A two-component drug delivery system using Her-2-targeting thermosensitive liposomes

Functionalized liposomes for targeted breast cancer drug delivery

Despite the exceptional progress in breast cancer pathogenesis, prognosis, diagnosis, and treatment strategies, it remains a prominent cause of female mortality worldwide. Additionally, although chemotherapies are effective, they are associated with critical limitations, most notably their lack of specificity resulting in systemic toxicity and the eventual development of multi-drug resistance (MDR) cancer cells. Liposomes have proven to be an invaluable drug delivery system but of the multitudes of liposomal systems developed every year only a few have been approved for clinical use, none of which employ active targeting. In this review, we summarize the most recent strategies in development for actively targeted liposomal drug delivery systems for surface, transmembrane and internal cell receptors, enzymes, direct cell targeting and dual-targeting of breast cancer and breast cancer-associated cells, e.g., cancer stem cells, cells associated with the tumor microenvironment, etc.

Towards the use of localised delivery strategies to counteract cancer therapy-induced cardiotoxicities

Cancer therapies have significantly improved cancer survival; however, these therapies can often result in undesired side effects to off target organs. Cardiac disease ranging from mild hypertension to heart failure can occur as a result of cancer therapies. This can warrant the discontinuation of cancer treatment in patients which can be detrimental, especially when the treatment is effective. There is an urgent need to mitigate cardiac disease that occurs as a result of cancer therapy. Delivery strategies such as the use of nanoparticles, hydrogels, and medical devices can be used to localise the treatment to the tumour and prevent off target side effects. This review summarises the advancements in localised delivery of anti-cancer therapies to tumours. It also examines the localised delivery of cardioprotectants to the heart for patients with systemic disease such as leukaemia where localised tumour delivery might not be an option.

Thermosensitive Liposomes for Image-Guided Drug Delivery

Liposomes have been employed as cancer therapy clinically since the 1990s, with the primary benefit of reduced toxicity but no appreciable efficacy improvement. Thermosensitive liposomes (TSLs) are specifically formulated such that they release the encapsulated drug when exposed to hyperthermic temperatures in the fever range (~40-42°C) and have been investigated as cancer therapy for several decades, with first clinical trials initiated in the last decade. Combined with localized hyperthermia, TSLs allow precise drug delivery to a targeted region. Typically, the targeted tissue is exposed to localized hyperthermia facilitated by an image-guided hyperthermia device. Thus, TSLs enable image-guided drug delivery where drug is delivered to a tissue region identified by medical imaging. Recent TSL formulations are based on the more recent paradigm of intravascular triggered release, where drug is released rapidly (within seconds) while TSLs pass through the vasculature of the heated tissue region. The drug released within the blood then extravasates and is taken up by cancer cells. These TSLs enable up to 20-30 times higher tumor drug uptake compared to infusion of unencapsulated drug, and the dose locally delivered to the heated region can be modulated based on heating duration. This chapter reviews various TSL formulations, the different anticancer agents that have been encapsulated, as well as targeted cancer types. Further, the various hyperthermia devices that have been used for image-guided hyperthermia are reviewed, focusing on those that have been employed in human patients.

Trastuzumab-targeted gene delivery to Her2-overexpressing breast cancer cells

We describe a novel gene delivery system that specifically targets human epidermal growth factor receptor 2 (Her2)-overexpressing breast cancer cells. The targeting complexes consist of a PEGylated polylysine core that is bound to DNA molecules coding for either green fluorescent protein or shrimp luciferase. The complex is disulfide linked to the monoclonal antibody trastuzumab and to a pore-forming protein, Listeriolysin O (LLO). Trastuzumab is responsible for specific targeting of Her2 receptors and uptake of the gene delivery complex into endosomes of recipient cells, whereas LLO ensures that the DNA molecules are capable of transit from the endosomes into the cytoplasm. Omission of either trastuzumab or LLO from the nanocomplexes results in minimal gene product in targeted cells. Treatment of isogeneic MCF7 and MCF7/Her18 cell lines, differing only in number of Her2 receptors, with the complete gene delivery system results in a 30-fold greater expression of luciferase activity in the Her2-overexpressing MCF7/Her18 cells. Our nanocomplexes are small (150–250 nm), stable to storage, nontoxic and generic in make-up such that any plasmid DNA or antibody specific for cell-surface receptors can be coupled to the PEGylated polylysine core.

Monoclonal antibody-targeted, temperature-sensitive liposomes: in vivo tumor chemotherapeutics in combination with mild hyperthermia

The development of actively targeted, responsive delivery vectors holds great promise for cancer therapy. Here, we investigated whether enhanced therapeutic activity of temperature sensitive liposomes (TSL) could be obtained by mild hyperthermia-triggered release of the chemotherapeutic drug doxorubicin (DOX) after hCTMO1 monoclonal antibody (anti-MUC-1) binding and uptake into cancer cells. We showed that traditional TSL (TTSL) liposome systems maintained their physicochemical and thermal properties after conjugation to hCTMO1 full IgG. Receptor-mediated cellular uptake and cytotoxic efficacy of antibody-targeted TTSL (TTSL-Ab) were investigated using 2D and 3D cell culture models. Significant enhancement in cellular uptake and cytotoxic activity after 1h of heating at 42 °C was observed for TTSL-Ab compared to non-targeted liposomes in MUC-1 over-expressing breast cancer cells (MDA-MB-435). Tissue distribution and in vivo therapeutic activity were studied using different heating protocols to explore the effect of mild hyperthermia on the tumor accumulation of targeted TTSL and their therapeutic effect. Application of local, mild hyperthermia (42°C) significantly increased the tumor accumulation of targeted TSL compared to non-targeted liposomes, associated with a moderate improvement in therapeutic activity and survival.

Thermosensitive liposomal drug delivery systems: state of the art review

Thermosensitive liposomes are a promising tool for external targeting of drugs to solid tumors when used in combination with local hyperthermia or high intensity focused ultrasound. In vivo results have demonstrated strong evidence that external targeting is superior over passive targeting achieved by highly stable long-circulating drug formulations like PEGylated liposomal doxorubicin. Up to March 2014, the Web of Science listed 371 original papers in this field, with 45 in 2013 alone. Several formulations have been developed since 1978, with lysolipid-containing, low temperature-sensitive liposomes currently under clinical investigation. This review summarizes the historical development and effects of particular phospholipids and surfactants on the biophysical properties and in vivo efficacy of thermosensitive liposome formulations. Further, treatment strategies for solid tumors are discussed. Here we focus on temperature-triggered intravascular and interstitial drug release. Drug delivery guided by magnetic resonance imaging further adds the possibility of performing online monitoring of a heating focus to calculate locally released drug concentrations and to externally control drug release by steering the heating volume and power. The combination of external targeting with thermosensitive liposomes and magnetic resonance-guided drug delivery will be the unique characteristic of this nanotechnology approach in medicine.

Thermosensitive liposomes with higher phase transition temperature for targeted drug delivery to tumor

Thermosensitive liposomes (TSL) in combination with local hyperthermia (HT) represent a promising tool for tumor specific drug delivery. The objective of the study was to investigate the influence of phase transition temperature (Tm) on the properties of TSL. High temperature triggered TSL (HTSL), low temperature triggered TSL (LTSL) and non-TSL (NTSL) were prepared and temperature sensitive release properties were extensively compared in different media. Mouse plasma was determined to have similar effect on the release profiles compared to human plasma, in which complete release were obtained at 38 °C and 40 °C for LTSL and HTSL, respectively. The temperature at which complete release achieved was found to be obviously lower than Tm. Brucine, an antitumor alkaloid, was encapsulated into different TSLs. After HT treatment, the viabilities of SMMC 7721 cells were determined to be 21.3±3.8% and 16.8±3.3% for 127 μM brucine LTSL and HTSL, respectively. Treating the tumor-bearing mice with LTSL, HTSL and NTSL led to significantly increased brucine uptake in the heated tumor site compared to the brucine solution group by 2.30, 3.80 and 2.26-fold, respectively. The results of this study suggested that Tm of TSL should be increased to obtain improved drug delivery efficiency to tumor.

Perspectives of breast cancer thermotherapies

In this article, the use of different types of thermotherapies to treat breast cancer is reviewed. While hyperthermia is most commonly used as an adjuvant in combination with radiotherapy, chemotherapy, targeted therapy or cryotherapy to enhance the therapeutic effect of these therapies, thermoablation is usually carried out alone to eradicate small breast tumors. A recently developed thermotherapy, called magnetic hyperthermia, which involves localized heating of nanoparticles under the application of an alternating magnetic field, is also presented. The advantages and drawbacks of these different thermotherapies are highlighted.

Molecular characterization of duck enteritis virus CHv strain UL49.5 protein and its colocalization with glycoprotein M

The UL49.5 gene of most herpesviruses is conserved and encodes glycoprotein N. However, the UL49.5 protein of duck enteritis virus (DEV) (pUL49.5) has not been reported. In the current study, the DEV pUL49.5 gene was first subjected to molecular characterization. To verify the predicted intracellular localization of gene expression, the recombinant plasmid pEGFP-C1/pUL49.5 was constructed and used to transfect duck embryo fibroblasts. Next, the recombinant plasmid pDsRed1-N1/glycoprotein M (gM) was produced and used for co-transfection with the pEGFP-C1/pUL49.5 plasmid to determine whether DEV pUL49.5 and gM (a conserved protein in herpesviruses) colocalize. DEV pUL49.5 was thought to be an envelope glycoprotein with a signal peptide and two transmembrane domains. This protein was also predicted to localize in the cytoplasm and endoplasmic reticulum with a probability of 66.7%. Images taken by a fluorescence microscope at different time points revealed that the DEV pUL49.5 and gM proteins were both expressed in the cytoplasm. Overlap of the two different fluorescence signals appeared 12 h after transfection and continued to persist until the end of the experiment. These data indicate a possible interaction between DEV pUL49.5 and gM.

Targeted thermosensitive liposomes: an attractive novel approach for increased drug delivery to solid tumors

INTRODUCTION

Currently available chemotherapy is hampered by a lack in tumor specificity and resulting toxicity. Small and long-circulating liposomes can preferentially deliver chemotherapeutic drugs to tumors upon extravasation from tumor vasculature. Although clinically used liposomal formulations demonstrated significant reduction in toxicity, enhancement of therapeutic activity has not fully met expectations.

AREAS COVERED

Low drug bioavailability from liposomal formulations and limited tumor accumulation remain major challenges to further improve therapeutic activity of liposomal chemotherapy. The aim of this review is to highlight strategies addressing these challenges. A first strategy uses hyperthermia and thermosensitive liposomes to improve tumor accumulation and trigger liposomal drug bioavailability. Image-guidance can aid online monitoring of heat and drug delivery and further personalize the treatment. A second strategy involves tumor-specific targeting to enhance drug delivery specificity and drug internalization. In addition, we review the potential of combinations of the two in one targeted thermosensitive-triggered drug delivery system.

EXPERT OPINION

Heat-triggered drug delivery using thermosensitive liposomes as well as the use of tumor vasculature or tumor cell-targeted liposomes are both promising strategies to improve liposomal chemotherapy. Preclinical evidence has been encouraging and both strategies are currently undergoing clinical evaluation. A combination of both strategies rendering targeted thermosensitive liposomes (TTSL) may appear as a new and attractive approach promoting tumor drug delivery.

Pre-targeting and direct immunotargeting of liposomal drug carriers to ovarian carcinoma

Background

Epidermal growth factor receptor (EGFR) is overexpressed in many solid tumor types, such as ovarian carcinoma. Immunoliposome based drug targeting has shown promising results in drug delivery to the tumors. However, the ratio of tumor-to-normal tissue concentrations should be increased to minimize the adverse effects of cytostatic drugs.

Methodology/Principal Findings

We studied the EGFR-targeted doxorubicin immunoliposomes using pre-targeting and local intraperitoneal (i.p.) administration of the liposomes. This approach was used to increase drug delivery to tumors as compared to direct intravenous (i.v.) administration of liposomes. EGFR antibodies were attached on the surface of PEG coated liposomes using biotin-neutravidin binding. Receptor mediated cellular uptake and cytotoxic efficacy of EGFR-targeted liposomes were investigated in human ovarian adenocarcinoma (SKOV-3 and SKOV3.ip1) cells. In vivo distribution of the liposomes in mice was explored using direct and pre-targeting approaches and SPECT/CT imaging. Targeted liposomes showed efficient and specific receptor-mediated binding to ovarian carcinoma cells in vitro, but the difference in cytotoxicity between targeted and non-targeted liposomes remained small. The relatively low cytotoxic efficacy is probably due to insufficient doxorubicin release from the liposomes rather than lack of target binding. Tumor uptake of targeted liposomes in vivo was comparable to that of non-targeted liposomes after both direct and pre-targeting administration. For both EGFR-targeted and non-targeted liposomes, the i.p. administration increased liposome accumulation to the tumors compared to i.v. injections.

Conclusions/Significance

Intraperitoneal administration of liposomes may be a beneficial approach to treat the tumors in the abdominal cavity. The i.p. pre-targeting method warrants further studies as a potential approach in cancer therapy.

Multimodality treatment of cancer with herceptin conjugated, thermomagnetic iron oxides and docetaxel loaded nanoparticles of biodegradable polymers

We developed a system of nanoparticles of poly(lactide)-d-α-tocopheryl polyethylene glycol succinate (PLA-TPGS) and carboxyl group-terminated TPGS (TPGS-COOH) copolymer blend for multimodality treatment of cancer, which formulated docetaxel for chemotherapy, herceptin for biotherapy and targeting, and iron oxides (IOs) for hyperthermia therapy, which are denoted as MMNPs. It is demonstrated that the MMNPs achieved a significantly higher therapeutic effects than the various combination of the corresponding individual modality treatment NPs and the dual modality treatment NPs due to the synergistic effects among the chemo, bio, and thermo therapies. We further developed a method by employing the concept of NPs IC50, the concentration of the agent-, or agents-loaded nanoparticles that is needed to kill 50% of the cancer cells, to quantitatively access the synergistic effects of the multimodality treatment. It is shown by employing the SK-BR-3 cell line as an in vitro model of the HER2-positive breast cancer that the NPs IC50 is 0.42 mg/mL DCL-NPs plus 1.33 mg/mL Her-NPs plus 0.59 mg/mL IOs-NPs, a total NPs concentration of 2.34 mg/mL for the treatment of a physical mixture of the DCL-NPs, Her-NPs and IOs-NPs at the 1:2:7 weight ratio, while it is only 0.0011 mg/mL for the MMNPs for 24 h, which is 2130 fold more efficient than the physical mixture of the corresponding single modality treatments.

Targeting Her-2+ breast cancer cells with bleomycin immunoliposomes linked to LLO

Bleomycin is a membrane impermeable chemotherapeutic agent that is relatively innocuous extracellularly but highly cytotoxic when delivered directly to the cytoplasm. We report on the development of a liposome delivery system that targets Her-2 overexpressing breast cancer cells and breaches the endosomal barrier, delivering bleomycin to the cytoplasm. The liposomes are conjugated to the antibody trastuzumab, which results in specific binding and internalization of liposomes into Her-2 overexpressing cells. In addition, the liposomes are disulfide bonded to a pore-forming protein listeriolysin O (LLO) which forms pores in the endosome and allows the liposomal cargo to pass into the cytoplasm. We demonstrate specific delivery to Her-2 positive MCF-7/Her18 cells relative to Her-2 negative MCF-7 cells using a fluorescent probe calcein within the immunoliposomes. When calcein is replaced by bleomycin, the liposomes effectively reduce viability of five different Her-2 overexpressing cell lines (BT-474, SKBR-3, MCF-7/Her18, HCC-1954 and MDA-453) while harming to a much lesser extent Her-2 negative breast cell lines (MCF-7, MCF-12a and MCF-10a). The liposomes also affect trastuzumab-resistant cells, reducing MDA-453 cell number by 97% compared to untreated cells. Importantly, the concentration of drug needed to reduce tumor cell growth and viability using this liposome therapy is approximately 57,000-fold less than the concentration needed if drug is delivered extracellularly, raising the possibility of increased therapeutic specificity with decreased side effects.

Efficient intracellular drug-targeting of macrophages using stealth liposomes directed to the hemoglobin scavenger receptor CD163

The hemoglobin scavenger receptor CD163 is exclusively expressed in the monocytic lineage and preferentially in tissue resident macrophages of the M2 phenotype and in macrophages in sites of inflammation and tumor growth. In the present study we have designed liposomes specifically targeting CD163 by hydrophobic linkage of CD163-binding monoclonal antibodies to polyethylene glycol-coated liposomes ('stealth liposomes'). Targeting to the endocytic CD163 protein greatly increased the uptake of liposomes in CD163 transfected cells and macrophages as visualized by confocal microscopy and flow cytometry of cells exposed to CD163 targeting liposomes loaded with calcein. Strong cytotoxic effects were seen in CD163-expressing human monocytes by using the chemotherapeutic agent doxorubicin as cargo of the liposomes. In conclusion, the use of stealth liposomes modified to recognize CD163 is a potential way to target drugs to macrophages that support inflammatory and malignant processes.

Selective death of human breast cancer cells by lytic immunoliposomes: Correlation with their HER2 expression level

Trastuzumab (Herceptin) targets the human epidermal growth factor receptor 2 (HER2), which is overexpressed in 20-30% of breast and ovarian cancers carrying a bad prognosis. Our purpose was to target HER2-overexpressing human breast cancer cells with pegylated immunoliposomes bearing trastuzumab and containing melittin, which has recently shown anticancer properties. Using a panel of human breast cancer cells with different HER2 expression levels, these immunoliposomes decreased cancer cells viability in a dose-response manner and in correlation to their level of HER2 expression. Specific binding of the immunoliposomes to SKBr3 breast cancer cells was shown by ImageStream-based analysis. The morphological changes observed in the treated cells suggested a cytolytic process. This preclinical approach may suppose an effective strategy for the treatment of HER2-overexpressing tumors, and can support the development of an early phases I-II clinical trial. Trastuzumab resistant breast cancer cells (JIMT-1), can also be targeted using this approach.