Cancer immunotherapy has been firmly established as a new milestone for cancer therapy, with the development of multiple immune cells as therapeutic tools. Natural killer (NK) cells are innate immune ...cells endowed with potent cytolytic activity against tumors, and meanwhile act as regulatory cells for the immune system. The efficacy of NK cell-mediated immunotherapy can be enhanced by immune stimulants such as cytokines and antibodies, and adoptive transfer of activated NK cells expanded
. In addition, NK cells can arm themselves with chimeric antigen receptors (CARs), which may greatly enhance their anti-tumor activity. Most recently, extracellular vesicles (EVs) derived from NK cells show promising anti-tumor effects in preclinical studies. Herein, we carefully review the current progress in these NK cell-based immunotherapeutic strategies (NK cells combined with stimulants, adoptive transfer of NK cells, CAR-NK cells, and NK EVs) for the treatment of cancers, and discussed the challenges and opportunities for opening a new horizon for cancer immunotherapy.
The specific sizes that determine optimal nanoparticle tumor accumulation, penetration, and treatment remain inconclusive because many studies compared nanoparticles with multiple physicochemical ...variables (e.g., chemical structures, shapes, and other physical properties) in addition to the size. In this study, we synthesized amphiphilic block copolymers of 7-ethyl-10-hydroxylcamptothecin (SN38) prodrug and fabricated micelles with sizes ranging from 20 to 300 nm from a single copolymer. The as-prepared micelles had exactly the same chemical structures and similar physical properties except for size, which provided an ideal platform for a systematic investigation of the size effects in cancer drug delivery. We found that the micelle’s blood circulation time and tumor accumulation increased with the increase in their diameters, with optimal diameter range of 100 to 160 nm. However, the much higher tumor accumulation of the large micelles (100 nm) did not result in significantly improved therapeutic efficacy, because the large micelles had poorer tumor penetration than the small ones (30 nm). An optimal size that balances drug accumulation and penetration in tumors is critical for improving the therapeutic efficacy of nanoparticulate drugs.
A key barrier to the development of gene therapy remains the lack of safe, efficient and easily controllable vehicles for gene delivery. The fundamental problems associated with the viral vehicles, ...e.g. lack of specificity and immunogenic potential, have driven the development of non-viral systems of gene delivery. In the last decade, studies on p53 gene replacement therapy have dominated the literature. Although clinical trials of p53 gene therapy have achieved limited success, it remains the only tumor suppressor gene to be evaluated formally in clinical trials for cancer treatment, with increasing focus on delivery using non-viral systems. In this article, we particularly review current investigations on p53 gene delivery using non-viral methods, including both physical and chemical approaches, with an emphasis on the latter. The existing opportunities and challenges for successful p53 cancer gene therapy are also discussed.
Multi-arm star poly(ethylene glycol) (PEG) polymers have a number of advantages over linear PEG polymers when used as carriers for drug delivery and controlled release. For instance, they have more ...terminals that can be modified to form multi-functional delivery systems with significantly increased drug loading. They can form micelles with higher stability and lower critical micelle concentration (CMC), which helps to improve the blood circulation and reduce the unfavorable burst drug release. Moreover, star PEG polymers can form three-dimensional hydrogels with controllable size and adjustable functions through cross-linking. Indeed, these unique advantages of star PEG polymers have promoted investigations on star PEG-based drug delivery systems. Herein, for the first time, we carefully reviewed the advances on the research and development of star PEG polymers, especially the 4-, 6- and 8-armed star PEG polymers, in delivery and controlled release of a series of bioactive agents, including both small molecules and biomacromolecules. Opportunities and challenges for successful translation of star PEG-based drug formulations into clinical use were also discussed.
The upper panel shows the representative structures of star PEG derivatives.
The lower panel shows three different dosage forms based on star PEG derivatives. Display omitted
•Advantages of star PEG polymers as carriers for drug delivery were introduced.•Star PEG derivatives can be classified into conjugates, hydrogels and nanoparticles.•Small- and macro-molecules delivered by star PEG-based materials were reviewed.•Future directions for research on star PEG-based drug formulations were discussed.
Nuclear drug delivery for cancer chemotherapy Sui, Meihua; Liu, Wenwen; Shen, Youqing
Journal of controlled release,
10/2011, Volume:
155, Issue:
2
Journal Article, Conference Proceeding
Peer reviewed
Nanosystems with unique physical and biological properties have been extensively explored for cancer targeted intracellular delivery of small-molecular chemotherapeutic drugs to increase their ...therapeutic efficacies and to minimize their side effects. A large number of anticancer drugs are DNA-toxins that bind nuclear DNA or its associated enzymes to exert their cytotoxicity to cancer cells. After entering tumor cells, they need to be further delivered to the nucleus for actions. Herein, we discuss the biological barriers and summarize recent progress of nuclear drug delivery for cancer chemotherapy, emphasizing strategies that appear useful for design of vehicles capable of delivering drugs to the nucleus, particularly for in vivo applications. The existing obstacles or problems that need to be overcome before successful applications of nuclear drug delivery for cancer chemotherapy are also discussed.
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Various types of nanoparticles, such as liposomes, polymeric micelles, dendrimers, superparamagnetic iron oxide crystals, and colloidal gold, have been employed in targeted therapies for cancer. Both ...passive and active targeting strategies can be utilized for nano-drug delivery. Passive targeting is based on the enhanced permeability and retention (EPR) effect of the vasculature surrounding tumors. Active targeting relies on ligand-directed binding of nanoparticles to receptors expressed by tumor cells. Release of loaded drugs from nanoparticles may be controlled in response to changes in environmental condition such as temperature and pH. Biodistribution profiles and anticancer efficacy of nano-drugs in vivo would be different depending upon their size, surface charge, PEGylation and other biophysical properties. This review focuses on the recent development of nanoparticles for tumor targeted therapies, including physicochemical properties, tumor targeting, control of drug release, pharmacokinetics, anticancer efficacy and safety. Future perspectives are discussed as well.
Anticancer drugs embedded in or conjugated with inert nanocarriers, referred to as nanomedicines, show many therapeutic advantages over free drugs, but the inert carrier materials are the major ...component (generally more than 90%) in nanomedicines, causing low drug loading contents and thus excessive uses of parenteral excipients. Herein, we demonstrate a new concept directly using drug molecules to fabricate nanocarriers in order to minimize use of inert materials, substantially increase the drug loading content, and suppress premature burst release. Taking advantage of the strong hydrophobicity of the anticancer drug camptothecin (CPT), one or two CPT molecule(s) were conjugated to a very short oligomer chain of ethylene glycol (OEG), forming amphiphilic phospholipid-mimicking prodrugs, OEG-CPT or OEG-DiCPT. The prodrugs formed stable liposome-like nanocapsules with a CPT loading content as high as 40 or 58 wt % with no burst release in aqueous solution. OEG-DiCPT released CPT once inside cells, which showed high in vitro and in vivo antitumor activity. Meanwhile, the resulting nanocapsules can be loaded with a water-soluble drugdoxorubicin salt (DOX·HCl)with a high loading efficiency. The DOX·HCl-loaded nanocapsules simultaneously delivered two anticancer drugs, leading to a synergetic cytotoxicity to cancer cells. The concept directly using drugs as part of a carrier is applicable to fabricating other highly efficient nanocarriers with a substantially reduced use of inert carrier materials and increased drug loading content without premature burst release.
The clinical utility of CPT-11 is restricted by factors such as the low conversion rate to SN38, high interpatient variability and dose-limiting toxicity. SN38 is significantly more potent than ...CPT-11, but parental administration of SN38 is impossible due to its poor solubility and low stability. This study aimed to develop a novel SN38 prodrug (OEG-SN38) that may overcome the various drawbacks of CPT-11 and SN38 and be useful for clinics. We attached a very low molecular weight oligo (ethylene glycol) (OEG) chain selected as the hydrophilic part to hydrophobic SN38 via ester bond at the C20 position to form the amphiphilic OEG-SN38. In aqueous solution OEG-SN38 formed micelles with diameter of 28.74±2.51nm, and showed greatly improved drug loading, solubility and stability, with drug loading as high as 36% (wt.%). Moreover, these micelles were stable in PBS with only 4.71% SN38 released from the prodrug even after 35h incubation, but released SN38 promptly by esterase hydrolysis. Most importantly, OEG-SN38 exhibited potent antitumor activity against a panel of human tumor cell lines, as well as favorable antitumor activity and high safety in human xenograft models. These encouraging data merit further preclinical and clinical investigation on this novel SN38 delivery system.
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Pancreatic ductal adenocarcinoma (PDAC) is a lethal cancer with a dismal overall prognosis mainly unchanged over the past decades. PDAC is generally refractory to conventional treatments, and thus ...novel therapies are urgently needed. Recently, accumulating evidence has indicated that human pancreatic stellate cells (PSCs) facilitate PDAC development and drug resistance through paracrine activation of hedgehog pathway. Here, we report that smart SN38 (active metabolite of irinotecan) polymeric prodrug-based nanoparticles effectively encapsulate the commercial hedgehog pathway inhibitor GDC-0449 for co-delivery. More intriguingly, we obtained size-tunable nanoparticles with increased GDC-0449 loading efficiency by simply extending the chain length of the hydrophobic SN38 block. To better evaluate the efficacy and investigate the synergistic mechanisms, we immortalized human PSCs and established fibroblast-containing models in vitro and in vivo. In PSCs, BxPC-3 cells and MIA PaCa-2 cells, GDC-0449 suppressed the co-culture induced up-regulations of the two drug resistance contributors: sonic hedgehog transcription factor glioma-associated protein1 (GLI-1) and UGT1A glucuronosyltransferase. Importantly, the nanoparticle-mediated co-delivery system exhibited potent antitumor efficacy with enhanced apoptosis and reduced collagen, α-SMA and GLI-1 expression in tumor tissues. These findings reveal a potential strategy to utilize nanoparticle-mediated drug co-delivery platform as an effective combination therapy for fibroblast-enriched PDAC.
Novel classes of jellyfish-shaped amphiphilic dendrimers composed of 7 hydrophilic poly(ethylene glycol) (PEG) arms and 14 hydrophobic polyester dendrons with β-cyclodextrin (βCD) as the core ...molecule were synthesized by a facile method. Seven PEG chains were first conjugated to the C-6 positions of native βCD. Subsequently, dendritic polyester architectures were constructed from the remaining 14 secondary hydroxyl groups at C-2 and C-3 positions of the βCD moiety, resulting in jellyfish-shaped amphiphilic dendrimers of different generations (7PEG-βCD-Gx) with well-defined molecular structures. The amphiphilic dendrimers self-assembled into different morphologies dependent upon the hydrophilic fraction of the dendrimers, and very surprisingly, the fourth-generation dendrimers consisting of only several percent of PEG could form aggregates with extremely narrow size distributions.
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