Tumor targeting using anti-her2 immunoliposomes

Nano-Micron Combined Hydrogel Microspheres: Novel Answer for Minimal Invasive Biomedical Applications

Hydrogels, key in biomedical research for their hydrophilicity and versatility, have evolved with hydrogel microspheres (HMs) of micron-scale dimensions, enhancing their role in minimally invasive therapeutic delivery, tissue repair, and regeneration. The recent emergence of nanomaterials has ushered in a revolutionary transformation in the biomedical field, which demonstrates tremendous potential in targeted therapies, biological imaging, and disease diagnostics. Consequently, the integration of advanced nanotechnology promises to trigger a new revolution in the realm of hydrogels. HMs loaded with nanomaterials combine the advantages of both hydrogels and nanomaterials, which enables multifaceted functionalities such as efficient drug delivery, sustained release, targeted therapy, biological lubrication, biochemical detection, medical imaging, biosensing monitoring, and micro-robotics. Here, this review comprehensively expounds upon commonly used nanomaterials and their classifications. Then, it provides comprehensive insights into the raw materials and preparation methods of HMs. Besides, the common strategies employed to achieve nano-micron combinations are summarized, and the latest applications of these advanced nano-micron combined HMs in the biomedical field are elucidated. Finally, valuable insights into the future design and development of nano-micron combined HMs are provided.

Immunoliposomes As a Promising Antiviral Agent against SARS-CoV-2

According to the World Health Organization, as of January 3, 2020 to September 13, 2023, there were approximately 23 million confirmed cases of COVID-19 reported in the Russian Federation, about 400 thousand of which were fatal. Considering the high rate of mutation of the RNA-containing virus genome, which inevitably leads to the emergence of new infectious strains (Eris and Pyrola), the search for medicinal antiviral agents remains an urgent task. Moreover, taking into account the actively mutating receptor-binding domain, this task requires fundamentally new solutions. This study proposes a candidate immunoliposomal drug that targets the S protein of SARS-CoV-2 by the monoclonal neutralizing antibody P4A1 and ensures the penetration of a highly active ribonuclease into the virus-infected cell, which degrades, among cellular RNA, viral RNA too. We demonstrate a more than 40-fold increase in the neutralizing activity of the developed drug compared to the free monoclonal neutralizing antibody.

Unleashing the Potential: Designing Antibody-Targeted Lipid Nanoparticles for Industrial Applications with CMC Considerations and Clinical Outlook

Antibody-targeted lipid nanoparticles (Ab-LNPs) are rapidly gaining traction as multifaceted platforms in precision medicine, adept at delivering a diverse array of therapeutic agents, including nucleic acids and small molecules. This review provides an incisive overview of the latest developments in the field of Ab-LNP technology, with a special emphasis on pivotal design aspects such as antibody engineering, bioconjugation strategies, and advanced formulation techniques. Furthermore, it addresses critical chemistry, manufacturing, and controls (CMC) considerations and thoroughly examines the in vivo dynamics of Ab-LNPs, underscoring their promising potential for clinical application. By seamlessly blending scientific advancements with practical industrial perspectives, this review casts a spotlight on the burgeoning role of Ab-LNPs as an innovative and potent tool in the realm of targeted drug delivery.

Anti-HER2 Super Stealth Immunoliposomes for Targeted-Chemotherapy

Liposomes play an important role in the field of drug delivery by virtue of their biocompatibility and versatility as carriers. Stealth liposomes, obtained by surface decoration with hydrophilic polyethylene glycol (PEG) molecules, represent an important turning point in liposome technology, leading to significant improvements in the pharmacokinetic profile compared to naked liposomes. Nevertheless, the generation of effective targeted liposomes-a central issue for cancer therapy-has faced several difficulties and clinical phase failures. Active targeting remains a challenge for liposomes. In this direction, a new Super Stealth Immunoliposomes (SSIL2) composed of a PEG-bi-phospholipids derivative is designed that stabilizes the polymer shielding over the liposomes. Furthermore, its counterpart, conjugated to the fragment antigen-binding of trastuzumab (Fab'TRZ -PEG-bi-phospholipids), is firmly anchored on the liposomes surface and correctly orients outward the targeting moiety. Throughout this study, the performances of SSIL2 are evaluated and compared to classic stealth liposomes and stealth immunoliposomes in vitro in a panel of cell lines and in vivo studies in zebrafish larvae and rodent models. Overall, SSIL2 shows superior in vitro and in vivo outcomes, both in terms of safety and anticancer efficacy, thus representing a step forward in targeted cancer therapy, and valuable for future development.

Nanomedicine Technologies for Diagnosis and Treatment of Breast Cancer

Breast cancer is one of the most common cancers in women worldwide, yet conventional treatments have several shortcomings, including low specificity, systemic toxicity, and drug resistance. Nanomedicine technologies provide a promising alternative while also overcoming the limitations posed by conventional therapies. This mini-Review highlights important signaling pathways related to occurrence and development of breast cancer and current breast cancer therapies, followed by an analysis of various nanomedicine technologies developed for diagnosis and treatment of breast cancers.

Multifunctional targetable liposomal drug delivery system in the management of leukemia: Potential, opportunities, and emerging strategies

The concern impeding the success of chemotherapy in leukemia treatment is descending efficacy of drugs because of multiple drug resistance (MDR). The previous failure of traditional treatment methods is primarily responsible for the present era of innovative agents to treat leukemia effectively. The treatment option is a chemotherapeutic agent in most available treatment strategies, which unfortunately leads to high unavoidable toxicities. As a result of the recent surge in marketed products, theranostic nanoparticles, i.e., multifunctional targetable liposomes (MFTL), have been approved for improved and more successful leukemia treatment that blends therapeutic and diagnostic characteristics. Since they broadly offer the required characteristics to get past the traditional/previous limitations, such as the absence of site-specific anti-cancer therapeutic delivery and ongoing real-time surveillance of the leukemia target sites while administering therapeutic activities. To prepare MFTL, suitable targeting ligands or tumor-specific antibodies are required to attach to the surface of the liposomes. This review exhaustively covered and summarized the liposomal-based formulation in leukemia treatment, emphasizing leukemia types; regulatory considerations, patents, and clinical portfolios to overcome clinical translation hurdles have all been explored.

Liposomes in Cancer Therapy: How Did We Start and Where Are We Now

Since their first discovery in the 1960s by Alec Bangham, liposomes have been shown to be effective drug delivery systems for treating various cancers. Several liposome-based formulations received approval by the U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA), with many others in clinical trials. Liposomes have several advantages, including improved pharmacokinetic properties of the encapsulated drug, reduced systemic toxicity, extended circulation time, and targeted disposition in tumor sites due to the enhanced permeability and retention (EPR) mechanism. However, it is worth noting that despite their efficacy in treating various cancers, liposomes still have some potential toxicity and lack specific targeting and disposition. This explains, in part, why their translation into the clinic has progressed only incrementally, which poses the need for more research to focus on addressing such translational limitations. This review summarizes the main properties of liposomes, their current status in cancer therapy, and their limitations and challenges to achieving maximal therapeutic efficacy.

Targeted delivery of liposomal chemoimmunotherapy for cancer treatment

Chemoimmunotherapy that utilizes the immunomodulatory effect of chemotherapeutics has shown great promise for treating poorly immunogenic solid tumors. However, there remains a significant room for improving the synergy between chemotherapy and immunotherapy, including the efficient, concurrent delivery of chemotherapeutics and immunomodulators into tumors. Here, we report the use of metabolic glycan labeling to facilitate cancer-targeted delivery of liposomal chemoimmunotherapy. 4T1 triple-negative breast cancer cells can be metabolically labeled with azido groups for subsequently targeted conjugation of dibenzocycoloctyne (DBCO)-bearing liposomes loaded with doxorubicin and imiquimod (R837) adjuvant via efficient click chemistry. The encased doxorubicin can induce the immunogenic death of cancer cells and upregulate the expression of CD47 and calreticulin on the surface of cancer cells, while R837 can activate dendritic cells for enhanced processing and presentation of tumor antigens. Targeted delivery of liposomes encapsulating doxorubicin and R837 to 4T1 tumors, enabled by metabolic glycan labeling and click chemistry, showed the promise to reshape the immunosuppressive tumor microenvironment of solid tumors. This cancer-targetable liposomal chemoimmunotherapy could provide a new approach to improving conventional chemotherapy.

Lipid-based nanoparticulate delivery systems for HER2-positive breast cancer immunotherapy

Lipid-based nanoparticulate delivery platforms such as liposomes help overcome cell and tissue barriers and allow prolonged therapeutic plasma drug concentrations, simultaneous targeting of tumor tissue, and increased bioavailability of numerous drugs used for treatment of cancer. The human epidermal growth factor receptor, HER2, is an important player in the pathogenesis of breast cancer and is considered a potential cancer biomarker for the design of immunotherapeutics. HER2-positive breast cancer is found in up to 30% of breast cancer patients. Currently, a variety of lipid nanoparticulate systems are being evaluated in preclinical settings and in clinical trials for targeting HER2-positive breast cancer. Advances in functionalized anti-HER2 lipid nanoparticulates have demonstrated promise and may lead to the development of new nano-immunotherapy protocols against HER2 positive breast cancer. Here we present a review of the most up-to-date literature, including our own research, on the use of lipid nanoparticulate carriers in immunotherapy of HER2-positive breast cancer.

Research progress in strategies to improve the efficacy and safety of doxorubicin for cancer chemotherapy

INTRODUCTION

DOX exerts strong anticancer activity and is commonly used to treat different cancers, including bone sarcomas, soft tissues, bladder, ovary, stomach, thyroid, breast, acute lymphoblastic leukemia, Hodgkin lymphoma, lung cancer, and myeloblastic leukemia. However, the cumulative doses of DOX above 550mg/m2 cause irreversible cardiotoxicity and other severe adverse effects. In this context, concerning DOX, several patents have been published in the last two decades. This activity highlights various aspects of DOX, such as registered patent analysis, pharmacological action, toxicityminimization, formulation development such as those approved by FDA, under clinical trials, and newly developed nano-delivery systems.

AREAS COVERED

This review analyzes the different aspects of DOX-based chemotherapeutics and the development of drug delivery systems in theliterature published from 2000 to early 2020.

EXPERT OPINION

DOX-based chemotherapy is still few steps away from being "perfect and safe" therapy. Certain severe systemic side effects are associated with DOX therapy. It is expected that, in the near future, DOX therapy can be much effective by selecting an ideal nanocarrier system, DOX conjugates, proper structural modifications, DOX-immunotherapy, and combination therapy. The advanced formulationsof DOX from the registered patents and recent research articles need clinical trials to bring safe treatment for cancer patients.

The ROS-generating photosensitizer-free NaYF4:Yb,Tm@SiO2upconverting nanoparticles for photodynamic therapy application

In this work we adapt rare-earth-ion-doped NaYF₄nanoparticles coated with a silicon oxide shell (NaYF₄:20%Yb,0.2%Tm@SiO₂) for biological and medical applications (for example, imaging of cancer cells and therapy at the nano level). The wide upconversion emission range under 980 nm excitation allows one to use the nanoparticles for cancer cell (4T1) photodynamic therapy (PDT) without a photosensitizer. The reactive oxygen species (ROS) are generated by Tm/Yb ion upconversion emission (blue and UV light). Thein vitroPDT was tested on 4T1 cells incubated with NaYF₄:20%Yb,0.2%Tm@SiO₂nanoparticles and irradiated with NIR light. After 24 h, cell viability decreased to below 10%, demonstrating very good treatment efficiency. High modification susceptibility of the SiO₂shell allows for attachment of biological molecules (specific antibodies). In this work we attached the anti-human IgG antibody to silane-PEG-NHS-modified NaYF₄:20%Yb,0.2%Tm@SiO₂nanoparticles and a specifically marked membrane model by bio-conjugation. Thus, it was possible to perform a selective search (a high-quality optical method with a very low-level organic background) and eventually damage the targeted cancer cells. The study focuses on therapeutic properties of NaYF₄:20%Yb,0.2%Tm@SiO₂nanoparticles and demonstrates, upon biological functionalization, their potential for targeted therapy.

Tumor uptake and associated greater efficacy of anti-Her2 immunoliposome does not rely on Her2 expression status: study of a docetaxel-trastuzumab immunoliposome on Her2+ breast cancer model (SKBR3)

Nanoparticles have been used for decades in breast cancer. More recently, anti-human epidermal receptor 2 (Her2) immunoliposomes are of rising interest. However, recent studies have questioned the actual relevance of using anti-Her2 antibodies to improve liposome distribution and efficacy. Using standard thin-film method and maleimide linker, we have synthesized a 140-nm docetaxel-trastuzumab immunoliposome. This nanoparticle was then tested on a canonical Her2-overexpressing breast cancer model (i.e., SKBR3), using 3D spheroids and xenografted mice. Its efficacy was compared with free docetaxel + trastuzumab, liposomal docetaxel + free trastuzumab and to reference antibody-drug conjugate trastuzumab-emtansine (T-DM1). Immunoliposomes resulted in better efficacy as compared with all other treatments, both in vitro and in vivo. To explain such an improvement, immunoliposome biodistribution was investigated using live imaging in xenografted mice. Surprisingly, no difference in tumor uptake was found between anti-Her2 immunoliposomes and standard docetaxel liposomes (i.e., 1.9 ± 1.2 vs. 1.7 ± 0.5% at the end of treatment and 1.4 ± 0.6 vs. 1.6 ± 0.4% at the end of the study, respectively, P > 0.05). We hypothesized that passive targeting (i.e., enhanced permeation and retention effect) contributed more to tumor distribution than active targeting and that the observed differences in efficacy could come from a better internalization of immunoliposomes into Her2+ cells as compared with standard liposomes, and not from a higher specificity towards tumor tissue.

Immunoliposomes bearing lymphocyte activation gene 3 fusion protein and P5 peptide: A novel vaccine for breast cancer

LAG3-Ig as an immune adjuvant has elicited potent anti-tumor immune responses in several preclinical and clinical studies, but the full potential immunostimulatory of LAG3-Ig has yet to be achieved. We hypothesized that by anchoring LAG3-Ig to the surface of liposomes, the adjuvant activity of LAG3-Ig could be improved. We also investigated the immunotherapy by co-delivery of liposome-coupled LAG3-Ig and P5 tumor antigen in mice model of TUBO breast cancer. We prepared and characterized novel PEGylated liposomes bearing surface conjugated LAG3-Ig and P5. Consistent with our hypothesis, liposomes-conjugated LAG3-Ig via multivalent binding to MHC class II molecules exerted immunostimulatory of LAG3-Ig and markedly induced maturation of dendritic cells more efficiently than free LAG3-Ig. LAG3-Ig-P5-immunoliposomes effectively elicited protective anti-tumor responses more than locally injected soluble LAG3-Ig + P5. The higher percentage of CD4⁺ and CD8⁺ T cells in the spleen and more rapid and pronounced infiltration of these effector cells into the site of the tumor were seen following immunoliposome therapy. Finally, anti-tumor immunity induced by LAG3-Ig-P5-immunoliposomes translated into the more tumor regression and prolonged survival of treated mice, compared to soluble immunotherapy. Taken together, our findings suggest that LAG3-Ig-P5-immunoliposomes can be considered as a valuable candidate for developing a liposome-based therapeutic cancer vaccine in treating HER2/ neu⁺ breast cancer patients.

When liposomes met antibodies: Drug delivery and beyond

Drug encapsulated liposomes and monoclonal antibodies (Mabs) are two distinctively different classes of therapeutics, but both aim to become the ultimate "magic bullet". While PEGylated liposomes rely on the enhanced permeability and retention (EPR) effect for accumulation in solid tumor tissues, Mabs are designed to bind tightly to specific surface antigens on target cells to exert effector functions. Immunoliposome (IL) refers to the structural combination of liposomes and antibodies, whereas the antibodies are usually decorated on the liposome surface. ILs can therefore take advantage of interactions between antibodies and cancer cells for more efficient endocytosis and intracellular drug delivery. The antibody structure, affinity, density, as well as the liposome surface properties and drug to lipid ratios all contribute to the IL pharmacokinetic(PK) and pharmacodynamic(PD) behaviors. The optimal formulation parameters may vary for different target cells and tissues. Furthermore, besides the delivery of cytotoxic drugs to cancer cells, new ILs are being developed to interact with multiple target receptors, multiple target cells and trigger multiple therapeutic effects. We envision that the IL format can be a great platform for the molecular engineering of multi-valent, multi-specific interactions to achieve complex biological functions for therapeutic benefits, especially in the area of cancer immunotherapy.

Engineering peptide-targeted liposomal nanoparticles optimized for improved selectivity for HER2-positive breast cancer cells to achieve enhanced in vivo efficacy

Here, we report rationally engineered peptide-targeted liposomal doxorubicin nanoparticles that have an enhanced selectivity for HER2-positive breast tumor cells with high purity, reproducibility, and precision in controlling stoichiometry of targeting peptides. To increase HER2-positive tumor cell selective drug delivery, we optimized the two most important design parameters, peptide density and linker length, via systematic evaluations of their effects on both in vitro cellular uptake and in vivo tumor accumulation and cellular uptake. The optimally designed nanoparticles were finally evaluated for their tumor inhibition efficacy using in vivo MMTV-neu transplantation mouse model. In vitro, we demonstrated that ~1% peptide density and EG8 linker were optimal parameters for targeted nanoparticle formulations to enhance HER2-positive cancer cellular uptake while preventing non-selectivity. In vivo results demonstrated that at 0.5% peptide density, enhancement of tumor cell uptake over non-targeted nanoparticles was ~2.7 fold and ~3.4 fold higher for targeted nanoparticles with EG8 and EG18 linker, respectively, while their accumulation levels at tumor tissue were similar to the non-targeted nanoparticles. These results were consistent with in vivo efficacy outcomes that ~90% tumor growth inhibition was achieved by Dox-loaded HER2 receptor targeted nanoparticles, TNP^HER2pep, over control while all nanoparticle formulations minimized overall systemic toxicity relative to free Dox. This study highlights the significance of understanding and optimizing the effects of liposomal nanoparticle design parameters for enhancement of tumor selectivity to achieve improved in vivo therapeutic outcomes.

A glance over doxorubicin based-nanotherapeutics: From proof-of-concept studies to solutions in the market

Cancer is one of the leading causes of death worldwide and, as such, efforts are being done to find new chemotherapeutic drugs or, alternatively, novel approaches for the delivery of old ones. In this scope, when used as vehicles for drugs, nanomaterials may potentially maximize the efficacy of the treatment and reduce its side effects, for example by a change in drug's pharmacokinetics, cell targeting and/or specific stimuli-responsiveness. This is the case of doxorubicin (DOX) that presents a broad spectrum of activity and is one of the most widely used chemotherapeutic drugs as first-line treatment. Indeed, DOX is a very interesting example of a drug for which several nanosized delivery systems have been developed over the years. While it is true that some of these systems are already in the market, it is also true that research on this subject remains very active and that there is a continuing search for new solutions. In this sense, this review takes the example of doxorubicin, not so much with the focus on the drug itself, but rather as a case study around which very diverse and imaginative nanotechnology approaches have emerged.

Urotensin-II-Targeted Liposomes as a New Drug Delivery System towards Prostate and Colon Cancer Cells

Urotensin-II (UT-II) and its receptor (UTR) are involved in the occurrence of different epithelial cancers. In particular, UTR was found overexpressed on colon, bladder, and prostate cancer cells. The conjugation of ligands, able to specifically bind receptors that are overexpressed on cancer cells, to liposome surface represents an efficient active targeting strategy to enhance selectivity and efficiency of drug delivery systems. The aim of this study was to develop liposomes conjugated with UT-II (LipoUT) for efficient targeting of cancer cells that overexpress UTR. The liposomes had a mean diameter between 150 nm and 160 nm with a narrow size distribution (PI ≤ 0.1) and a doxo encapsulation efficiency of 96%. Moreover, the conjugation of UT-II to liposomes weakly reduced the zeta potential. We evaluated UTR expression on prostate (DU145, PC3, and LNCaP) and colon (WIDR and LoVo) cancer cells by FACS and western blotting analysis. UTR protein was expressed in all the tested cell lines; the level of expression was higher in WIDR, PC3, and LNCaP cells compared with LoVo and DU145. MTT cell viability assay showed that LipoUT-doxo was more active than Lipo-doxo on the growth inhibition of cells that overexpressed UTR (PC3, LNCaP, and WIDR) while in LoVo and DU145 cell lines, the activity was similar to or lower than that one of Lipo-doxo, respectively. Moreover, we found that cell uptake of Bodipy-labeled liposomes in PC3 and DU145 was higher for LipoUT than the not-armed counterparts but at higher extent in UTR overexpressing PC3 cells (about 2-fold higher), as evaluated by both confocal and FACS. In conclusion, the encapsulation of doxo in UT-II-targeted liposomes potentiated its delivery in UTR-overexpressing cells and could represent a new tool for the targeting of prostate and colon cancer.

Effect of Dose and Selection of Two Different Ligands on the Deposition and Antitumor Efficacy of Targeted Nanoparticles in Brain Tumors

Deposition of nanoparticles to tumors often can be enhanced by targeting receptors overexpressed in a tumor. However, a tumor may exhibit a finite number of a biomarker that is accessible and targetable by nanoparticles, limiting the available landing spots. To explore this, we selected two different biomarkers that effectively home nanoparticles in brain tumors. Specifically, we used either an α_vβ₃ integrin-targeting peptide or a fibronectin-targeting peptide as a ligand on nanoparticles termed RGD-NP and CREKA-NP, respectively. In mouse models of glioblastoma multiforme, we systemically injected the nanoparticles loaded with a cytotoxic drug at different doses ranging from 2 to 8 mg/kg drug. The upper dose threshold of RGD-NP is ∼2 mg/kg. CREKA-NP reached its upper dose threshold at 5 mg/kg. For both targeted nanoparticle variants, higher dose did not ensure higher intratumoral drug levels, but it contributed to elevated off-target deposition and potentially greater toxicity. A cocktail combining RGD-NP and CREKA-NP was then administered at a dose corresponding to the upper dose threshold for each formulation resulting in a 3-fold higher intratumoral deposition than the individual formulations. The combination of the two different targeting schemes at the appropriate dose for each nanoparticle variant facilitated remarkable increase in intratumoral drug levels that was not achievable by a sole targeting nanoparticle alone.

Development of anti-HER2-targeted doxorubicin-core-shell chitosan nanoparticles for the treatment of human breast cancer

Purpose: Doxorubicin (DOX) encapsulated O-succinyl chitosan graft Pluronic^® F127 (OCP) copolymer nanoparticles conjugated with an anti-HER2 monoclonal antibody were developed as targeted drug delivery vehicles for the treatment of HER2-overexpressing breast cancer.

Methods: Five percent and 10% (w/w) of O-succinyl chitosan was grafted onto Pluronic^® F127 using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) as mediated cross-linking agents. DOX was added to the copolymer solution to form DOX-nanoparticles before conjugation with anti-HER2 on the surface of the nanoparticles.

Results: DOX was encapsulated within the NP matrices at an encapsulation efficiency of 73.69 ± 0.53% to 74.65 ± 0.44% (the initial DOX concentration was 5 µg/mL). Anti-HER2 was successfully conjugated onto the surface of the nanoparticles at a moderately high conjugation efficiency of approximately 57.23 ± 0.38% to 61.20 ± 4.42%. In the in vitro DOX dissolution study, the nanoparticle formulations exhibited a biphasic drug release with an initial burst release followed by a sustained release profile at both pH 5.0 and pH 7.4. The drug was rapidly and completely released from the nanoparticles at pH 5.0. In the in vitro cytotoxicity, the anti-HER2 conjugated OCP copolymer nanoparticles showed the lowest IC₅₀, which indicated an increase in the therapeutic efficacy of DOX to treat human breast cancer cells with the HER2 overexpression.

Conclusion: Our study shows that anti-HER2 conjugated OCP copolymer nanoparticles have the potential for the development of anticancer drug carriers.

Eradication of Human Immunodeficiency Virus Type-1 (HIV-1)-Infected Cells

Predictions made soon after the introduction of human immunodeficiency virus type-1 (HIV-1) protease inhibitors about potentially eradicating the cellular reservoirs of HIV-1 in infected individuals were too optimistic. The ability of the HIV-1 genome to remain in the chromosomes of resting CD4+ T cells and macrophages without being expressed (HIV-1 latency) has prompted studies to activate the cells in the hopes that the immune system can recognize and clear these cells. The absence of natural clearance of latently infected cells has led to the recognition that additional interventions are necessary. Here, we review the potential of utilizing suicide gene therapy to kill infected cells, excising the chromosome-integrated HIV-1 DNA, and targeting cytotoxic liposomes to latency-reversed HIV-1-infected cells.

Polymeric nanogels as drug delivery systems

The present review focuses on the description of the design, synthesis and physico-chemical and biological evaluation of polymer nanogels. Nanogels are robust swollen cross-linked polymer nanoparticles that can be used as highly efficient and biodegradable carriers for the transport of drugs in controlled drug delivery. In this article, various types of nanogels are described and methods for their preparation discussed. The possibility of using synthesized nanosystems for targeting are reviewed to show the potential of tailored structures to reach either solid tumor tissue or direct tumor cells. Finally, the methods for encapsulation or attachment of biologically active molecules, e.g. drugs, proteins, are described and compared.

Exploring Molecular-Biomembrane Interactions with Surface Plasmon Resonance and Dual Polarization Interferometry Technology: Expanding the Spotlight onto Biomembrane Structure

The molecular analysis of biomolecular-membrane interactions is central to understanding most cellular systems but has emerged as a complex technical challenge given the complexities of membrane structure and composition across all living cells. We present a review of the application of surface plasmon resonance and dual polarization interferometry-based biosensors to the study of biomembrane-based systems using both planar mono- or bilayers or liposomes. We first describe the optical principals and instrumentation of surface plasmon resonance, including both linear and extraordinary transmission modes and dual polarization interferometry. We then describe the wide range of model membrane systems that have been developed for deposition on the chips surfaces that include planar, polymer cushioned, tethered bilayers, and liposomes. This is followed by a description of the different chemical immobilization or physisorption techniques. The application of this broad range of engineered membrane surfaces to biomolecular-membrane interactions is then overviewed and how the information obtained using these techniques enhance our molecular understanding of membrane-mediated peptide and protein function. We first discuss experiments where SPR alone has been used to characterize membrane binding and describe how these studies yielded novel insight into the molecular events associated with membrane interactions and how they provided a significant impetus to more recent studies that focus on coincident membrane structure changes during binding of peptides and proteins. We then discuss the emerging limitations of not monitoring the effects on membrane structure and how SPR data can be combined with DPI to provide significant new information on how a membrane responds to the binding of peptides and proteins.

Peptide and protein nanoparticle conjugates: versatile platforms for biomedical applications

Peptide- and protein-nanoparticle conjugates have emerged as powerful tools for biomedical applications, enabling the treatment, diagnosis, and prevention of disease. In this review, we focus on the key roles played by peptides and proteins in improving, controlling, and defining the performance of nanotechnologies. Within this framework, we provide a comprehensive overview of the key sequences and structures utilised to provide biological and physical stability to nano-constructs, direct particles to their target and influence their cellular and tissue distribution, induce and control biological responses, and form polypeptide self-assembled nanoparticles. In doing so, we highlight the great advances made by the field, as well as the challenges still faced in achieving the clinical translation of peptide- and protein-functionalised nano-drug delivery vehicles, imaging species, and active therapeutics.

From Conventional to Stealth Liposomes a new Frontier in Cancer Chemotherapy

Many attempts have been made to achieve good selectivity to targeted tumor cells by preparing specialized carrier agents that are therapeutically profitable for anticancer therapy. Among these, liposomes are the most studied colloidal particles thus far applied in medicine and in particular in antitumor therapy. Although they were first described in the 1960s, only at the beginning of 1990s did the first therapeutic liposomes appear on the market. The first-generation liposomes (conventional liposomes) comprised a liposome-containing amphotericin B, Ambisome (Nexstar, Boulder, CO, USA), used as an antifungal drug, and Myocet (Elan Pharma Int, Princeton, NJ, USA), a doxorubicin-containing liposome, used in clinical trials to treat metastatic breast cancer. The second-generation liposomes (“pure lipid approach”) were long-circulating liposomes, such as Daunoxome, a daunorubicin-containing liposome approved in the US and Europe to treat AIDS-related Kaposi's sarcoma. The third-generation liposomes were surface-modified liposomes with gangliosides or sialic acid, which can evade the immune system responsible for removing liposomes from circulation. The fourth-generation liposomes, pegylated liposomal doxorubicin, were called “stealth liposomes” because of their ability to evade interception by the immune system, in the same way as the stealth bomber was able to evade radar. Actually, the only stealth liposome on the market is Caelyx/Doxil (Schering-Plough, Madison NJ, USA), used to cure AIDS-related Kaposi's sarcoma, resistant ovarian cancer and metastatic breast cancer. Pegylated liposomal doxorubicin is characterized by a very long-circulation half-life, favorable pharmacokinetic behavior and specific accumulation in tumor tissues. These features account for the much lower toxicity shown by Caelyx in comparison to free doxorubicin, in terms of cardiotoxicity, vesicant effects, nausea, vomiting and alopecia. Pegylated liposomal doxorubicin also appeared to be less myelotoxic than doxorubicin. Typical forms of toxicity associated to it are acute infusion reaction, mucositis and palmar plantar erythrodysesthesia, which occur especially at high doses or short dosing intervals. Active and cell targeted liposomes can be obtained by attaching some antigen-directed monoclonal antibodies (Moab or Moab fragments) or small proteins and molecules (folate, epidermal growth factor, transferrin) to the distal end of polyethylene glycol in pegylated liposomal doxorubicin. The most promising therapeutic application of liposomes is as non-viral vector agents in gene therapy, characterized by the use of cationic phospholipids complexed with the negatively charged DNA plasmid. The use of liposome formulations in local-regional anticancer therapy is also discussed. Finally, pegylated liposomal doxorubicin containing radionuclides are used in clinical trials as tumor-imaging agents or in positron emission tomography.

Towards clinical translation of ligand-functionalized liposomes in targeted cancer therapy: Challenges and opportunities

The development of therapeutic resistance to targeted anticancer therapies remains a significant clinical problem, with intratumoral heterogeneity playing a key role. In this context, improving the therapeutic outcome through simultaneous targeting of multiple tumor cell subtypes within a heterogeneous tumor is a promising approach. Liposomes have emerged as useful drug carriers that can reduce systemic toxicity and increase drug delivery to the tumor site. While clinically used liposomal drug formulations show marked therapeutic advantages over free drug formulations, ligand-functionalized liposomes that can target multiple tumor cell subtypes may further improve the therapeutic efficacy by facilitating drug delivery to a broader population of tumor cells making up the heterogeneous tumor tissue. Ligand-directed liposomes enable the so-called active targeting of cell receptors via surface-attached ligands that direct drug uptake into tumor cells or tumor-associated stromal cells, and so can increase the selectivity of drug delivery. Despite promising preclinical results demonstrating improved targeting and anti-tumor effects of ligand-directed liposomes, there has been limited translation of this approach to the clinic. Key challenges for translation include the lack of established methods to scale up production and comprehensively characterize ligand-functionalized liposome formulations, as well as the inadequate recapitulation of in vivo tumors in the preclinical models currently used to evaluate their performance. Herein, we discuss the utility of recent ligand-directed liposome approaches, with a focus on dual-ligand liposomes, for the treatment of solid tumors and examine the drawbacks limiting their progression to clinical adoption.

Organ-based drug delivery

The phenomenal advances in pharmaceutical sciences over the last few decades have led to the development of new therapeutics like peptides, proteins, RNAs, DNAs and highly potent small molecules. Fruitful applications of these therapeutics have been challenged by several anatomical and physiological barriers that limit adequate drug disposition at the site-of-action and by off-target drug distribution to undesired tissues, which together result in the reduced effectiveness and increased side effects of therapeutic agents. As such, the development of drug delivery and targeting systems has been recognised as a cornerstone for future drug development. Research in pharmaceutical sciences is now devoted to tackling delivery challenges through engineering delivery systems that move beyond conventional dosage forms and regimens into state-of-the-art targeted drug delivery tailored toward specific therapeutic needs. Modern drug delivery systems comprise passive and active targeting approaches. While passive targeting relies on the natural course of distribution of drugs or drug carriers in the body, as governed by their physicochemical properties, active targeting often exploits targeting moieties that home preferentially into target tissues. Here, we provide an overview of theories of and approaches to passive and active drug delivery. As the design of drug delivery is dependent on the unique structure of target tissues and organs, we present our discussion in an organ-specific manner with the aim to inspire the development of new strategies for curing disease with high accuracy and efficiency.

Multifunctional Liposomes

Liposomes have come a long way since their conception in the 1960s, when they were envisioned primarily for drug delivery. Besides serving the important function of the delivery of a variety of drugs, liposomes offer a platform for the co-delivery of a range of therapeutic and diagnostic agents with different physicochemical properties. They are also amenable to the addition of various targeting moieties such as proteins, sugars, and antibodies for selective targeting at a desired site, including tumors. Currently, the design of stimuli-sensitive liposomes for drug delivery is a lively area of research. Compared to conventional liposomes, stimuli-sensitive nanoplatforms respond to local conditions that are characteristics of the pathological area of interest, allowing the release of active agents at the targeted site. Acidic pH, abnormal levels of enzymes, temperature, altered redox potential, and external magnetic field are examples of internal and external stimuli exploited in the design of stimuli-sensitive liposomes. The penetration of the liposomes into the cells can be enhanced with the help of a variety of cell penetrating peptides, which can be incorporated into the liposomes with the help of various lipid-polymer conjugates. Liposomes are now being employed in diagnostics as well. Imaging of a tumor can be made easier by the inclusion of fluorescent probes. They can also be used for gamma or MR imaging using chelated reporter metals and incorporating them either into the core of the liposome or in the lipid bilayer facing outwards. In this chapter, we discuss methods that are commonly used for the preparation of liposomes with a vast range of functions to meet a variety of needs in diagnostics and drug delivery.

Discovery of internalizing antibodies to basal breast cancer cells

We present a strategy to discover recombinant monoclonal antibodies (mAbs) to specific cancers and demonstrate this approach using basal subtype breast cancers. A phage antibody library was depleted of antibodies to common cell surface molecules by incubation with luminal breast cancer cell lines, and then selected on a single basal-like breast cancer cell line (MDA-MB-231) for binding associated receptor-mediated endocytosis. Additional profiling against two luminal and four basal-like cell lines revealed 61 unique basal-specific mAbs from a pool of 1440 phage antibodies. The unique mAbs were further screened on nine basal and seven luminal cell lines to identify those with the greatest affinity, specificity, and internalizing capability for basal-like breast cancer cells. Among the internalizing basal-specific mAbs were those recognizing four transmembrane receptors (EphA2, CD44, CD73 and EGFR), identified by immunoprecipitation-mass spectrometry and yeast-displayed antigen screening. Basal-like breast cancer expression of these four receptors was confirmed using a bioinformatic approach, and expression microarray data on 683 intrinsically subtyped primary breast tumors. This overall approach, which sequentially employs phage display antibody library selection, antigen identification and bioinformatic confirmation of antigen expression by cancer subtypes, offers efficient production of high-affinity mAbs with diagnostic and therapeutic utility against specific cancer subtypes.

Current Challenges of Cancer Anti-angiogenic Therapy and the Promise of Nanotherapeutics

With growing interest in cancer therapeutics, anti-angiogenic therapy has received considerable attention and is widely administered in several types of human cancers. Nonetheless, this type of therapy may induce multiple signaling pathways compared with cytotoxics and lead to worse outcomes in terms of resistance, invasion, metastasis, and overall survival (OS). Moreover, there are important challenges that limit the translation of promising biomarkers into clinical practice to monitor the efficiency of anti-angiogenic therapy. These pitfalls emphasize the urgent need for discovering alternative angiogenic inhibitors that target multiple angiogenic factors or developing a new drug delivery system for the current inhibitors. The great advantages of nanoparticles are their ability to offer effective routes that target the biological system and regulate different vital processes based on their unique features. Limited studies so far have addressed the effectiveness of nanoparticles in the normalization of the delicate balance between stimulating (pro-angiogenic) and inhibiting (anti-angiogenic) factors. In this review, we shed light on tumor vessels and their microenvironment and consider the current directions of anti-angiogenic and nanotherapeutic treatments. To the best of our knowledge, we consider an important effort in the understanding of anti-angiogenic agents (often a small volume of metals, nonmetallic molecules, or polymers) that can control the growth of new vessels.

Immunoliposomes: A review on functionalization strategies and targets for drug delivery

Nanoparticles, especially liposomes, have gained prominence in the field of drug delivery for the treatment of human diseases, particularly cancer; they provide several advantages, including controlled drug release, protection of the drug against degradation, improved pharmacokinetics, long circulation, and passive targeting to tumors and inflammatory sites due to the enhanced permeability and retention effect. The functionalization of liposomes with monoclonal antibodies or antibody fragments to generate immunoliposomes has emerged as a promising strategy for targeted delivery to and uptake by cells overexpressing the antigens to these antibodies, with a consequent reduction in side effects. In this review, we address functionalization strategies for the non-covalent and covalent attachment of monoclonal antibodies and their fragments to liposomal surfaces. The main reaction occurs between the sulfhydryl groups of thiolated antibodies and maleimide-containing liposomes. Furthermore, we explore the main targeting possibilities with these ligands for the treatment of a variety of pathologies, including HER2- and EGFR-positive cancers, inflammatory and cardiovascular diseases, infectious diseases, and autoimmune and neurodegenerative diseases, which have not previously been reviewed together. Overall, many studies have shown selective delivery of immunoliposomes to target cells, with promising in vivo results, particularly for cancer treatment. Although clinical trials have been conducted, immunoliposomes have not yet received clinical approval. However, immunoliposomes are promising formulations that are expected to become available for therapeutic use after clinical trials prove their safety and efficacy, and after scaling issues are resolved.

Antibodies as stratagems against cancer

Antibodies have been in the frontline of anticancer research during the last few decades, since a number of different ways have been discovered to utilize them as parts or main components of anticancer drugs. Antibodies are used as the only component of some anticancer drugs, but they can also be conjugated with a variety of substances. Antibody engineering methods such as humanization, chimerization and Fc engineering are applied in order to modify their properties according to the requirements of anticancer drug application. Given the continuous advances in biology and informatics, the role of antibodies in anticancer treatment is expected to be prominent.

Ternary complexes of folate-PEG-appended dendrimer (G4)/α-cyclodextrin conjugate, siRNA and low-molecular-weight polysaccharide sacran as a novel tumor-selective siRNA delivery system

We previously developed a tumor-selective siRNA carrier by preparing polyamidoamine dendrimer (generation 4, G4) conjugates with α-cyclodextrin and folate-polyethylene glycol (Fol-PαC (G4)). In the present study, we developed ternary complexes of Fol-PαC (G4)/siRNA with low-molecular-weight-sacrans to achieve more effective siRNA transfer activity. Among the different molecular-weight sacrans, i.e. sacran 100, 1000 and 10,000 (MW 44,889Da, 943,692Da and 1,488,281Da, respectively), sacran 100 significantly increased the cellular uptake and the RNAi effects of Fol-PαC (G4)/siRNA binary complex with negligible cytotoxicity in KB cells (folate receptor-α positive cells). In addition, the ζ-potential and particle size of Fol-PαC (G4)/siRNA complex were decreased by the ternary complexation with sacran 100. Importantly, the in vivo RNAi effect of the ternary complex after the intravenous administration to tumor-bearing BALB/c mice was significantly higher than that of the binary complex. In conclusion, Fol-PαC (G4)/siRNA/sacran 100 ternary complex has a potential as a novel tumor-selective siRNA delivery system.

Liposomes derivatized with multimeric copies of KCCYSL peptide as targeting agents for HER-2-overexpressing tumor cells

Mixed liposomes, obtained by coaggregation of 1,2-dioleoyl-sn-glycero-3-phosphocholine and of the synthetic monomer containing a gadolinium complex ([C18]₂DTPA[Gd]) have been prepared. Liposomes externally decorated with KCCYSL (P6.1 peptide) sequence in its monomeric, dimeric, and tetrameric forms are studied as target-selective delivery systems toward cancer cells overexpressing human epidermal growth factor receptor-2 (HER-2) receptors. Derivatization of liposomal surface with targeting peptides is achieved using the postmodification method: the alkyne-peptide derivative Pra-KCCYSL reacts, through click chemistry procedures, with a synthetic surfactant modified with 1, 2, or 4 azido moieties previously inserted in liposome formulation. Preliminary in vitro data on MDA-MB-231 and BT-474 cells indicated that liposomes functionalized with P6.1 peptide in its tetrameric form had better binding to and uptake into BT-474 cells compared to liposomes decorated with monomeric or dimeric versions of the P6.1 peptide. BT-474 cells treated with liposomes functionalized with the tetrameric form of P6.1 showed high degree of liposome uptake, which was comparable with the uptake of anti-HER-2 antibodies such as Herceptin. Moreover, magnetic MRI experiments have demonstrated the potential of liposomes to act as MRI contrast agents.

Passive and semi-active targeting of bone marrow and leukemia cells using anionic low cholesterol liposomes

Historically, the use of liposomes to enhance delivery of anticancer agents to cancer cells has focused primarily on solid tumors, which are characterized by rapid angiogenesis resulting in a poorly formed hypervasculature with abnormal vessel walls. The leaky vasculature in combination with poor lymphatic drainage has been demonstrated to lead to the accumulation of liposomes via the enhanced permeation and retention effect. However, only very limited information exists on the disposition of such delivery systems in the bone marrow compartment, the primary site of tumor cell origination and growth for many hematological malignancies. In this review we discuss the biological properties of anionic low-cholesterol liposome formulations and their potential for passively accumulating within the bone marrow and being selectively engulfed by leukemia cells compared to normal bone marrow cells. The therapeutic implications for preferential bone marrow delivery as well as the potential routes for the internalization of drug-encapsulated liposomes into cells in the absence of a targeting ligand are reviewed.