time that CRGDK functionalization can be a promising strategy for efficient delivery of SN38, and C-SN38 is a potent drug candidate for the treatment of neuropilin-1 overexpressing tumors.

A Phase I/II Study for Dose-finding, and to Investigate the Safety, Pharmacokinetics and Preliminary Efficacy of NK012, an SN-38-Incorporating Macromolecular Polymeric Micelle, in Patients with Multiple Myeloma

Objective Multiple myeloma (MM) is the second most common hematological cancer. An attempt to treat MM using a topoisomerase I inhibitor was made based on our previous non-clinical studies suggesting the usefulness of an SN-38 derivative. Our aim was to conduct a phase I/II study of NK012, a micelle-forming SN-38 conjugate, in patients with relapsed/refractory multiple myeloma (RRMM). Methods NK012 was administered at doses of 12-24 mg/m² and the safety, pharmacokinetics and preliminary efficacy were evaluated. Results Neutropenia was the most common grade 3 or 4 adverse drug reaction. Grade 4 neutropenia accounted for the majority of dose-limiting toxicities and only appeared at a dose of 24 mg/m². The maximum concentrations and the area under the concentration-time curves from time zero to infinity for both NK012 and its active metabolite SN-38 increased in a dose-dependent manner. The best overall response was stable disease, which was achieved in 12 out of 16 patients. Conclusion The recommended dose of NK012 monotherapy for RRMM patients was concluded to be 20 mg/m². However, this phase I/II study was terminated at the end of the phase I stage because no patients showed an objective response. Additional clinical studies of combination therapy with NK012 and other agents are warranted.

PEG-modification on the endo-position of an antisense oligonucleotide increases tumor accumulation via the EPR effect

Nucleic acid medicine is the next-generation therapeutic modality for refractory diseases with its unique mode of action as an alternative to traditional therapies. A nucleic acid delivery system targeted to liver was validated clinically; however, the delivery system of nucleic acids targeting solid tumors following systemic administration is not efficient enough for clinical use. In this study, we first utilized an antisense oligonucleotide (ASO) and polyethylene glycol (PEG) in one-to-one conjugation (PEG-ASO) at the endo-position of the ASO (endo-PEG-ASO). The effects of ASO modification position, PEG structure and molecular weight, and PEG-ASO tumor accumulation were evaluated in vivo. The endo-PEG-ASO showed prolonged pharmacokinetics and enhanced tumor accumulation compared with the conventional ASO and the PEG-ASO modified at the ASO exo-position (exo-PEG-ASO), indicating that the modification position of PEG is crucial for targeting tumors. We also observed that the endo-PEG-ASO indicated possibility of enhanced permeability inside the tumor. Further research is needed to optimize the linker in the endo-PEG-ASO for clinical application as a novel and promising therapeutic format for targeting solid tumors.

Polymer Prodrug-Based Nanoreactors Activated by Tumor Acidity for Orchestrated Oxidation/Chemotherapy

Therapeutic nanoreactors have been proposed to treat cancers through in situ transformation of low-toxicity prodrugs into toxic therapeutics in the body. However, the in vivo applications are limited by low tissue-specificity and different tissue distributions between sequentially injected nanoreactors and prodrugs. Herein, we construct a block copolymer prodrug-based polymersome nanoreactor that can achieve novel orchestrated oxidation/chemotherapy of cancer via specific activation at tumor sites. The block copolymers composed of poly(ethylene glycol) (PEG) and copolymerized monomers of camptothecin (CPT) and piperidine-modified methacrylate [P(CPTMA-co-PEMA)] were optimized to self-assemble into polymersomes in aqueous solution for encapsulation of glucose oxidase (GOD) to obtain GOD-loaded polymersome nanoreactors (GOD@PCPT-NR). GOD@PCPT-NR maintained inactive in normal tissues upon systemic administration. After deposition in tumor tissues, tumor acidity-triggered protonation of PPEMA segments resulted in high permeability of the polymersome membranes and oxidation reaction of diffused glucose and O₂ under the catalysis of GOD. The activation of the reaction generated H₂O₂, improving the oxidative stress in tumors. Simultaneously, a high level of H₂O₂ further activated PCPTMA prodrugs, releasing active CPT drugs. High tumor oxidative stress and released CPT drugs synergistically killed cancer cells and suppressed tumor growth via oxidation/chemotherapy. Our study provides a new strategy for engineering therapeutic nanoreactors in an orchestrated fashion for cancer therapy.

In vitro and in vivo evaluation of SN-38 nanocrystals with different particle sizes

7-Ethyl-10-hydroxycamptothecin (SN-38) is a potent broad-spectrum antitumor drug derived from irinotecan hydrochloride (CPT-11). Due to its poor solubility and instability of the active lactone ring, its clinical use is significantly limited. As one of the most promising formulations for poorly water-soluble drugs, nanocrystals have attracted increasing attention. In order to solve these problems and evaluate the antitumor effect of SN-38 in vitro and in vivo, two nanocrystals with markedly different particle sizes were prepared. Dynamic light scattering and transmission electron microscopy were used to investigate the two nanocrystals. The particle sizes of SN-38 nanocrystals A (SN-38/NCs-A) and SN-38 nanocrystals B (SN-38/NCs-B) were 229.5±1.99 and 799.2±14.44 nm, respectively. X-ray powder diffraction analysis showed that the crystalline state of SN-38 did not change in the size reduction process. An accelerated dissolution velocity of SN-38 was achieved by nanocrystals, and release rate of SN-38/NCs-A was significantly faster than that of SN-38/NCs-B. Cellular uptake, cellular cytotoxicity, pharmacokinetics, animal antitumor efficacy, and tissue distribution were subsequently examined. As a result, enhanced intracellular accumulation in HT1080 cells and cytotoxicity on different tumor cells were observed for SN-38/NCs-A compared to that for SN-38/NCs-B and solution. Besides, compared to the SN-38 solution, SN-38/NCs-A had a higher bioavailability after intravenous injection; while the bioavailability of SN-38/NCs-B was even lower than that of the SN-38 solution. SN-38/NCs-A exhibited a significant inhibition of tumor growth compared to SN-38 solution and SN-38/NCs-B in vivo. The antitumor effect of SN-38/NCs-B was stronger than SN-38 solution. The tissue distribution study in tumor-bearing mice showed that nanocrystals could markedly improve the drug accumulation in tumor tissue by the enhanced permeability and retention effect compared to SN-38 solution, and the amount of SN-38 in tumors of SN-38/NCs-A group was much more than that of SN-38/NCs-B group. In conclusion, nanocrystals dramatically enhanced the anticancer efficacy of SN-38 in vitro and in vivo, and the particle size had a significant influence on the dissolution behavior, pharmacokinetic properties, and tumor inhibition of nanocrystals.

Photothermal, Targeting, Theranostic Near-Infrared Nanoagent with SN38 against Colorectal Cancer for Chemothermal Therapy

Cancer research regarding near-infrared (NIR) agents for chemothermal therapy (CTT) has shown that agents with specific functions are able to inhibit tumor growth. The aim of current study was to optimize CTT efficacy for treatment of colorectal cancer (CRC) by exploring strategies which can localize high temperature within tumors and maximize chemotherapeutic drug uptake. We designed a new and simple multifunctional NIR nanoagent composed of the NIR cyanine dye, polyethylene glycol, and a cyclic arginine-glycine-aspartic acid peptide and loaded with the anti-CRC chemotherapeutic agent, 7-ethyl-10-hydroxy-camptothecin (SN38). Each component of this nanoagent exhibited its specific functions that help boost CTT efficacy. The results showed that this nanoagent greatly strengthens the theranostic effect of SN38 and CTT against CRC due to its NIR imaging ability, photothermal, enhanced permeability and retention (EPR) effect, reticuloendothelial system avoidance, and angiogenic blood vessel-targeting properties. This NIR nanoagent will help facilitate development of new strategies for treating CRC.

Acidity-Triggered Tumor Retention/Internalization of Chimeric Peptide for Enhanced Photodynamic Therapy and Real-Time Monitoring of Therapeutic Effects

Photodynamic therapy (PDT) holds great promise in tumor treatment. Nevertheless, it remains highly desirable to develop easy-to-fabricated PDT systems with improved tumor accumulation/internalization and timely therapeutic feedback. Here, we report a tumor-acidity-responsive chimeric peptide for enhanced PDT and noninvasive real-time apoptosis imaging. Both in vitro and in vivo studies revealed that a tumor mildly acidic microenvironment could trigger rapid protonation of carboxylate anions in chimeric peptide, which led to increased ζ potential, improved hydrophobicity, controlled size enlargement, and precise morphology switching from sphere to spherocylinder shape of the chimeric peptide. All of these factors realized superfast accumulation and prolonged retention in the tumor region, selective cellular internalization, and enhanced PDT against the tumor. Meanwhile, this chimeric peptide could further generate reactive oxygen species and initiate cell apoptosis during PDT. The subsequent formation of caspase-3 enzyme hydrolyzed the chimeric peptide, achieving a high signal/noise ratio and timely fluorescence feedback. Importantly, direct utilization of the acidity responsiveness of a biofunctional Asp-Glu-Val-Asp-Gly (DEVDG, caspase-3 enzyme substrate) peptide sequence dramatically simplified the preparation and increased the performance of the chimeric peptide furthest.

Targeted drug distribution in tumor extracellular fluid of GD2-expressing neuroblastoma patient-derived xenografts using SN-38-loaded nanoparticles conjugated to the monoclonal antibody 3F8

Neuroblastoma is a pediatric solid tumor with high expression of the tumor associated antigen disialoganglioside GD2. Despite initial response to induction therapy, nearly 50% of high-risk neuroblastomas recur because of chemoresistance. Here we encapsulated the topoisomerase-I inhibitor SN-38 in polymeric nanoparticles (NPs) surface-decorated with the anti-GD2 mouse mAb 3F8 at a mean density of seven antibody molecules per NP. The accumulation of drug-loaded NPs targeted with 3F8 versus with control antibody was monitored by microdialysis in patient-derived GD2-expressing neuroblastoma xenografts. We showed that the extent of tumor penetration by SN-38 was significantly higher in mice receiving the targeted nano-drug delivery system when compared to non-targeted system or free drug. This selective penetration of the tumor extracellular fluid translated into a strong anti-tumor effect prolonging survival of mice bearing GD2-high neuroblastomas in vivo.

A multi-stimuli responsive nanoparticulate SN38 prodrug for cancer chemotherapy

Modification of drug delivery systems (DDSs) with stimuli-responsive elements could significantly increase the tumor-specific delivery of anticancer drugs.

Safe approaches for camptothecin delivery: Structural analogues and nanomedicines

Twenty-(S)-camptothecin is a strongly cytotoxic molecule with excellent antitumor activity over a wide spectrum of human cancers. However, the direct formulation is limited by its poor water solubility, low plasmatic stability and severe toxicity, which currently limits its clinical use. As a consequence, two strategies have been developed in order to achieve safe and efficient delivery of camptothecin to target cells: structural analogues and nanomedicines. In this review, we summarize recent advances in the design, synthesis and development of camptothecin molecular derivatives and supramolecular vehicles, following a systematic classification according to structure-activity relationships (structural analogues) or chemical nature (nanomedicines). A series of organic, inorganic and hybrid materials are presented as nanoplatforms to overcome camptothecin restrictions in administration, biodistribution, pharmacokinetics and toxicity. Nanocarriers which respond to a variety of stimuli endogenously (e.g., pH, redox potential, enzyme activity) or exogenously (e.g., magnetic field, light, temperature, ultrasound) seem the best positioned therapeutic materials for optimal spatial and temporal control over drug release. The main goal of this review is to be used as a source of relevant literature for others interested in the field of camptothecin-based therapeutics. To this end, final remarks on the most important formulations currently under clinical trial are provided.

Polymeric micelles of suberoylanilide hydroxamic acid to enhance the anticancer potential in vitro and in vivo

AIM

To improve the bioavailability and anticancer potential of suberoylanilide hydroxamic acid (SAHA) by developing a drug-loaded polymeric nanomicellar system.

METHODS

SAHA-loaded Poly(ethylene glycol)-block-poly(caprolactone) (PEG-PCL) micelles were developed, and physico-chemically characterized. In vitro cellular uptake, viability and apoptosis-inducing ability of the SAHA-PEG-PCL micelles were investigated. In vivo anticancer activity was evaluated in C57BL/6 mice-bearing tumor.

RESULTS

The SAHA-PEG-PCL micelles had optimum size (∼130 nm) with an entrapment efficiency of approximately 67%. The SAHA-PEG-PCL induced stronger cell cycle arrest in G2/M phase leading to higher rate of apoptosis compared to free SAHA. SAHA-PEG-PCL demonstrated significant tumor suppression compared to free SAHA in vivo.

CONCLUSION

The physicochemical properties and the antitumor efficacy of SAHA were improved by encapsulating in polymeric micelles.

Trends on polymer- and lipid-based nanostructures for parenteral drug delivery to tumors

PURPOSE

The dawn of the state-of-the-art methods of cancer treatments, nano-based delivery systems, has dispensed with the mainstream chemotherapy for being inadequate in yielding productive results and the numerous reported side effects. The popularity of this complementary approach in the course of the last two decades has been primarily attributed to its capacity to elevate the therapeutic index of anticancer drugs as well as removing the impassable delivery barriers in solid tumors with the minimal damage to the normal tissues.

METHODS

The PubMed database was consulted to compile this review.

RESULTS

A wide range of minuscule organic and inorganic nanomaterials, with dimensions not exceeding hundred nanometers, has led to hope for cancer therapy to flare-up once again due to possessing a number of exclusive traits for passive and active tumor targeting, some of which are EPR effect, high interstitial pressure of tumor, overexpressed receptors and angiogenesis. Although a limited number of liposomal and polymer-based therapeutic nanoparticles have gained applicability, a vast number of nanoparticles are still being trailed in order to be fully developed.

CONCLUSIONS

This study provides an overview of the advantages/disadvantages of nanocarriers for cancer drug delivery.

pH and redox dual-responsive biodegradable polymeric micelles with high drug loading for effective anticancer drug delivery

Diblock copolymers of poly(ethylene glycol) (PEG) and biodegradable polycarbonate functionalized with GSH-sensitive disulfide bonds and pH-responsive carboxylic acid groups were synthesized via organocatalytic ring-opening polymerization of functional cyclic carbonates with PEG having different molecular weights as macroinitiators. These narrowly-dispersed polymers had predictable molecular weights, and were used to load doxorubicin (DOX) into micelles primarily through ionic interactions. The DOX-loaded micelles exhibited the requisite small particle size (<100 nm), narrow size distribution and high drug loading capacity. When exposed to endolysosomal pH of 5.0, drug release was accelerated by at least two-fold. The introduction of GSH further expedited DOX release. Effective DOX release enhanced cytotoxicity against cancer cells. More importantly, the DOX-loaded micelles with the optimized composition showed excellent antitumor efficacy in nude mice bearing BT-474 xenografts without inducing toxicity. These pH and redox dual-responsive micelles have the potential as delivery carriers to maximize the therapeutic effect of anticancer drugs.

Development of polymeric irinotecan nanoparticles using a novel lactone preservation strategy

Irinotecan (IRT) is an important part of the first- and second-line regimen for metastatic colorectal and some other cancers. However, IRT suffers the constraints of pH-dependent conversion of active lactone form to inactive carboxylate form, burst release owing to its aqueous solubility, short half-life and dose-dependent side effects. In this study, we developed polymeric nanoparticles (NPs) that not only deliver IRT to tumor sites, but also overcome its drawbacks by preserving active lactone conformation, prolonging the plasma circulation time, and by providing sustained release. IRT complex was rendered hydrophobic by ion-pairing with anions (docusate sodium, sodium lauryl sulfate, and sodium tripolyphosphate), and loaded in PEG-PLGA NPs via water/oil/water double emulsification method. The NPs were spherical, ∼60nm, monodispersed, and had shell-core morphology. They retained >80% lactone form for more than 1 month of storage and exhibited sustained release characteristics. In addition, sub -100nm size of NPs offered elevated cellular internalization. Owing to the presence of hydrophilic PEG outer layer and drug-loaded hydrophobic PLGA core, NPs conferred excellent plasma stability and prolonged the retention time of IRT by more than 10-fold as compared to free IRT. Therefore, this system could provide an excellent platform for efficient and sustained delivery of IRT and similar labile drugs to the tumor site, while maintaining their chemical integrity.

Integrating a novel SN38 prodrug into the PEGylated liposomal system as a robust platform for efficient cancer therapy in solid tumors

Liposomal nanoassemblies have been used extensively as carriers for the delivery of both lipophilic and hydrophilic drugs. They represent a mature, versatile technology with considerable potential for improving the pharmacokinetics of drugs. However, the formulation of many chemotherapeutics into liposome systems has posed a significant challenge due to their incompatible physicochemical properties, as was the case with camptothecin-based chemotherapeutics. Here, we present a rational paradigm of potent chemotherapeutics that were reconstructed and subsequently integrated into liposomal nanoassemblies. Using SN38 (7-ethyl-10-hydroxy camptothecin) as a model drug, a lipophilic prodrug 1 (designated as LA-SN38) was constructed by tethering the linoleic acid (LA) moiety via esterification, which was further facilitated to form liposomal nanoparticles (LipoNP) through supramolecular nanoassembly. The resulting 1-loaded LipoNP exhibited sustained drug release kinetics and decreased cellular uptake by macrophage cells. Uptake by tumor cells was enhanced relative to our previous supramolecular nanoparticles (SNP 1), which were derived from the self-assembling prodrug 1. Notably, LipoNP outperformed SNP 1 in terms of pharmacokinetics and in vivo therapeutic efficacy in both human BEL-7402 hepatocellular carcinoma (HCC) and HCT-116 colorectal cancer-derived xenograft mouse models. These results were likely due to the improved systemic circulation and preferential accumulation of nanodrugs in tumors. Hence, our results suggest that the combination of liposomal delivery platforms with rational prodrug engineering may emerge as a promising approach for the effective and safe delivery of anticancer chemotherapeutics.

Nanoparticle-mediated co-delivery of chemotherapeutic agent and siRNA for combination cancer therapy

INTRODUCTION

Cancer is the leading cause of death worldwide. Current cancer treatments in the clinic mainly include chemotherapy, radiotherapy and surgery, with chemotherapy being the most common. Areas covered: Cancer treatments based on the single 'magic-bullet' concept are often associated with limited therapeutic efficacy, unwanted adverse effects, and drug resistance. The combination of multiple drugs is a promising strategy for effective cancer treatment due to the synergistic or additive effects. Small interfering RNA (siRNA) has the ability to knock down the expression of carcinogenic genes or drug efflux transporter genes, paving the way for cancer treatment. Treatment with both a chemotherapeutic agent and siRNA based on nanoparticle (NP)-mediated co-delivery is a promising approach for combination cancer therapy. Expert opinion: The combination of chemotherapeutic agents and siRNAs for cancer treatment offers the potential to enhance therapeutic efficacy, decrease side effects, and overcome drug resistance. Co-delivery of chemical drug and siRNA in the same NP would be much more effective in cancer therapy than application of chemical agent or siRNA alone. With the development of material science, NPs have come to be the most widely used platform for co-delivery of chemotherapeutic drugs and siRNAs.

Enhanced efficacy against cervical carcinomas through polymeric micelles physically incorporating the proteasome inhibitor MG132

Treatment of recurrent or advanced cervical cancer is still limited, and new therapeutic choices are needed for improving prognosis and quality of life of patients. Because human papilloma virus (HPV) infection is critical in cervical carcinogenesis, with the E6 and E7 oncogenes of HPV degrading tumor suppressor proteins through the ubiquitin proteasome system, the inhibition of the ubiquitin proteasome system appears to be an ideal target to suppress the growth of cervical tumors. Herein, we focused on the ubiquitin proteasome inhibitor MG132 (carbobenzoxy‐Leu‐Leu‐leucinal) as an anticancer agent against cervical cancer cells, and physically incorporated it into micellar nanomedicines for achieving selective delivery to solid tumors and improving its in vivo efficacy. These MG132‐loaded polymeric micelles (MG132/m) showed strong tumor inhibitory in vivo effect against HPV‐positive tumors from HeLa and CaSki cells, and even in HPV‐negative tumors from C33A cells. Repeated injection of MG132/m showed no significant toxicity to mice under analysis by weight change or histopathology. Moreover, the tumors treated with MG132/m showed higher levels of tumor suppressing proteins, hScrib and p53, as well as apoptotic degree, than tumors treated with free MG132. This enhanced efficacy of MG132/m was attributed to their prolonged circulation in the bloodstream, which allowed their gradual extravasation and penetration within the tumor tissue, as determined by intravital microscopy. These results support the use of MG132 incorporated into polymeric micelles as a safe and effective therapeutic strategy against cervical tumors.

Development of bioactive materials for glioblastoma therapy

Glioblastoma is the most common and deadly human brain cancers. Unique barriers hinder the drug delivering pathway due to the individual position of glioblastoma, including blood-brain barrier and blood-brain tumor barrier. Numerous bioactive materials have been exploited and applied as the transvascular delivery carriers of therapeutic drugs. They promote site-specific accumulation and long term release of the encapsulated drugs at the tumor sites and reduce side effects with systemic delivery. And the delivery systems exhibit a certain extent of anti-glioblastoma effect and extend the median survival time. However, few of them step into the clinical trials. In this review, we will investigate the recent studies of bioactive materials for glioblastoma chemotherapy, including the inorganic materials, lipids and polymers. These bioactive materials construct diverse delivery vehicles to trigger tumor sites in brain intravenously. Herein, we exploit their functionality in drug delivery and discuss the deficiency for the featured tumors, to provide guidance for establishing optimized therapeutic drug formulation for anti-glioblastoma therapy and pave the way for clinical application.

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Numerous bioactive materials have been exploited as delivery carriers of therapeutic drugs for glioblastoma chemotherapy.

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The functionality and deficiency of the bioactive materials are discussed.

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Combing the chemo- and immunotherapy will provide a promising strategy for glioblastoma therapy and inhibiting recurrence.

Relationship Between Increased Fucosylation and Metastatic Potential in Colorectal Cancer

BACKGROUND

Fucose is utilized for the modification of different molecules involved in blood group determination, immunological reactions, and signal transduction pathways. We have recently reported that enhanced activity of the fucosyltransferase 3 and/or 6 promoted TGF-ß-mediated epithelial mesenchymal transition and was associated with increased metastatic potential of colorectal cancer (CRC), suggesting that fucose is required by CRC cells. With this in mind, we examined requirement of L-fucose in CRC cells and developed fucose-bound nanoparticles as vehicles for delivery of anticancer drugs specific to CRC.

METHODS

In this study, we first examined the expression of fucosylated proteins in 50 cases of CRC by immunochistochemical staining with biotinylated Aleuria aurantia lectin (AAL). Then we carried out an L-fucose uptake assay using three CRC cell lines. Finally, we developed fucose-bound nanoparticles as vehicles for the delivery of an anticancer drug, SN38, and examined tumor growth inhibition in mouse xenograft model (n = 6 mice per group). All statistical tests were two-sided.

RESULTS

We found a statistically significant relationship between vascular invasion, clinical stage, and intensity score of AAL staining (P≤ .02). L-fucose uptake assay revealed that L-fucose incorporation, as well as fucosylated protein release, was high in cells rich in fucosylated proteins. L-fucose-bound liposomes effectively delivered Cy5.5 into CRC cells. The excess of L-fucose decreased the efficiency of Cy5.5 uptake through L-fucose-bound liposomes, suggesting an L-fucose receptor dependency. Intravenously injected, L-fucose-bound liposomes carrying SN38 were successfully delivered to CRC cells, mediating efficient tumor growth inhibition (relative tumor growth ratio: no treatment group [NT], 8.29 ± 3.09; SN38-treated group [SN38], 3.53 ± 1.47; liposome-carrying, SN38-treated group [F0], 3.1 ± 1.39; L-fucose-bound, liposome-carrying, SN38-treated group [F50], 0.94 ± 0.89; F50 vs NT,P= .003; F50 vs SN38,P= .02, F50 vs F0,P= .04), as well as prolonging survival of mouse xenograft models (log-rank test,P< .001).

CONCLUSIONS

Thus, fucose-bound liposomes carrying anticancer drugs provide a new strategy for the treatment of CRC patients.

Paclitaxel-loaded polymeric depots as injectable drug delivery system for cancer chemotherapy of hepatocellular carcinoma

In this work, paclitaxel-encapsulated polymeric depots were prepared and characterized as drug delivery system for cancer chemotherapy against hepatocellular carcinoma. Effects of different parameters, including drug-loading content, polymer concentration and depot weight on depot formation, percentage of sustained-release taxol and drug release profile were evaluated. Paclitaxel-loaded depots were successfully formed at the polymer concentration above 25% w/v. For all formulations, paclitaxel could be encapsulated with very high percentage of sustained-release taxol (>90%). The release rate of paclitaxel from depots could be controlled by the amount of drug-loading content, polymer concentration and depot weight. Cytotoxicity against liver cancer cell line, HepG2, was evaluated by medium extraction method. Paclitaxel releasing from depots showed cytotoxic effect against HepG2 at different incubation times, whereas blank depots exhibited no cytotoxicity.

A theranostic micelleplex co-delivering SN-38 and VEGF siRNA for colorectal cancer therapy

The development of an efficient colorectal cancer therapy is currently a public health priority. In the present work, we proposed a multifunctional theranostic micellar drug delivery system utilizing cationic PDMA-block-poly(ε-caprolactone) (PDMA-b-PCL) micelles as nanocarriers of SN-38 (7-ethyl-10-hydroxycamptothecin), ultra-small superparamagnetic iron oxide nanoparticles (USPIO), and small interfering RNA (siRNA) that targets human vascular endothelial growth factor (VEGF). The VEGF siRNA was conjugated to polyethylene glycol (PEG) (siRNA-PEG) before complexation with the micelles in order to improve the siRNA's stability and to prolong its retention time in the blood circulation. To further improve the in vivo biosafety, we prepared mixed micelles using mPEG-PCL together with PDMA-b-PCL copolymer. The SN-38/USPIO-loaded siRNA-PEG mixed micelleplexes passively targeted to tumor regions and synergistically facilitated VEGF silencing and chemotherapy, thus efficiently suppressing tumor growth via a multi-dose therapy regimen. Additionally, the SN-38/USPIO-loaded siRNA-PEG mixed micelleplexes acted as a negative magnetic resonance imaging (MRI) contrast agent in T2-weighted imaging, resulting in a powerful tool for the diagnosis and for tracking of the therapeutic outcomes. In summary, we established a theranostic micellar drug and gene delivery system that not only synergistically combined gene silencing and chemotherapy but also served as a negative MRI contrast agent, which reveal its potential as a novel colorectal cancer therapy.

Mucoadhesive nanogels by ionotropic crosslinking of chitosan-g-oligo(NiPAam) polymeric micelles as novel drug nanocarriers

AIM

To investigate a novel kind of mucoadhesive nanogel based on the supramolecular aggregation of chitosan-g-oligo(N-isopropylacrylamide) copolymers.

MATERIALS & METHODS

Copolymers were synthesized by the graft-free radical polymerization of N-isopropylacrylamide on chitosan. The aggregation was studied by dynamic light scattering and nanoparticle tracking analysis (NTA), the nanostructure by transmission electron microscopy(TEM)/cryo-TEM, the mucoadhesiveness in vitro with mucin and the cytocompatibility in Caco2 cells.

RESULTS

Copolymers (36-74% w/w N-isopropylacrylamide content) showed critical micellar concentration between 2.0 and 40.0 × 10(-3)% w/v and micelles were nanometric and positively charged. Physical stabilization was achieved with ionotropic crosslinking. TEM/cryo-TEM revealed multimicellar aggregates with good mucoadhesion and cytocompatibility properties. Micellar systems (1-10% w/v) increased the solubility of efavirenz up to 1249-fold.

CONCLUSION

Results support the potential of these nano-drug delivery systems for improved mucosal administration of hydrophobic drugs.

Therapeutic and scintigraphic applications of polymeric micelles: combination of chemotherapy and radiotherapy in hepatocellular carcinoma

This study evaluated a multifunctional micelle simultaneously loaded with doxorubicin (Dox) and labeled with radionuclide rhenium-188 ((188)Re) as a combined radiotherapy and chemotherapy treatment for hepatocellular carcinoma. We investigated the single photon emission computed tomography, biodistribution, antitumor efficacy, and pathology of (188)Re-Dox micelles in a murine orthotopic luciferase-transfected BNL tumor cells hepatocellular carcinoma model. The single photon emission computed tomography and computed tomography images showed high radioactivity in the liver and tumor, which was in agreement with the biodistribution measured by γ-counting. In vivo bioluminescence images showed the smallest size tumor (P<0.05) in mice treated with the combined micelles throughout the experimental period. In addition, the combined (188)Re-Dox micelles group had significantly longer survival compared with the control, (188)ReO4 alone (P<0.005), and Dox micelles alone (P<0.01) groups. Pathohistological analysis revealed that tumors treated with (188)Re-Dox micelles had more necrotic features and decreased cell proliferation. Therefore, (188)Re-Dox micelles may enable combined radiotherapy and chemotherapy to maximize the effectiveness of treatment for hepatocellular carcinoma.

Methoxy poly (ethylene glycol)-block-poly (glutamic acid)-graft-6-(2-nitroimidazole) hexyl amine nanoparticles for potential hypoxia-responsive delivery of doxorubicin

Tumor microenvironment-responsive nano drug delivery vehicles are gaining mounting attention in the field of biomedical sciences. The hypoxic response of the tumorous cells due to very low partial pressure of oxygen (some time less than 2.5 mm of Hg) in the tumor tissues makes hypoxia-responsive drug delivery system as the more appealing in cancer chemotherapy. Based on these considerations, we synthesized hypoxia-responsive polymeric materials methoxy poly (ethylene glycol)-block-poly (glutamic acid)-graft-6-(2-nitroimidazole) hexyl amine (mPEG-b-PLG-g-NID) by conjugation of the hydrophobic nitro imidazole derivative (NID)[6-(2-nitroimidazole) hexyl amine] with the pendant carboxylic group of poly (ethylene glycol)-block-poly (L-glutamic acid)(mPEG-b-PLG). The structure and degree of substitution were confirmed by proton NMR, FTIR, and UV-Vis spectroscopy. The degree of substitution was found to enhance with the increase in NID to polymer ratio. The hypoxia response of the material was evaluated by UV-Vis spectroscopy and zeta potential measurements. Doxorubicin was hydrophobically encapsulated in the micellar core of the hypoxia-responsive nanoparticles. The drug-loaded micelles showed faster release in hypoxic condition as compared to normoxic conditions. Moreover, the developed polymeric system was found non-toxic to MCF-7 cell line, thus suggesting its biocompatibility and suitability as drug delivery device.

Triple Negative Breast Cancer: Nanosolutions for a Big Challenge

Triple negative breast cancer (TNBC) is a particular immunopathological subtype of breast cancer that lacks expression of estrogen and progesterone receptors (ER/PR) and amplification of the human epidermal growth factor receptor 2 (HER2) gene. Characterized by aggressive and metastatic phenotypes and high rates of relapse, TNBC is the only breast cancer subgroup still lacking effective therapeutic options, thus presenting the worst prognosis. The development of targeted therapies, as well as early diagnosis methods, is vital to ensure an adequate and timely therapeutic intervention in patients with TNBC. This review intends to discuss potentially emerging approaches for the diagnosis and treatment of TNBC patients, with a special focus on nano-based solutions that actively target these particular tumors.

Polymeric Micelles: Recent Advancements in the Delivery of Anticancer Drugs

Nanotechnology, in health and medicine, extensively improves the safety and efficacy of different therapeutic agents, particularly the aspects related to drug delivery and targeting. Among various nano-carriers, polymer based macromolecular approaches have resulted in improved drug delivery for the diseases like cancers, diabetes, autoimmune disorders and many more. Polymeric micelles consisting of hydrophilic exterior and hydrophobic core have established a record of anticancer drug delivery from the laboratory to commercial reality. The nanometric size, tailor made functionality, multiple choices of polymeric micelle synthesis and stability are the unique properties, which have attracted scientists and researchers around the world to work upon in this opportunistic drug carrier. The capability of polymeric micelles as nano-carriers are nowhere less significant than nanoparticles, liposomes and other nanocarriers, as per as the commercial feasibility and presence is concerned. In fact polymeric micelles are among the most extensively studied delivery platforms for the effective treatment of different cancers as well as non-cancerous disorders. The present review highlights the sequential and recent developments in the design, synthesis, characterization and evaluation of polymeric micelles to achieve the effective anticancer drug delivery. The future possibilities and clinical outcome have also been discussed, briefly.

SN-38 active loading in poly(lactic-co-glycolic acid) nanoparticles and assessment of their anticancer properties on COLO-205 human colon adenocarcinoma cells

SN-38 is a highly effective drug against many cancers. The development of an optimal delivery system for SN-38 is extremely challenging due to its low solubility and labile lactone ring. Herein, SN-38 encapsulated in poly(D,L-lactide-co-glycolide) nanoparticles (NPs) is introduced to enhance its solubility, stability and cellular uptake. SN-38-loaded NPs prepared by spontaneous emulsification solvent diffusion (SESD) method had an average diameter of 310 nm, a zeta potential of -9.69 mV and a loading efficiency of 71%. They were able to protect the active lactone ring of SN-38 against inactivation under physiological condition. A colorectal adenocarcinoma cell line (COLO-205) was used to assess the NPs effects on cytotoxicity and cellular uptake. Result showed a significant decreased cell proliferation and cell apoptosis. These results suggest that these SN-38-loaded NPs can be an effective delivery system for the treatment of colon cancer and potentially for other types of cancers.

Polymeric Micelles: Recent Advancements in the Delivery of Anticancer Drugs

Nanotechnology, in health and medicine, extensively improves the safety and efficacy of different therapeutic agents, particularly the aspects related to drug delivery and targeting. Among various nano-carriers, polymer based macromolecular approaches have resulted in improved drug delivery for the diseases like cancers, diabetes, autoimmune disorders and many more. Polymeric micelles consisting of hydrophilic exterior and hydrophobic core have established a record of anticancer drug delivery from the laboratory to commercial reality. The nanometric size, tailor made functionality, multiple choices of polymeric micelle synthesis and stability are the unique properties, which have attracted scientists and researchers around the world to work upon in this opportunistic drug carrier. The capability of polymeric micelles as nano-carriers are nowhere less significant than nanoparticles, liposomes and other nanocarriers, as per as the commercial feasibility and presence is concerned. In fact polymeric micelles are among the most extensively studied delivery platforms for the effective treatment of different cancers as well as non-cancerous disorders. The present review highlights the sequential and recent developments in the design, synthesis, characterization and evaluation of polymeric micelles to achieve the effective anticancer drug delivery. The future possibilities and clinical outcome have also been discussed, briefly.