Macromolecular Therapeutics

Impact of the polymer backbone chemistry on interactions of amino-acid-derived zwitterionic polymers with cells

Zwitterionic polymers are known to interact with cells and have been shown to reveal cancer cell specificity. In this work, the importance of the chemistry of the polymer backbone for the cellular specificity of amino-acid-derived polyzwitterions is demonstrated. A series of glutamic acid (Glu)-based vinyl monomers (i.e., an acrylate, a methacrylate, an acrylamide, and a methacrylamide) were prepared and used for reversible addition-fragmentation chain-transfer (RAFT) polymerisation, yielding defined polymers with narrow size distribution (Р< 1.3). All Glu-functionalised, zwitterionic polymers revealed high cytocompatibility; however, differences in cellular association and specificity were observed. In particular, the methacrylamide-derived polymers showed high association with both, breast cancer cells and non-cancerous dendritic cells and, consequently, lack specificity. In contrast, high specificity to only breast cancer cells was observed for polyacrylates, -methacrylates, and -acrylamides. Detailed analysis of the polymers revealed differences in hydrophobicity, zeta potential, and potential side chain hydrolysis, which are impacted by the polymer backbone and might be responsible for the altered the cell association of these polymers. It is shown that a slightly negative net charge is preferred over a neutral charge to retain cell specificity. This was also confirmed by association experiments in the presence of competitive amino acid transporter substrates. The affinity of slightly negatively charged Glu-derived polymers to the xCT Glu/cystine cell membrane antiporter was found to be higher than that of neutrally charged polymers. Our results emphasise the importance of the polymer backbone for the design of cell-specific polymers. This study further highlights the potential to tailor amino-acid-derived zwitterionic materials beyond their side chain functionality.

Fundamental concepts of protein therapeutics and spacing in oncology: an updated comprehensive review

Current treatment regimens in cancer cases cause significant side effects and cannot effectively eradicate the advanced disease. Hence, much effort has been expended over the past years to understand how cancer grows and responds to therapies. Meanwhile, proteins as a type of biopolymers have been under commercial development for over three decades and have been proven to improve the healthcare system as effective medicines for treating many types of progressive disease, such as cancer. Following approving the first recombinant protein therapeutics by FDA (Humulin), there have been a revolution for drawing attention toward protein-based therapeutics (PTs). Since then, the ability to tailor proteins with ideal pharmacokinetics has provided the pharmaceutical industry with an important noble path to discuss the clinical potential of proteins in oncology research. Unlike traditional chemotherapy molecules, PTs actively target cancerous cells by binding to their surface receptors and the other biomarkers particularly associated with tumorous or healthy tissue. This review analyzes the potential and limitations of protein therapeutics (PTs) in the treatment of cancer as well as highlighting the evolving strategies by addressing all possible factors, including pharmacology profile and targeted therapy approaches. This review provides a comprehensive overview of the current state of PTs in oncology, including their pharmacology profile, targeted therapy approaches, and prospects. The reviewed data show that several current and future challenges remain to make PTs a promising and effective anticancer drug, such as safety, immunogenicity, protein stability/degradation, and protein-adjuvant interactions.

Dendrimer: An update on recent developments and future opportunities for the brain tumors diagnosis and treatment

A brain tumor is an uncontrolled cell proliferation, a mass of tissue composed of cells that grow and divide abnormally and appear to be uncontrollable by the processes that normally control normal cells. Approximately 25,690 primary malignant brain tumors are discovered each year, 70% of which originate in glial cells. It has been observed that the blood-brain barrier (BBB) limits the distribution of drugs into the tumour environment, which complicates the oncological therapy of malignant brain tumours. Numerous studies have found that nanocarriers have demonstrated significant therapeutic efficacy in brain diseases. This review, based on a non-systematic search of the existing literature, provides an update on the existing knowledge of the types of dendrimers, synthesis methods, and mechanisms of action in relation to brain tumours. It also discusses the use of dendrimers in the diagnosis and treatment of brain tumours and the future possibilities of dendrimers. Dendrimers are of particular interest in the diagnosis and treatment of brain tumours because they can transport biochemical agents across the BBB to the tumour and into the brain after systemic administration. Dendrimers are being used to develop novel therapeutics such as prolonged release of drugs, immunotherapy, and antineoplastic effects. The use of PAMAM, PPI, PLL and surface engineered dendrimers has proven revolutionary in the effective diagnosis and treatment of brain tumours.

Erythrocyte-Inspired Functional Materials for Biomedical Applications

Erythrocytes are the most abundant cells in the blood. As the results of long-term natural selection, their specific biconcave discoid morphology and cellular composition are responsible for gaining excellent biological performance. Inspired by the intrinsic features of erythrocytes, various artificial biomaterials emerge and find broad prospects in biomedical applications such as therapeutic delivery, bioimaging, and tissue engineering. Here, a comprehensive review from the fabrication to the applications of erythrocyte-inspired functional materials is given. After summarizing the biomaterials mimicking the biological functions of erythrocytes, the synthesis strategies of particles with erythrocyte-inspired morphologies are presented. The emphasis is on practical biomedical applications of these bioinspired functional materials. The perspectives for the future possibilities of the advanced erythrocyte-inspired biomaterials are also discussed. It is hoped that the summary of existing studies can inspire researchers to develop novel biomaterials; thus, accelerating the progress of these biomaterials toward clinical biomedical applications.

Applications and challenges of ultra-small particle size nanoparticles in tumor therapy

With the development of nanotechnology, nanomedicines are widely used in tumor therapy. However, biological barriers in the delivery of nanoparticles still limit their application in tumor therapy. As one of the most fundamental properties of nanoparticles, particle size plays a crucial role in the process of the nanoparticles delivery process. It is difficult for large size nanoparticles with fixed size to achieve satisfactory outcomes in every process. In order to overcome the poor penetration of larger size, nanoparticles with ultra-small particle size are proposed, which are more conducive to deep tumor penetration and uniform drug distribution. In this review, the latest progresses and advantages of ultra-small nanoparticles are systematically summarized, the perspectives and challenges of ultra-small nanoparticles strategy for cancer treatment are also discussed.

Exploration of Site-Specific Drug Targeting—A Review on EPR-, Stimuli-, Chemical-, and Receptor-Based Approaches as Potential Drug Targeting Methods in Cancer Treatment

Cancer has been one of the most dominant causes of mortality globally over the last few decades. In cancer treatment, the selective targeting of tumor cells is indispensable, making it a better replacement for conventional chemotherapies by diminishing their adverse side effects. While designing a drug to be delivered selectively in the target organ, the drug development scientists should focus on various factors such as the type of cancer they are dealing with according to which drug, targeting moieties, and pharmaceutical carriers should be targeted. All published articles have been collected regarding cancer and drug-targeting approaches from well reputed databases including MEDLINE, Embase, Cochrane Library, CENTRAL and ClinicalTrials.gov, Science Direct, PubMed, Scopus, Wiley, and Springer. The articles published between January 2010 and December 2020 were considered. Due to the existence of various mechanisms, it is challenging to choose which one is appropriate for a specific case. Moreover, a combination of more than one approach is often utilized to achieve optimal drug effects. In this review, we have summarized and highlighted central mechanisms of how the targeted drug delivery system works in the specific diseased microenvironment, along with the strategies to make an approach more effective. We have also included some pictorial illustrations to have a precise idea about different types of drug targeting. The core contribution of this work includes providing a cancer drug development scientist with a broad preliminary idea to choose the appropriate approach among the various targeted drug delivery mechanisms. Also, the study will contribute to improving anticancer treatment approaches by providing a pathway for lesser side effects observed in conventional chemotherapeutic techniques.

Influence of Association on Binding of Disaccharides to YKL-39 and hHyal-1 Enzymes

Disaccharide complexes have been shown experimentally to be useful for drug delivery or as an antifouling surface biofilm, and are promising drug-encapsulation and delivery candidates. Although such complexes are intended for medical applications, to date no studies at the molecular level have been devoted to the influence of complexation on the enzymatic decomposition of polysaccharides. A theoretical approach to this problem has been hampered by the lack of a suitable computational tool for binding such non-covalent complexes to enzymes. Herein, we combine quantum-mechanical calculations of disaccharides complexes with a nonstandard docking GaudiMM engine that can perform such a task. Our results on four different complexes show that they are mostly stabilized by electrostatic interactions and hydrogen bonds. This strong non-covalent stabilization demonstrates the studied complexes are some excellent candidates for self-assembly smart materials, useful for drug encapsulation and delivery. Their advantage lies also in their biocompatible and biodegradable character.

Zwitterionic Amino Acid-Derived Polyacrylates as Smart Materials Exhibiting Cellular Specificity and Therapeutic Activity

The synthesis of new amino acid-containing, cell-specific, therapeutically active polymers is presented. Amino acids served as starting material for the preparation of tailored polymers with different amino acids in the side chain. The reversible addition-fragmentation chain-transfer (RAFT) polymerization of acrylate monomers yielded polymers of narrow size distribution (Đ ≤ 1.3). In particular, glutamate (Glu)-functionalized, zwitterionic polymers revealed a high degree of cytocompatibility and cellular specificity, i.e., showing association to different cancer cell lines, but not with nontumor fibroblasts. Energy-dependent uptake mechanisms were confirmed by means of temperature-dependent cellular uptake experiments as well as localization of the polymers in cellular lysosomes determined by confocal laser scanning microscopy (CLSM). The amino acid receptor antagonist O-benzyl-l-serine (BzlSer) was chosen as an active ingredient for the design of therapeutic copolymers. RAFT copolymerization of Glu acrylate and BzlSer acrylate resulted in tailored macromolecules with distinct monomer ratios. The targeted, cytotoxic activity of copolymers was demonstrated by means of multiday in vitro cell viability assays. To this end, polymers with 25 mol % BzlSer content showed cytotoxicity against cancer cells, while leaving fibroblasts unaffected over a period of 3 days. Our results emphasize the importance of biologically derived materials to be included in synthetic polymers and the potential of zwitterionic, amino acid-derived materials for cellular targeting. Furthermore, it highlights that the fine balance between cellular specificity and unspecific cytotoxicity can be tailored by monomer ratios within a copolymer.

Fabrication of cellulose nanocrystals as potential anticancer drug delivery systems for colorectal cancer treatment

Polysaccharide nanocrystals have great potential to be used as improved drug carriers due to their low cost, high biodegradability, and biocompatibility. This study reports the synthesis of cellulose nanocrystals (CNC) loaded with 5-fluorouracil (CNC/5FU) to evaluate their anticancer activity against colorectal cancer cells. X-ray and Fourier-transform infrared spectroscopy demonstrated that acid hydrolysis successfully degraded the amorphous cellulose to liberate the crystal regions. From transmission electron microscopy, CNC/5FU appeared as rod-like nanocrystals with an average length and width of 69.53 ± 1.14 nm and 8.13 ± 0.72 nm, respectively. The anticancer drug 5FU showed improved thermal stability after being loading onto CNC. From UV-vis spectroscopy data, the drug encapsulation efficiency in CNC/5FU was estimated to be 83.50 ± 1.52%. The drug release of CNC/5FU was higher at pH 7.4 compared to those at pH 4.2 and 1.2. From the cytotoxicity assays, CNC did not affect the viability of CCD112 colon normal cells. On the other hand, CNC/5FU exhibited anticancer effects against HCT116 and HT-29 colorectal cancer cells. The anticancer actions of CNC/5FU against HCT116 cells were then confirmed using an in vitro tumor-on-chip model and clonogenic assay. Mechanistic studies demonstrated that CNC/5FU killed the cancer cells by mainly inducing cell apoptosis and mitochondrial membrane damage. Overall, this study indicated that CNC/5FU could be a potential nanoformulation for improved drug delivery and colorectal cancer treatment.

Enhanced Anticancer Activity of Nanoformulation of Dasatinib against Triple-Negative Breast Cancer

Triple negative breast cancer (TNBC) is the most aggressive breast cancer accounting for around 15% of identified breast cancer cases. TNBC lacks human epidermal growth factor receptor 2 (HER2) amplification, is hormone independent estrogen (ER) and progesterone receptors (PR) negative, and is not reactive to current targeted therapies. Existing treatment relies on chemotherapeutic treatment, but in spite of an initial response to chemotherapy, the inception of resistance and relapse is unfortunately common. Dasatinib is an approved second-generation inhibitor of multiple tyrosine kinases, and literature data strongly support its use in the management of TNBC. However, dasatinib binds to plasma proteins and undergoes extensive metabolism through oxidation and conjugation. To protect dasatinib from fast pharmacokinetic degradation and to prolong its activity, it was encapsulated on poly(styrene-co-maleic acid) (SMA) micelles. The obtained SMA-dasatinib nanoparticles (NPs) were evaluated for their physicochemical properties, in vitro antiproliferative activity in different TNBC cell lines, and in vivo anticancer activity in a syngeneic model of breast cancer. Obtained results showed that SMA-dasatinib is more potent against 4T1 TNBC tumor growth in vivo compared to free drug. This enhanced effect was ascribed to the encapsulation of the drug protecting it from a rapid metabolism. Our finding highlights the often-overlooked value of nanoformulations in protecting its cargo from degradation. Overall, results may provide an alternative therapeutic strategy for TNBC management.

Selective Targeting of Breast Cancer by Tafuramycin A Using SMA-Nanoassemblies

Triple-negative breast cancer (TNBC) is a heterogeneous subtype of tumors that tests negative for estrogen receptors, progesterone receptors, and excess HER2 protein. The mainstay of treatment remains chemotherapy, but the therapeutic outcome remains inadequate. This paper investigates the potential of a duocarmycin derivative, tafuramycin A (TFA), as a new and more effective chemotherapy agent in TNBC treatment. To this extent, we optimized the chemical synthesis of TFA, and we encapsulated TFA in a micellar system to reduce side effects and increase tumor accumulation. In vitro and in vivo studies suggest that both TFA and SMA–TFA possess high anticancer effects in TNBC models. Finally, the encapsulation of TFA offered a preferential avenue to tumor accumulation by increasing its concentration at the tumor tissues by around four times in comparison with the free drug. Overall, the results provide a new potential strategy useful for TNBC treatment.

Drug Resistance in Metastatic Breast Cancer: Tumor Targeted Nanomedicine to the Rescue

Breast cancer, specifically metastatic breast, is a leading cause of morbidity and mortality in women. This is mainly due to relapse and reoccurrence of tumor. The primary reason for cancer relapse is the development of multidrug resistance (MDR) hampering the treatment and prognosis. MDR can occur due to a multitude of molecular events, including increased expression of efflux transporters such as P-gp, BCRP, or MRP1; epithelial to mesenchymal transition; and resistance development in breast cancer stem cells. Excessive dose dumping in chemotherapy can cause intrinsic anti-cancer MDR to appear prior to chemotherapy and after the treatment. Hence, novel targeted nanomedicines encapsulating chemotherapeutics and gene therapy products may assist to overcome cancer drug resistance. Targeted nanomedicines offer innovative strategies to overcome the limitations of conventional chemotherapy while permitting enhanced selectivity to cancer cells. Targeted nanotheranostics permit targeted drug release, precise breast cancer diagnosis, and importantly, the ability to overcome MDR. The article discusses various nanomedicines designed to selectively target breast cancer, triple negative breast cancer, and breast cancer stem cells. In addition, the review discusses recent approaches, including combination nanoparticles (NPs), theranostic NPs, and stimuli sensitive or “smart” NPs. Recent innovations in microRNA NPs and personalized medicine NPs are also discussed. Future perspective research for complex targeted and multi-stage responsive nanomedicines for metastatic breast cancer is discussed.

CD44 Targeted Nanomaterials for Treatment of Triple-Negative Breast Cancer

Identified as the second leading cause of cancer-related deaths among American women after lung cancer, breast cancer of all types has been the focus of numerous research studies. Even though triple-negative breast cancer (TNBC) represents 15-20% of the number of breast cancer cases worldwide, its existing therapeutic options are fairly limited. Due to the pivotal role of the presence/absence of specific receptors to luminal A, luminal B, HER-2+, and TNBC in the molecular classification of breast cancer, the lack of these receptors has accounted for the aforementioned limitation. Thereupon, in an attempt to participate in the ongoing research endeavors to overcome such a limitation, the conducted study adopts a combination strategy as a therapeutic paradigm for TNBC, which has proven notable results with respect to both: improving patient outcomes and survivability rates. The study hinges upon an investigation of a promising NPs platform for CD44 mediated theranostic that can be combined with JAK/STAT inhibitors for the treatment of TNBC. The ability of momelotinib (MMB), which is a JAK/STAT inhibitor, to sensitize the TNBC to apoptosis inducer (CFM-4.16) has been evaluated in MDA-MB-231 and MDA-MB-468. MMB + CFM-4.16 combination with a combination index (CI) ≤0.5, has been selected for in vitro and in vivo studies. MMB has been combined with CD44 directed polymeric nanoparticles (PNPs) loaded with CFM-4.16, namely CD44-T-PNPs, which selectively delivered the payload to CD44 overexpressing TNBC with a significant decrease in cell viability associated with a high dose reduction index (DRI). The mechanism underlying their synergism is based on the simultaneous downregulation of P-STAT3 and the up-regulation of CARP-1, which has induced ROS-dependent apoptosis leading to caspase 3/7 elevation, cell shrinkage, DNA damage, and suppressed migration. CD44-T-PNPs showed a remarkable cellular internalization, demonstrated by uptake of a Rhodamine B dye in vitro and S0456 (NIR dye) in vivo. S0456 was conjugated to PNPs to form CD44-T-PNPs/S0456 that simultaneously delivered CFM-4.16 and S0456 parenterally with selective tumor targeting, prolonged circulation, minimized off-target distribution.

Nanodrug Delivery Systems Modulate Tumor Vessels to Increase the Enhanced Permeability and Retention Effect

The use of nanomedicine for antitumor therapy has been extensively investigated for a long time. Enhanced permeability and retention (EPR) effect-mediated drug delivery is currently regarded as an effective way to bring drugs to tumors, especially macromolecular drugs and drug-loaded pharmaceutical nanocarriers. However, a disordered vessel network, and occluded or embolized tumor blood vessels seriously limit the EPR effect. To augment the EPR effect and improve curative effects, in this review, we focused on the perspective of tumor blood vessels, and analyzed the relationship among abnormal angiogenesis, abnormal vascular structure, irregular blood flow, extensive permeability of tumor vessels, and the EPR effect. In this commentary, nanoparticles including liposomes, micelles, and polymers extravasate through the tumor vasculature, which are based on modulating tumor vessels, to increase the EPR effect, thereby increasing their therapeutic effect.

Present Situation and Future Progress of Inhaled Lung Cancer Therapy: Necessity of Inhaled Formulations with Drug Delivery Functions

Inhaled lung cancer therapy is promising because of direct and noninvasive drug delivery to the lungs with low potential for severe systemic toxicity. Thus chemotherapeutic drugs have been administered clinically by nebulization of solution or suspension formulations, which demonstrated their limited pulmonary absorption and relatively mild systemic toxicity. In all these clinical trials, however, there was no obviously superior anticancer efficacy in lung cancer patients even at the maximum doses of drugs limited by pulmonary toxicity. Therefore methods that deliver both higher anticancer efficacy and lower pulmonary toxicity are strongly desired. In addition to the worldwide availability of pressured metered dose inhalers (pMDIs) and dry powder inhalers (DPIs) to treat local respiratory diseases, recent innovations in medicines and technologies are encouraging next steps toward effective inhaled lung cancer therapy with new therapeutic or drug delivery concepts. These include the discovery of target cells/molecules and drug candidates for novel cancer therapy, the development of high-performance inhalation devices for effective pulmonary drug delivery, and the establishment of manufacturing technologies for functional nanoparticles/microparticles. This review highlights the present situation and future progress of inhaled drugs for lung cancer therapy, including an overview of available inhalation devices, pharmacokinetics, and outcomes in clinical trials so far and some novel formulation strategies based on drug delivery systems to achieve enhanced anticancer efficacy and attenuated pulmonary toxicity.

Factors affecting the dynamics and heterogeneity of the EPR effect: pathophysiological and pathoanatomic features, drug formulations and physicochemical factors

INTRODUCTION

The enhanced permeability and retention (EPR) effect serves as the foundation of anticancer nanomedicine design. EPR effect-based drug delivery is an effective strategy for most solid tumors. However, the degree of efficacy depends on the pathophysiological conditions of tumors, drug formulations, and other factors.

AREAS COVERED

Vascular mediators including nitric oxide, bradykinin , and prostaglandins are vital for facilitating and maintaining EPR effect dynamics. Progression to large, advanced cancers may induce activated blood coagulation cascades, which lead to thrombus formation in tumor vasculature. Rapidly growing tumors cause obstructed or suppressed blood flow in tumor vasculature related to embolism or occluded blood vessels. The resulting limited tumor blood flow leads to less drug delivered to tumors, i.e. no or poor EPR effect. High stromal content also suppresses vascular permeability and drug diffusion. Restoring obstructed tumor blood flow and improving tumor vascular permeability via vascular mediators will improve drug delivery and the EPR effect. Physicochemical features of nanomedicines also influence therapeutic outcomes and are vital for the EPR effect.

EXPERT OPINION

The tumor microenvironment, especially tumor blood flow, is critical for a potent EPR effect. A rational strategy for circumventing EPR effect barriers must include restoring tumor blood flow.

Say no to drugs: Bioactive macromolecular therapeutics without conventional drugs

The vast majority of nanomedicines (NM) investigated today consists of a macromolecular carrier and a drug payload (conjugated or encapsulated), with a purpose of preferential delivery of the drug to the desired site of action, either through passive accumulation, or by active targeting via ligand-receptor interaction. Several drug delivery systems (DDS) have already been approved for clinical use. However, recent reports are corroborating the notion that NM do not necessarily need to include a drug payload, but can exert biological effects through specific binding/blocking of important target proteins at the site of action. The seminal work of Kopeček et al. on N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers containing biorecognition motifs (peptides or oligonucleotides) for crosslinking cell surface non-internalizing receptors of malignant cells and inducing their apoptosis, without containing any low molecular weight drug, led to the definition of a special group of NM, termed Drug-Free Macromolecular Therapeutics (DFMT). Systems utilizing this approach are typically designed to employ pendant targeting-ligands on the same macromolecule to facilitate multivalent interactions with receptors. The lack of conventional small molecule drugs reduces toxicity and adverse effects at off-target sites. In this review, we describe different types of DFMT that possess biological activity without attached low molecular weight drugs. We classified the relevant research into several groups by their mechanisms of action, and compare the advantages and disadvantages of these different approaches. We show that identification of target sites, specificity of attached targeting ligands, binding affinity and the synthesis of carriers of defined size and ligand spacing are crucial aspects of DFMT development. We further discuss how knowledge in the field of NM accumulated in the past few decades can help in the design of a successful DFMT to speed up the translation into clinical practice.

Advanced drug delivery 2020 and beyond: Perspectives on the future

Drug delivery systems are developed to maximize drug efficacy and minimize side effects. As drug delivery technologies improve, the drug becomes safer and more comfortable for patients to use. During the last seven decades, extraordinary progress has been made in drug delivery technologies, such as systems for long-term delivery for months and years, localized delivery, and targeted delivery. The advances, however, will face a next phase considering the future technologies we need to overcome many physicochemical barriers for new formulation development and biological unknowns for treating various diseases. For immediate and long-term progress into the future, the drug delivery field should use time and resources for more translatable research ideas. The drug delivery discipline has to continue working on basic, applied, translational, and clinical research in a concerted manner to produce drug delivery systems that work for patients. It is a time to focus our attention on things that matter. It is also a time to develop realistic research goals and outcomes, diversify drug delivery technologies, and take the collective responsibility for our actions.

The effect of zwitterionic surface content on blood circulation time of nanocapsule

Zwitterionic modification can prolong the blood circulation time of nanocarrier in vivo, but zwitterionic content will affect the functions of nanocarrier such as enzyme-responsive and intracellular or extracellular delivery. Therefore, it is necessary to explore the relationship between the zwitterionic content and circulation time of nanocarrier so as to figure out what content of zwitterion can enable the nanocarrier to obtain both the long blood circulation ability and other functions mentioned above. Herein, using nanocapsule as a research model, we investigated the nanocapsule modified with zwitterion of phosphorylcholine (PC) or carboxybetaine (CB) respectively, and through ¹H-NMR quantification we determined the zwitterionic surface content, so as to study the effect of PC or CB surface content on blood circulation performance of nanocapsule. In vivo study showed that the nanocapsule possessed an optimal surface filling ratios range for blood circulation of 43-68% for PC and of 20-68% for CB, with the longest t_1/2=37.35 h for PC-nanocapsule and t_1/2=45.27 h for CB-nanocapsule. Furthermore, the protein adsorption and macrophage endocytosis experiments indicated that when the surface filling ratio reached 43% for PC-nanocapsule and 20% for CB-nanocapsule, it could effectively reduce the protein adsorption and weaken macrophage endocytosis, thus explaining the phenomenon of long circulation time of nanocapsules from the point of protein adsorption and interaction with immune cells. This study proposes a new direction for designing long-circulating nanocarrier, and provides basis for constructing enzyme-responsive and intracellular or extracellular delivery platform.

Exploiting the dynamics of the EPR effect and strategies to improve the therapeutic effects of nanomedicines by using EPR effect enhancers

The enhanced permeability and retention (EPR) effect is a unique phenomenon of solid tumors that is related to their particular anatomical and pathophysiological characteristics, e.g. defective vascular architecture; large gaps between endothelial cells in blood vessels; abundant vascular mediators such as bradykinin, nitric oxide, carbon monoxide, and vascular endothelial growth factor; and impaired lymphatic recovery. These features lead to tumor tissues showing considerable extravasation of plasma components and nanomedicines. These data comprise the basic theory underlying the development of macromolecular agents or nanomedicines. The EPR effect is not necessarily valid for all solid tumors, because tumor blood flow and vascular permeability vary greatly. Tumor blood flow is frequently obstructed as tumor size increases, as often seen clinically; early stage, small tumors show a more uniform EPR effect, whereas advanced large tumor show heterogeneity in EPR effect. Accordingly, it would be very important to apply enhancers of EPR effect in clinical setting to make EPR effect more uniform. In this review, we discuss the EPR effect: its history, factors involved, and dynamics and heterogeneity. Strategies to overcome the EPR effect's heterogeneity may guarantee better therapeutic outcomes of drug delivery to advanced cancers.

Advances in Nanoparticles as Anticancer Drug Delivery Vector: Need of this Century

Background:

Nanotechnology has contributed a great deal to the field of medical science. Smart drugdelivery vectors, combined with stimuli-based characteristics, are becoming increasingly important. The use of external and internal stimulating factors can have enormous benefits and increase the targeting efficiency of nanotechnology platforms. The pH values of tumor vascular tissues are acidic in nature, allowing the improved targeting of anticancer drug payloads using drug-delivery vectors. Nanopolymers are smart drug-delivery vectors that have recently been developed and recommended for use by scientists because of their potential targeting capabilities, non-toxicity and biocompatibility, and make them ideal nanocarriers for personalized drug delivery.

Method:

The present review article provides an overview of current advances in the use of nanoparticles (NPs) as anticancer drug-delivery vectors.

Results:

This article reviews the molecular basis for the use of NPs in medicine, including personalized medicine, personalized therapy, emerging vistas in anticancer therapy, nanopolymer targeting, passive and active targeting transports, pH-responsive drug carriers, biological barriers, computer-aided drug design, future challenges and perspectives, biodegradability and safety.

Conclusions:

This article will benefit academia, researchers, clinicians, and government authorities by providing a basis for further research advancements.

Tumor Targeting Strategies of Smart Fluorescent Nanoparticles and Their Applications in Cancer Diagnosis and Treatment

Advantages such as strong signal strength, resistance to photobleaching, tunable fluorescence emissions, high sensitivity, and biocompatibility are the driving forces for the application of fluorescent nanoparticles (FNPs) in cancer diagnosis and therapy. In addition, the large surface area and easy modification of FNPs provide a platform for the design of multifunctional nanoparticles (MFNPs) for tumor targeting, diagnosis, and treatment. In order to obtain better targeting and therapeutic effects, it is necessary to understand the properties and targeting mechanisms of FNPs, which are the foundation and play a key role in the targeting design of nanoparticles (NPs). Widely accepted and applied targeting mechanisms such as enhanced permeability and retention (EPR) effect, active targeting, and tumor microenvironment (TME) targeting are summarized here. Additionally, a freshly discovered targeting mechanism is introduced, termed cell membrane permeability targeting (CMPT), which improves the tumor-targeting rate from less than 5% of the EPR effect to more than 50%. A new design strategy is also summarized, which is promising for future clinical targeting NPs/nanomedicines design. The targeting mechanism and design strategy will inspire new insights and thoughts on targeting design and will speed up precision medicine and contribute to cancer therapy and early diagnosis.

Design of Safe Nanotherapeutics for the Excretion of Excess Systemic Toxic Iron

Chronic transfusion of red blood cells (RBCs) to patients with β-thalassemia, sickle cell disease, and other acquired anemic disorders generates significant amounts of bioactive iron deposits in the body. The inactivation and excretion of redox active iron(III) from the blood pool and organs are critical to prevent organ damage, and are the focus of iron chelation therapy (ICT) using low molecular weight Fe(III) specific chelators. However, the current ICT is suboptimal because of the short circulation time of chelators, toxicity, severe side effects, difficult regime of administration, and patient noncompliance. To address this issue, we have designed long circulating and biodegradable nanoconjugates with enhanced circulation time and well-defined biodegradability to improve iron excretion and avoid nonspecific organ accumulation. A series of iron chelating nanoconjugates were generated with deferoxamine (DFO) as the iron(III) specific chelator using polymer scaffolds containing structurally different acidic pH sensitive ketal groups. The type of degradation linkages used in the polymer scaffold significantly influenced the vascular residence time, biodistribution, and mode of excretion of chelators in mice. Remarkably, the conjugate, BGD-60 (140 kDa; R h, 10.6 nm; cyclic ketal), exhibited the long circulation half-life (t 1/2β, 64 h), a 768-fold increase compared to DFO, and showed minimal polymer accumulation in major organs. The nanoconjugates were found to be nontoxic and excreted iron significantly better than DFO in iron overloaded mice. BGD-60 showed greater iron mobilization from plasma (p = 0.0390), spleen (p < 0.0001), and pancreas (p < 0.0001) whereas BDD-200 (340 kDa; R h, 13.7 nm; linear ketal) mobilized iron significantly better from the spleen, liver, and pancreas (p < 0.0001, p < 0.0001, and p < 0.0001, respectively) compared to DFO at equivalent doses. The nanoconjugate's favorable long blood circulation time, biodegradability, and iron excretion profiles highlight their potential for future clinical translation.

Liposomal Irinotecan for Treatment of Colorectal Cancer in a Preclinical Model

Colorectal cancer (CRC) is the most frequently diagnosed cancer and leading cause of cancer-related deaths worldwide. Because of the use of first-line CRC treatments, such as irinotecan (IRI), is hindered by dose-limiting side effects, improved drug delivery systems may have major clinical benefits for CRC treatment. In this study, we generate and characterize liposomal irinotecan (Lipo-IRI), a lipid-based nanoparticle, which shows excellent bioavailability and pharmacokinetics. Additionally, this formulation allows IRI to be maintained in active form and prolongs its half-life in circulation compared to IRI in solution. Compared with IRI statistically, the level of prostaglandin E2 (PGE2) in colonic tissue decreases, and Bifidobacterium spp. (beneficial intestinal microbiota) content increases in the Lipo-IRI-treated group. Moreover, no damage is observed by the hematoxylin and eosin staining of the normal tissue samples from the Lipo-IRI-treated group. In a xenograft mouse model, CRC tumors shrink markedly following Lipo-IRI treatment, and mice receiving a targeted combination of Lipo-IRI and liposomal doxorubicin (Lipo-Dox) extend their survival rate significantly. Overall, our results demonstrate that this formulation of Lipo-IRI shows a great potential for the treatment of colorectal cancer.

Development of liposomal drug formulations: quality attributes and methods for quality control

The use of nanostructured components in drug manufacturing and, more specifically, targeted drug delivery has recently become a major trend in the pharmaceutical industry. Nanodrugs encompass a wide range of pharmaceutical agents containing dendrimers, nanocrystals, micelles, liposomes, and polymer nanoparticles. Liposomes are the most well-studied nanoparticles and effective drug carriers. However, the more complex their structure is, the more process controls are needed and the more quality attributes have to be monitored, including the chemical properties of the liposomal fraction such as the shape, size and charge of the nanoparticle, conjugation efficacy, and distribution of the active ingredient. We believe that quality control of key liposome characteristics should rely on dynamic and laser light scattering coupled with electrophoresis, differential scanning calorimetry, cryo-electron microscopy, nuclear magnetic resonance, laser diffraction analysis, and gel filtration chromatography.

Fabrication and evaluation of a γ-PGA-based self-assembly transferrin receptor-targeting anticancer drug carrier

Background

cis-Dichlorodiamineplatinum (CDDP) was one of the most common used drugs in clinic for cancer treatment. However, CDDP caused a variety of side effects. The abundant carboxyl groups on the surface of poly glutamic acid (PGA) could be modified with various kinds of targeted ligands. PGA delivery system loaded CDDP for cancer therapies possesses potential to overcome the side effects.

Materials and methods

In this study, we constructed a safe and efficient anticancer drug delivery system PGA–Asp–maleimide–cisplatin–peptide complex (PAMCP), which was loaded with CDDP and conjugated with the transferrin receptor (TFR)-targeting peptide through a maleimide functional linker. The size of PAMCP was identified by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Fluorescence microscopy and flow cytometry methods were used to detect the cell targeting ability in vitro. The MTT assay was used to detect targeted toxicity in vitro. The in vivo acute toxicity was tested in Kun Ming (KM) mice. The tumor suppression activity and drug distribution was analyzed in nude mice bearing with HeLa tumor cells.

Results

The nano-size was 110±28 nm detected with TEM and 89±18 nm detected with DLS, respectively. Fluorescence microscopy and flow cytometry methods indicated that PAMCP possessed excellent cell targeting ability in vitro. The MTT assay suggested that PAMCP was excellent for targeted toxicity. The acute in vivo toxicity study revealed that the body mass index and serum index in the PAMCP-treated group were superior to those in the CDDP-treated group (P<0.001), and no obvious differences were detected on comparing with the PBS- or PGA–Asp–maleimide–P8 (PAMP)-treated groups. PAMCP reduced the toxicity of CDDP, suppressed tumor cell growth, and achieved efficient anti-tumor effects in vivo. After PAMCP treatment, the toxicity of CDDP was reduced and tumor growth was more remarkably inhibited compared with the free CDDP treatment group (P<0.01). Much stronger (5–10 folds) fluorescence intensity in tumor tissue was detected compared with the irrelevant-peptide group for drug distribution analysis detected with the frozen section approach.

Conclusion

Our data highlighted that PAMCP reduced the side effects of CDDP and exhibited stronger anti-tumor effects. Therefore, PAMCP presented the potential to be a safe and effective anticancer pharmaceutical formulation for future clinical applications.

Magnetic delivery of Fe3O4@polydopamine nanoparticle-loaded natural killer cells suggest a promising anticancer treatment

Natural killer (NK)-cell-based immunotherapy has been reported to have promising prospects in the treatment of non-small cell lung cancer, one of the most common malignancies in the world. It has been proven that higher the NK cell infiltration into the tumor, the better is the curative effect. Therefore, it would be beneficial to develop a method that increases NK cell recruitment and infiltration into the tumor site. The purpose of this study was to establish an immune-cell delivery system for clear lung cancer cells based on magnetic nanoparticle (NP)-labeled NK cells that can be accumulated at the tumor site by placing a tiny external magnetic device inside animals. We developed superparamagnetic iron oxide NPs consisting of a magnetic Fe3O4 core and a shell of polydopamine (PDA) for magnetic targeting therapy. Fe3O4@PDA NPs possess favorable physiological stability and biocompatibility that facilitate their active uptake by NK cells. The biology of NK cells was not affected by the presence of NPs. In vitro and in vivo studies showed that Fe3O4@PDA NP-labeled NK cells significantly inhibited tumor growth and reduced the expression of Ki-67 and increased the apoptosis of A549 cancer cells. H&E staining showed Fe3O4@PDA NP-labeled NK cells, under a magnetic field, had higher intra-tumoral iron density and increased accumulation of CD56+ NK cells. Our results suggest that Fe3O4@PDA NPs are a promising magnetic nanomaterial that can manipulate immune cells, thereby inhibiting tumor growth.

Carbon Nanomaterials for Targeted Cancer Therapy Drugs: A Critical Review

Cancer represents one of the main causes of human death in developed countries. Most current therapies, unfortunately, carry a number of side effects, such as toxicity and damage to healthy cells, as well as the risk of resistance and recurrence. Therefore, cancer research is trying to develop therapeutic procedures with minimal negative consequences. The use of nanomaterial-based systems appears to be one of them. In recent years, great progress has been made in the field using nanomaterials with high potential in biomedical applications. Carbon nanomaterials, thanks to their unique physicochemical properties, are gaining more and more popularity in cancer therapy. They are valued especially for their ability to deliver drugs or small therapeutic molecules to these cells. Through surface functionalization, they can specifically target tumor tissues, increasing the therapeutic potential and significantly reducing the adverse effects of therapy. Their potential future use could, therefore, be as vehicles for drug delivery. This review presents the latest findings of research studies using carbon nanomaterials in the treatment of various types of cancer. To carry out this study, different databases such as Web of Science, PubMed, MEDLINE and Google Scholar were employed. The findings of research studies chosen from more than 2000 viewed scientific publications from the last 15 years were compared.

Impact of Particle Size and Polydispersity Index on the Clinical Applications of Lipidic Nanocarrier Systems

Lipid-based drug delivery systems, or lipidic carriers, are being extensively employed to enhance the bioavailability of poorly-soluble drugs. They have the ability to incorporate both lipophilic and hydrophilic molecules and protecting them against degradation in vitro and in vivo. There is a number of physical attributes of lipid-based nanocarriers that determine their safety, stability, efficacy, as well as their in vitro and in vivo behaviour. These include average particle size/diameter and the polydispersity index (PDI), which is an indication of their quality with respect to the size distribution. The suitability of nanocarrier formulations for a particular route of drug administration depends on their average diameter, PDI and size stability, among other parameters. Controlling and validating these parameters are of key importance for the effective clinical applications of nanocarrier formulations. This review highlights the significance of size and PDI in the successful design, formulation and development of nanosystems for pharmaceutical, nutraceutical and other applications. Liposomes, nanoliposomes, vesicular phospholipid gels, solid lipid nanoparticles, transfersomes and tocosomes are presented as frequently-used lipidic drug carriers. The advantages and limitations of a range of available analytical techniques used to characterize lipidic nanocarrier formulations are also covered.

Sildenafil citrate improves the delivery and anticancer activity of doxorubicin formulations in a mouse model of breast cancer

Sildenafil is an approved drug for the treatment of erectile dysfunction. The drug exerts its action through the relaxation of smooth muscles and the modulation of vascular endothelial permeability. In this work, we tested whether the aforementioned effects of sildenafil on tumour vasculatures could result in an improvement of anticancer drug concentration in tumour tissues and hence improves its anticancer effect. Sildenafil when added to doxorubicin showed synergistic anticancer activity against 4T1 breast cancer cells in vitro. Adding 1, 30 and 100 μM of Viagra to 1 μM of doxorubicin resulted in 1.8-fold, 6.2-fold and 21-fold statistically significant increases in its cytotoxic effect, respectively. As a result, 4T1 tumour-bearing mice showed up to 2.7-fold increase in drug concentrations of the fluorescent Dye DiI and doxorubicin in tumour tissues, as well as their nanoformulations. Animals treated with the combinations of both Sildenafil citrate and doxorubicin showed a statistically significant 4.7-fold reduction in tumour size compared to doxorubicin alone. This work highlights the effect of Sildenafil on tumour vasculatures and provides a rational for further testing the combination on breast cancer patients.

HPMA copolymer conjugate with pirarubicin: In vitro and ex vivo stability and drug release study

We have developed a tumor environment-responsive polymeric anticancer prodrug containing pirarubicin (THP) conjugated to N-(2-hydroxypropyl) methacrylamide copolymer (PHPMA), [P-THP], through a spacer containing pH-sensitive hydrazone bond, that showed remarkable therapeutic effect against various tumor models and in a human pilot study. Toward clinical development, here we report THP release profile from its HPMA copolymer conjugate, the conjugate stability, protein and cell-binding and solubility of P-THP. Size exclusion chromatography of P-THP (molecular weight 38 kDa) showed similar hydrodynamic volume as bovine serum albumin (BSA) in aqueous solution, with no apparent interactions with BSA, nor aggregation by itself. pH-responsive release of free THP was reconfirmed at pHs 6.5 and lower. The drug release was significantly affected by a type of used buffer. Phosphate buffer seems to facilitate faster hydrazone bond cleavage at pH 7.4 whereas higher stability was achieved in L-arginine solution which yielded only little cleavage and THP release, approx. 15% within 2 weeks at the same pH at 25 °C. Furthermore, ex vivo study using sera of different animal species showed very high stability of P-THP. Incubation with blood showed high stability of P-THP during circulation, without binding to blood cells. These findings revealed that L-arginine solution provides appropriate media for formulation of P-THP infusion solution as tumor-targeted polymeric anticancer drug based on EPR effect.

Styrene maleic acid-encapsulated RL71 micelles suppress tumor growth in a murine xenograft model of triple negative breast cancer

Patients with triple negative breast cancer have a poor prognosis due in part to the lack of targeted therapies. In the search for novel drugs, our laboratory has developed a second-generation curcumin derivative, 3,5-bis(3,4,5-trimethoxybenzylidene)-1-methylpiperidine-4-one (RL71), that exhibits potent in vitro cytotoxicity. To improve the clinical potential of this drug, we have encapsulated it in styrene maleic acid (SMA) micelles. SMA-RL71 showed improved biodistribution, and drug accumulation in the tumor increased 16-fold compared to control. SMA-RL71 (10 mg/kg, intravenously, two times a week for 2 weeks) also significantly suppressed tumor growth compared to control in a xenograft model of triple negative breast cancer. Free RL71 was unable to alter tumor growth. Tumors from SMA-RL71-treated mice showed a decrease in angiogenesis and an increase in apoptosis. The drug treatment also modulated various cell signaling proteins including the epidermal growth factor receptor, with the mechanisms for tumor suppression consistent with previous work with RL71 in vitro. The nanoformulation was also nontoxic as shown by normal levels of plasma markers for liver and kidney injury following weekly administration of SMA-RL71 (10 mg/kg) for 90 days. Thus, we report clinical potential following encapsulation of a novel curcumin derivative, RL71, in SMA micelles.

Coagulation and fibrinolysis in gastric cancer

Coagulation is a highly conserved process occurring after an injury to a blood vessel and resulting in hemostasis. In the thrombus microenvironment, finely orchestrated events restore vessel integrity through platelet activation, adhesion, and aggregation (primary hemostasis), followed by the coagulation cascades, thrombin generation, and fibrin clot deposition (secondary hemostasis). Several studies on cancer have provided insight into dramatic changes to coagulation-related events (i.e., fibrin clot deposition, fibrinolysis) during tumor pathogenesis, progression, and metastasis, in addition to a tumor-driven systemic activation of hemostasis and thrombosis (Trousseau's syndrome). Diverse molecular and cellular effectors participate in the cross talk between hemostasis and tumors. Here, we focus on some aspects of the interconnection between cancer biology and hemostatic components, with particular attention to some key coagulation-related proteins (e.g., tissue factor, thrombin, fibrinogen, and D-dimers) in the particular case of gastric cancer (GC). Recent advances in deciphering the complex molecular link between GC and the coagulation system are described, showing their important roles in better management of patients affected by GC.

Styrene maleic acid encapsulated raloxifene micelles for management of inflammatory bowel disease

Background

Inflammatory bowel disease (IBD) comprises a group of disorders that manifest through chronic inflammation of the colon and small intestine. Although the exact cause of IBD is still unclear, dysfunctional immunoregulation involving overproduction of inflammatory cytokines such as TNF-α, and IL-6 have been implicated in pathogenesis. Current therapy relies on immunosuppression, cytotoxic drugs, and monoclonal antibodies against TNF-α. These classes of drugs have severe side-effects, especially when used for long duration. Our previous work with raloxifene, a selective estrogen receptor modulator, has shown that the drug, and to a greater extent its micellar formulation, has a significant suppressive effect on NF-κB, an essential immune-regulator. This finding directed the current work towards testing the anti-inflammatory and immunomodulatory effects of raloxifene using cell lines, as well as testing the potential use of the styrene maleic acid (SMA) micelles loaded with raloxifene (SMA-Ral) against dextran sulfate sodium (DSS) induced colitis in an in vivo model of IBD.

Results

Treatment of MCF-7 cells with TNF-α was shown to protect the cells from the cytotoxic effect of raloxifene (42 vs. 10% cell death, with TNF-α. Treating CaCo-2 cells with both free and SMA-Ral improved cell survival after exposure to 2% DDS with significantly higher protection with SMA-Ral. Treatment of U-937 with SMA-Ral and free-Ral resulted in down-regulation of TNF-α, IL-1β, IL-6, and MIP1α, with greater inhibition of the SMA-Ral, compared to free Ral. Balb/c mice treated with raloxifene and SMA-Ral showed weight gain at 14 days, compared to the control group (122, and 115% respectively). Treatment with raloxifene prevented DSS-induced diarrhea in 6/6 of free raloxifene treated mice and in 5/6 mice treated with SMA-Ral. Control group of DSS-treated mice showed average colon length of 7.4 cm compared to 13 cm in the control group. The average colon length was 12.3 and 11.5 cm for raloxifene and SMA-Ral treated groups, respectively. Furthermore, inflammatory cytokines such as IL-6 and TNF-α were reduced in serum of animals treated with free-Ral and SMA-Ral.

Conclusions

Raloxifene and its micellar formulation warrants further studies to understand their effect on the treatment of colitis.Graphical abstract

Drug-Free Macromolecular Therapeutics--A New Paradigm in Polymeric Nanomedicines

This review highlights a unique research area in polymer-based nanomedicine designs. Drug-free macromolecular therapeutics induce apoptosis of malignant cells by the crosslinking of surface non-internalizing receptors. The receptor crosslinking is mediated by the biorecognition of high-fidelity natural binding motifs (such as antiparallel coiled-coil peptides or complementary oligonucleotides) that are grafted to the side chains of polymers or attached to targeting moieties against cell receptors. This approach features the absence of low-molecular-weight cytotoxic compounds. Here, we summarize the rationales, different designs, and advantages of drug-free macromolecular therapeutics. Recent developments of novel therapeutic systems for B-cell lymphomas are discussed, as well as relevant approaches for other diseases. We conclude by pointing out various potential future directions in this exciting new field.

Biointerfacing and Applications of Cell Membrane-Coated Nanoparticles

The cell membrane-coated nanoparticle is a biomimetic platform consisting of a nanoparticulate core coated with membrane derived from a cell, such as a red blood cell, platelet, or cancer cell. The cell membrane "disguise" allows the particles to be perceived by the body as the source cell by interacting with its surroundings using the translocated surface membrane components. The newly bestowed characteristics of the membrane-coated nanoparticle can be utilized for biological interfacing in the body, providing natural solutions to many biomedical issues. This Review will cover the interactions of these cell membrane-coated nanoparticles and their applications within three biomedical areas of interest, including (i) drug delivery, (ii) detoxification, and (iii) immune modulation.

The influence of different long-circulating materials on the pharmacokinetics of liposomal vincristine sulfate

PURPOSE

This study was designed to improve the in vivo pharmacokinetics of long-circulating vincristine sulfate (VS)-loaded liposomes; three different long-circulating materials, chitosan, poly(ethylene glycol)-1,2-distearoyl sn-glycero-3-phosphatidylethanolamine (PEG-DSPE), and poly(ethylene glycol)-poly-lactide-co-glycolide (PEG-PLGA), were evaluated at the same coating molar ratio with the commercial product Marqibo(®) (vincristine sulfate liposome injection [VSLI]).

MATERIALS AND METHODS

VS-loaded liposomes were prepared by a pH gradient method and were then coated with chitosan, PEG-DSPE, or PEG-PLGA. Physicochemical properties, including the morphology, particle size, zeta potential, encapsulation efficiency (EE%), pH, drug loading, and in vitro release, were determined. Preservation stability and pharmacokinetic studies were performed to compare the membrane-coated liposomes with either commercially available liposomes or the VS solution.

RESULTS

The sphere-like morphology of the vesicles was confirmed by transmission electron microscope. Increased particle size, especially for the chitosan formulation, was observed after the coating process. However, the EE% was ~99.0% with drug loading at 2.0 mg/mL, which did not change after the coating process. The coating of long-circulation materials, except for chitosan, resulted in negatively charged and stable vesicles at physiological pH. The near-zero zeta potential exhibited by the PEG-DSPE formulation leads to a longer circulation lifetime and improved absorption for VS, when compared with the PEG-PLGA formulation. Compared with the commercial product, PEG was responsible for a higher plasma VS concentration and a longer half-life.

CONCLUSION

PEG-DSPE coating may be related to better absorption, based on the stability and a pharmacokinetic improvement in the blood circulation time.

Dendrimer-mediated approaches for the treatment of brain tumor

Worldwide, the cancer appeared as one of the most leading cause of morbidity and mortality. Among the various cancer types, brain tumors are most life threatening with low survival rate. Every year approximately 238,000 new cases of brain and other central nervous system tumors are diagnosed. The dendrimeric approaches have a huge potential for diagnosis and treatment of brain tumor with targeting abilities of molecular cargoes to the tumor sites and the efficiency of crossing the blood brain barrier and penetration to brain after systemic administration. The various generations of dendrimers have been designed as novel targeted drug delivery tools for new therapies including sustained drug release, gene therapy, and antiangiogenic activities. At present era, various types of dendrimers like PAMAM, PPI, and PLL dendrimers validated them as milestones for the treatment and diagnosis of brain tumor as well as other cancers. This review highlights the recent research, opportunities, advantages, and challenges involved in development of novel dendrimeric complex for the therapy of brain tumor.

Drug delivery system targeting advanced hepatocellular carcinoma: Current and future

Hepatocellular carcinoma (HCC) has a fairly high morbidity and is notoriously difficult to treat due to long latent period before detection, multidrug resistance and severe drug-related adverse effects from chemotherapy. Targeted drug delivery systems (DDS) that can selectively deliver therapeutic drugs into tumor sites have demonstrated a great potential in cancer treatment, which could be utilized to resolve the limitations of conventional chemotherapy. Numerous preclinical studies of DDS have been published, but targeted DDS for HCC has yet to be made for practical clinical use. Since rational targeted DDS design should take cancer-specific properties into consideration, we have reviewed the biological and physicochemical properties of HCC extensively to provide a comprehensive understanding on HCC, and recent DDS studies on HCC, aiming to find some potential targeted DDSs for HCC treatment and a meaningful platform for further development of HCC treatments.

FROM THE CLINICAL EDITOR

Hepatocellular carcinoma has a high incidence worldwide and is known to be multidrug resistant. Thus, intensive research is being carried out to find better chemotherapeutic agents as well as new drug delivery systems. In this article, the authors reviewed in depth the current challenges facing new drug designs and also outlined novel targeted drug delivery systems (DDS) in the fight against HCC.

Anti-Resorptive Functions of Poly(ethylene sodium phosphate) on Human Osteoclasts

Osteoporosis involves hyperactive osteoclasts. A large number of current drugs result in side effects affecting their efficacy in the clinic. Polyphosphoesters are unique polymeric biomaterials because of their biocompatibility, biodegradability, and bone affinity. We studied the viability and ability of human osteoclasts to resorb bone when dosed with poly(ethylene sodium phosphate) (PEP·Na). This did not trigger any change in osteoblast cell viability, however the polymer diminished human osteoclasts and their ability to resorb bone at concentrations as low as 10(-4) m · mL(-1). This is the first report to validate the possibility of using polyphosphoesters for selective inhibition of human osteoclast functions, indicating its potential to be used as an effective polymer prodrug for treatment of osteoporosis.

Phase 2 trial of paclitaxel polyglumex with capecitabine for metastatic breast cancer

BACKGROUND

Capecitabine and paclitaxel are established effective treatments, alone and combined with other cytotoxic and targeted agents, for metastatic breast cancer (MBC). Paclitaxel polyglumex (a macromolecular conjugate of paclitaxel bound to poly-L-glutamic acid) has potential advantages over conventional paclitaxel, including little alopecia, short infusion time with no premedication, enhanced tumor permeability/retention effect, and improved tolerability. We therefore examined tolerability and efficacy of paclitaxel polyglumex with capecitabine in patients with MBC.

PATIENTS AND METHODS

This was a single-stage phase 2 study, with interim analysis conducted with endpoints of tumor response, adverse events (toxicities), time to progression, and overall survival. The main eligibility criteria were: age >18 years, no prior MBC chemotherapy, Eastern Cooperative Oncology Group performance score <2, disease measurable by RECIST criteria, no HER2 overexpression or amplification, no brain metastases or peripheral sensory neuropathy. Treatment consisted of paclitaxel polyglumex (135 mg/m) by intravenous infusion on day 1+capecitabine (825 mg/m) orally twice daily on days 1 to 14, repeated on a 3-week cycle. Forty-one evaluable patients were required to test the null hypothesis that the complete and partial tumor response rate (CR+PR) was at the most 40% against the alternative of at least 60%. Paclitaxel polyglumex+capecitabine would be considered promising in this population if ≥21 responses were observed among first 41 evaluable patients.

RESULTS

Forty-eight patients were enrolled between April 2006 and April 2007; all patients were evaluable. The median number of treatment cycles administered was 6. Eighteen patients [38%; 95% confidence interval (CI), 24%-53%] had a confirmed tumor response (2 CR, 16 PR) by RECIST criteria. Fifteen (38%; 95% CI, 23%-53%) responses occurred in first 41 patients, falling short of prespecified goal of 21 responses. Median duration of tumor response was 13.2 months. Three of the responders were progression free at last follow-up with a median follow-up of 43 months. Median progression-free survival was 5.1 months (95% CI, 4.0-7.6 mo). Six-month progression-free survival was 42% (95% CI, 30%-58%). Median dose level administered was paclitaxel polyglumex (135 mg/m) and capecitabine (825 mg/m) for cycles 1 to 7. Most common severe (grade 3/4) toxicities (at least possibly related to study drug) were: leukopenia 9 (19%), neutropenia 8 (17%), neurosensory 4 (8%), skin reaction-hand/foot 4 (8%), and dyspnea 2 (4%). Forty-six percent (22/47) of patients experienced grade ≥3 toxicity and 8% (4/48) experienced grade ≥4 toxicity. No alopecia was reported.

CONCLUSIONS

Although the trial failed to reach goal of 21 confirmed tumor responses among the first 41 evaluable patients, paclitaxel polyglumex and capecitabine is well tolerated and effective in MBC.

Current status of nanomedicine and nanosurgery

Nanotechnology is a multidisciplinary field that covers a vast and diverse array of devices derived from physics, biology, engineering, and chemistry. Applications of nanotechnology to medicine and physiology imply materials and devices designed to interact with the body at subcellular (i.e., molecular) scales with a high degree of specificity. There is considerable useful information about nanotechnology available and already in use. However, at present, it is very incomplete and scattered. We realized many doctors are unaware of nanotechnology used during surgery and its future prospects in patients. Though most medical products that use nanotechnology are still in the research and development stage, there are a few which are commercially available. Nanotechnology has grown by leaps and bounds over the last few years; applications of this technology in the field of medicine and surgery have been an important spin-off. Many biological structures are at nanometer scale used by surgeons in orthopedic, dental, and neurosurgeries. This article starts with the basics of the nanotechnology and how it is utilized through most medical products. This important article, which is felt to offer high educational value for the doctors, have been selected from an extensive search on the internet, and elaborately discussed. In this review, the scientific and technical aspects of nanotechnology are introduced, and some of its potential clinical applications are discussed.