Antibody modified Bovine Serum Albumin microspheres for targeted delivery of anticancer agent Gemcitabine

Inhibition of the EGFR signaling pathway is one of the attractive therapeutic targets for pancreatic cancer as recent studies demonstrated that EGFR is over‐expressed in pancreatic cancer. In this article we have demonstrated the design of targeted drug delivery system containing Bovine Serum Albumin (BSA) microspheres as delivery vehicle, gemcitabine as anticancer drug and anti‐EGFR (epidermal growth factor receptor) monoclonal antibody as targeting agent. The conjugated BSA microspheres were characterized by several physico‐chemical techniques such as scanning electron microscope, optical microscopy, fluorescent microscopy etc. Administration of these BSA microspheres containing gemcitabine and anti‐EGFR (BSA‐Gem‐EGFR) shows significant inhibition of pancreatic cancer cells (AsPC1) compared to the cells treated with only BSA microspheres, BSA with gemcitabine (BSA‐Gem), and free gemcitabine. This strategy could be used as a generalized approach for the treatment of pancreatic cancer along with other cancers which overexpress EGFR on cell surface. Copyright © 2012 John Wiley & Sons, Ltd.     

Carrier‐Free Delivery of Precise Drug–Chemogene Conjugates for Synergistic Treatment of Drug‐Resistant Cancer

Combinatorial antitumor therapies using different combinations of drugs and genes are emerging as promising ways to overcome drug resistance, which is a major cause for the failure of cancer treatment. However, dramatic pharmacokinetic differences of drugs greatly impede their combined use in cancer therapy, raising the demand for drug delivery systems (DDSs) for tumor treatment. By employing fluorescent dithiomaleimide (DTM) as a linker, we conjugate two paclitaxel (PTX) molecules with a floxuridine (FdU)‐integrated antisense oligonucleotide (termed chemogene) to form a drug–chemogene conjugate. This PTX–chemogene conjugate can self‐assemble into a spherical nucleic acid (SNA)‐like micellular nanoparticle as a carrier‐free DDS, which knocks down the expression of P‐glycoprotein and subsequently releases FdU and PTX to exert a synergistic antitumor effect and greatly inhibit tumor growth.     

Enzyme‐Responsive Multifunctional Magnetic Nanoparticles for Tumor Intracellular Drug Delivery and Imaging

Enzyme‐responsive, hybrid, magnetic silica nanoparticles have been employed for multifunctional applications in selective drug delivery and intracellular tumor imaging. In this study, doxorubicin (Dox)‐conjugated, enzyme‐cleavable peptide precursors were covalently tethered onto the surface of uniform silica‐coated magnetic nanoparticles through click chemistry. This enzyme‐responsive nanoparticle conjugate demonstrated highly efficient Dox release upon specific enzyme interactions in vitro. It also exhibits multiple functions in selective tumor intracellular drug delivery and imaging in the tumor cells with high cathepsin B expression, whereas it exhibited lower cytotoxicity towards other cells without enzyme expression.     

Stem cell membrane vesicle–coated nanoparticles for efficient tumor‐targeted therapy of orthotopic breast cancer

Nanoparticles‐based drug delivery strategies have been widely researched for cancer therapy. However, most of them are expected to accumulate in tumor sites via the enhanced permeability and retention (EPR) effect, which is insufficient to deliver the loaded drug into tumors. Cell membrane–camouflaged nanoparticles have obtained much attention for their excellent stability and long blood circulation and reduced the macrophage cells uptake in drug delivery. Herein, bone marrow–derived mesenchymal stem cell membrane vesicle (SCV)–coated paclitaxel (PTX)–loaded poly (lactide‐co‐glycolide) (PLGA) nanoparticles (SCV/PLGA/PTX) were fabricated as the efficient orthotopic breast cancer–targeted drug delivery system. The SCV/PLGA/PTX showed excellent stability, more controlled PTX release, and more effective antitumor effect in vitro. After administration in vivo, SCV/PLGA/PTX exhibited the long‐term retention and enhanced accumulation at tumor sites due to the immune escape and mesenchymal stem cell–mimicking cancer‐targeting capacity. As expected, the SCV/PLGA/PTX could significantly suppress the primary tumor growth by increased apoptosis and necrosis areas within tumor tissues and attenuated the toxic side effects of PTX in 4T1 orthotopic breast cancer model. The study indicated the mesenchymal stem cell membrane coating strategy was highly efficient for targeted drug delivery, which provided a new insight for precise and effective breast cancer treatment.     

Dendrimer Functionalization with a Membrane‐Interacting Domain of Herpes Simplex Virus Type 1: Towards Intracellular Delivery

A poly(amide)‐based dendrimer was synthesized and functionalized with the membrane‐interacting peptide gH(625–644) (gH625) derived from the herpes simplex virus type 1 (HSV‐1) envelope glycoprotein H, which has previously been shown to assist in delivering large cargoes across the cellular membrane. We demonstrate that the attachment of the gH625 peptide sequence to the termini of a dendrimer allows the conjugate to penetrate into the cellular matrix, whereas the unfunctionalized dendrimer is excluded from translocation. The peptide‐functionalized dendrimer is rapidly taken into the cells mainly through a non‐active translocation mechanism. Our results suggest that the presented peptidodendrimeric scaffold may be a promising material for efficient drug delivery.     

Three‐Arm,Biotin‐Tagged Carbazole–Dicyanovinyl–Chlorambucil Conjugate: Simultaneous Tumor Targeting,Sensing, and Photoresponsive Anticancer Drug Delivery

The design, synthesis, and in vitro biological studies of a biotin–carbazole–dicyanovinyl–chlorambucil conjugate (Bio‐CBZ‐DCV‐CBL; 6 ) are reported. This conjugate ( 6 ) is a multifunctional single‐molecule appliance composed of a thiol‐sensor DCV functionality, a CBZ‐derived phototrigger as well as fluorescent reporter, and CBL as the anticancer drug, and Bio as the cancer‐targeting ligand. In conjugate 6 , the DCV bond undergoes a thiol–ene click reaction at pH<7 with intracellular thiols, thereby shutting down internal charge transfer between the donor CBZ and acceptor DCV units, resulting in a change of the fluorescence color from green to blue, and thereby, sensing the tumor microenvironment. Subsequent photoirradiation results in release of the anticancer drug CBL in a controlled manner.     

Self‐Assembly Drug Delivery System Based on Programmable Dendritic Peptide Applied in Multidrug Resistance Tumor Therapy

In recent decades, diverse drug delivery systems (DDS) constructed by self‐assembly of dendritic peptides have shown advantages and improvable potential for cancer treatment. Here, an arginine‐enriched dendritic amphiphilic chimeric peptide CRRK(RRCG(Fmoc))₂ containing multiple thiol groups is programmed to form drug‐loaded nano‐micelles by self‐assembly. With a rational design, the branched hydrophobic groups (Fmoc) of the peptides provide a strong hydrophobic force to prevent the drug from premature release, and the reduction‐sensitive disulfide linkages formed between contiguous peptides can control drug release under reducing stimulation. As expected, specific to multidrug resistance (MDR) tumor cells, the arginine‐enriched peptide/drug (PD) nano‐micelles show accurate nuclear localization ability to prevent the drug being pumped by P‐glycoprotein (P‐gp) in vitro, as well as exhibiting satisfactory efficacy for MDR tumor treatment in vivo. This design successfully realizes stimuli‐responsive drug release aimed at MDR tumor cells via an ingenious sequence arrangement.     

A Reduction‐responsive Amphiphilic Methotrexate‐Podophyllotoxin Conjugate for Targeted Chemotherapy

Owing to the naturally high toxicity, poor water solubility, and other side effects of podophyllotoxin (PPT), its applications are limited. To address these issues, we developed a new PPT delivery system, in which the hydrophilic drug methotrexate (MTX) and the hydrophobic drug PPT were linked by a reduction‐responsive disulfide bond to form an amphiphilic drug‐drug conjugate prodrug (MTX‐SS‐PPT). The conjugate could self‐assemble into spherical nanoaggregates in aqueous solution and self‐deliver to tumor tissues. In addition, MTX could target to folate‐receptor‐positive cells. Over‐expression of glutathione in tumor cells broke the disulfide bonds and released the free drug. In vitro and in vivo experiments indicated that the nanodrug could effectively improve the biocompatibility and reduce the toxicity of PPT.     

Tailor-made dual pH-sensitive polymer-doxorubicin nanoparticles for efficient anticancer drug delivery

Efficient delivery of therapeutics into tumor cells to increase the intracellular drug concentration is a major challenge for cancer therapy due to drug resistance and inefficient cellular uptake. Herein, we have designed a tailor-made dual pH-sensitive polymer-drug conjugate nanoparticulate system to overcome the challenges. The nanoparticle is capable of reversing its surface charge from negative to positive at tumor extracellular pH (～6.8) to facilitate cell internalization. Subsequently, the significantly increased acidity in subcellular compartments such as the endosome (～5.0) further promotes doxorubicin release from the endocytosed drug carriers. This dual pH-sensitive nanoparticle has showed enhanced cytotoxicity in drug-resistant cancer stem cells, indicating its great potential for cancer therapy.     

Microenvironment‐Induced In Situ Self‐Assembly of Polymer–Peptide Conjugates That Attack Solid Tumors Deeply

In cancer treatment, the unsatisfactory solid‐tumor penetration of nanomaterials limits their therapeutic efficacy. We employed an in vivo self‐assembly strategy and designed polymer–peptide conjugates (PPCs) that underwent an acid‐induced hydrophobicity increase with a narrow pH‐response range (from 7.4 to 6.5). In situ self‐assembly in the tumor microenvironment at appropriate molecular concentrations (around the IC₅₀ values of PPCs) enabled drug delivery deeper into the tumor. A cytotoxic peptide KLAK, decorated with the pH‐sensitive moiety cis‐aconitic anhydride (CAA), and a cell‐penetrating peptide TAT were conjugated onto poly(β‐thioester) backbones to produce PT‐K‐CAA, which can penetrate deeply into solid tumors owing to its small size as a single chain. During penetration in vivo, CAA responds to the weak acid, leading to the self‐assembly of PPCs and the recovery of therapeutic activity. Therefore, a deep‐penetration ability for enhanced cancer therapy is provided by this in vivo assembly strategy.     

Human Serum Albumin Conjugated Nanoparticles for pH and Redox‐Responsive Delivery of a Prodrug of Cisplatin

Platinum anticancer drugs are particularly in need of controlled drug delivery because of their severe side effects. Platinum(IV) agents are designed as prodrugs to reduce the side effects of platinum(II) drugs; however, premature reduction could limit the effect as a prodrug. In this work, a highly biocompatible, pH and redox dual‐responsive delivery system is prepared by using hybrid nanoparticles of human serum albumin (HSA) and calcium phosphate (CaP) for the Pt^IV prodrug of cisplatin. This conjugate is very stable under extracellular conditions, so that it protects the platinum(IV) prodrug in HSA. Upon reaching the acidic and hypoxic environment, the platinum drug is released in its active form and is able to bind to the target DNA. The Pt–HSA/CaP hybrid inhibits the proliferation of various cancer cells more efficiently than cisplatin. Different cell cycle arrests suggest different cellular responses of the Pt^IV prodrug in the CaP nanocarrier. Interestingly, this delivery system demonstrates enhanced cytotoxicity to tumor cells, but not to normal cells.     

Nuclear-targeted drug delivery of TAT peptide-conjugated monodisperse mesoporous silica nanoparticles

Most present nanodrug delivery systems have been developed to target cancer cells but rarely nuclei. However, nuclear-targeted drug delivery is expected to kill cancer cells more directly and efficiently. In this work, TAT peptide has been employed to conjugate onto mesoporous silica nanoparticles (MSNs-TAT) with high payload for nuclear-targeted drug delivery for the first time. Monodispersed MSNs-TAT of varied particle sizes have been synthesized to investigate the effects of particle size and TAT conjugation on the nuclear membrane penetrability of MSNs. MSNs-TAT with a diameter of 50 nm or smaller can efficiently target the nucleus and deliver the active anticancer drug doxorubicin (DOX) into the targeted nucleus, killing these cancer cells with much enhanced efficiencies. This study may provide an effective strategy for the design and development of cell-nuclear-targeted drug delivery.     

Treating Tumors at Low Drug Doses Using an Aptamer–Peptide Synergistic Drug Conjugate

Combination chemotherapy must strike a difficult balance between safety and efficacy. Current regimens suffer from poor therapeutic impact because drugs are given at their maximum tolerated dose (MTD), which compounds the toxicity risk and exposes tumors to non‐optimal drug ratios. A modular framework has been developed that selectively delivers drug combinations at synergistic ratios via tumor‐targeting aptamers for effective low‐dose treatment. A nucleolin‐recognizing aptamer was coupled to peptide scaffolds laden with precise ratios of doxorubicin (DOX) and camptothecin (CPT). This construct had an extremely low IC₅₀ (31.9 nm ) against MDA‐MB‐231 breast cancer cells in vitro, and exhibited in vivo efficacy at micro‐dose injections (500 and 350 μg kg^?1 dose^?1 of DOX and CPT, respectively) that are 20–30‐fold lower than their previously‐reported MTDs. This approach represents a generalizable strategy for the safe and consistent delivery of combination drugs in oncology.     

Cancer-Cell-Specific Drug Delivery by a Tumor-Homing CPP-Gossypol Conjugate Employing a Tracelessly Cleavable Linker

Tumor-targeted drug delivery is highly important for improving chemotherapy, as it reduces the dose of cytotoxic agents and minimizes the death of healthy tissues. Towards this goal, a conjugate was synthesized of gossypol and a MCF-7 cancer cell specific CPP (cell penetrating peptide), thus providing a selective drug delivery system. Utilizing the aldehyde moiety of gossypol, the tumor homing CPP RLYMRYYSPTTRRYG was attached through a semi-labile imine linker, which was cleaved in a traceless fashion under aqueous conditions and had a half-life of approximately 10 hours. The conjugate killed MCF-7 cells to a significantly greater extent than HeLa cells or healthy fibroblasts.     

A Self‐Delivery Chimeric Peptide for Photodynamic Therapy Amplified Immunotherapy

In this paper, a self‐delivery chimeric peptide PpIX‐PEG₈‐KVPRNQDWL is designed for photodynamic therapy (PDT) amplified immunotherapy against malignant melanoma. After self‐assembly into nanoparticles (designated as PPMA), this self‐delivery system shows high drug loading rate, good dispersion, and stability as well as an excellent capability in producing reactive oxygen species (ROS). After cellular uptake, the ROS generated under light irradiation could induce the apoptosis and/or necrosis of tumor cells, which would subsequently stimulate the anti‐tumor immune response. On the other hand, the melanoma specific antigen (KVPRNQDWL) peptide could also activate the specific cytotoxic T cells for anti‐tumor immunity. Compared to immunotherapy alone, the combined photodynamic immunotherapy exhibits significantly enhanced inhibition of melanoma growth. Both in vitro and in vivo investigations confirm that PDT of PPMA has a positive effect on anti‐tumor immune response. This self‐delivery system demonstrates a great potential of this PDT amplified immunotherapy strategy for advanced or metastatic tumor treatment.     

Structurally Defined αMHC‐II Nanobody–Drug Conjugates: A Therapeutic and Imaging System for B‐Cell Lymphoma

Antibody–drug conjugates (ADCs) of defined structure hold great promise for cancer therapies, but further advances are constrained by the complex structures of full‐sized antibodies. Camelid‐derived single‐domain antibody fragments (VHHs or nanobodies) offer a possible solution to this challenge by providing expedited target screening and validation through switching between imaging and therapeutic activities. We used a nanobody (VHH7) specific for murine MHC‐II and rendered “sortase‐ready” for the introduction of oligoglycine‐modified cytotoxic payloads or NIR fluorophores. The VHH7 conjugates outcompeted commercial monoclonal antibodies (mAbs) for internalization and exhibited high specificity and cytotoxicity against A20 murine B‐cell lymphoma. Non‐invasive NIR imaging with a VHH7–fluorophore conjugate showed rapid tumor targeting on both localized and metastatic lymphoma models. Subsequent treatment with the nanobody–drug conjugate efficiently controlled tumor growth and metastasis without obvious systemic toxicity.     

Delivery of ROS Generating Anthraquinones Using Reduction‐Responsive Peptide‐Based Nanoparticles

In order to limit the side effects associated with antitumor drugs such as doxorubicin, nanosized drug‐delivery systems capable of selectively delivering and releasing the drug in the diseased tissue are required. We describe nanoparticles (NPs), self‐assembled from a reduction responsive amphiphilic peptide, capable of entrapping high amounts of a redox active anticancer drug candidate and releasing it in presence of a reducing agent. This system shows a high entrapment efficiency with up to 15 mg drug per gram of peptide (5.8 mol‐%). Treatment of the NPs with reducing agent results in the disassembly of the NPs and release of the drug molecules. A reduction in cell viability is observed at drug concentrations above 250 nm in HEK293T and HeLa cell lines. This drug delivery system has potential for targeting tumor sites via the EPR effect while taking advantage of the increased reduction potential in tumor microenvironment.     

Carrier-Free Delivery of Precise Drug–Chemogene Conjugates for Synergistic Treatment of Drug-Resistant Cancer

Combinatorial antitumor therapies using different combinations of drugs and genes are emerging as promising ways to overcome drug resistance, which is a major cause for the failure of cancer treatment. However, dramatic pharmacokinetic differences of drugs greatly impede their combined use in cancer therapy, raising the demand for drug delivery systems (DDSs) for tumor treatment. By employing fluorescent dithiomaleimide (DTM) as a linker, we conjugate two paclitaxel (PTX) molecules with a floxuridine (FdU)-integrated antisense oligonucleotide (termed chemogene) to form a drug–chemogene conjugate. This PTX–chemogene conjugate can self-assemble into a spherical nucleic acid (SNA)-like micellular nanoparticle as a carrier-free DDS, which knocks down the expression of P-glycoprotein and subsequently releases FdU and PTX to exert a synergistic antitumor effect and greatly inhibit tumor growth.     

GRP78‐Targeted HPMA Copolymer‐Photosensitizer Conjugate for Hyperthermia‐Induced Enhanced Uptake and Cytotoxicity in MCF‐7 Breast Cancer Cells

Photodynamic therapy (PDT) is a promising cancer treatment approach. However, the photosensitizers (PS) used for PDT are often limited by their poor solubility and selectivity for tumors. The goal of this study is to improve water solubility and delivery of the photosensitizer 2‐[1‐hexyloxyethyl]‐2‐divinyl pyropheophorbide‐a (HPPH) to breast cancer cells. An N‐(2‐hydroxypropyl)methacrylamide (HPMA) copolymer–HPPH photosensitizer conjugate is synthesized with heat shock receptor glucose‐regulated protein 78 (GRP78), targeting to GRP78 receptors of MCF‐7 cells, which are upregulated under mild hyperthermia. It is found that the uptake of the GRP78 targeted pep‐HPMA‐HPPH copolymer conjugate in MCF‐7 cells is improved through heat induction. Under mild hyperthermia the targeted copolymers are more effective compared to free HPPH. These results show potential for the utility of mild hyperthermia and copolymer delivery vehicles to enhance the efficacy of photodynamic therapy.     

Photoacoustic Imaging Quantifies Drug Release from Nanocarriers via Redox Chemistry of Dye‐Labeled Cargo

We report a new approach to monitor drug release from nanocarriers via a paclitaxel–methylene blue conjugate (PTX‐MB) with redox activity. This construct is in a photoacoustically silent reduced state inside poly(lactic‐co‐glycolic acid) (PLGA) nanoparticles (PTX‐MB@PLGA NPs). During release, PTX‐MB is spontaneously oxidized to produce a concentration‐dependent photoacoustic signal. An in vitro drug‐release study showed an initial burst release (25 %) between 0–24 h and a sustained release between 24–120 h with a cumulative release of 40.6 % and a 670‐fold increase in photoacoustic signal. An in vivo murine drug release showed a photoacoustic signal enhancement of up to 649 % after 10 hours. PTX‐MB@PLGA NPs showed an IC₅₀ of 78 μg mL^?1 and 44.7±4.8 % decrease of tumor burden in an orthotopic model of colon cancer via luciferase‐positive CT26 cells.