Nanomedicines for active targeting: Physico-chemical characterization of paclitaxel-loaded anti-HER2 immunonanoparticles and in vitro functional studies on target cells

Antibody-Nanoparticle Conjugates in Therapy: Combining the Best of Two Worlds

Monoclonal antibodies (mAbs) and antibody fragments have revolutionized medicine as highly specific binding agents and inhibitors. At the same time, several types of nanomaterials, including liposomes, lipid nanoparticles (NPs), polymersomes, metal and metal oxide NPs, and protein nanostructures, are increasingly utilized and explored for therapeutic potential due to their versatility, chemical and physical properties, and tunability. However, nanomaterials alone often lack specificity, leading to relatively low efficacy and/or high toxicity. To address this problem, a rapidly emerging area is antibody-nanomaterial conjugates (ANCs), which combine the precise targeting specificity of antibodies with the effector functionality of the nanomaterial. In this review, we give a brief introduction to mAbs and major conjugation techniques, describe major classes of nanomaterials being studied for therapeutic potential, and review the literature on ANCs of each class. Special focus is given to emerging applications including ANCs addressing the blood-brain barrier, ANCs delivering nucleic acids, and light-activated ANCs. While many disease targets are related to cancer, ANCs are also under development to address autoimmune, neurological, and infectious diseases. While important challenges remain, ANCs are poised to become a next-generation therapeutic technology.

Targeted therapy of breast tumor by PLGA-based nanostructures: The versatile function in doxorubicin delivery

Breast carcinoma is a molecularly diverse illness, and it is among the most prominent and often reported malignancies in female across the globe. Surgical intervention, chemotherapy, immunotherapy, gene therapy, and endocrine treatment are among the currently viable treatment options for the carcinoma of breast. Chemotherapy is among the most prevalent cancer management strategy. Doxorubicin (DOX) widely employed as a cytostatic medication for the treatment of a variety of malignancies. Despite its widespread acceptance and excellent efficacy against an extensive line up of neoplasia, it has a variety of shortcomings that limit its therapeutic potential in the previously mentioned indications. Employment of nanoparticulate systems has come up as a unique chemo medication delivery strategy and are being considerably explored for the amelioration of breast carcinoma. Polylactic-co-glycolic acid (PLGA)-based nano systems are being utilized in a number of areas within the medical research and medication delivery constitutes one of the primary functions for PLGA given their inherent physiochemical attributes, including their aqueous solubility, biocompatibility, biodegradability, versatility in formulation, and limited toxicity. Herein along with the different application of PLGA-based nano formulations in cancer therapy, the present review intends to describe the various research investigations that have been conducted to enumerate the effectiveness of DOX-encapsulated PLGA nanoparticles (DOX-PLGA NPs) as a feasible treatment option for breast cancer.

Smart Nanocarrier-Based Cancer Therapeutics

Considerable advances in the field of cancer have been made; however, these have not been translated into similar clinical progress which results in the high prevalence and increased cancer-related mortality rate worldwide. Available treatments have several challenges such as off-target side effects, non-specific long-term potential biodisruption, drug resistance, and overall inadequate response rates and high probability of recurrence. The limitations associated with independent cancer diagnosis and therapy can be minimized by an emerging interdisciplinary research field of nanotheranostics which include successful integration of diagnosis and therapy on a single agent using nanoparticles. This may offer a powerful tool in developing innovative strategies to enable "personalized medicine" for diagnosis and treatment of cancer. Nanoparticles have been proven to be powerful imaging tools or potent agents for cancer diagnosis, treatment, and prevention. The nanotheranostic provides minimally invasive in vivo visualization of drug biodistribution and accumulation at the target site with real-time monitoring of therapeutic outcome. This chapter intends to cover several important aspects and the advances in the field of nanoparticles-mediated cancer therapeutics including nanocarrier development, drug/gene delivery, intrinsically active nanoparticles, tumor microenvironment, and nanotoxicity. The chapter represents an overview of challenges associated with cancer treatment, rational for nanotechnology in cancer therapeutics, novel concepts of multifunctional nanomaterials for cancer therapy along with their classification and their clinical prospective in different cancers. A special focus is on the nanotechnology: regulatory perspective for drug development in cancer therapeutics. Obstacles hindering further development of nanomaterials-mediated cancer therapy are also discussed. In general, the objective of this chapter is to improve our perceptive in the design and development of nanotechnology for cancer therapeutics.

Role of Nanotechnology in Overcoming the Multidrug Resistance in Cancer Therapy: A Review

Cancer is one of the leading causes of morbidity and mortality around the globe and is likely to become the major cause of global death in the coming years. As per World Health Organization (WHO) report, every year there are over 10 and 9 million new cases and deaths from this disease. Chemotherapy, radiotherapy, and surgery are the three basic approaches to treating cancer. These approaches are aiming at eradicating all cancer cells with minimum off-target effects on other cell types. Most drugs have serious adverse effects due to the lack of target selectivity. On the other hand, resistance to already available drugs has emerged as a major obstacle in cancer chemotherapy, allowing cancer to proliferate irrespective of the chemotherapeutic agent. Consequently, it leads to multidrug resistance (MDR), a growing concern in the scientific community. To overcome this problem, in recent years, nanotechnology-based drug therapies have been explored and have shown great promise in overcoming resistance, with most nano-based drugs being explored at the clinical level. Through this review, we try to explain various mechanisms involved in multidrug resistance in cancer and the role nanotechnology has played in overcoming or reversing this resistance.

CD-340 functionalized doxorubicin-loaded nanoparticle induces apoptosis and reduces tumor volume along with drug-related cardiotoxicity in mice

Background and objective

Targeted drug delivery of nanoparticles decorated with site-specific recognition ligands is of considerable interest to minimize cytotoxicity of chemotherapeutics in the normal cells. The study was designed to develop CD-340 antibody-conjugated polylactic-co-glycolic acid (PLGA) nanoparticles loaded with a highly water-soluble potent anticancer drug, doxorubicin (DOX), to specifically deliver entrapped DOX to breast cancer cells.

Methods

The study showed how to incorporate water-soluble drug in a hydrophobic PLGA (85:15) based matrix which otherwise shows poor drug loading due to leaching effect. The optimized formulation was covalently conjugated to anti-human epidermal growth factor receptor-2 (HER2) antibody (CD-340). Surface conjugation of the ligand was assessed by flow cytometry, confocal microscopy, and gel electrophoresis. Selectivity and cytotoxicity of the experimental nanoparticles were tested on human breast cancer cells SKBR-3, MCF-7, and MDA-MB-231. Both CD-340-conjugated and unconjugated nanoparticles were undergone in vitro and in vivo characterization.

Result

Higher level of incorporation of DOX (8.5% W/W), which otherwise shows poor drug loading due to leaching effect of the highly water-soluble drug, was seen in this method. In HER2-overexpressing tumor xenograft model, radiolabeled antibody-conjugated nanoparticles showed preferentially more of the formulation accumulation in the tumor area when compared to the treatments with the unconjugated one or with the other control groups of mice. The ligand conjugated nanoparticles showed considerable potential in reduction of tumor growth and cardiac toxicity of DOX in mice, a prominent side-effect of the drug.

Conclusion

In conclusion, CD-340-conjugated PLGA nanoparticles containing DOX preferentially delivered encapsulated drug to the breast cancer cells and in breast tumor and reduced the breast tumor cells by apoptosis. Site-specific delivery of the formulation to neoplastic cells did not affect normal cells and showed a drastic reduction of DOX-related cardiotoxicity.

Recent advances in "smart" delivery systems for extended drug release in cancer therapy

Advances in nanomedicine have become indispensable for targeted drug delivery, early detection, and increasingly personalized approaches to cancer treatment. Nanoparticle-based drug-delivery systems have overcome some of the limitations associated with traditional cancer-therapy administration, such as reduced drug solubility, chemoresistance, systemic toxicity, narrow therapeutic indices, and poor oral bioavailability. Advances in the field of nanomedicine include “smart” drug delivery, or multiple levels of targeting, and extended-release drug-delivery systems that provide additional methods of overcoming these limitations. More recently, the idea of combining smart drug delivery with extended-release has emerged in hopes of developing highly efficient nanoparticles with improved delivery, bioavailability, and safety profiles. Although functionalized and extended-release drug-delivery systems have been studied extensively, there remain gaps in the literature concerning their application in cancer treatment. We aim to provide an overview of smart and extended-release drug-delivery systems for the delivery of cancer therapies, as well as to introduce innovative advancements in nanoparticle design incorporating these principles. With the growing need for increasingly personalized medicine in cancer treatment, smart extended-release nanoparticles have the potential to enhance chemotherapy delivery, patient adherence, and treatment outcomes in cancer patients.

Epidermal growth factor receptor based active targeting: a paradigm shift towards advance tumor therapy

The epidermal growth factor receptor (EGFR) is a cell surface receptor belonging to erythroblastic leukemia viral oncogene homologue (ErbB) family of tyrosine kinase. It plays critical role in the regulation of cell proliferation, survival and differentiation. The EGFR receptor is crucial in a variety of tumor development due to unlikely triggered by receptor overexpression, chromosomal mutation and or ligand-dependent receptor dimerization. The EGFR inhibition established a major therapeutic target in cancer therapy. The signal transduction pathway of EGFR is directly involved in tumor pathogenesis and progression. The combinatorial approach with EGFR inhibitors bring novel therapeutic regime with proved clinical efficacy. This critique briefly addressed EGFR receptor characteristics, worldwide report on various cancers and EGFR based potential targeting modalities in skin, breast, ovary, brain, lungs, pancreas, gastric and colorectal tumors and molecular pathways involved in EGFR targeting.

Targeted Therapeutic Nanoparticles: An Immense Promise to Fight against Cancer

In nanomedicine, targeted therapeutic nanoparticle (NP) is a virtual outcome of nanotechnology taking the advantage of cancer propagation pattern. Tying up all elements such as therapeutic or imaging agent, targeting ligand, and cross-linking agent with the NPs is the key concept to deliver the payload selectively where it intends to reach. The microenvironment of tumor tissues in lymphatic vessels can also help targeted NPs to achieve their anticipated accumulation depending on the formulation objectives. This review accumulates the application of poly(lactic-co-glycolic acid) (PLGA) and polyethylene glycol (PEG) based NP systems, with a specific perspective in cancer. Nowadays, PLGA, PEG, or their combinations are the mostly used polymers to serve the purpose of targeted therapeutic NPs. Their unique physicochemical properties along with their biological activities are also discussed. Depending on the biological effects from parameters associated with existing NPs, several advantages and limitations have been explored in teaming up all the essential facts to give birth to targeted therapeutic NPs. Therefore, the current article will provide a comprehensive review of various approaches to fabricate a targeted system to achieve appropriate physicochemical properties. Based on such findings, researchers can realize the benefits and challenges for the next generation of delivery systems.

Preclinical development of drug delivery systems for paclitaxel-based cancer chemotherapy

Paclitaxel (PTX) is one of the most successful drugs ever used in cancer chemotherapy, acting against a variety of cancer types. Formulating PTX with Cremophor EL and ethanol (Taxol®) realized its clinical potential, but the formulation falls short of expectations due to side effects such as peripheral neuropathy, hypotension, and hypersensitivity. Abraxane®, the albumin bound PTX, represents a superior replacement of Taxol® that mitigates the side effects associated with Cremophor EL. While Abraxane® is now considered a gold standard in chemotherapy, its 21% response rate leaves much room for further improvement. The quest for safer and more effective cancer treatments has led to the development of a plethora of innovative PTX formulations, many of which are currently undergoing clinical trials. In this context, we review recent development of PTX drug delivery systems and analyze the design principles underpinning each delivery strategy. We chose several representative examples to highlight the opportunities and challenges of polymeric systems, lipid-based formulations, as well as prodrug strategies.

Circulating GRP78 antibodies from ovarian cancer patients: a promising tool for cancer cell targeting drug delivery system?

Glucose-regulated protein 78 (GRP78) is a chaperone protein that has a high frequency in tumor cells. Normally it is found in the endoplasmic reticulum to assist in protein folding, but under cellular stress, GRP78 influences proliferative signaling pathways at the cell surface. The increased expression elicits autoantibody production, providing a biomarker of ovarian cancer, as well as other types of cancer. This study aims to determine the epitope recognition of GRP78 autoantibodies isolated from serum of ovarian cancer patients and use the identified antibodies to design new drug delivery systems to specifically target cancer cells. We first confirmed that the membrane GRP78 levels are increased in ovarian cancer cells and positively correlate with proliferation. However, the level of circulating GRP78 autoantibodies did not correlate with membrane GRP78 expression in ovarian cancer cells and was lower, although not significantly, compared to control patients. We then determined the epitope recognition of GRP78 autoantibodies and showed that treatment with paclitaxel-loaded nanoparticles coated with anti-GRP78 antibodies significantly decreased tumor development in chick embryo culture of ovarian cancer cell tumors compared to paclitaxel treatment alone. This evidence suggests that nanoparticle drug delivery systems coupled with antibodies against GRP78 has potential as a powerful therapy against ovarian cancer.

Enhanced intracellular delivery and controlled drug release of magnetic PLGA nanoparticles modified with transferrin

Owing to the presence of multidrug resistance in tumor cells, conventional chemotherapy remains clinically intractable. To enhance the therapeutic efficacy of chemotherapeutic agents, targeting strategies based on magnetic polymeric nanoparticles modified with targeting ligands have gained significant attention in cancer therapy. In this study, we synthesized transferrin (Tf)-modified poly(D,L-lactic-co-glycolic acid) nanoparticles (PLGA NPs) loaded with paclitaxel (PTX) and superparamagnetic nanoparticle (MNP) using a solid-in-oil-in-water solvent evaporation method, followed by Tf adsorption on the surface of NPs. The Tf-modified magnetic PLGA NPs were characterized in terms of particle morphology and size, magnetic properties, encapsulation efficiency and drug release. Furthermore, the cytotoxicity and cellular uptake of the drug-loaded magnetic PLGA NPs were evaluated in both MCF-7 breast cancer and U-87 glioma cells in vitro. We found that Tf-modified PTX-MNP-PLGA NPs showed the highest cytotoxicity effect and cellular uptake efficiency under Tf receptor mediation in both MCF-7 and U-87 cells compared to unmodified PLGA NPs and free PTX. The cellular uptake efficiency of Tf-modified magnetic PLGA NPs appeared to be facilitated by the applied magnetic field, but the difference did not reach statistical significance. This study illustrates that this proposed formulation can be used as one new alternative treatment for patients bearing inaccessible tumors.

5-Fluorouracil enteric-coated nanoparticles for improved apoptotic activity and therapeutic index in treating colorectal cancer

5-Fluorouracil (5-FU) is one among the anti-cancer agents in FOLFORINOX treatment along with oxaliplatin and irinotecan for the treatment of colorectal cancer. Despite its potential activity on the tumor cells, it lacks site specificity partly attributed by its biodistribution to healthy cells resulting in toxic effects to healthy cells. Therefore, we have formulated 5-fluorouracil enteric-coated nanoparticles (5-FUEC) to localize the drug in the colon area that enables its prolonged presence in target area in a sustained manner. The current work emphasizes on enhanced anti-cancer activity of 5-FUEC sequencing its apoptotic activity on HCT 116 colorectal cancer cell lines in vitro. MTT assay exhibited 5.5-fold decrease in IC50 value of nanoparticles comparable to 5-FU. Nuclear fragmentation with irregular edges in nucleus of cells justified its improved activity. Furthermore, flow cytometric analysis confirms the majority of cells gated in early apoptotic (39.75%) and late apoptotic phase (36.25%). Acridine orange/ethidium bromide staining (AO/EB) exhibited cells with red fluorescence (indicating apoptosis) comparable to the control and 5-FU. γ-Scintigraphic studies determined the applicability and feasibility of the enteric coating with mean gastric emptying time, mean intestinal transit time and mean colon arrival time of 1.89 ± 0.03, 2.15 ± 0.05 and 4.03 ± 0.27 h, respectively. Moreover, nanoparticulate approach was found significant in reducing tumor size and volume in xenograft tumor models in vivo along with sustained release. These superior anti-cancer activities exhibited by 5-FUEC indicated that it could be a potential alternative to chemotherapy for colorectal cancer.

Acute and subchronic toxicity analysis of surface modified paclitaxel attached hydroxyapatite and titanium dioxide nanoparticles

Nanoparticles are widely used for targeted drug delivery applications. Surface modification with appropriate polymer and ligands is carried out to target the drug to the affected area. Toxicity analysis is carried out to evaluate the safety of the surface modified nanoparticles. In this study, paclitaxel attached, folic acid functionalized, polyethylene glycol modified hydroxyapatite and titanium dioxide nanoparticles were used for targeted drug delivery system. The toxicological behavior of the system was studied in vivo in rats and mice. Acute and subchronic studies were carried out. Biochemical, hematological, and histopathological analysis was also done. There were no significant alterations in the biochemical parameters at a low dosage. There was a small change in alkaline phosphatase (ALP) level at a high dosage. The results indicate a safe toxicological profile.

Advanced targeted therapies in cancer: Drug nanocarriers, the future of chemotherapy

Cancer is the second worldwide cause of death, exceeded only by cardiovascular diseases. It is characterized by uncontrolled cell proliferation and an absence of cell death that, except for hematological cancers, generates an abnormal cell mass or tumor. This primary tumor grows thanks to new vascularization and, in time, acquires metastatic potential and spreads to other body sites, which causes metastasis and finally death. Cancer is caused by damage or mutations in the genetic material of the cells due to environmental or inherited factors. While surgery and radiotherapy are the primary treatment used for local and non-metastatic cancers, anti-cancer drugs (chemotherapy, hormone and biological therapies) are the choice currently used in metastatic cancers. Chemotherapy is based on the inhibition of the division of rapidly growing cells, which is a characteristic of the cancerous cells, but unfortunately, it also affects normal cells with fast proliferation rates, such as the hair follicles, bone marrow and gastrointestinal tract cells, generating the characteristic side effects of chemotherapy. The indiscriminate destruction of normal cells, the toxicity of conventional chemotherapeutic drugs, as well as the development of multidrug resistance, support the need to find new effective targeted treatments based on the changes in the molecular biology of the tumor cells. These novel targeted therapies, of increasing interest as evidenced by FDA-approved targeted cancer drugs in recent years, block biologic transduction pathways and/or specific cancer proteins to induce the death of cancer cells by means of apoptosis and stimulation of the immune system, or specifically deliver chemotherapeutic agents to cancer cells, minimizing the undesirable side effects. Although targeted therapies can be achieved directly by altering specific cell signaling by means of monoclonal antibodies or small molecules inhibitors, this review focuses on indirect targeted approaches that mainly deliver chemotherapeutic agents to molecular targets overexpressed on the surface of tumor cells. In particular, we offer a detailed description of different cytotoxic drug carriers, such as liposomes, carbon nanotubes, dendrimers, polymeric micelles, polymeric conjugates and polymeric nanoparticles, in passive and active targeted cancer therapy, by enhancing the permeability and retention or by the functionalization of the surface of the carriers, respectively, emphasizing those that have received FDA approval or are part of the most important clinical studies up to date. These drug carriers not only transport the chemotherapeutic agents to tumors, avoiding normal tissues and reducing toxicity in the rest of the body, but also protect cytotoxic drugs from degradation, increase the half-life, payload and solubility of cytotoxic agents and reduce renal clearance. Despite the many advantages of all the anticancer drug carriers analyzed, only a few of them have reached the FDA approval, in particular, two polymer-protein conjugates, five liposomal formulations and one polymeric nanoparticle are available in the market, in contrast to the sixteen FDA approval of monoclonal antibodies. However, there are numerous clinical trials in progress of polymer-protein and polymer-drug conjugates, liposomal formulations, including immunoliposomes, polymeric micelles and polymeric nanoparticles. Regarding carbon nanotubes or dendrimers, there are no FDA approvals or clinical trials in process up to date due to their unresolved toxicity. Moreover, we analyze in detail the more promising and advanced preclinical studies of the particular case of polymeric nanoparticles as carriers of different cytotoxic agents to active and passive tumor targeting published in the last 5 years, since they have a huge potential in cancer therapy, being one of the most widely studied nano-platforms in this field in the last years. The interest that these formulations have recently achieved is stressed by the fact that 90% of the papers based on cancer therapeutics with polymeric nanoparticles have been published in the last 6 years (PubMed search).

Formulation and characterization of 5-Fluorouracil enteric coated nanoparticles for sustained and localized release in treating colorectal cancer

5-Fluorouracil is used in the treatment of colorectal cancer along with oxaliplatin as first line treatment, but it is having lack of site specificity and poor therapeutic effect. Also toxic effects to healthy cells and unavailability of major proportion of drug at the colon region remain as limitations. Toxic effects prevention and drug localization at colon area was achieved by preparing enteric-coated chitosan polymeric nanoparticles as it can be delivered directly to large bowel. Enteric coating helps in preventing the drug degradation at gastric pH. So the main objective was to prepare chitosan polymeric nanoparticles by solvent evaporation emulsification method by using different ratios of polymer (1:1, 1:2, 1:3, 1:4). Optimized polymer ratio was characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), entrapment efficiency and particle size and further subjected to enteric coating. In vitro drug release studies were done using dialysis bag technique using simulated fluids at various pH (1.2, 4.5, 7.5, 7.0) to mimic the GIT tract. 5-FU nanoparticles with drug: polymer ratio of 1:2 and 1:3 has shown better particle size (149 ± 1.28 nm and 138 ± 1.01 nm respectively), entrapment efficiency (48.12 ± 0.08% and 69.18 ± 1.89 respectively). 5-FU E1 has shown better drug release after 4 h and has shown 82% drug release till 24 h in a sustained manner comparable to the non-enteric coated tablets, which released more than 50% of the drug before entering the colon region. So we can conclude that nanoparticles prepared by this method using the same polymer with the optimized ratio can represent as potential drug delivery approach for effective delivery of the active pharmaceutical ingredient to the colorectal tumors.

Development of nanoscale approaches for ovarian cancer therapeutics and diagnostics

Ovarian cancer is the deadliest of all gynecological cancers and the fifth leading cause of death due to cancer in women. This is largely due to late-stage diagnosis, poor prognosis related to advanced-stage disease, and the high recurrence rate associated with development of chemoresistance. Survival statistics have not improved significantly over the last three decades, highlighting the fact that improved therapeutic strategies and early detection require substantial improvements. Here, we review and highlight nanotechnology-based approaches that seek to address this need. The success of Doxil, a PEGylated liposomal nanoencapsulation of doxorubicin, which was approved by the FDA for use on recurrent ovarian cancer, has paved the way for the current wave of nanoparticle formulations in drug discovery and clinical trials. We discuss and summarize new nanoformulations that are currently moving into clinical trials and highlight novel nanotherapeutic strategies that have shown promising results in preclinical in vivo studies. Further, the potential for nanomaterials in diagnostic imaging techniques and the ability to leverage nanotechnology for early detection of ovarian cancer are also discussed.

Nanodrug delivery in reversing multidrug resistance in cancer cells

Different mechanisms in cancer cells become resistant to one or more chemotherapeutics is known as multidrug resistance (MDR) which hinders chemotherapy efficacy. Potential factors for MDR includes enhanced drug detoxification, decreased drug uptake, increased intracellular nucleophiles levels, enhanced repair of drug induced DNA damage, overexpression of drug transporter such as P-glycoprotein(P-gp), multidrug resistance-associated proteins (MRP1, MRP2), and breast cancer resistance protein (BCRP). Currently nanoassemblies such as polymeric/solid lipid/inorganic/metal nanoparticles, quantum dots, dendrimers, liposomes, micelles has emerged as an innovative, effective, and promising platforms for treatment of drug resistant cancer cells. Nanocarriers have potential to improve drug therapeutic index, ability for multifunctionality, divert ABC-transporter mediated drug efflux mechanism and selective targeting to tumor cells, cancer stem cells, tumor initiating cells, or cancer microenvironment. Selective nanocarrier targeting to tumor overcomes dose-limiting side effects, lack of selectivity, tissue toxicity, limited drug access to tumor tissues, high drug doses, and emergence of multiple drug resistance with conventional or combination chemotherapy. Current review highlights various nanodrug delivery systems to overcome mechanism of MDR by neutralizing, evading, or exploiting the drug efflux pumps and those independent of drug efflux pump mechanism by silencing Bcl-2 and HIF1α gene expressions by siRNA and miRNA, modulating ceramide levels and targeting NF-κB. “Theragnostics” combining a cytotoxic agent, targeting moiety, chemosensitizing agent, and diagnostic imaging aid are highlighted as effective and innovative systems for tumor localization and overcoming MDR. Physical approaches such as combination of drug with thermal/ultrasound/photodynamic therapies to overcome MDR are focused. The review focuses on newer drug delivery systems developed to overcome MDR in cancer cell.

Nanotechnology in Cancer Drug Delivery and Selective Targeting

Nanoparticles are rapidly being developed and trialed to overcome several limitations of traditional drug delivery systems and are coming up as a distinct therapeutics for cancer treatment. Conventional chemotherapeutics possess some serious side effects including damage of the immune system and other organs with rapidly proliferating cells due to nonspecific targeting, lack of solubility, and inability to enter the core of the tumors resulting in impaired treatment with reduced dose and with low survival rate. Nanotechnology has provided the opportunity to get direct access of the cancerous cells selectively with increased drug localization and cellular uptake. Nanoparticles can be programmed for recognizing the cancerous cells and giving selective and accurate drug delivery avoiding interaction with the healthy cells. This review focuses on cell recognizing ability of nanoparticles by various strategies having unique identifying properties that distinguish them from previous anticancer therapies. It also discusses specific drug delivery by nanoparticles inside the cells illustrating many successful researches and how nanoparticles remove the side effects of conventional therapies with tailored cancer treatment.

Paclitaxel Nano-Delivery Systems: A Comprehensive Review

Paclitaxel is one of the most effective chemotherapeutic drugs ever developed and is active against a broad range of cancers, such as lung, ovarian, and breast cancers. Due to its low water solubility, paclitaxel is formulated in a mixture of Cremophor EL and dehydrated ethanol (50:50, v/v) a combination known as Taxol. However, Taxol has some severe side effects related to Cremophor EL and ethanol. Therefore, there is an urgent need for the development of alternative Taxol formulations. The encapsulation of paclitaxel in biodegradable and non-toxic nano-delivery systems can protect the drug from degradation during circulation and in-turn protect the body from toxic side effects of the drug thereby lowering its toxicity, increasing its circulation half-life, exhibiting improved pharmacokinetic profiles, and demonstrating better patient compliance. Also, nanoparticle-based delivery systems can take advantage of the enhanced permeability and retention (EPR) effect for passive tumor targeting, therefore, they are promising carriers to improve the therapeutic index and decrease the side effects of paclitaxel. To date, paclitaxel albumin-bound nanoparticles (Abraxane®) have been approved by the FDA for the treatment of metastatic breast cancer and non-small cell lung cancer (NSCLC). In addition, there are a number of novel paclitaxel nanoparticle formulations in clinical trials. In this comprehensive review, several types of developed paclitaxel nano-delivery systems will be covered and discussed, such as polymeric nanoparticles, lipid-based formulations, polymer conjugates, inorganic nanoparticles, carbon nanotubes, nanocrystals, and cyclodextrin nanoparticles.

GRP78-targeted nanotherapy against castrate-resistant prostate cancer cells expressing membrane GRP78

Glucose-regulated protein 78, GRP78, is a chaperone protein mainly located in the endoplasmic reticulum (ER) of normal cells. In stress conditions, GRP78 is overexpressed and in different cancer cell types, it is expressed at the cell surface, whereas it stays intracellular in non-cancerous cells. Therefore, it appears as a strategic target to recognize malignant cells. Prostate cancer is one of the most diagnosed cancers in men. The development of castrate resistant tumors and the resistance to chemotherapy frequently occur. The carboxy-terminal ER retention domain is defined by the KDEL amino acid sequence. We developed anti-KDEL functionalized polymeric nanoparticles (NPs) loaded with paclitaxel (Tx) to specifically target prostate cancer cells expressing GRP78. The sensitivity to Tx in different formulations was compared in three prostate cell lines: PNT1B, a normal cell line, PC3, a cancer cell line faintly expressing GRP78 at its surface, and DU145, a cancer cell line expressing GRP78 at its cell surface. Our results show that the targeted formulation significantly increases Tx sensitivity of cell line expressing GRP78 at its surface compared to other treatments suggesting the added value of GRP78 targeted therapy for castrate resistant tumor which expresses GRP78 at its cell surface.

Multifunctional particles for melanoma-targeted drug delivery

New magnetic-based core-shell particles (MBCSPs) were developed to target skin cancer cells while delivering chemotherapeutic drugs in a controlled fashion. MBCSPs consist of a thermo-responsive shell of poly(N-isopropylacrylamide-acrylamide-allylamine) and a core of poly(lactic-co-glycolic acid) (PLGA) embedded with magnetite nanoparticles. To target melanoma cancer cells, MBCSPs were conjugated with Gly-Arg-Gly-Asp-Ser (GRGDS) peptides that specifically bind to the α(5)β(3) receptors of melanoma cells. MBCSPs consist of unique multifunctional and controlled drug delivery characteristics. Specially, they can provide dual drug release mechanisms (a sustained release of drugs through degradation of PLGA core and a controlled release in response to changes in temperature via thermo-responsive polymer shell), and dual targeting mechanisms (magnetic localization and receptor-mediated targeting). Results from in vitro studies indicate that GRGDS-conjugated MBCSPs have an average diameter of 296 nm and exhibit no cytotoxicity towards human dermal fibroblasts up to 500 μg ml(-1). Further, a sustained release of curcumin from the core and a temperature-dependent release of doxorubicin from the shell of MBCSPs were observed. The particles also produced a dark contrast signal in magnetic resonance imaging. Finally, the particles were accumulated at the tumor site in a B16F10 melanoma orthotopic mouse model, especially in the presence of a magnet. Results indicate great potential of MBCSPs as a platform technology to target, treat and monitor melanoma for targeted drug delivery to reduce side effects of chemotherapeutic reagents.

Anti-KDEL-coated nanoparticles: a promising tumor targeting approach for ovarian cancer?

The purpose of this study was to target ovarian cancer cells by coupling paclitaxel (Tx)-loaded nanoparticles (NPs-Tx) to antibodies against KDEL sequence, able to recognize GRP94 and GRP78 that are located at cell surface in cancer cells whereas they are in the endoplasmic reticulum in healthy cells. Tx-loaded poly (DL-lactic acid) nanoparticles coated with anti-KDEL antibodies (NPs-Tx-KDEL) were successfully prepared and characterized. Interaction between tumor cells and NPs-Tx or NPs-Tx-KDEL was observed by microscopy with fluorescently labeled NPs and the efficacy of the different formulations was compared by a viability assay. Particles functionalized with monoclonal antibodies (mAb) showed a higher binding to the cells even though the internalization rate appeared limited. The effect of NPs-Tx-KDEL on cell viability (proliferation) was compared to Tx, NPs, NPs-Tx, anti-KDEL mAb or anti-KDEL mAb in combination with NPs-Tx in Bg-1 ovarian cell line. Our data indicate that NPs-Tx-KDEL significantly increase sensitivity of Bg-1 cells to Tx compared to other treatments. This study confirms the interest of anti-cancer therapy by targeting cell surface GRP78 and GRP94 on cancer cells, and demonstrates the efficiency of coupling KDEL antibodies to NPs.

Enhancement of cellular uptake and cytotoxicity of curcumin-loaded PLGA nanoparticles by conjugation with anti-P-glycoprotein in drug resistance cancer cells

AIM

To compare the anti-cancer activity and cellular uptake of curcumin (Cur) delivered by targeted and non-targeted drug delivery systems in multidrug-resistant cervical cancer cells.

METHODS

Cur was entrapped into poly (DL-lactide-co-glycolide) (PLGA) nanoparticles (Cur-NPs) in the presence of modified-pluronic F127 stabilizer using nano-precipitation technique. On the surface of Cur-NPs, the carboxy-terminal of modified pluronic F127 was conjugated to the amino-terminal of anti-P-glycoprotein (P-gp) (Cur-NPs-APgp). The physical properties of the Cur-NPs, including particle size, zeta potential, particle morphology and Cur release kinetics, were investigated. Cellular uptake and specificity of the Cur-NPs and Cur-NPs-APgp were detected in cervical cancer cell lines KB-V1 (higher expression of P-gp) and KB-3-1 (lower expression of P-gp) using fluorescence microscope and flow cytometry, respectively. Cytotoxicity of the Cur-NPs and Cur-NPs-APgp was determined using MTT assay.

RESULTS

The particle size of Cur-NPs and Cur-NPs-APgp was 127 and 132 nm, respectively. The entrapment efficiency and actual loading of Cur-NPs-APgp (60% and 5 μg Cur/mg NP) were lower than those of Cur-NPs (99% and 7 μg Cur/mg NP). The specific binding of Cur-NPs-APgp to KB-V1 cells was significantly higher than that to KB-3-1 cells. Cellular uptake of Cur-NPs-APgp into KB-V1 cells was higher, as compared to KB-3-1 cells. However, the cellular uptake of Cur-NPs and Cur-NPs-IgG did not differ between the two types of cells. Besides, the cytotoxicity of Cur-NPs-APgp in KB-V1 cells was higher than those of Cur and Cur-NPs.

CONCLUSION

The results demonstrate that Cur-NPs-APgp targeted to P-gp on the cell surface membrane of KB-V1 cells, thus enhancing the cellular uptake and cytotoxicity of Cur.

Targeting epidermal growth factor receptor in tumors: from conventional monoclonal antibodies via heavy chain-only antibodies to nanobodies

The discovery of naturally occurring heavy chain only antibodies and their further development into small recombinant 'nanobodies' offers attractive applications in drug targeting. Here, we describe the properties of nanobodies that have been developed to target the epidermal growth factor receptor (EGFR) and contrast these to the characteristics of heavy chain only antibodies and conventional antibodies. EGFR is overexpressed in many tumors and is an attractive target for tumor-directed drug targeting.

Nanotoxicology--a pathologist's perspective

Advances in chemistry and engineering have created a new technology, nanotechnology, involving the tiniest known manufactured products. These products have a rapidly increasing market share and appear poised to revolutionize engineering, cosmetics, and medicine. Unfortunately, nanotoxicology, the study of nanoparticulate health effects, lags behind advances in nanotechnology. Over the past decade, existing literature on ultrafine particles and respirable durable fibers has been supplemented by studies of first-generation nanotechnology products. These studies suggest that nanosizing increases the toxicity of many particulates. First, as size decreases, surface area increases, thereby speeding up dissolution of soluble particulates and exposing more of the reactive surface of durable but reactive particulates. Second, nanosizing facilitates movement of particulates across cellular and intracellular barriers. Third, nanosizing allows particulates to interact with, and sometimes even hybridize with, subcellular structures, including in some cases microtubules and DNA. Finally, nanosizing of some particulates, increases pathologic and physiologic responses, including inflammation, fibrosis, allergic responses, genotoxicity, and carcinogenicity, and may alter cardiovascular and lymphatic function. Knowing how the size and physiochemical properties of nanoparticulates affect bioactivity is important in assuring that the exciting new products of nanotechnology are used safely. This review provides an introduction to the pathology and toxicology of nanoparticulates.

A strategy for precision engineering of nanoparticles of biodegradable copolymers for quantitative control of targeted drug delivery

Research on quantitative control of targeting effect for the drug delivery system of ligand-conjugated nanoparticles of biodegradable polymers is at the cutting edge in the design of drug delivery device. In this work, we developed a post-conjugation strategy, which makes the ligand conjugation after the preparation of the drug-loaded nanoparticles of two copolymers blend. We synthesized the PLGA-PEG copolymer with PEG functioning as the linker molecule needed for herceptin conjugation. Docetaxel-loaded nanoparticles of the PLGA-PEG/PLGA copolymer blend were prepared by the nanoprecipitation method. Anti-HER2 antibody (heceptin), which targets the breast cancer cells of HER2 receptor overexpression, was conjugated on the drug-loaded PLGA-PEG/PLGA nanoparticles for sustained, controlled and targeted delivery of docetaxel. We demonstrated that the targeting effect can be quantitatively controlled by two ways, i.e. (1) adjusting the copolymer blend ratio of the nanoparticle matrix, which showed within the range of 20% PLGA/PEG in the copolymer blend a linear relation with the ligand density on the nanoparticle surface, and (2) adjusting the herceptin feed molar ratio to NH2 in the linker molecules appearing on the nanoparticle surface, which also showed a linear relation. Compared with the pre-conjugation strategy developed recently in the literature, in which the ligand was firstly conjugated onto the PLGA-PEG copolymer before preparation of the nanoparticles of the PLGA-PEG/PLGA copolymer blend, the post-conjugation strategy provides more efficient use of the ligand and protects its bioactivity in the nanoparticle preparation process, thus resulting in much better performance in drug targeting, which was assessed in vitro with SK-BR-3 breast cancer cells of HER2 receptor overexpression and MCF7 breast cancer cells of HER2 receptors moderate expression.

Mucins in ovarian cancer diagnosis and therapy

Ovarian cancer is the most lethal gynecologic malignancy and the five-year survival rate is only 35% after diagnosis. Epithelial ovarian cancer is a highly metastatic disease characterized by widespread peritoneal dissemination and ascites. The death incidences from ovarian cancer could be significantly lowered by developing new methods for the early diagnosis and treatment of this fatal disease. Several potential markers have been identified recently. However, mucins are the most promising markers for ovarian cancer diagnosis. Mucins are large extracellular, heavily glycosylated proteins and their aberrant expression has been implicated in the pathogenesis of a variety of cancers, including ovarian cancer. This review will summarize known facts about the pathological and molecular characteristics of ovarian cancer, the current status of ovarian cancer markers, as well as general information about mucins, the putative role of mucins in the progression of ovarian cancer and their potential use for the early diagnosis and treatment of this disease.