Complete regression of breast tumour with a single dose of docetaxel-entrapped core-cross-linked polymeric micelles

Translational considerations in nanomedicine: The oncology perspective

Nanoparticles can provide effective control of the release rate and tissue distribution of their drug payload, leading to major pharmacokinetic and pharmacodynamic changes vis-à-vis the conventional administration of free drugs. In the last two decades, we have witnessed major progress in the synthesis and characterization of engineered nanoparticles for imaging and treatment of cancers, resulting in the approval for clinical use of several products and in new and promising approaches. Despite these advances, clinical applications of nanoparticle-based therapeutic and imaging agents remain limited due to biological, immunological, and translational barriers. There is a need to make high impact advances toward translation. In this review, we address biological, toxicological, immunological, and translational aspects of nanomedicine and discuss approaches to move the field forward productively. Overcoming these barriers may dramatically improve the development potential and role of nanomedicines in the oncology field and help meet the high expectations.

Smart cancer nanomedicine

Nanomedicines are extensively employed in cancer therapy. We here propose four strategic directions to improve nanomedicine translation and exploitation. (1) Patient stratification has become common practice in oncology drug development. Accordingly, probes and protocols for patient stratification are urgently needed in cancer nanomedicine, to identify individuals suitable for inclusion in clinical trials. (2) Rational drug selection is crucial for clinical and commercial success. Opportunistic choices based on drug availability should be replaced by investments in modular (pro)drug and nanocarrier design. (3) Combination therapies are the mainstay of clinical cancer care. Nanomedicines synergize with pharmacological and physical co-treatments, and should be increasingly integrated in multimodal combination therapy regimens. (4) Immunotherapy is revolutionizing the treatment of cancer. Nanomedicines can modulate the behaviour of myeloid and lymphoid cells, thereby empowering anticancer immunity and immunotherapy efficacy. Alone and especially together, these four directions will fuel and foster the development of successful cancer nanomedicine therapies.

Functionalized docetaxel-loaded lipid-based-nanosuspensions to enhance antitumor efficacy in vivo

Purpose: To further enhance the antitumor efficacy through targeted delivery, DTX loaded lipid-based-nanosuspensions (DTX-LNS) were prepared and functionalized by PEGylation or NGR modification to develop DSPE-PEG₂₀₀₀ modified DTX-LNS (P-DTX-LNS) or DSPE-PEG₂₀₀₀-NGR modified DTX-LNS (N-DTX-LNS), respectively.

Methods: Based on our previous work, functionalized DTX-LNS including P-DTX-LNS and N-DTX-LNS were prepared using thin-film hydration, and then characterized. Release behavior, stability in vitro, cytotoxicity and cellular uptake of functionalized LNS were observed. To demonstrate tumor targeting efficiency of functionalized DTX-LNS, in vivo real-time and ex vivo imaging study were conducted. Furthermore, therapeutic efficacy in vivo was evaluated in an H22-bearing mice model.

Results: Functionalized DTX-LNS 100–110 nm in diameter were successfully prepared and exhibited good stability under various conditions. In vitro release studies demonstrated that DTX was released from functionalized DTX-LNS steadily and reached approximately 95% at 48 hrs. Functionalized DTX-LNS showed dose-dependent cytotoxicity and time-dependent internalization in human hepatocellular liver carcinoma cells (HepG2) cells. In vivo real-time and ex vivo imaging results indicated that tumor targeting efficiencies of P-DiR-LNS and N-DiR-LNS were 29.9% and 34.3%, respectively. Moreover, evaluations of in vivo antitumor efficacy indicated that functionalized DTX-LNS effectively inhibited tumor growth with low toxicity.

Conclusion: The functionalized LNS exhibited suitable particle size, nearly spherical structure, enough drug loading and great potentials for large-scale production. The results in vitro and in vivo demonstrated that functionalized LNS could realize tumor targeting and antitumor efficacy. Consequently, functionalized DTX-LNS could be expected to be used for tumor targeting therapy.

Polymer-drug conjugate therapeutics: advances, insights and prospects

Polymer-drug conjugates have long been a mainstay of the drug delivery field, with several conjugates successfully translated into clinical practice. The conjugation of therapeutic agents to polymeric carriers, such as polyethylene glycol, offers several advantages, including improved drug solubilization, prolonged circulation, reduced immunogenicity, controlled release and enhanced safety. In this Review, we discuss the rational design, physicochemical characteristics and recent advances in the development of different classes of polymer-drug conjugates, including polymer-protein and polymer-small-molecule drug conjugates, dendrimers, polymer nanoparticles and multifunctional systems. Current obstacles hampering the clinical translation of polymer-drug conjugate therapeutics and future prospects are also presented.

Current advances in development of new docetaxel formulations

INTRODUCTION

Docetaxel (DTX) is one of the most important chemotherapeutic agents and has been widely used for treatment of various types of cancers. However, the clinical chemotherapy of DTX gives many undesirable side effects due to the usage of organic solvent in the injection and its low selectivity for tumor cells. With the evolution of pharmaceutical technologies, great efforts have been paid to develop new DTX formulations to overcome these problems.

AREAS COVERED

This review provided an overview of the preparation and activities of new DTX formulations, which were classified by administration methods, including injection, oral, transdermal and rectal administration. Besides, up to date information of the clinical status of new DTX formulations was summarized. We also discussed the challenges and perspectives of the future development of DTX formulations.

EXPERT OPINION

There have been numerous studies on new DTX-based formulations in recent years, and many of them exhibited significantly enhanced anti-tumor and targeting activity compared with DTX in preclinical studies. However, only a few entered clinical trials, and none has been approved into market. The clinical translation of experimental drug faces many hurdles, including the limited knowledge of nanomedicine and oncology, safety issues, controllable and reproducible production.

A new method for the determination of total and released docetaxel from docetaxel-entrapped core-crosslinked polymeric micelles (CriPec®) by LC-MS/MS and its clinical application in plasma and tissues in patients with various tumours

A sensitive, high-performance liquid chromatographic method was developed and validated, for determination of docetaxel from docetaxel-entrapped core-crosslinked polymeric micelles (CriPec®) in human potassium EDTA plasma and released docetaxel to support the clinical development of Cripec® docetaxel. CriPec® docetaxel is a novel formulation of docetaxel - covalently conjugated via a linker agent in a nanoparticle. The analytical characterization of CriPec® docetaxel comprises determination of both released and total docetaxel, the first being the already deconjugated docetaxel, whereas total is representative of all docetaxel (deconjugated as well as CriPec® nanoparticle conjugated material). Total docetaxel was determined by incubation of human plasma with 0.5 M ammonium acetate buffer pH 7.4 for 3-days at 37 °C. Hereafter, a liquid-liquid extraction with 1-chlorobutane was performed using paclitaxel as internal standard. Released docetaxel from CriPec® docetaxel nanoparticles was determined in human plasma stabilized with 5 M ammonium acetate, pH 5.0. Hereafter, a liquid-liquid extraction with 1-chlorobutane was performed using docetaxel-d5 in acetonitrile as internal standard. Released docetaxel and its internal standard were eluted. The validated ranges for total docetaxel were 2,000-100,000 ng/mL for the high concentrations and 2-500 ng/mL for the low concentrations and 0.250-100 ng/mL for released docetaxel. In conclusion the newly developed assay met the required standards for validation and was applied successfully to support pharmacokinetic analysis in both serum and tissue in patients treated with Cripec®.

Surface design and preparation of multi-functional magnetic nanoparticles for cancer cell targeting, therapy, and imaging

Recently, theranostic candidates based on superparamagnetic iron oxide nanoparticles (SPIONs) providing the combination of therapy and diagnosis have become one of the most promising system in cancer research. However, poor stability, premature drug release, lack of specific tumor cell targeting, and complicated multi-step synthesis processes still hinder them for potential clinical applications. In this research, the multi-functional magnetic nanoparticles (MNPs-DOX) were prepared via a simple assembly process for targeted delivery of doxorubicin (DOX) and enhanced magnetic resonance (MR) imaging detection. Firstly, the multi-functional copolymer coating, polyamidoamine (PAMAM), was designed and synthesized by Michael addition reaction, where N,N-bis(acryloyl)cystamine served as backbone linker, and DOX, dopamine (DA), and polyethylene glycol (PEG) acted as comonomers. The PAMAM was then directly assembled to the surface of SPIONs by the ligand exchange reaction with SPIONs forming the MNPs-DOX. The hydrophilic PEG moieties provide the nanoparticles with colloidal stability and good-dispersity in aqueous solution. Comparing with the quick release of free DOX, the drug release behavior of MNPs-DOX exhibited a sustained drug release. Because the chemical cleavage of disulfide in the polymer backbone, a high cumulative drug release up to 60% in GSH within 48 h was observed, rather than only 26% in PBS (pH 7.4) without GSH. The MR imaging detection experiment showed that the MNPs-DOX had an enhanced T₂ relaxivity of 126 mM⁻¹ S⁻¹ for MR imaging. The results of the cytotoxicity assays showed a remarkable killing effect of cancer cells by MNPs-DOX due to the FA tumor-targeting ligand, comparing with non-targeted drug molecules. All the results showed that the as prepared multi-functional magnetic nanoparticles may serve as a promising theranostic candidate for targeted anticancer drug delivery and efficient detection through MR imaging in medical application.

Multi-functional magnetic nanoparticles for targeted anticancer drug delivery and efficient MR imaging detection in theranostics.

Design of theranostic nanomedicine (II): synthesis and physicochemical properties of a biocompatible polyphosphazene-docetaxel conjugate

To prepare an efficient theranostic polyphosphazene–docetaxel (DTX) conjugate, a new drug delivery system was designed by grafting a multifunctional lysine ethylester (LysOEt) as a spacer group along with methoxy poly(ethylene glycol) (MPEG) to the polyphosphazene backbone ([NP]_n), and then DTX was conjugated to the carrier polymer using acid-cleavable cis-aconitic acid (AA) as a linker. The resultant polyphosphazene–DTX conjugate, formulated as [NP(MPEG550)₃(Lys-OEt)(AA)(DTX)]_n and named “Polytaxel”, exhibited high water solubility and stability by forming stable polymeric micelles as shown in its transmission electron microscopy image and dynamic light scattering measurements. Another important aspect of Polytaxel is that it can easily be labeled with various imaging agents using the lysine amino group, enabling studies on various aspects, such as its organ distribution, tumor-targeting properties, pharmacokinetics, toxicity, and excretion. The pharmacokinetics of Polytaxel was remarkably improved, with prolonged elimination half-life and enhanced area under the curve. Ex vivo imaging study of cyanine dye-labeled Polytaxel showed that intravenously injected Polytaxel is long circulating in the blood stream and selectively accumulates in tumor tissues. Polytaxel distributed in other organs was cleared from all major organs at ~6 weeks after injection. The in vitro study of DTX release from the carrier polymer showed that >95% of conjugated DTX was released at pH 5.4 over a period of 7 days. Xenograft trials of Polytaxel using nude mice against the human gastric tumor cell line MKN-28 showed complete tumor regression, with low systemic toxicity. Polytaxel is currently in preclinical study.

EGFR and CD44 Dual-Targeted Multifunctional Hyaluronic Acid Nanogels Boost Protein Delivery to Ovarian and Breast Cancers In Vitro and In Vivo

Protein drugs with intracellular targets like Granzyme B (GrB) have demonstrated great proliferative inhibition activity in cancer cells. Their clinical translation, however, relies on the development of safe, efficient, and selective protein-delivery vehicles. Here, we report that epidermal growth factor receptor (EGFR) and CD44 dual-targeted multifunctional hyaluronic acid nanogels (EGFR/CD44-NGs) boost protein delivery to ovarian and breast cancers in vitro and in vivo. EGFR/CD44-NGs obtained via nanoprecipitation and photoclick chemistry from hyaluronic acid derivatives with tetrazole, GE11 peptide/tetrazole, and cystamine methacrylate groups had nearly quantitative loading of therapeutic proteins like cytochrome C (CC) and GrB, a small size of ca. 165 nm, excellent stability in serum, and fast protein release under a reductive condition. Flow cytometry assays showed that EGFR/CD44-NGs exhibited over 6-fold better uptake in CD44 and EGFR-positive SKOV-3 ovarian cancer cells than CD44-NGs. In accordance, GrB-loaded EGFR/CD44-NGs (GrB-EGFR/CD44-NGs) displayed enhanced caspase activity and growth inhibition in SKOV-3 cells as compared to GrB-loaded CD44-NGs (GrB-CD44-NGs) control. Intriguingly, the therapeutic studies in SKOV-3 human ovarian carcinoma and MDA-MB-231 human breast tumor xenografted in nude mice revealed that GrB-EGFR/CD44-NGs at a low dose of 3.85 nmol GrB equiv/kg induced nearly complete growth suppression of both tumors, which was obviously more effective than GrB-CD44-NGs, without causing any adverse effects. EGFR and CD44 dual-targeted multifunctional hyaluronic acid nanogels have appeared as a safe and efficacious platform for cancer protein therapy.

Rational Design of Cancer Nanomedicine: Nanoproperty Integration and Synchronization

Current cancer nanomedicines can only mitigate adverse effects but fail to enhance therapeutic efficacies of anticancer drugs. Rational design of next-generation cancer nanomedicines should aim to enhance their therapeutic efficacies. Taking this into account, this review first analyzes the typical cancer-drug-delivery process of an intravenously administered nanomedicine and concludes that the delivery involves a five-step CAPIR cascade and that high efficiency at every step is critical to guarantee high overall therapeutic efficiency. Further analysis shows that the nanoproperties needed in each step for a nanomedicine to maximize its efficiency are different and even opposing in different steps, particularly what the authors call the PEG, surface-charge, size and stability dilemmas. To resolve those dilemmas in order to integrate all needed nanoproperties into one nanomedicine, stability, surface and size nanoproperty transitions (3S transitions for short) are proposed and the reported strategies to realize these transitions are comprehensively summarized. Examples of nanomedicines capable of the 3S transitions are discussed, as are future research directions to design high-performance cancer nanomedicines and their clinical translations.

Improved Bioavailability and Antitumor Effect of Docetaxel by TPGS Modified Proniosomes: In Vitro and In Vivo Evaluations

A novel oral drug delivery system, TPGS modified docetaxel proniosomes (DTX-TPGS-PNs), was designed to enhance the oral bioavailability and antitumor efficiency of the poorly water-soluble drug docetaxel. DTX-TPGS-PN niosomes were 93 ± 6.5 nm in size, -18.53 ± 1.65 mV in zeta potential and exhibited spherical morphology, with an encapsulation efficiency of 97.31 ± 0.60%. The system showed sustained release in both simulated gastric and intestinal fluid. The results of caco-2 monolayer, everted gut sac model and improved single-pass intestinal perfusion model transport studies showed that DTX-TPGS-PN niosomes could significantly improve the absorption of DTX. The pharmacokinetics study suggested the absolute bioavailability of DTX-TPGS-PN niosomes were 7.3 times that of DTX solution. In addition, a higher antitumor efficacy than DTX solution was demonstrated in MCF-7 and MDA-MB-231 cells in vitro and in MCF-7 tumor-bearing mice model in vivo. Our results demonstrated DTX-TPGS-PN is promising in enhancing the bioavailability and efficiency of poorly water-soluble drug DTX, and the potential of proniosomes as stable precursors for oral drug delivery.

Robust, Responsive, and Targeted PLGA Anticancer Nanomedicines by Combination of Reductively Cleavable Surfactant and Covalent Hyaluronic Acid Coating

PLGA-based nanomedicines have enormous potential for targeted cancer therapy. To boost their stability, targetability, and intracellular drug release, here we developed novel multifunctional PLGA anticancer nanomedicines by combining a reductively cleavable surfactant (RCS), vitamin E-SS-oligo(methyl diglycol l-glutamate), with covalent hyaluronic acid (HA) coating. Reduction-sensitive HA-coated PLGA nanoparticles (rHPNPs) were obtained with small sizes of 55-61 nm and ζ potentials of -26.7 to -28.8 mV at 18.4-40.3 wt % RSC. rHPNPs were stable against dilution and 10% FBS while destabilized under reductive condition. The release studies revealed significantly accelerated docetaxel (DTX) release in the presence of 10 mM glutathione. DTX-rHPNPs exhibited potent and specific antitumor effect to CD44 + A549 lung cancer cells (IC₅₀ = 0.52 μg DTX equiv/mL). The in vivo studies demonstrated that DTX-rHPNPs had an extended circulation time and greatly enhanced tolerance in mice. Strikingly, DTX-rHPNPs completely inhibited growth of orthotopic human A549-Luc lung tumor in mice, leading to a significantly improved survival rate and reduced adverse effect as compared to free DTX. This study highlights that advanced nanomedicines can be rationally designed by combining functional surfactants and surface coating.

TNF-α sensitizes chemotherapy and radiotherapy against breast cancer cells

Purpose

Despite new developments in cancer therapy, chemotherapy and radiotherapy remain the cornerstone of breast cancer treatment. Therefore, finding ways to reduce the toxicity and increase sensitivity is particularly important. Tumor necrosis factor alpha (TNF-α) exerts multiple functions in cell proliferation, differentiation and apoptosis. In the present study, we investigated whether TNF-α could enhance the effect of chemotherapy and radiotherapy against breast cancer cells.

Methods

Cell growth was determined by MTT assay in vitro, and by using nude mouse tumor xenograft model in vivo. Cell cycle and apoptosis/necrosis were evaluated by flow cytometry. DNA damage was visualized by phospho-Histone H2A.X staining. mRNA expression was assessed by using real-time PCR. Protein expression was tested by Western blot assay.

Results

TNF-α strengthened the cytotoxicity of docetaxel, 5-FU and cisplatin against breast cancer cells both in vitro and in vivo. TNF-α activated NF-κB pathway and dependently up-regulated expressions of CyclinD1, CyclinD2, CyclinE, CDK2, CDK4 and CDK6, the key regulators participating in G1→S phase transition. As a result, TNF-α drove cells out of quiescent G0/G1 phase, entering vulnerable proliferating phases. Treatment of TNF-α brought more DNA damage after Cs¹³⁷-irradiation and strengthened G2/M and S phase cell cycle arrest induced by docetaxel and cisplatin respectively. Moreover, the up-regulation of RIP3 (a necroptosis marker) by 5-FU, and the activation of RIP3 by TNF-α, synergistically triggered necroptosis (programmed necrosis). Knockdown of RIP3 attenuated the synergetic effect of TNF-α and 5-FU.

Conclusion

TNF-α presented radiotherapy- and chemotherapy-sensitizing effects against breast cancer cells.

Physico-Chemical Strategies to Enhance Stability and Drug Retention of Polymeric Micelles for Tumor-Targeted Drug Delivery

Polymeric micelles (PM) have been extensively used for tumor-targeted delivery of hydrophobic anti-cancer drugs. The lipophilic core of PM is naturally suitable for loading hydrophobic drugs and the hydrophilic shell endows them with colloidal stability and stealth properties. Decades of research on PM have resulted in tremendous numbers of PM-forming amphiphilic polymers, and approximately a dozen micellar nanomedicines have entered the clinic. The first generation of PM can be considered solubilizers of hydrophobic drugs, with short circulation times resulting from poor micelle stability and unstable drug entrapment. To more optimally exploit the potential of PM for targeted drug delivery, several physical (e.g., π-π stacking, stereocomplexation, hydrogen bonding, host-guest complexation, and coordination interaction) and chemical (e.g., free radical polymerization, click chemistry, disulfide and hydrazone bonding) strategies have been developed to improve micelle stability and drug retention. In this review, the most promising physico-chemical approaches to enhance micelle stability and drug retention are described, and how these strategies have resulted in systems with promising therapeutic efficacy in animal models, paving the way for clinical translation, is summarized.

SPIONs/DOX loaded polymer nanoparticles for MRI detection and efficient cell targeting drug delivery

Reducible polydopamine coated magnetic nanoparticles (SPIONs@PDA) for both magnetic resonance imaging (MRI) detection and cell targeting drug delivery.

Intelligent polymeric micelles: development and application as drug delivery for docetaxel

Recent years, docetaxel (DTX)-loaded intelligent polymeric micelles have been regarded as a promising vehicle for DTX for the reason that compared with conventional DTX-loaded micelles, DTX-loaded intelligent micelles not only preserve the basic functions of micelles such as DTX solubilization, enhanced accumulation in tumor tissue, and improved bioavailability and biocompatibility of DTX, but also possess other new properties, for instance, tumor-specific DTX delivery and series of responses to endogenous or exogenous stimulations. In this paper, basic theories and action mechanism of intelligent polymeric micelles are discussed in detail, especially the related theories of DTX-loaded stimuli-responsive micelles. The relevant examples of stimuli-responsive DTX-loaded micelles are also provided in this paper to sufficiently illustrate the advantages of relevant technology for the clinical application of anticancer drug, especially for the medical application of DTX.

Clinical advances of nanocarrier-based cancer therapy and diagnostics

INTRODUCTION

Cancer is a leading cause of death worldwide and efficient new strategies are urgently needed to combat its high mortality and morbidity statistics. Fortunately, over the years, nanotechnology has evolved as a frontrunner in the areas of imaging, diagnostics and therapy, giving the possibility of monitoring, evaluating and individualizing cancer treatments in real-time. Areas covered: Polymer-based nanocarriers have been extensively studied to maximize cancer treatment efficacy and minimize the adverse effects of standard therapeutics. Regarding diagnosis, nanomaterials like quantum dots, iron oxide nanoparticles or gold nanoparticles have been developed to provide rapid, sensitive detection of cancer and, therefore, facilitate early treatment and monitoring of the disease. Therefore, multifunctional nanosystems with both imaging and therapy functionalities bring us a step closer to delivering precision/personalized medicine in the cancer setting. Expert opinion: There are multiple barriers for these new nanosystems to enter the clinic, but it is expected that in the near future, nanocarriers, together with new 'targeted drugs', could replace our current treatments and cancer could become a nonfatal disease with good recovery rates. Joint efforts between scientists, clinicians, the pharmaceutical industry and legislative bodies are needed to bring to fruition the application of nanosystems in the clinical management of cancer.

Folic acid functionalized long-circulating co-encapsulated docetaxel and curcumin solid lipid nanoparticles: In vitro evaluation, pharmacokinetic and biodistribution in rats

The purpose of this study was to develop folic acid functionalized long-circulating co-encapsulated docetaxel (DTX) and curcumin (CRM) solid lipid nanoparticles (F-DC-SLN) to improve the pharmacokinetic and efficacy of DTX therapy. F-DC-SLN was prepared by hot melt-emulsification method and optimized by face centered-central composite design (FC-CCD). The SLN was characterized in terms of size and size distribution, drug entrapment efficiency and release profile. The cytotoxicity and cell uptake of the SLN formulations were evaluated in MCF-7 and MDA-MB-231 cell lines. The in vivo pharmacokinetic and biodistribution were studied in Wistar rats. F-DC-SLN exhibited 247.5 ± 3.40 nm particle size with 73.88 ± 1.08% entrapment efficiency and zeta potential of 14.53 ± 3.6 mV. Transmission electron microscopy (TEM) revealed spherical morphology of the SLN. Fluorescence microscopy confirmed the targeting efficacy of F-DC-SLN in MCF-7 cells. F-DC-SLN exhibited a significant increase in area under the curve (594.21 ± 64.34 versus 39.05 ± 7.41 μg/mL h) and mean residence time (31.14 ± 19.94 versus 7.24 ± 4.51 h) in comparison to Taxotere®. In addition, decreased DTX accumulation from F-DC-SLN in the heart and kidney in comparison to Taxotere may avoid to toxicity these vital organs. In conclusion, the F-DC-SLN improved the efficacy and pharmacokinetic profile of DTX exhibiting enhanced potential in optimizing breast cancer therapy.

Polymeric complex micelles based on the double-hydrazone linkage and dual drug-loading strategy for pH-sensitive docetaxel delivery

Complex micelles, which integrated double-hydrazone linkage and dual drug-loading patterns, were constructed for the first time.

Chain length effect on drug delivery of chrysin modified mPEG–PCL micelles

The chain length effect of chrysin modified mPEG–PCL micelles with exciting doxorubicin loading capacity on drug delivery was investigated.