Retention In Tumor Tissue Research Articles

Effects of molecular weight and structural conformation of multivalent-based elastin-like polypeptides on tumor accumulation and tissue biodistribution.

In order to improve clinical outcomes for novel drug delivery systems, distinct optimization of size, shape, multifunctionality, and site-specificity are of utmost importance. In this study, we designed various multivalent elastin-like polypeptide (ELP)-based tumor-targeting polymers in which multiple copies of IL-4 receptor (IL-4R)-targeting ligand (AP1 peptide) were periodically incorporated into the ELP polymer backbone to enhance the affinity and avidity towards tumor cells expressing high levels of IL-4R. Several ELPs with different molecular sizes and structures ranging from unimer to micelle-forming polymers were evaluated for their tumor accumulation as well as in vivo bio-distribution patterns. Different percentages of cell binding and uptake were detected corresponding to polymer size, number of targeting peptides, or unimer versus micelle structure. As compared to low molecular weight polypeptides, high molecular weight AP1-ELP showed superior binding activity with faster entry and efficient processing in the IL-4R-dependent endocytic pathway. In addition, in vivo studies revealed that the high molecular weight micelle-forming AP1-ELPs (A86 and A100) displayed better tumor penetration and extensive retention in tumor tissue along with reduced non-specific accumulation in vital organs, when compared to low molecular weight non-micelle forming AP1-ELPs. It is suggested that the superior binding activities shown by A86 and A100 may depend on the multiple presentation of ligands upon transition to a micelle-like structure rather than a larger molecular weight. Thus, this study has significance in elucidating the different patterns underlying unimer and micelle-forming ELP-mediated tumor targeting as well as the in vivo biodistribution.

Tumor cell-derived exosomes home to their cells of origin and can be used as Trojan horses to deliver cancer drugs.

Cancer is the second leading cause of death worldwide and patients are in urgent need of therapies that can effectively target cancer with minimal off-target side effects. Exosomes are extracellular nano-shuttles that facilitate intercellular communication between cells and organs. It has been established that tumor-derived exosomes contain a similar protein and lipid composition to that of the cells that secrete them, indicating that exosomes might be uniquely employed as carriers for anti-cancer therapeutics.Methods: We isolated exosomes from two cancer cell lines, then co-cultured each type of cancer cells with these two kinds of exosomes and quantified exosome. HT1080 or Hela exosomes were systemically injected to Nude mice bearing a subcutaneous HT1080 tumor to investigate their cancer-homing behavior. Moreover, cancer cell-derived exosomes were engineered to carry Doxil (a common chemotherapy drug), known as D-exo, were used to detect their target and therapeutic efficacy as anti-cancer drugs. Exosome proteome array analysis were used to reveal the mechanism underly this phenomenon.Results: Exosomes derived from cancer cells fuse preferentially with their parent cancer cells, in vitro. Systemically injected tumor-derived exosomes home to their original tumor tissues. Moreover, compared to Doxil alone, the drug-loaded exosomes showed enhanced therapeutic retention in tumor tissues and eradicated them more effectively in nude mice. Exosome proteome array analysis revealed distinct integrin expression patterns, which might shed light on the underlying mechanisms that explain the exosomal cancer-homing behavior.Conclusion: Here we demonstrate that the exosomes' ability to target the parent cancer is a phenomenon that opens up new ways to devise targeted therapies to deliver anti-tumor drugs.

Intratumor Performance and Therapeutic Efficacy of PAMAM Dendrimers Carried by Clustered Nanoparticles.

In recent years, small nanoparticles (NPs) with a diameter ofless than 10 nm have aroused considerable interest in biomedical applications. However, their intratumor performance, as well as the antitumor efficacy, has not been well understood due to their size-dependent pharmacokinetics, which presents a formidable challenge for delivering a comparable amount of different small NPs to tumor tissues. Utilizing the multistage delivery strategy, we construct G3-, G5-, and G7-iCluster delivery systems by using poly(amidoamine) (PAMAM) dendrimers of different generations (G3-, G5-, and G7-PAMAM) as building blocks. The iCluster nanoparticles showed comparable pharmacokinetics and similar initial tumor deposition due to their similarity in size and surface chemistry. After accumulating at a tumor site, individual small dendrimers were released, and thus, their intratumor performance was comparatively investigated. Our results indicated that a subtle change in generation markedly affects their intratumor activities. G5-iCluster outperformed G3-iCluster and G7-iCluster in the treatment efficacy in an orthotopic pancreatic tumor model. The mechanistic study revealed that G3-PAMAM showed reduced particle retention in tumor tissue due to its small size and weak cell internalization, while G7-PAMAM was much less penetrative because of its relatively large size and strong particle-cell interaction. In contrast, G5-PAMAM exhibited balanced tumor penetration, cell internalization, and tumor retention. Our finding highlights the huge influence of the subtle difference of small NPs in their intratumor performance.

Sub-10 nm Theranostic Unimolecular Micelles with High Tumor-Specific Accumulation, Retention, and Inhibitory Effect.

Theranostic agents that integrate far-red/near-infrared fluorescence and anticancer drugs are useful for biomedical applications such as imaging-guided therapy of cancers. However, the clinical translation of previously reported theranostic agents is still limited by factors such as weak fluorescence of the imaging probe, premature and off-target release of fluorophores and drugs during blood circulation, the long-term retention in the reticuloendothelial system, and side effects of toxicity. Here, we report a new type of ultrasmall theranostic unimolecular micelles with an average diameter below 10 nm, and dual functionalities of bright fluorescence in the spectral window of 600-800 nm toward noninvasive in vivo bioimaging and covalently bound anticancer drugs for specific cancer treatment. Each unimolecular micelle is formed by an amphiphilic bottlebrush copolymer containing a fluorescent conjugated backbone of poly(fluorene-alt-(4,7-bis(hexylthien)-2,1,3-benzothiadiazole)), from which hydrophobic disulfide-linked camptothecin as an anticancer drug and hydrophilic oligo(ethylene glycol) are grafted. These ultrasmall unimolecular micelles exhibit remarkably high efficiency of accumulation and retention in tumor tissues with a tumor inhibitory rate of 50%, but little distribution in other healthy organs and tissues. Such a feature of enhanced tumor targeting and reduced toxic side effects against healthy cells and tissues is promising for future clinical translation of imaging-guided cancer therapy.

Recombinant human insulin as a solid tumor potential imaging agent: Radio-synthesis and biological evaluation

The aim of this study was to synthesis an imaging agent for tumor targeting. New recombinant insulin analogue was successfully produced from E. coli by recombinant DNA technique, and was well labeled with Technetium-99m with a high radiochemical yield of 93.3 ± 2.1 %. Moreover, it showed good in-vitro stability in both saline and human serum. Preclinical evaluation of Technetium-99m [99mTc] Tc-insulin in solid tumor-bearing mice showed high accumulation in tumor tissues. The T/NT (target to non-target ratio) was of 5.4, after 60 min. of post injection (p.i). The direct intra-tumoral (I.T) injection of [99mTc] Tc-insulin showed good retention in tumor tissues with a ratio more than 50 % after 15 min. As a result of the promising bio-distribution studies; the newly recombinant insulin showed good uptake in tumor site, which assured high concentration of insulin receptor on tumor cell surface, accompanied with high cell density of tumor cells as well. This work affords a potential radio-carrier that could be used as a good tumor marker and imaging probe via SPECT (Single Photon Emission Computed Tomography) technique, after further preclinical studies.

Vinblastine-Loaded Nanoparticles with Enhanced Tumor-Targeting Efficiency and Decreasing Toxicity: Developed by One-Step Molecular Imprinting Process.

Molecularly imprinted polymers have exhibited good performance as carriers on drug loading and sustained release. In this paper, vinblastine (VBL)-loaded polymeric nanoparticles (VBL-NPs) were prepared by a one-step molecular imprinting process, avoiding the waste and incomplete removal of the template, and evaluated as targeting carriers for VBL delivery after modification. Using acryloyl amino acid comonomers and disulfide cross-linkers, VBL-NPs were synthesized and then conjugated with poly(ethylene glycol)-folate. The dynamic size of the obtained VBL-NPs-PEG-FA was 258.3 nm (PDI = 0.250), and the encapsulation efficiency was 45.82 ± 1.45%. The nanoparticles of VBL-NPs-PEG-FA were able to completely release VBL during 48 h under a mimic tumor intracellular condition (pH 4.5, 10 mM glutathione (GSH)), displaying significant redox responsiveness, whereas the release rates were much slower in the mimic body liquid (pH 7.4, 2 μM GSH) and tumor extracellular environment (pH 6.5, 2 μM GSH). Furthermore, the carriers NPs-PEG-FA, prepared without VBL, showed satisfactory intrinsic hemocompatibility, cellular compatibility, and tumor-targeting properties: they could rapidly and efficiently accumulate to folate receptor positive Hela cells and then internalized via receptor-mediated endocytosis, and the retention in tumor tissues could last for over 48 h. Interestingly, VBL-NPs-PEG-FA could evidently increase the accumulation of VBL in tumor tissues while decreasing the distribution of VBL in organs, exert similar anticancer efficacy against Hela tumors in the xenograft model of nude mice to VBL injection, and significantly improve the abnormality of liver and spleen observed in VBL injection. VBL-NPs-PEG-FA has the potential to be the delivery carrier for VBL by enhancing the tumor-targeting efficacy of VBL and decreasing toxicity to normal tissues.

Self-assembly of nanoparticles by human serum albumin and photosensitizer for targeted near-infrared emission fluorescence imaging and effective phototherapy of cancer.

Photodynamic therapy (PDT) and photothermal therapy (PTT) are effective cancer treatments, and photosensitizers play the most important role in the treatment. However, photosensitizers are insufficient for in vivo tumor treatment. Herein, we develop a small molecule fluorophore Cy-HPT as a novel photosensitizer, which possesses the advantages of near-infrared (NIR) emission, high photothermal conversion efficiency and high singlet oxygen generation efficiency. Moreover, a nanoplatform of HSA@Cy-HPT was synthesized by self-assembly of Cy-HPT and human serum albumin (HSA) in aqueous solution. Compared to Cy-HPT, HSA@Cy-HPT possesses more stable spectral properties, enhances the effect of PDT/PTT, and exhibits more satisfactory in vivo metabolism. HSA@Cy-HPT demonstrates outstanding tumor targeting in subcutaneous tumor xenograft models owing to its enhanced permeability and retention in tumor tissue. Furthermore, HSA@Cy-HPT was successfully utilized in tumor xenograft models and tumor tissue growth was clearly inhibited without any regrowth, extending survival rate of the models. Also, no distinct damage of the normal tissue of tumor xenograft models was observed using hematoxylin & eosin staining. This study presents a promising therapeutic agent for the synergetic PDT and PTT cancer treatment.

Magnetically targeted photothemal cancer therapy in vivo with bacterial magnetic nanoparticles.

The biomineralized bacterial magnetic nanoparticles (BMPs) have been widely studied for biomedical applications with their magnetic properties and a layer of biomembrane. Herein, BMPs were firstly used for magnetically targeted photothermal cancer therapy in vivo. A self-build C-shaped bipolar permanent magnet was used for magnetic targeting though the generation of a high gradient magnetic field within a small target area. For in vitro simulated experiment, BMPs had a high retention rate in magnetically targeted region with different flow rates. In H22 tumor bearing mice, the magnetic targeting induced a 40% increase of BMPs retention in tumor tissues. In vivo photothermal therapy with 808 nm laser irradiation could induce a complete tumor elimination with magnetic targeting. These results indicated that the systematically administrated BMPs with magnetic targeting would be promising for photothermal cancer therapy.

Abstract 4115: Comparison of IL-4 receptor targeting elastin-like polypeptide based on size and structure

Abstract For novel drug delivery systems, in order to improve clinical outcomes clear optimization of size, shape, multifuntionality, and site-specificity are highly considered. As molecular size significantly influenced the biodistribution, precise control of molecular sizes must be considered for optimum targeting effect in cancer therapy. Elastin like polypeptide (ELP), has been utilized as an attractive vehicle for cancer therapy as it provide unparalleled control over sequence and structure in genetic level thereby allowing generation of various polymers with defined architectures and functional properties. In this study, we designed various multivalent elastin-like polypeptide based tumor targeting polymer in which multiple copies of IL-4 receptor (IL-4R) targeting ligands, AP1 peptide were subjected into ELP polymer backbone periodically to enhance affinity and avidity towards IL-4R- highly expressed tumor cells. Several ELP with different molecular sizes and structure from unimer to micelle forming polymer have been designed to investigate the pattern of accumulation in tumor, as well as their bio-distribution in vivo. Different percentage of cell binding and uptake depend on size, number of targeting peptides, or based on unimer compared with micelle were determined. The high molecular weight AP1-ELP showed superior binding activity with faster entry and efficiently processed in the IL-4R dependent endocytic pathway compared to low molecular weight polypeptides. In addition the high molecular weight, micelle forming AP1-ELP displayed better tumor penetration and extensive retention in tumor tissue with decrease non-specific accumulation in vital organs compared to low molecular weight AP1-ELP in xenograft model. It was suggested that superior binding activities shown by A86 and A100 may depends on multiple presentation of ligands upon transition to micelle like structure rather than increased number of targeting ligands and molecular weight. Thus this study have significance in demonstrating different pattern underlying unimer and micelle forming ELP mediated tumor targeting as well as biodistribution in vivo. Citation Format: Boyeon Seo, Vijaya Sarangthem, Aena Yi, Rang-Woon Park. Comparison of IL-4 receptor targeting elastin-like polypeptide based on size and structure [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4115.

Preparation of PGA-PAE-Micelles for Enhanced Antitumor Efficacy of Cisplatin.

Poly-γ-l-glutamic acid (PGA) is an outstanding drug carrier candidate owning to its excellent biodegradability and biocompatibility. The PGA carrier may shield toxic drugs from the body and enable the delivery of poorly soluble or unstable drugs and thereby minimize the side effects and improve drug efficacy. However, the limitation of PGA as a drug carrier is low drug loading efficiency (DLE), which is usually below 30%. In this study, we reported a chemical modification method using l-phenylalanine ethyl ester (PAE). PGA-PAE construct was amphiphilic, which could form micelles in aqueous solution. Cisplatin (CDDP), a commonly used chemotherapy drug whose side effect is well-known, was used as a model molecule to test the drug-loading efficiency of PGA-PAE. In this paper, two sizes of CDDP-loaded PGA-PAE micelles (M(Pt)-1 and M(Pt)-2) were prepared, the average diameter of M(Pt)-1 was 106 ± 6 nm and M(Pt)-2 was 210 ± 9 nm. The DLE of M(Pt)-1 and M(Pt)-2 was 52.8 ± 2.2 and 55.8 ± 1.2%, respectively. Both exhibited excellent biocompatibility, stability, and drug-retaining capability in physiological condition. The in vitro accumulative drug-releasing profile, IC50 for different tumor cell lines HeLa, A549, and HCCC9810, and in vivo pharmacokinetics were similar between these two micelles; however, M(Pt)-1 showed higher tumor tissue retention and longer efficient cancer cell internalization time (up to 20 d). Our results suggested PGA-PAE micelle carriers reduced the toxicity of CDDP and its size at around 100 nm was the better for CDDP high-efficacy.

Positron Emission Tomography (PET) and Pharmacokinetics: Classical Blood Sampling Versus Image-Derived Analysis of [18F]FAZA and [18F]FDG in a Murine Tumor Bearing Model.

Pharmacokinetic (PK) data are generally derived from blood samples withdrawn serially over a defined period after dosing. In small animals, blood sampling after dosing presents technical difficulties, particularly when short time intervals and frequent sampling are required. Positron emission tomography (PET) is a non-invasive functional imaging technique that can provide semi-quantitative temporal data for defined volume regions of interest (vROI), to support kinetic analyses in blood and other tissues. The application of preclinical small-animal PET to determine and compare PK parameters for [18F]FDG and [18F]FAZA, radiopharmaceuticals used clinically for assessing glucose metabolism and hypoxic fractions, respectively, in the same mammary EMT6 tumor-bearing mouse model, is reported here. Two study groups were used: normal BALB/c mice under isoflurane anesthesia were intravenously injected with either [18F]FDG or [18F]FAZA. For the first group, blood-sampling by tail artery puncture was used to collect blood samples which were then analyzed with Radio-microTLC. Dynamic PET experiments were performed with the second group of mice and analyzed for blood input function and tumor uptake utilizing a modified two compartment kinetic model. Heart and inferior vena cava vROIs were sampled to obtain image-derived data. PK parameters were calculated from blood samples and image-derived data. Time-activity curves (TACs) were also generated over regions of liver, kidney and urinary bladder to depict clearance profiles for each radiotracer. PK values generated by classical blood sampling and PET image-derived analysis were comparable to each other for both radiotracers. Heart vROI data were suitable for analysis of [18F]FAZA kinetics, but metabolic uptake of radioactivity mandated the use of inferior vena cava vROIs for [18F]FDG analysis. While clearance (CL) and blood half-life (t½) were similar for both [18F]FDG and [18F]FAZA for both sampling methods, volume of distribution yielded larger differences, indicative of limitations such as partial volume effects within quantitative image-derived data. [18F]FDG underwent faster blood clearance and had a shorter blood half-life than [18F]FAZA. Kinetic analysis of tumor uptake from PET image data showed higher uptake and longer tumor tissue retention of [18F]FDG, indicative of the tumor's glucose metabolism rate, versus lower tumor uptake and retention of [18F]FAZA. While [18F]FAZA possesses a somewhat greater hepatobiliary clearance , [18F]FDG clears faster through the renal system which results in faster radioactivity accumulation in the urinary bladder. The present study provides a working example of the applicability of functional PET imaging as a suitable tool to determine PK parameters in small animals. The comparative analysis in the current study demonstrates that it is feasible to use [18F]FDG PET and [18F]FAZA PET in the same model to analyze their blood PK parameters, and to estimate kinetic parameters for these tracers in tumor. This non-invasive imaging-based determination of tissue kinetic parameters facilitates translation from pre-clinical to clinical phases of drug development.This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.

Hydrophobic structure of hairpin ten-ring pyrrole-imidazole polyamides enhances tumor tissue accumulation/retention in vivo

To examine the hydrophobic structure of PI polyamides on tumor accumulation in vivo, PI polyamide-fluorescein conjugates 1–5 with the distinct number of N-methylimidazole (Im) units were synthesized. There existed an inverse relationship between the Im unit number of the compounds and their hydrophobicity. Compound 1 with one Im unit and 3 with three Im units accumulated and retained preferentially in tumor tissues compared to 5 with five Im units. These results suggest the importance of a PI polyamide’s primary structure, which partly contributes to its hydrophobic property, on its accumulation and/or retention in tumor tissues in vivo.

Phosphaplatin Anti-tumor Effect Enhanced by Liposomes Partly via an Up-regulation of PEDF in Breast Cancer.

Phosphaplatin platinum (IV) (RRD4) complex has exceptional antitumor properties. The aim of this study was to investigate the effects and the mechanism of action of free and liposome-encapsulated RRD4 in breast cancer. Liposome-encapsulated RRD4 prepared by thin-film dehydration: hydration and free RRD4 were tested in vivo and in vitro against 4T1 breast cancer cells. Cell proliferation, migration and viability were determined. Tissue and cell production and expression of pigment epithelium-derived factor (PEDF) were assessed by ELISA and western blot. 4T1 cells treated with PEDF siRNA were evaluated for viability and apoptosis. RRD4 inhibited tumor growth and prevented distant metastasis. Liposome formulation enhanced this therapeutic benefit without increasing toxicity and prolonged RRD4 retention in tumor tissues. In vitro, RRD4 induced 4T1 apoptosis through up-regulation of FAS, BAX, and PUMA, and down-regulation of BCL2. RRD4 facilitates a FAS-intrinsic signaling mechanism. PEDF up-regulation represents another antitumor mechanism associated with this phosphaplatin compound. Free RRD4 or formulated into liposomes, are excellent candidates for adjuvant therapy against breast tumor growth and metastasis.

Enzyme-sensitive gemcitabine conjugated albumin nanoparticles as a versatile theranostic nanoplatform for pancreatic cancer treatment

Development of gemcitabine (GEM) nanocarriers as theranostic agents for pancreatic cancer chemotherapy has received extensive attention in recent years. A novel enzyme-sensitive albumin-based GEM delivery nanoplatform was developed in this research by simple conjugation of GEM to human serum albumin (HSA) via cathepsin B cleavable peptide GFLG and then complexing with near-infrared (NIR) dye IR780, forming a HSA-GEM/IR780 complex. The successful preparation of HSA-GEM/IR780 complex was confirmed by Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS), UV–vis–NIR absorption spectra and fluorescent emission spectra. The in vivo performance of HSA-GEM/IR780 complex was carried out on BxPC-3 pancreatic tumor xenografted mice. As revealed by in vivo NIR imaging, HSA-GEM/IR780 exhibited enhanced accumulation and long-term retention in tumor tissues compared to free IR780. Meanwhile, compared to free GEM, the deamination of GEM nanovectors into inactive 2′,2′-difluorodeoxyuridine (dFdU) can be greatly suppressed, while the concentration of the activated form of GEM (gemcitabine triphosphate, dFdCTP) was significantly increased in tumor tissue, thus exhibiting superior tumor inhibition activity with minimal side effects.

Use of boron cluster-containing redox nanoparticles with ROS scavenging ability in boron neutron capture therapy to achieve high therapeutic efficiency and low adverse effects.

A boron delivery system with high therapeutic efficiency and low adverse effects is crucial for a successful boron neutron capture therapy (BNCT). In this study, we developed boron cluster-containing redox nanoparticles (BNPs) via polyion complex (PIC) formation, using a newly synthesized poly(ethylene glycol)-polyanion (PEG-polyanion, possessing a (10)B-enriched boron cluster as a side chain of one of its segments) and PEG-polycation (possessing a reactive oxygen species (ROS) scavenger as a side chain of one of its segments). The BNPs exhibited high colloidal stability, selective uptake in tumor cells, specific accumulation, and long retention in tumor tissue and ROS scavenging ability. After thermal neutron irradiation, significant suppression of tumor growth was observed in the BNP-treated group, with only 5-ppm (10)B in tumor tissues, whereas at least 20-ppm (10)B is generally required for low molecular weight (LMW) (10)B agents. In addition, increased leukocyte levels were observed in the LMW (10)B agent-treated group after thermal neutron irradiation, and not in BNP-treated group, which might be attributed to its ROS scavenging ability. No visual metastasis of tumor cells to other organs was observed 1 month after irradiation in the BNP-treated group. These results suggest that BNPs are promising for enhancing the BNCT performance.

Doxorubicin-induced co-assembling nanomedicines with temperature-sensitive acidic polymer and their in-situ-forming hydrogels for intratumoral administration

Doxorubicin (DOX)-induced co-assembling nanomedicines (D-PNAx) with temperature-sensitive PNAx triblock polymers have been developed for regional chemotherapy against liver cancer via intratumoral administration in the present work. Owing to the formation of insoluble DOX carboxylate, D-PNAx nanomedicines showed high drug-loading and entrapment efficacy via a simple mixing of doxorubicin hydrochloride and PNAx polymers. The sustained releasing profile of D-PNA100 nanomedicines indicated that only 9.4% of DOX was released within 1day, and 60% was released during 10days. Based on DOX-induced co-assembling behavior and their temperature sensitive in-situ-forming hydrogels, D-PNA100 nanomedicines showed excellent antitumor activity against H22 tumor using intratumoral administration. In contrast to that by free DOX solution (1.13±0.04 times at 9days) and blank PNA100 (2.11±0.34 times), the tumor volume treated by D-PNA100 had been falling to only 0.77±0.13 times of original tumor volume throughout the experimental period. In vivo biodistribution of DOX indicated that D-PNA100 nanomedicines exhibited much stronger DOX retention in tumor tissues than free DOX solution via intratumoral injection. D-PNA100 nanomedicines were hopeful to be developed as new temperature sensitive in-situ-forming hydrogels via i.t. injection for regional chemotherapy.

Therapeutic Enzyme-Responsive Nanoparticles for Targeted Delivery and Accumulation in Tumors.

An enzyme-responsive, paclitaxel-loaded nanoparticle is described and assessed in vivo in a human fibrosarcoma murine xenograft. This work represents a proof-of-concept study demonstrating the utility of enzyme-responsive nanoscale drug carriers capable of targeted accumulation and retention in tumor tissue in response to overexpressed endogenous enzymes.

A novel engineered VEGF blocker with an excellent pharmacokinetic profile and robust anti-tumor activity.

BackgroundRelatively poor penetration and retention in tumor tissue has been documented for large molecule drugs including therapeutic antibodies and recombinant immunoglobulin constant region (Fc)-fusion proteins due to their large size, positive charge, and strong target binding affinity. Therefore, when designing a large molecular drug candidate, smaller size, neutral charge, and optimal affinity should be considered.MethodsWe engineered a recombinant protein by molecular engineering the second domain of VEGFR1 and a few flanking residues fused with the Fc fragment of human IgG1, which we named HB-002.1. This recombinant protein was extensively characterized both in vitro and in vivo for its target-binding and target-blocking activities, pharmacokinetic profile, angiogenesis inhibition activity, and anti-tumor therapeutic efficacy.ResultsHB-002.1 has a molecular weight of ~80 kDa, isoelectric point of ~6.7, and an optimal target binding affinity of <1 nM. The pharmacokinetic profile was excellent with a half-life of 5 days, maximal concentration of 20.27 μg/ml, and area under the curve of 81.46 μg · days/ml. When tested in a transgenic zebrafish embryonic angiogenesis model, dramatic inhibition in angiogenesis was exhibited by a markedly reduced number of subintestinal vessels. When tested for anti-tumor efficacy, HB-002.1 was confirmed in two xenograft tumor models (A549 and Colo-205) to have a robust tumor killing activity, showing a percentage of inhibition over 90% at the dose of 20 mg/kg. Most promisingly, HB-002.1 showed a superior therapeutic efficacy compared to bevacizumab in the A549 xenograft model (tumor inhibition: 84.7% for HB-002.1 versus 67.6% for bevacizumab, P < 0.0001).ConclusionsHB-002.1 is a strong angiogenesis inhibitor that has the potential to be a novel promising drug for angiogenesis-related diseases such as tumor neoplasms and age-related macular degeneration.

Gold nanoparticles in breast cancer treatment: Promise and potential pitfalls

Despite remarkable achievements in the treatment of breast cancer, some obstacles still remain. Gold nanoparticles may prove valuable in addressing these problems owing to their unique characteristics, including their enhanced permeability and retention in tumor tissue, their light absorbance and surface plasmon resonance in near-infrared light, their interaction with radiation to generate secondary electrons, and their ability to be conjugated with drugs or other agents. Herein, we discuss some basic concepts of gold nanoparticles, and early results from studies regarding their use in breast cancer, including toxicity and side effects. We also discuss these particles’ potential clinical applications.

GE11-modified liposomes for non-small cell lung cancer targeting: preparation, ex vitro and in vivo evaluation

Non-small cell lung cancer (NSCLC) is a serious threat to human health, and 40%–80% of NSCLCs express high levels of epidermal growth factor receptor (EGFR). GE11 is a novel peptide and exhibits high affinity for EGFR binding. The aim of this study was to construct and evaluate GE11-modified liposomes for targeted drug delivery to EGFR-positive NSCLC. Doxorubicin, a broad-spectrum antitumor agent, was chosen as the payload. GE11 was conjugated to the distal end of DSPE-PEG2000-Mal by an addition reaction with a conjugation efficiency above 90%. Doxorubicin-loaded liposomes containing GE11 (GE11-LP/DOX) at densities ranging from 0% to 15% were prepared by combination of a thin film hydration method and a post insertion method. Irrespective of GE11 density, the physicochemical properties of these targeted liposomes, including particle size, zeta potential, and drug entrapment efficiency, were nearly identical. Interestingly, the cytotoxic effect of the liposomes on A549 tumor cells was closely related to GE11 density, and liposomes with 10% GE11 had the highest tumor cell killing activity and a 2.6-fold lower half maximal inhibitory concentration than that of the nontargeted counterpart (PEG-LP/DOX). Fluorescence microscopy and flow cytometry analysis revealed that GE11 significantly increased cellular uptake of the liposomes, which could be ascribed to specific EGFR-mediated endocytosis. It was found that multiple endocytic pathways were involved in entry of GE11-LP/DOX into cells, but GE11 assisted in cellular internalization mainly via the clathrin-mediated endocytosis pathway. Importantly, the GE11-modified liposomes showed enhanced accumulation and prolonged retention in tumor tissue, as evidenced by a 2.2-fold stronger mean fluorescence intensity in tumor tissue than the unmodified liposomes at 24 hours. In summary, GE11-modified liposomes may be a promising platform for targeted delivery of chemotherapeutic drugs in NSCLC.