Modulation of cancer cell survival pathways using multivalent liposomal therapeutic antibody constructs

Surface modification strategies in translocating nano-vesicles across different barriers and the role of bio-vesicles in improving anticancer therapy

Nanovesicles and bio-vesicles (BVs) have emerged as promising tools to achieve targeted cancer therapy due to their ability to overcome many of the key challenges currently being faced with conventional chemotherapy. These challenges include the diverse and often complex pathophysiology involving the progression of cancer, as well as the various biological barriers that circumvent therapeutic molecules reaching their target site in optimum concentration. The scientific evidence suggests that surface-functionalized nanovesicles and BVs camouflaged nano-carriers (NCs) both can bypass the established biological barriers and facilitate fourth-generation targeting for the improved regimen of treatment. In this review, we intend to emphasize the role of surface-functionalized nanovesicles and BVs camouflaged NCs through various approaches that lead to an improved internalization to achieve improved and targeted oncotherapy. We have explored various strategies that have been employed to surface-functionalize and biologically modify these vesicles, including the use of biomolecule functionalized target ligands such as peptides, antibodies, and aptamers, as well as the targeting of specific receptors on cancer cells. Further, the utility of BVs, which are made from the membranes of cells such as mesenchymal stem cells (MSCs), white blood cells (WBCs), red blood cells (RBCs), platelets (PLTs) as well as cancer cells also been investigated. Lastly, we have discussed the translational challenges and limitations that these NCs can encounter and still need to be overcome in order to fully realize the potential of nanovesicles and BVs for targeted cancer therapy. The fundamental challenges that currently prevent successful cancer therapy and the necessity of novel delivery systems are in the offing.

Recent advances in the liposomal nanovesicles based immunotherapy in the treatment of cancer: A review

Immunotherapy, along with chemotherapy, targeted delivery, radiation and surgery has become one of the most common cancer treatments. The aim of cancer immunology is to use the bodys immune system to combat tumors and develop a robust antitumor immune response. In the last few years, immune checkpoint inhibitors and chimeric antigen receptor-modified T cells have made substantial advancements in cancer immunotherapy. By boosting cell type-specific delivery and immunological responses, nanocarriers like liposomes have the ability to enhance greater immune responses. The efficacy of anti-tumor therapeutics is being significantly improved as liposomes can assist in resolving a number of issues that can arise from a variety of cancer immunotherapies. Since, liposomes can be loaded with both hydrophilic and hydrophobic drugs and protect the immunotherapeutic agents loaded inside the core, they offer significant advantages over other nano delivery systems. The use of liposomes for accurate and timely delivery of immunotherapies to particular targeted neoplasms, with little or no injury to healthy cells, maximizes immunotherapy efficacy. Liposomes are also suitable vehicles for delivering medications simultaneously with other therapies such as chemotherapy, radiation, and phototherapy. Liposomal nanoparticles will be introduced and used as an objective immunotherapy delivery system for great precision, making them a viable cancer treatment approach.With an emphasis on dendritic cells, T cells, tumor and natural killer cells, and macrophages; outline of many forms of immune-therapies in oncology and cutting-edge advances in liposomal nanovesicles for cancer immunotherapy are covered in this review.

Lipid-Based Nanomaterials for Drug Delivery Systems in Breast Cancer Therapy

Globally, breast cancer is one of the most prevalent diseases, inducing critical intimidation to human health. Lipid-based nanomaterials have been successfully demonstrated as drug carriers for breast cancer treatment. To date, the development of a better drug delivery system based on lipid nanomaterials is still urgent to make the treatment and diagnosis easily accessible to breast cancer patients. In a drug delivery system, lipid nanomaterials have revealed distinctive features, including high biocompatibility and efficient drug delivery. Specifically, a targeted drug delivery system based on lipid nanomaterials has inherited the advantage of optimum dosage and low side effects. In this review, insights on currently used potential lipid-based nanomaterials are collected and introduced. The review sheds light on conjugation, targeting, diagnosis, treatment, and clinical significance of lipid-based nanomaterials to treat breast cancer. Furthermore, a brighter side of lipid-based nanomaterials as future potential drug delivery systems for breast cancer therapy is discussed.

Mechanistic Approach of Nano Carriers for Targeted in Cancer Chemotherapy: A Newer Strategy for Novel Drug Delivery System

The application of nanomedicine represents an innovative approach for the treatment in the modern field of cancer chemotherapy. In the present research work, tamoxifen citrate loaded nanolipid vesicles were prepared conjugated with phosphoethanolamine as the linker molecule, and the specific antibody was tagged with the linker molecule on the bilayer surface of the vesicles. The main objective of this study is to determine the efficacy and biological behavior of antibody conjugated nanoliposome in breast cancer cell lines. Percentage of drug loading and loading efficiency was done and their results were compared to theoretical drug loading. The average diameter of those vesicles was within the 100 nm range, which is revealed in FESEM and TEM images and their lamellarity was observed in cryo-TEM images. The hydrodynamic diameter was done by particle size analysis and the surface charge was determined by the zeta potential parameter. Predominant cellular uptake was observed for antibody conjugated nanolipid vesicles in MCF-7 and MDA-MB-453 human breast cancer cell lines. A cellular apoptosis assay was conducted by flow cytometer (FACS). All experimental data would be more beneficial for the treatment of breast cancer chemotherapy. Further studies are warranted to investigate the efficacy and safety of antibody conjugated nanolipid vesicles in vivo for breast cancer animal model.

Smart Nanocarriers for Targeted Cancer Therapy

Cancer is considered one of the most threatening diseases worldwide. Although many therapeutic approaches have been developed and optimized for ameliorating patient's conditions and life expectancy, however, it frequently remains an incurable pathology. Notably, conventional treatments may reveal inefficient in the presence of metastasis development, multidrug resistance and inability to achieve targeted drug delivery. In the last decades, nanomedicine has gained a prominent role, due to many properties ascribable to nanomaterials. It is worth mentioning their small size, their ability to be loaded with small drugs and bioactive molecules and the possibility to be functionalized for tumor targeting. Natural vehicles have been exploited, such as exosomes, and designed, such as liposomes. Biomimetic nanomaterials have been engineered, by modification with biological membrane coating. Several nanoparticles have already entered clinical trials and some liposomal formulations have been approved for therapeutic applications. In this review, natural and synthetic nanocarriers functionalized for actively targeting cancer cells will be described, focusing on their advantages with respect to conventional treatments. Recent innovations related to biomimetic nanoparticles camouflaged with membranes isolated from different types of cells will be reported, together with their promising applications. Finally, a short overview on the latest advances in carrier-free nanomaterials will be provided.

Nanomaterials for T-cell cancer immunotherapy

T-cell-based immunotherapies hold promise for the treatment of many types of cancer, with three approved products for B-cell malignancies and a large pipeline of treatments in clinical trials. However, there are several challenges to their broad implementation. These include insufficient expansion of adoptively transferred T cells, inefficient trafficking of T cells into solid tumours, decreased T-cell activity due to a hostile tumour microenvironment and the loss of target antigen expression. Together, these factors restrict the number of therapeutically active T cells engaging with tumours. Nanomaterials are uniquely suited to overcome these challenges, as they can be rationally designed to enhance T-cell expansion, navigate complex physical barriers and modulate tumour microenvironments. Here, we present an overview of nanomaterials that have been used to overcome clinical barriers to T-cell-based immunotherapies and provide our outlook of this emerging field at the interface of cancer immunotherapy and nanomaterial design.

Nanotherapeutics for Immuno-Oncology: A Crossroad for New Paradigms

With the rapid increase in the use of nanotechnology and immunotherapy for cancer management in the recent past, there are great implications for using nanotechnology in immuno-oncology. However, to deliver clinical success, the scientific and clinical rationale must be critically evaluated when applying nanotechnology to immuno-oncology challenges. This opinion article distinguishes between designing nanotherapeutics for immunotherapy and the past focus on the placement of chemotherapy agents in nanoparticles. We believe the integration of nanotechnology with cancer immunotherapy for nano-immunotherapeutics provides unique opportunities for both fields, paving the way for entirely new therapeutic paradigms. As a particular focus in our article, we envision the necessities and challenges of nanotechnology in the development of in situ cancer vaccines, immune checkpoint inhibitors, adoptive cell transfer, and bispecific antibody therapy.

Rituximab conjugated iron oxide nanoparticles for targeted imaging and enhanced treatment against CD20-positive lymphoma

The Fe₃O₄-PEG-nAb multivalent nanoprobes provide a possible avenue to improve the cancer therapy of rituximab towards clinical application.

Phospholipase-Cγ1 Signaling Protein Down-Regulation by Oligoclonal-VHHs based Immuno-Liposome: A Potent Metastasis Deterrent in HER2 Positive Breast Cancer Cells

Objective

The purpose of this study was to develop multivalent antibody constructs via grafting anti-HER2 antibodies, including Herceptin and oligoclonal-variable domain of heavy chain antibodies (VHHs), onto liposome membranes to enhance antibody activity and compare their effect on phospholipase C (PLC) signaling pathway with control.

Materials and Methods

In this experimental study, SKBR3 and BT-474 cell lines as HER2 positive and MCF10A cell line as normal cell were screened with anti-HER2 antibodies, including constructs of multivalent liposomal antibody developed with Herceptin and anti-HER2 oligoclonal-VHHs. To confirm the accuracy of the study, immunofluorescent assay, migration assay and immuno-liposome binding ability to HER2 were evaluated. Finally, the antibodies effect on PLCγ1 protein level was measured by an immunoassay method (ELISA).

Results

In the present study, by using multivalent form of antibodies, we were able to significantly inhibit the PLCγ1 protein level. Interestingly, the results of migration assay, used for study the motility of different types of cell, shows correspondingly decreased number of immigrated cells in SKBR3 and BT-474 cell lines. Since MCF10A cells show no overexpression of HER2, as expected, the result did not show any change in PLCγ1 level. Moreover, immunofluorescent assay has confirmed high expression of HER2 in SKBR3 and BT-474 cell lines and low HER2 expression on MCF10A cell line. High binding of immuno-liposome to SKBR3 and BT-474 cells and low binding to MCF10A confirmed that in this study anti-HER2 antibodies have conserved binding ability to HER2 even after conjugation with liposome.

Conclusion

PLCγ1 protein levels did indeed decrease after treatment with immuno-liposome form of compounds in both two tested cell lines, verifying the inhibition ability of them. Moreover, an elevated antibody activity is associated with liposomes conjugation suggesting that immuno-liposome may be a potential target for enhancing the antibody activity.

Dual-Mode Dark Field and Surface-Enhanced Raman Scattering Liposomes for Lymphoma and Leukemia Cell Imaging

Multifunctional probes are needed to characterize individual cells simultaneously by different techniques to provide complementary information. A preparative method and an in vitro demonstration of function are presented for a dual-function dark field microscopy/surface-enhanced Raman scattering (SERS) liposome probe for cancer. Liposomes composed of zwitterionic lipids are valuable both to limit biofouling and to serve as a modular matrix to incorporate a variety of functional molecules and hence are used here as vehicles for SERS-active materials. Dark field microscopy and SERS represent new combined functionalities for targeted liposomal probes. Two methods of antibody conjugation to SERS liposomes are demonstrated: (i) direct conjugation to functional groups on the SERS liposome surface and (ii) postinsertion of lipid-functionalized antibody fragments (Fabs) into preformed SERS liposomes. In vitro experiments targeting both lymphoma cell line LY10 and primary human chronic lymphocytic leukemia (CLL) cells demonstrate the usefulness of these probes as optical contrast agents in both dark field and Raman microscopy.

Apoptosis-promoting effect of rituximab-conjugated magnetic nanoprobes on malignant lymphoma cells with CD20 overexpression

Background

Cancer targeting nanoprobes with precisely designed physicochemical properties may show enhanced pharmacological targeting and therapeutic efficacy. As a widely used commercialized antibody, rituximab has been in clinical use for three decades and has lengthened or even saved thousands of lives. However, many people cannot benefit from rituximab treatment because of drug resistance or side effects.

Methods

In this study, a 13-nm rituximab-conjugated magnetic nanoparticle was developed as a therapeutic nanoprobe targeting CD20 overexpressing malignant lymphoma cells to enhance the treatment effects of rituximab. The magnetic cores (2,3-dimercaptosuccinicacid modified Fe₃O₄ nanoparticles, Fe₃O₄@DMSA) of the nanoprobes with an average diameter of 6.5 nm were synthesized using a co-precipitation method. Rituximab was then conjugated on the surface of Fe₃O₄@DMSA using a cross-linking agent (carbodiimide/N-hydroxysulfosuccinimide sodium salt). Based on theoretical calculations, approximately one antibody was coupled with one nanoparticle, excluding the multivalent antibody effect.

Results

Cell targeting experiments and magnetic resonance (MR) signal and T2 measurements showed that the Fe₃O₄@DMSA@Ab nanoprobes have specific binding affinity for CD20-positive cells. Compared to rituximab and Fe₃O₄@DMSA, Fe₃O₄@DMSA@Ab nanoprobes significantly reduced cell viability and promoted Raji cell apoptosis. Initiating events of apoptosis, including increased intracellular calcium and reactive oxygen species, were observed in nanoprobe-treated Raji cells. Nanoprobe-treated Raji cells also showed the most drastic decrease in mitochondrial membrane potential and Bcl-2 expression, compared to rituximab and Fe₃O₄@DMSA-treated Raji cells.

Conclusion

These results indicate that Fe₃O₄@DMSA@Ab nanoprobes have the potential to serve as MRI tracers and therapeutic agents for CD20-positive cells.

Novel Immunoliposome Technology for Enhancing the Activity of the Agonistic Antibody against the Tumor Necrosis Factor Receptor Superfamily

We have developed a technology for efficiently enhancing the anticancer apoptosis-inducing activity of agonistic antibodies against the tumor necrosis factor receptor (TNFR) superfamily by the formation of immunoliposomes. To induce apoptosis in cancer cells, agonistic antibodies to the TNFR superfamily normally need cross-linking by internal immune effector cells via the Fc region after binding to receptors on the cell membrane. To develop apoptosis-inducing antibodies that do not require the support of cross-linking by immune cells, we prepared immunoliposomes conjugated with TRA-8, an agonistic antibody against death receptor 5 (DR5), with various densities of antibody on the liposome surface, and evaluated their activities. The TRA-8 immunoliposomes exhibited apoptosis-inducing activity against various DR5-positive human carcinoma cells at a significantly lower concentration without cross-linking than that of the original TRA-8 and its natural ligand (TRAIL). The activity of the immunoliposomes was correlated with the density of antibodies on the surface. As the antibody component, not only the full-length antibody but also the Fab' fragment could be used, and the TRA-8 Fab' immunoliposomes also showed exceedingly high activity compared with the parental antibody, namely, TRA-8. Moreover, cytotoxicity of the TRA-8 full-length or Fab' immunoliposome against normal cells, such as human primary hepatocytes, was lower than that for TRAIL. Enhanced activity was also observed for immunoliposomes conjugated with other apoptosis-inducing antibodies against other receptors of the TNFR superfamily, such as death receptor 4 (DR4) and Fas. Thus, immunoliposomes are promising as a new modality that could exhibit significant activity at a low dose, for cost-effective application of an antibody fragment and with stable efficacy independent of the intratumoral environment of patients as a TNF superfamily agonistic therapy.

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.

Association of rituximab with graphene oxide confers direct cytotoxicity for CD20-positive lymphoma cells

Non-Hodgkin lymphoma (NHL) is one of the most common hematologic malignancies among adults for which the chimeric monoclonal anti-CD20 antibody (Ab) rituximab (RTX) is used as first-line therapy. As RTX itself is not directly cytotoxic but relies on host immune effector mechanisms or chemotherapeutic agents to attack target cells, its therapeutic capacity may become limited when host effector mechanisms are compromised. Currently, refractory disease and relapse with NHL are still common, highlighting the need for novel anti-CD20 antibody strategies with superior therapeutic efficacy over current protocols. We hypothesized that making RTX directly cytotoxic might improve the therapeutic efficacy. Graphene oxide (GO) has recently emerged as a highly attractive nanomaterial for biomedical applications; and several studies have reported cytotoxic effect of GO on benign and malignant cells in vitro. Herein, we report that RTX can be stably associated with GO, and that GO-associated RTX (RTX/GO) demonstrates remarkably high avidity for CD20. Binding of GO-associated RTX to CD20-positive lymphoma cells induces CD20 capping and target cell death through an actin dependent mechanism. In vivo, GO-associated RTX, but not free RTX, quickly eliminates high-grade lymphomas in the absence of host effector mechanisms in a xenograft lymphoma mouse model. Our findings represent the first demonstration of using GO-associated antibody as effective cytotoxic therapy for human B cell malignancies in the absence of chemotherapy, and these findings could have important clinical implications.

A new paradigm for antiangiogenic therapy through controlled release of bevacizumab from PLGA nanoparticles

Monoclonal antibodies have deserved a remarkable interest for more than 40 years as a vital tool for the treatment of various diseases. Still, there is a raising interest to develop advanced monoclonal antibody delivery systems able to tailor pharmacokinetics. Bevacizumab is a humanized immunoglobulin IgG1 used in antiangiogenic therapies due to its capacity to inhibit the interaction between vascular endothelial growth factor and its receptor. However, bevacizumab-based antiangiogenic therapy is not always effective due to poor treatment compliance associated to multiples administrations and drug resistance. In this work, we show a promising strategy of encapsulating bevacizumab to protect and deliver it, in a controlled manner, increasing the time between administrations and formulation shelf-life. Nanoencapsulation of bevacizumab represents a significant advance for selective antiangiogenic therapies since extracellular, cell surface and intracellular targets can be reached. The present study shows that bevacizumab-loaded poly (lactic-co-glycolic acid) (PLGA) nanoparticles does not impair its native-like structure after encapsulation and fully retain the bioactivity, making this nanosystem a new paradigm for the improvement of angiogenic therapy.

Inhibition of HIV Virus by Neutralizing Vhh Attached to Dual Functional Liposomes Encapsulating Dapivirine

Although highly active antiretroviral therapy (HAART) has greatly improved the life expectancy of HIV/AIDS patients, the treatment is not curative. It is a global challenge which fosters an urgent need to develop an effective drug or neutralizing antibody delivery approach for the prevention and treatment of this disease. Due to the low density of envelope spikes with restricted mobility present on the surface of HIV virus, which limit the antibody potency and allow virus mutation and escape from the immune system, it is important for a neutralizing antibody to form bivalent or multivalent bonds with the virus. Liposome constructs could fulfil this need due to the flexible mobility of the membrane with its attached antibodies and the capacity for drug encapsulation. In this study, we evaluated the neutralization activity of a range of liposome formulations in different sizes coated with anti-gp120 llama antibody fragments (Vhhs) conjugated via either non-covalent metal chelation or a covalent linkage. The non-covalent construct demonstrated identical binding affinity to HIV-1 envelope glycoprotein gp120 and neutralizing ability for HIV virus as free Vhh. Although covalently linked Vhh showed significant binding affinity to gp120, it unexpectedly had a lower neutralization potency. This may be due to the comparability in size of the viral and liposome particles restricting the number which can be bound to the liposome surface so involving only a fraction of the antibodies, whereas non-covalently attached antibodies dissociate from the surface after acting with gp120 and free the remainder to bind further viruses. Covalently conjugated Vhh might also trigger the cellular uptake of a liposome-virion complex. To explore the possible ability of the antibody-coated liposomes to have a further function, we encapsulated the hydrophobic antiviral drug dapivirine into both of the non-covalently and covalently conjugated liposome formulations, both of which revealed high efficacy in reducing viral replication in vitro. Thus, dual function liposomes may lead to a novel strategy for the prophylaxis of HIV/AIDS by combining the neutralizing activity of Vhh with antiviral effects of high drug concentrations.

Antibody-targeted biodegradable nanoparticles for cancer therapy

The use of nanotechnology has great potentials to revolutionize the future cancer diagnosis and therapy. In this context, various nanoparticles (NPs) have been developed for targeted delivery of diagnostic/therapeutic agents to the tumor sites, which thus result in greater efficacy and much less side effects. The targeting property of NPs is often achieved by functionalizing their surface with tumor-specific ligands, such as antibodies, peptides, small molecules and oligonucleotides. In this review, we will discuss recent progress in the multifunctional design of antibody-targeted NPs with a special focus on liposomal, polymeric and protein-based delivery systems.

Extensive crosslinking of CD22 by epratuzumab triggers BCR signaling and caspase-dependent apoptosis in human lymphoma cells

Epratuzumab has demonstrated therapeutic activity in patients with non-Hodgkin lymphoma, acute lymphoblastic leukemia, systemic lupus erythematosus, and Sjögren's syndrome, but its mechanism of affecting normal and malignant B cells remains incompletely understood. We reported previously that epratuzumab displayed in vitro cytotoxicity to CD22-expressing Burkitt lymphoma cell lines (Daudi and Ramos) only when immobilized on plates or combined with a crosslinking antibody plus a suboptimal amount of anti-IgM (1 μg/mL). Herein, we show that, in the absence of additional anti-IgM ligation, extensive crosslinking of CD22 by plate-immobilized epratuzumab induced intracellular changes in Daudi cells similar to ligating B-cell antigen receptor with a sufficiently high amount of anti-IgM (10 μg/mL). Specifically, either treatment led to phosphorylation of CD22, CD79a and CD79b, along with their translocation to lipid rafts, both of which were essential for effecting caspase-dependent apoptosis. Moreover, such immobilization induced stabilization of F-actin, phosphorylation of Lyn, ERKs and JNKs, generation of reactive oxygen species (ROS), decrease in mitochondria membrane potential (Δψ_m), upregulation of pro-apoptotic Bax, and downregulation of anti-apoptotic Bcl-xl and Mcl-1. The physiological relevance of immobilized epratuzumab was implicated by noting that several of its in vitro effects, including apoptosis, drop in Δψ_m, and generation of ROS, could be observed with soluble epratuzumab in Daudi cells co-cultivated with human umbilical vein endothelial cells. These results suggest that the in vivo mechanism of non-ligand-blocking epratuzumab may, in part, involve the unmasking of CD22 to facilitate the trans-interaction of B cells with vascular endothelium.

Multifunctional, stimuli-sensitive nanoparticulate systems for drug delivery

The use of nanoparticulate pharmaceutical drug delivery systems (NDDSs) to enhance the in vivo effectiveness of drugs is now well established. The development of multifunctional and stimulus-sensitive NDDSs is an active area of current research. Such NDDSs can have long circulation times, target the site of the disease and enhance the intracellular delivery of a drug. This type of NDDS can also respond to local stimuli that are characteristic of the pathological site by, for example, releasing an entrapped drug or shedding a protective coating, thus facilitating the interaction between drug-loaded nanocarriers and target cells or tissues. In addition, imaging contrast moieties can be attached to these carriers to track their real-time biodistribution and accumulation in target cells or tissues. Here, I highlight recent developments with multifunctional and stimuli-sensitive NDDSs and their therapeutic potential for diseases including cancer, cardiovascular diseases and infectious diseases.

Multifunctional, stimuli-sensitive nanoparticulate systems for drug delivery

The use of nanoparticulate pharmaceutical drug delivery systems (NDDSs) to enhance the in vivo effectiveness of drugs is now well established. The development of multifunctional and stimulus-sensitive NDDSs is an active area of current research. Such NDDSs can have long circulation times, target the site of the disease and enhance the intracellular delivery of a drug. This type of NDDS can also respond to local stimuli that are characteristic of the pathological site by, for example, releasing an entrapped drug or shedding a protective coating, thus facilitating the interaction between drug-loaded nanocarriers and target cells or tissues. In addition, imaging contrast moieties can be attached to these carriers to track their real-time biodistribution and accumulation in target cells or tissues. Here, I highlight recent developments with multifunctional and stimuli-sensitive NDDSs and their therapeutic potential for diseases including cancer, cardiovascular diseases and infectious diseases.

Quantitative comparison of tumor delivery for multiple targeted nanoparticles simultaneously by multiplex ICP-MS

Given the rapidly expanding library of disease biomarkers and targeting agents, the number of unique targeted nanoparticles is growing exponentially. The high variability and expense of animal testing often makes it unfeasible to examine this large number of nanoparticles in vivo. This often leads to the investigation of a single formulation that performed best in vitro. However, nanoparticle performance in vivo depends on many variables, many of which cannot be adequately assessed with cell-based assays. To address this issue, we developed a lanthanide-doped nanoparticle method that allows quantitative comparison of multiple targeted nanoparticles simultaneously. Specifically, superparamagnetic iron oxide (SPIO) nanoparticles with different targeting ligands were created, each with a unique lanthanide dopant. Following the simultaneous injection of the various SPIO compositions into tumor-bearing mice, inductively coupled plasma mass spectroscopy was used to quantitatively and orthogonally assess the concentration of each SPIO composition in serial blood and resected tumor samples.

Ligand-targeted liposome design: challenges and fundamental considerations

Nanomedicine, particularly liposomal drug delivery, has expanded considerably over the past few decades, and several liposomal drugs are already providing improved clinical outcomes. Liposomes have now progressed beyond simple, inert drug carriers and can be designed to be highly responsive in vivo, with active targeting, increased stealth, and controlled drug-release properties. Ligand-targeted liposomes (LTLs) have the potential to revolutionize the treatment of cancer. However, these highly engineered liposomes generate new problems, such as accelerated clearance from circulation, compromised targeting owing to non-specific serum protein binding, and hindered tumor penetration. This article highlights recent challenges facing LTL strategies and describes the advanced design elements used to circumvent them.

Current trends in the use of liposomes for tumor targeting

The use of liposomes for drug delivery began early in the history of pharmaceutical nanocarriers. These nanosized, lipid bilayered vesicles have become popular as drug delivery systems owing to their efficiency, biocompatibility, nonimmunogenicity, enhanced solubility of chemotherapeutic agents and their ability to encapsulate a wide array of drugs. Passive and ligand-mediated active targeting promote tumor specificity with diminished adverse off-target effects. The current field of liposomes focuses on both clinical and diagnostic applications. Recent efforts have concentrated on the development of multifunctional liposomes that target cells and cellular organelles with a single delivery system. This review discusses the recent advances in liposome research in tumor targeting.

Targeted drug delivery and cross-linking induced apoptosis with anti-CD37 based dual-ligand immunoliposomes in B chronic lymphocytic leukemia cells

Despite advances in chemo and immunotherapeutic agents for B chronic lymphocytic leukemia (B-CLL), the undesirable adverse side effects due to non-specific cellular uptake remain to be addressed. We identified anti-CD37 monoclonal antibody immunoliposomes (ILs) as vehicles for targeted delivery to B chronic lymphocytic leukemia cells. To achieve maximal benefits for all patients, a new strategy of dual-ligand immunoliposomes (dILs) was developed. A combinatorial antibody microarray technology was adapted to quickly identify optimal antibody combinations for individual patient cells. For proof-of-concept, a B-cell specific antibody, either anti-CD19 or anti-CD20, was combined with anti-CD37 to construct dILs with enhanced selectivity and efficacy. Consistent with data from the antibody microarray, these dILs provided highly specific targeting to both leukemia cell lines and B-CLL patient cells. Compared with the single antibody ILs, the anti-CD19/CD37 dILs clearly demonstrated superior delivery efficiency and apoptosis induction to B-CLL patient cells, whereas the anti-CD20/anti-CD37 dILs were found to be the most efficient for delivery to leukemia cell lines. In addition, it was observed that anti-CD37 ILs without payload drug mediated effective CD37 cross-linking and induced potent apoptosis induction. The anti-CD19/CD20 dILs showed the improved cell apoptosis induction compared to either anti-CD19 ILs or anti-CD20 ILs. Our findings suggest that the dual-ligand ILs may provide a preferred strategy of personalized nanomedicine for the treatment of B-cell malignancies.

Cytophilic/cytophobic design of nanomaterials at biointerfaces

To control interactions between cells and nanomaterials has been a great challenge because numerous nanomaterials have been intensively explored in the fields of biology and medicine. However, current surface modification of nanomaterials is mainly carried out in an empirical way. Herein, a general strategy to tune the surface chemistry of nanomaterials is proposed based on cell affinity, that is, cytophilic or cytophobic. The cell affinity of nanomaterials directly affects cellular response to materials at the very early stage of cell-material interactions before other events, such as endocytosis, cell spreading, and cell differentiation, occur. In this Concept, it is suggested that there is a developing library of cytophilic and cytophobic moieties, and how the cell affinity of nanomaterials functions at biointerfaces is discussed by exemplifying several applications, namely therapy, tissue engineering, and biosensors. It is believed that control of the cytophilic/cytophobic property will be helpful in guiding the design of functional nanomaterials for their biomedical applications.

Heavy Chain Only Antibodies: A New Paradigm in Personalized HER2+ Breast Cancer Therapy

Unlike conventional antibodies, heavy chain only antibodies derived from camel contain a single variable domain (VHH) and two constant domains (CH2 and CH3). Cloned and isolated VHHs possess unique properties that enable them to excel conventional therapeutic antibodies and their smaller antigen-binding fragments in cancer targeting and therapy. VHHs express low immunogenicity, are highly robust and easy to manufacture and have the ability to recognize hidden or uncommon epitopes. We highlight the utility of VHH in design of new molecular, multifunctional particulate and immune cell-based systems for combating HER2+ breast cancer.

Targeted nanoparticle delivery overcomes off-target immunostimulatory effects of oligonucleotides and improves therapeutic efficacy in chronic lymphocytic leukemia

Several RNA-targeted therapeutics, including antisense oligonucleotides (ONs), small interfering RNAs, and miRNAs, constitute immunostimulatory CpG motifs as an integral part of their design. The limited success with free antisense ONs in hematologic malignancies in recent clinical trials has been attributed to the CpG motif-mediated, TLR-induced prosurvival effects and inefficient target modulation in desired cells. In an attempt to diminish their off-target prosurvival and proinflammatory effects and specific delivery, as a proof of principle, in the present study, we developed an Ab-targeted liposomal delivery strategy using a clinically relevant CD20 Ab (rituximab)-conjugated lipopolyplex nanoparticle (RIT-INP)- and Bcl-2-targeted antisense G3139 as archetypical antisense therapeutics. The adverse immunostimulatory responses were abrogated by selective B cell-targeted delivery and early endosomal compartmentalization of G3139-encapsulated RIT-INPs, resulting in reduced NF-κB activation, robust Bcl-2 down-regulation, and enhanced sensitivity to fludarabine-induced cytotoxicity. Furthermore, significant in vivo therapeutic efficacy was noted after RIT-INP-G3139 administration in a disseminated xenograft leukemia model. The results of the present study demonstrate that CD20-targeted delivery overcomes the immunostimulatory properties of CpG-containing ON therapeutics and improves efficient gene silencing and in vivo therapeutic efficacy for B-cell malignancies. The broader implications of similar approaches in overcoming immunostimulatory properties of RNA-directed therapeutics in hematologic malignancies are also discussed.

Effect of ligand density, receptor density, and nanoparticle size on cell targeting

It is generally accepted that the presentation of multiple ligands on a nanoparticle (NP) surface can improve cell targeting; however, little work has been done to determine whether an optimal ligand density exists. We have recently developed a site-specific bioconjugation strategy that allows for distinct control of ligand density on a NP through the combined utilization of expressed protein ligation (EPL) and copper-free click chemistry. This EPL-Click conjugation strategy was applied to create superparamagnetic iron oxide (SPIO) NPs labeled with HER2/neu targeting affibodies at differing ligand densities. It was discovered that an intermediate ligand density provided statistically significant improvements in cell binding in comparison with higher and lower ligand densities. This intermediate optimal ligand density was conserved across NPs with differing hydrodynamic diameters, different HER2/neu targeting ligands and also to cells with lower receptor densities. Additionally, an intermediate optimal ligand density was also evident when NPs were labeled with folic acid.

FROM THE CLINICAL EDITOR

The authors of this study investigated optimal ligand density with SPIO-based labeling and concluded that intermediate density appears to have the most optimal labeling properties from the standpoint of its T2* shortening effect.

Multivalent rituximab lipid nanoparticles as improved lymphoma therapies: indirect mechanisms of action and in vivo activity

AIMS

The activity of therapeutic antibodies can be enhanced by creating multivalent constructs, such as antibody lipid nanoparticles (LNPs). Here, we examine differences between rituximab (Ritux) and Ritux-LNPs in terms of their indirect mechanisms of action: complement-dependent cytotoxicity (CDC) and antibody-dependent cell-mediated cytotoxicity (ADCC).

MATERIALS & METHODS

We employed two mantle-cell lymphoma cell lines, Z138 and JVM2, which exhibit different in vivo sensitivities to Ritux along with variable expression levels of cell-surface proteins that regulate ADCC and CDC.

RESULTS

In both cell lines, CDC and ADCC were found to be significantly enhanced after treatment with Ritux-LNPs compared with Ritux. In vivo efficacy studies, however, suggested that the therapeutic activities of Ritux and Ritux-LNPs were equivalent, which was subsequently explained in part by pharmacokinetic studies indicating rapid elimination of Ritux-LNP.

CONCLUSION

Although indirect and direct mechanisms of multivalent Ritux are enhanced, its further development requires methods to improve its circulation lifetime.

More effective nanomedicines through particle design

Nanomedicine is an emerging field that applies concepts in nanotechnology to develop novel diagnostics and therapies. Physical and chemical properties of particles, including size, shape, modulus, surface charge and surface chemistry, play an important role in determining particle-cell interactions, cellular trafficking mechanisms, biodistribution, and pharmacokinetics. This discussion focuses on both nanoparticles and microparticles since microparticles can also provide many insights for the development of drug carriers and possess advantages over nanoparticles in certain applications. This review covers recent major advancement in the nanomedicine field and also highlights studies using the PRINT technology.

Peptide-conjugated polymeric micellar nanoparticles for Dual SPECT and optical imaging of EphB4 receptors in prostate cancer xenografts

EphB4, a member of the largest family of receptor tyrosine kinases, is overexpressed in numerous tumors. In this study, we developed a new class of multimodal nanoplatform for dual single photon emission computed tomography (SPECT) and near-infrared fluorescence imaging of EphB4. EphB4-binding peptide TNYL-FSPNGPIARAW (TNYL-RAW) was conjugated to polyethylene glycol-coated, core-crosslinked polymeric micelles (CCPM) dually labeled with near-infrared fluorescence fluorophores (Cy7) and a radioisotope (indium 111). In vitro, TNYL-RAW-CCPM selectively bound to EphB4-positive PC-3M prostate cancer cells, but not to EphB4-negative A549 lung cancer cells. In vivo, PC-3M tumors were clearly visualized by both SPECT and near-infrared fluorescence tomography after intravenous administration of (111)In-labeled TNYL-RAW-CCPM. In contrast, there was little signal in A549 tumors of mice injected with (111)In-labeled TNYL-RAW-CCPM or in PC-3M tumors of mice injected with (111)In-labeled CCPM. The high accumulation of (111)In-labeled TNYL-RAW-CCPM in PC-3M tumor could be significantly reduced after co-injection with an excess amount of TNYL-RAW peptide. Immunohistochemical analysis showed that fluorescence signal from the nanoparticles correlated with their radioactivity count, and co-localized with the EphB4 expressing region. (111)In-labeled TNYL-RAW-CCPM allowed visualization of cancer cells overexpressing EphB4 by both nuclear and optical techniques. The complementary information acquired with multiple imaging techniques should be advantageous in early detection of cancer.

Antibody-targeted nanoparticles for cancer therapy

In recent years, nanoparticulate-mediated drug delivery research has examined a full spectrum of nanoparticles that can be used in diagnostic and therapeutic cancer applications. A key aspect of this technology is in the potential to specifically target the nanoparticles to diseased cells using a range of molecules, in particular antibodies. Antibody–nanoparticle conjugates have the potential to elicit effective targeting and release of therapeutic targets at the disease site, while minimizing off-target side effects caused by dosing of normal tissues. This article provides an overview of various antibody-conjugated nanoparticle strategies, focusing on the rationale of cell-surface receptors targeted and their potential clinical application.

The complex role of multivalency in nanoparticles targeting the transferrin receptor for cancer therapies

Transferrin receptor (TfR, CD71) has long been a therapeutic target due to its overexpression in many malignant tissues. In this study, PRINT() nanoparticles were conjugated with TfR ligands for targeted drug delivery. Cylindrical poly(ethylene glycol)-based PRINT nanoparticles (diameter (d) = 200 nm, height (h) = 200 nm) labeled with transferrin receptor antibody (NP-OKT9) or human transferrin (NP-hTf) showed highly specific TfR-mediated uptake by all human tumor cell lines tested, relative to negative controls (IgG1 for OKT9 or bovine transferrin (bTf) for hTf). The targeting efficiency was dependent on particle concentration, ligand density, dosing time, and cell surface receptor expression level. Interestingly, NP-OKT9 or NP-hTf showed little cytotoxicity on all solid tumor cell lines tested but were very toxic to Ramos B-cell lymphoma, whereas free OKT9 or hTf was not toxic. There was a strong correlation between TfR ligand density on the particle surface and cell viability and particle uptake. NP-OKT9 and NP-hTf were internalized into acidic intracellular compartments but were not localized in EEA1-enriched early endosomes or lysosomes. Elevated caspase 3/7 activity indicates activation of apoptosis pathways upon particle treatment. Supplementation of iron suppressed the toxicity of NP-OKT9 but not NP-hTf, suggesting different mechanisms by which NP-hTf and NP-OKT9 exerts cytotoxicity on Ramos cells. On the basis of such an observation, the complex role of multivalency in nanoparticles is discussed. In addition, our data clearly reveal that one must be careful in making claims of "lack of toxicity" when a targeting molecule is used on nanoparticles and also raise concerns for unanticipated off-target effects when one is designing targeted chemotherapy nanodelivery agents.

Architectonics of phage-liposome nanowebs as optimized photosensitizer vehicles for photodynamic cancer therapy

Filamentous M13 phage can be engineered to display cancer cell-targeting or tumor-homing peptides through phage display. It would be highly desirable if the tumor-targeting phage can also carry anticancer drugs to deliver them to the cancer cells. We studied the evolution of structures of the complexes between anionic filamentous M13 phage and cationic serum-stable liposomes that encapsulate the monomeric photosensitizer zinc naphthalocyanine. At specific phage-liposome ratios, multiple phage nanofibers and liposomes are interwoven into a "nanoweb." The chemical and biological properties of the phage-liposome nanoweb were evaluated for possible application in drug delivery. This study highlights the ability of phage-liposome nanowebs to serve as efficient carriers in the transport of photosensitizers to cancer cells.

Enhanced loading efficiency and retention of 225Ac in rigid liposomes for potential targeted therapy of micrometastases

Targeted alpha-particle emitters are promising therapeutics for micrometastatic disease. Actinium-225 has a 10-day half-life and generates a total of four alpha-particles per parent decay rendering (225)Ac an attractive candidate for alpha-therapy. For cancer cells with low surface expression levels of molecular targets, targeting strategies of (225)Ac using radiolabeled carriers of low specific radioactivities (such as antibodies) may not deliver enough alpha-particle emitters at the targeted cancer cells to result in killing. We previously proposed and showed using passive (225)Ac entrapment that liposomes can stably retain encapsulated (225)Ac for long time periods, and that antibody-conjugated liposomes (immunoliposomes) with encapsulated (225)Ac can specifically target and become internalized by cancer cells. However, to enable therapeutic use of (225)Ac-containing liposomes, high activities of (225)Ac need to be stably encapsulated into liposomes. In this study, various conditions for active loading of (225)Ac in preformed liposomes (ionophore-type, encapsulated buffer solution, and loading time) were evaluated, and liposomes with up to 73 +/- 9% of the initial activity of (225)Ac (0.2-200 microCi) were developed. Retention of radioactive contents by liposomes was evaluated at 37 degrees C in phosphate buffer and in serum-supplemented media. The main fraction of released (225)Ac from liposomes occurs within the first two hours of incubation. Beyond this two hour point, the encapsulated radioactivity is released from liposomes slowly with an approximate half-life of the order of several days. In some cases, after 30 days, (225)Ac retention as high as 81 +/- 7% of the initially encapsulated radioactivity was achieved. The (225)Ac loading protocol was also applied to immunoliposome loading without significant loss of targeting efficacy. Liposomes with surface-conjugated antibodies that are loaded with (225)Ac overcome the limitations of low specific activity for molecular carriers and are expected to be therapeutically useful against tumor cells having a low antigen density.

Architecture Effects on the Binding of Cholera Toxin by Helical Glycopolypeptides

A variety of binding events in biological systems are mediated by multivalent interactions between oligosaccharides and saccharide receptors present on pathogens and cell surfaces. In particular, given the important role of multivalent interaction between proteins and carbohydrates in the initial step of pathogen recognition, many glycosylated molecules and polymers have been synthesized in order to mimic the carbohydrate ligands and to inhibit the binding of the pathogen to its target. In this work, we extend our evaluation of the impact of the architecture of well-defined glycopolypeptides on the inhibition of binding of the cholera toxin B pentamer (CT B(5)) subunit. Here we report the production of two families of α-helical glycopolypeptides which were synthesized via a combination of protein engineering and chemical methods. The presentation of pendant saccharides on the polypeptide backbones, as well as their valencies, can be well controlled via these methods. Control of the backbone conformation, introduced in this report, is also possible via these strategies. The polypeptides and glycopolypeptides were characterized via SDS-PAGE analysis, (1)H NMR, and MALDI-TOF mass spectrometry. Their conformation and hydrodynamic volume were characterized by circular dichroic (CD) spectroscopy and gel permeation chromatography (GPC), respectively. The binding of CT B(5) by these glycopolypeptides was evaluated via direct enzyme-linked immunosorbent assay (DELA). The effects of spacing and conformation were elucidated by comparison of the binding exhibited by helical glycopolypeptides with that of random-coil glycopolypeptides.

Surface-active liposomes for targeted cancer therapy

An overview of liposome-based drug-delivery carriers to cancer cells is presented. Properties related to interfacial interactions between liposomes and the biological milieu that determine the fate of liposomes in vivo are discussed. Original approaches to improve specificity for the target and to control the structural responsiveness of liposomes, depending on their immediate environment, with the aim of enhancing the delivered therapeutic doses, are summarized. This review is not exhaustive on research examples of liposomes as carriers for cancer therapy but, rather, aims to describe major directions of designs and strategies over recent years. The current therapeutic trends that exhibit increasingly higher complexity in structures and responses are also discussed.