iRGD tumor-penetrating peptide-modified oncolytic adenovirus shows enhanced tumor transduction, intratumoral dissemination and antitumor efficacy

Tumor-penetrating iRGD facilitates penetration of poly(floxuridine-ketal)-based nanomedicine for enhanced pancreatic cancer therapy

Efficient intratumoral penetration is essential for nanomedicine to eradicate pancreatic tumors. Although nanomedicine can enter the perivascular space of pancreatic tumors, their access to distal tumor cells, aloof from the vessels, remains a formidable challenge. Here, we synthesized an acid-activatable macromolecular prodrug of floxuridine (FUDR)-poly(FUDR-ketal), engineered a micellar nanomedicine of FUDR, and intravenously co-administered the nanomedicine with the tumor-penetrating peptide iRGD for enhanced treatment of pancreatic tumor. A FUDR-derived mono-isopropenyl ether was synthesized and underwent self-addition polymerization to afford the hydrophobic poly(FUDR-ketal), which was subsequently co-assembled with amphiphilic DSPE-mPEG into the micellar nanomedicine with size of 12 nm and drug content of 56.8 wt% using nanoprecipitation technique. The acetone-based ketal-linked poly(FUDR-ketal) was triggered by acid to release FUDR to inhibit cell proliferation. In an orthotopic pancreatic tumor model derived from KPC (KrasLSL-G12D/+; Trp53LSL-R172H/+; Pdx1-Cre) cells that overexpress neuropilin-1 (NRP-1) receptor, iRGD improved penetration of FUDR nanomedicine into tumor parenchyma and potentiated the therapeutic efficacy. Our nanoplatform, along with iRGD, thus appears to be promising for efficient penetration and activation of acid-responsive nanomedicines for enhanced pancreatic cancer therapy.

Recent advances in antimicrobial peptide-based therapy

Antimicrobial peptides (AMPs) are a group of polypeptide chains that have the property to target and kill a myriad of microbial organisms including viruses, bacteria, protists, etc. The first discovered AMP was named gramicidin, an extract of aerobic soil bacteria. Further studies discovered that these peptides are present not only in prokaryotes but in eukaryotes as well. They play a vital role in human innate immunity and wound repair. Consequently, they have maintained a high level of intrigue among scientists in the field of immunology, especially so with the rise of antibiotic-resistant pathogens decreasing the reliability of antibiotics in healthcare. While AMPs have promising potential to substitute for common antibiotics, their use as effective replacements is barred by certain limitations. First, they have the potential to be cytotoxic to human cells. Second, they are unstable in the blood due to action by various proteolytic agents and ions that cause their degradation. This review provides an overview of the mechanism of AMPs, their limitations, and developments in recent years that provide techniques to overcome those limitations. We also discuss the advantages and drawbacks of AMPs as a replacement for antibiotics as compared to other alternatives such as synthetically modified bacteriophages, traditional medicine, and probiotics.

Harnessing adenovirus in cancer immunotherapy: evoking cellular immunity and targeting delivery in cell-specific manner

Recombinant adenovirus (rAd) regimens, including replication-competent oncolytic adenovirus (OAV) and replication-deficient adenovirus, have been identified as potential cancer therapeutics. OAV presents advantages such as selective replication, oncolytic efficacy, and tumor microenvironment (TME) remodeling. In this perspective, the principles and advancements in developing OAV toolkits are reviewed. The burgeoning rAd may dictate efficacy of conventional cancer therapies as well as cancer immunotherapies, including cancer vaccines, synergy with adoptive cell therapy (ACT), and TME reshaping. Concurrently, we explored the potential of rAd hitchhiking to adoptive immune cells or stem cells, highlighting how this approach facilitates synergistic interactions between rAd and cellular therapeutics at tumor sites. Results from preclinical and clinical trials in which immune and stem cells were infected with rAd have been used to address significant oncological challenges, such as postsurgical residual tumor tissue and metastatic tissue. Briefly, rAd can eradicate tumors through various mechanisms, resulting from tumor immunogenicity, reprogramming of the TME, enhancement of cellular immunity, and effective tumor targeting. In this context, we argue that rAd holds immense potential for enhancing cellular immunity and synergistically improving antitumor effects in combination with novel cancer immunotherapies.

Tumor-homing peptide iRGD-conjugate enhances tumor accumulation of camptothecin for colon cancer therapy

Poor intracellular uptake of therapeutics in the tumor parenchyma is a key issue in cancer therapy. We describe a novel approach to enhance tumor targeting and achieve targeted delivery of camptothecin (CPT) based on a tumor-homing internalizing RGD peptide (iRGD). We synthesized an iRGD-camptothecin conjugate (iRGD-CPT) covalently coupled by a heterobifunctional linker and evaluated its in vitro and in vivo activity in human colon cancer cells. In vitro studies revealed that iRGD-CPT penetrated cells efficiently and reduced colon cancer cell viability to a significantly greater extent at micromolar concentrations than did the parent drug. Furthermore, iRGD-CPT showed high distribution toward tumor tissue, effectively suppressed tumor progression, and showed enhanced antitumor effects relative to the parent drug in a mouse model, demonstrating that iRGD-CPT is effective in vivo cancer treatment. These results suggest that intracellular delivery of CPT via the iRGD peptide is a promising drug delivery strategy that will facilitate the development of CPT derivatives and prodrugs with improved efficacy.

Joining Forces: The Combined Application of Therapeutic Viruses and Nanomaterials in Cancer Therapy

Cancer, on a global scale, presents a monumental challenge to our healthcare systems, posing a significant threat to human health. Despite the considerable progress we have made in the diagnosis and treatment of cancer, realizing precision cancer therapy, reducing side effects, and enhancing efficacy remain daunting tasks. Fortunately, the emergence of therapeutic viruses and nanomaterials provides new possibilities for tackling these issues. Therapeutic viruses possess the ability to accurately locate and attack tumor cells, while nanomaterials serve as efficient drug carriers, delivering medication precisely to tumor tissues. The synergy of these two elements has led to a novel approach to cancer treatment-the combination of therapeutic viruses and nanomaterials. This advantageous combination has overcome the limitations associated with the side effects of oncolytic viruses and the insufficient tumoricidal capacity of nanomedicines, enabling the oncolytic viruses to more effectively breach the tumor's immune barrier. It focuses on the lesion site and even allows for real-time monitoring of the distribution of therapeutic viruses and drug release, achieving a synergistic effect. This article comprehensively explores the application of therapeutic viruses and nanomaterials in tumor treatment, dissecting their working mechanisms, and integrating the latest scientific advancements to predict future development trends. This approach, which combines viral therapy with the application of nanomaterials, represents an innovative and more effective treatment strategy, offering new perspectives in the field of tumor therapy.

iRGD-targeted Physalis Mottle Virus-like Nanoparticles for Targeted Cancer Delivery

Nanomedicine provides a promising platform for the molecular treatment of disease. An ongoing challenge in nanomedicine is the targeted delivery of intravenously administered nanoparticles to particular tissues, which is of special interest in cancer. In this study, we show that the conjugation of iRGD peptides, which specifically target tumor neovasculature, to the surface of Physalis mottle virus (PhMV)-like nanoparticles leads to rapid cellular uptake in vitro and tumor homing in vivo. We then show that iRGD-targeted PhMV loaded with the chemotherapeutic doxorubicin shows increased potency in a murine flank xenograft model of cancer. Our results validate that PhMV-like nanoparticles can be targeted to tumors through iRGD-peptide conjugation and suggest that iRGD-PhMV provides a promising platform for the targeted delivery of molecular cargo to tumors.

Exploration of tumor penetrating peptide iRGD as a potential strategy to enhance tumor penetration of cancer nanotherapeutics

Cancer therapy continues to be a huge challenge as most chemotherapeutic agents exert serious adverse effects on healthy organs. Chemotherapeutic agents lack selective targeting and even the existing target specific therapies are failing due to poor distribution into the tumor microenvironment. Nanotechnology offers multiple advantages to address the limitations encountered by conventional therapy. However, the delivery of nanotherapeutics to tumor tissue has not improved over the years partly due to the poor and inadequate distribution of nanotherapeutics into deeper tumor regions resulting in resistance and relapse. To curb the penetration concerns, iRGD was explored and found to be highly effective in improving the delivery of cancer nanomedicine. The preclinical observations are highly encouraging; however, the clinical translation is at a nascent stage. Based on this, we have made an elaborative effort to give a detailed account of various promising applications of iRGD to increase anticancer and tumor imaging potential. Importantly, we have comprehensively discussed the shortcomings and uncertainties associated with the clinical translation of iRGD-based therapeutic approaches and future directions.

Tumor microenvironment penetrating chitosan nanoparticles for elimination of cancer relapse and minimal residual disease

Chitosan and its derivatives are among biomaterials with numerous medical applications, especially in cancer. Chitosan is amenable to forming innumerable shapes such as micelles, niosomes, hydrogels, nanoparticles, and scaffolds, among others. Chitosan derivatives can also bring unprecedented potential to cross numerous biological barriers. Combined with other biomaterials, hybrid and multitasking chitosan-based systems can be realized for many applications. These include controlled drug release, targeted drug delivery, post-surgery implants (immunovaccines), theranostics, biosensing of tumor-derived circulating materials, multimodal systems, and combination therapy platforms with the potential to eliminate bulk tumors as well as lingering tumor cells to treat minimal residual disease (MRD) and recurrent cancer. We first introduce different formats, derivatives, and properties of chitosan. Next, given the barriers to therapeutic efficacy in solid tumors, we review advanced formulations of chitosan modules as efficient drug delivery systems to overcome tumor heterogeneity, multi-drug resistance, MRD, and metastasis. Finally, we discuss chitosan NPs for clinical translation and treatment of recurrent cancer and their future perspective.

Engineering Cancer Selective Virotherapies: Are the Pieces of the Puzzle Falling into Place?

Advances in gene therapy, synthetic biology, cancer genomics, and patient-derived cancer models have expanded the repertoire of strategies for targeting human cancers using viral vectors. Novel capsids, synthetic promoters, and therapeutic payloads are being developed and assessed through approaches such as rational design, pooled library screening, and directed evolution. Ultimately, the goal is to generate precision-engineered viruses that target different facets of tumor cell biology, without compromising normal tissue and organ function. In this study, we briefly review the opportunities for engineering cancer selectivity into viral vectors at both the cell extrinsic and intrinsic level. Such stringently tumor-targeted vectors can subsequently act as platforms for the delivery of potent therapeutic transgenes, including the exciting prospect of immunotherapeutic payloads. These have the potential to eradicate nontransduced cells through stimulation of systemic anticancer immune responses, thereby side-stepping the inherent challenge of achieving gene delivery to the entire cancer cell population. We discuss the importance of using advanced primary human cellular models, such as patient-derived cultures and organoids, to enable rapid screening and triage of novel candidates using disease-relevant models. We believe this combination of improved delivery and selectivity, through novel capsids and promoters, coupled with more potent choices for the combinations of immunotherapy-based payloads seems capable of finally delivering innovative new gene therapies for oncology. Many pieces of the puzzle of how to build a virus capable of targeting human cancers appear to be falling into place.

Peptide-Drug Conjugates: A New Hope for Cancer Management

Cancer remains the leading cause of death worldwide despite advances in treatment options for patients. As such, safe and effective therapeutics are required. Short peptides provide advantages to be used in cancer management due to their unique properties, amazing versatility, and progress in biotechnology to overcome peptide limitations. Several appealing peptide-based therapeutic strategies have been developed. Here, we provide an overview of peptide conjugates, the better equivalents of antibody-drug conjugates, as the next generation of drugs for required precise targeting, enhanced cellular permeability, improved drug selectivity, and reduced toxicity for the efficient treatment of cancers. We discuss the basic components of drug conjugates and their release action, including the release of cytotoxins from the linker. We also present peptide-drug conjugates under different stages of clinical development as well as regulatory and other challenges.

An Optimized CRISPR/Cas9 Adenovirus Vector (AdZ-CRISPR) for High-Throughput Cloning of sgRNA, Using Enhanced sgRNA and Cas9 Variants

Recombinant adenovirus vectors enable highly efficient gene delivery in vitro and in vivo. As a result, they are widely used in gene therapy, vaccination, and anticancer applications. We have previously developed the AdZ vector system, which uses recombineering to permit high-throughput cloning of transgenes into Adenovirus vectors, simplifies alteration of the vector backbone, and enables rapid recovery of infectious virus, even if a transgene is incompatible with vector replication. In this study, we adapt this vector system to enable high-throughput cloning of sequences for CRISPR/Cas9 editing. Vectors were optimized to ensure efficient cloning, and high editing efficiency using spCas9 and single guide RNA (sgRNA) sequences in a single vector. Using a multiplicity of infection of 50, knockout efficiencies of up to 80% could be achieved with a single sgRNA. Vectors were further enhanced by altering the spCas9 sequence to match that of SniperCas9, which has reduced off-target activity, but maintains on-target efficiency, and by applying modifications to the sgRNA sequence that significantly enhance editing efficiency. Thus, the AdZ-CRISPR vectors offer highly efficient knockout, even in hard to transfect cells, and enables large-scale CRISPR/Cas9 projects to be undertaken easily and quickly.

Tumor-penetrating peptide internalizing RGD enhances radiotherapy efficacy through reducing tumor hypoxia

Resistance to irradiation (IR) remains a major therapeutic challenge in tumor radiotherapy. The development of novel tumor-specific radiosensitizers is crucial for effective radiotherapy against solid tumors. Here, we revealed that remodeling tumor tissue penetration via tumor-penetrating peptide internalizing arginine-glycine-aspartic acid RGD (iRGD) enhanced irradiation efficacy. The growth of 4T1 and CT26 multicellular tumor spheroids (MCTS) and tumors was delayed significantly by the treatment with IR and iRGD. Mechanistically, iRGD reduced hypoxia in MCTS and tumors, resulting in enhanced apoptosis after MCTS and tumors were treated with IR and iRGD. This is the first report that shows enhanced radiation efficacy by remodeling tumor-specific tissue penetration with iRGD, implying the potential clinical application of peptides in future tumor therapy.

Lipid based nanoparticles as a novel treatment modality for hepatocellular carcinoma: a comprehensive review on targeting and recent advances

Liver cancer is considered one of the deadliest diseases with one of the highest disease burdens worldwide. Among the different types of liver cancer, hepatocellular carcinoma is considered to be the most common type. Multiple conventional approaches are being used in treating hepatocellular carcinoma. Focusing on drug treatment, regular agents in conventional forms fail to achieve the intended clinical outcomes. In order to improve the treatment outcomes, utilizing nanoparticles-specifically lipid based nanoparticles-are considered to be one of the most promising approaches being set in motion. Multiple forms of lipid based nanoparticles exist including liposomes, solid lipid nanoparticles, nanostructured lipid carriers, microemulsion, nanoemulsion, phytosomes, lipid coated nanoparticles, and nanoassemblies. Multiple approaches are used to enhance the tumor uptake as well tumor specificity such as intratumoral injection, passive targeting, active targeting, and stimuli responsive nanoparticles. In this review, the effect of utilizing lipidic nanoparticles is being discussed as well as the different tumor uptake enhancement techniques used.

Vascular Endothelial Cells: Heterogeneity and Targeting Approaches

Forming the inner layer of the vascular system, endothelial cells (ECs) facilitate a multitude of crucial physiological processes throughout the body. Vascular ECs enable the vessel wall passage of nutrients and diffusion of oxygen from the blood into adjacent cellular structures. ECs regulate vascular tone and blood coagulation as well as adhesion and transmigration of circulating cells. The multitude of EC functions is reflected by tremendous cellular diversity. Vascular ECs can form extremely tight barriers, thereby restricting the passage of xenobiotics or immune cell invasion, whereas, in other organ systems, the endothelial layer is fenestrated (e.g., glomeruli in the kidney), or discontinuous (e.g., liver sinusoids) and less dense to allow for rapid molecular exchange. ECs not only differ between organs or vascular systems, they also change along the vascular tree and specialized subpopulations of ECs can be found within the capillaries of a single organ. Molecular tools that enable selective vascular targeting are helpful to experimentally dissect the role of distinct EC populations, to improve molecular imaging and pave the way for novel treatment options for vascular diseases. This review provides an overview of endothelial diversity and highlights the most successful methods for selective targeting of distinct EC subpopulations.

Deeply Infiltrating iRGD-Graphene Oxide for the Intensive Treatment of Metastatic Tumors through PTT-Mediated Chemosensitization and Strengthened Integrin Targeting-Based Antimigration

A limited infiltration and the subsequent low effective drug concentration result in poor chemotherapeutic outcomes against tumors, and even further promote tumor resistance and metastatic. Herein, iRGD-modified graphene oxide (GO) nanosheets (IPHG) are developed for the intensive treatment of metastatic tumors using focus-specific penetrated delivery together with photothermal therapy-mediated chemosensitization and photothermal therapy-strengthened integrin targeting-based antimigration. In vitro and in vivo data verified the mechanism of the tumor-selective infiltration of IPHG is based on a rigid 2D structure-associated advantage regarding hemodynamics and endothelial contact, followed by iRGD-endowed transendothelial and intratumoral transport. Once IPHG-DOX-penetrated 4T1 tumors are exposed to near-infrared irradiation, hyperthermia stress and photothermal therapy-elevated effective drug concentrations result in chemosensitization and prominent tumor suppression. Meanwhile, the specific binding of iRGD to integrins and photothermal therapy leads to the synergistic perturbation of cytoskeleton remodeling and subsequent impairment of cell motility and metastasis. The tailored design of IPHG validates a promising paradigm for drug delivery to combat tumor resistance and metastasis resulting from poor target access for single chemotherapy.

Transgene codon usage drives viral fitness and therapeutic efficacy in oncolytic adenoviruses

Arming oncolytic adenoviruses with therapeutic transgenes is a well-established strategy for multimodal tumour attack. However, this strategy sometimes leads to unexpected attenuated viral replication and a loss of oncolytic effects, preventing these viruses from reaching the clinic. Previous work has shown that altering codon usage in viral genes can hamper viral fitness. Here, we have analysed how transgene codon usage impacts viral replication and oncolytic activity. We observe that, although transgenes with optimized codons show high expression levels at the first round of infection, they impair viral fitness and are therefore not expressed in a sustained manner. Conversely, transgenes encoded by suboptimal codons do not compromise viral replication and are thus stably expressed over time, allowing a greater oncolytic activity both in vitro and in vivo. Altogether, our work shows that fine-tuning codon usage leads to a concerted optimization of transgene expression and viral replication paving the way for the rational design of more efficacious oncolytic therapies.

Inhibition of miR-222 by Oncolytic Adenovirus-Encoded miRNA Sponges Promotes Viral Oncolysis and Elicits Antitumor Effects in Pancreatic Cancer Models

Oncolytic adenoviruses (OA) are envisioned as a therapeutic option for patients with cancer, designed to preferentially replicate in cancer cells. However, the high number of genetic alterations in tumors can generate a context in which adenoviruses have difficulties replicating. Abnormal miRNAs expression is a trademark of pancreatic cancer, with several oncogenic miRNAs playing essential roles in cancer-associated pathways. The perturbed miRNome induces reprogramming of gene expression in host cells that can impact the complex interplay between cellular processes and viral replication. We have studied the effects of overexpressed miRNAs on oncolytic adenoviral activity and identified miRNAs modulators of adenoviral oncolysis in pancreatic cancer cells. Inhibition of the highly upregulated miR-222 sensitized cancer cells to oncolysis. To provide a therapeutic application to this insight, we engineered the oncolytic adenovirus AdNuPARmE1A with miR-222 binding sites, working as sponges to withdraw the miRNA from the cellular environment. AdNuPAR-E-miR222-S mediated-decrease of miR-222 expression in pancreatic cancer cells strongly improved the viral yield and enhanced the adenoviral cytotoxic effects. Antitumoral studies confirmed a high activity for AdNuPARmE1A-miR222-S in vivo, controlling tumor progression more effectively than the scrambled control virus in xenografts. We demonstrated that the increased antitumor potency of the novel oncolytic virus resulted from the combinatory effects of miR-222 oncomiR inhibition and the restoration of miR-222 target genes activity enhancing viral fitness.

Hyaluronidase expression within tumors increases virotherapy efficacy and T cell accumulation

Oncolytic viruses (OVs) preferentially infect and selectively replicate in cancer cells. OVs have been tested in clinical trials as monotherapy or in combination with chemotherapy, radiotherapy, and immunotherapy. However, the dense extracellular matrix hampers the intratumoral spreading and efficacy of OVs. Previously we described VCN-01, an oncolytic adenovirus expressing a soluble version of human sperm hyaluronidase (hyal) PH20, which exhibited enhanced intratumoral distribution and antitumor activity in different models. Here, we present two oncolytic adenoviruses designed to increase the secretion of PH20 compared to VCN-01. ICO15K-40SAPH20, encoding PH20 under an Ad40 splice acceptor, and ICO15K-E1aPH20 expressing PH20 fused to the E1A gene by P2A peptide. We demonstrate that increased hyal activity improves antitumor efficacy in both a sensitive immunodeficient model and an immunocompetent model. Moreover, we show that hyal activity impacts T cell accumulation in tumors, highlighting the value of a hyaluronidase-expressing virus for combinations with other immunotherapies in cancers involving dense stroma.

Multifunctional Nanotheranostic Gold Nanocage/Selenium Core-Shell for PAI-Guided Chemo-Photothermal Synergistic Therapy in vivo

Introduction

Cancer theragnosis involving cancer diagnosis and targeted therapy simultaneously in one integrated system would be a promising solution of cancer treatment. Herein, a convenient and practical cancer theragnosis agent was constructed by combining gold nanocages (AuNCs) covered with selenium and a chitosan (CS) shell (AuNCs/Se) to incorporate the anti-cancer drug doxorubicin (DOX) as a multifunctional targeting nanocomposite (AuNCs/DOX@Se-iRGD) for photoacoustic imaging (PAI)-guided chemo-photothermal synergistic therapy that contributes to enhanced anti-cancer efficacy. The novel design of AuNCs/DOX@Se-iRGD gives the nanocomposite two outstanding properties: (1) AuNCs, with excellent LSPR property in the NIR region, act as a contrast agent for enhanced PAI and photothermal therapy (PTT); (2) Se acts as an anti-cancer nanoagent and drug delivery cargo.

Methods

The photothermal performance of these nanocomposites was evaluated in different concentrations with laser powder densities. These nanocomposites were also incubated in pH 5.3, 6.5, 7.4 PBS and NIR laser to study their drug release ability. The cellular uptake was studied by measuring the Se and Au concentrations inside the cells using inductively coupled plasma-mass spectrometry (ICP-MS). Besides, in vitro and in vivo anti-tumor activity were carried out by cytotoxicity assay MTT and tumor model nude mice, respectively. As for imaging, the PA value and images of these nanocomposites accumulated in the tumor site were sequentially collected at specific time points for 48 h.

Results and Discussion

The prepared AuNCs/DOX@Se-iRGD showed excellent biocompatibility and physiological stability in different media. In vivo results indicated that the targeting nanocomposite presented the strongest contrast-enhanced PAI signals, which could provide contour and location information of tumor, 24 h after intravenous injection. Likewise, the combined treatment of chemo- and photothermal synergistic therapy significantly inhibited tumor growth when compared with the two treatments carried out separately and showed negligible acute toxicity to the major organs.

Conclusion

This study demonstrates that AuNCs/DOX@Se-iRGD has great prospect to become a multifunctional anti-tumor nanosystem for PAI-guided chemo- and photothermal synergistic therapy.

Biomaterial-based scaffold for in situ chemo-immunotherapy to treat poorly immunogenic tumors

Poorly immunogenic tumors, including triple negative breast cancers (TNBCs), remain resistant to current immunotherapies, due in part to the difficulty of reprogramming the highly immunosuppressive tumor microenvironment (TME). Here we show that peritumorally injected, macroporous alginate gels loaded with granulocyte-macrophage colony-stimulating factor (GM-CSF) for concentrating dendritic cells (DCs), CpG oligonucleotides, and a doxorubicin-iRGD conjugate enhance the immunogenic death of tumor cells, increase systemic tumor-specific CD8 + T cells, repolarize tumor-associated macrophages towards an inflammatory M1-like phenotype, and significantly improve antitumor efficacy against poorly immunogenic TNBCs. This system also prevents tumor recurrence after surgical resection and results in 100% metastasis-free survival upon re-challenge. This chemo-immunotherapy that concentrates DCs to present endogenous tumor antigens generated in situ may broadly serve as a facile platform to modulate the suppressive TME, and enable in situ personalized cancer vaccination.

The immunosuppressive tumour microenvironment impairs immunotherapy in poorly immunogenic cancer. Here, the authors load an alginate gel with GM-CSF, CpG oligonucleotides and doxorubicin-iRGD to promote immunogenic death of tumour cells and improve immunotherapy efficacy in triple negative breast cancer models.

Arming Oncolytic Adenoviruses: Effect of Insertion Site and Splice Acceptor on Transgene Expression and Viral Fitness

Oncolytic adenoviruses (OAds) present limited efficacy in clinics. The insertion of therapeutic transgenes into OAds genomes, known as "arming OAds", has been the main strategy to improve their therapeutic potential. Different approaches were published in the decade of the 2000s, but with few comparisons. Most armed OAds have complete or partial E3 deletions, leading to a shorter half-life in vivo. We generated E3+ OAds using two insertion sites, After-fiber and After-E4, and two different splice acceptors linked to the major late promoter, either the Ad5 protein IIIa acceptor (IIIaSA) or the Ad40 long fiber acceptor (40SA). The highest transgene levels were obtained with the After-fiber location and 40SA. However, the set of codons of the transgene affected viral fitness, highlighting the relevance of transgene codon usage when arming OAds using the major late promoter.

Retargeting adenoviruses for therapeutic applications and vaccines

Adenoviruses (Ads) are robust vectors for therapeutic applications and vaccines, but their use can be limited by differences in their in vitro and in vivo pharmacologies. This review emphasizes that there is not just one Ad, but a whole virome of diverse viruses that can be used as therapeutics. It discusses that true vector targeting involves not only retargeting viruses, but importantly also detargeting the viruses from off-target cells.

Targeting Tumors Using Peptides

To penetrate solid tumors, low molecular weight (Mw < 10 KDa) compounds have an edge over antibodies: their higher penetration because of their small size. Because of the dense stroma and high interstitial fluid pressure of solid tumors, the penetration of higher Mw compounds is unfavored and being small thus becomes an advantage. This review covers a wide range of peptidic ligands—linear, cyclic, macrocyclic and cyclotidic peptides—to target tumors: We describe the main tools to identify peptides experimentally, such as phage display, and the possible chemical modifications to enhance the properties of the identified peptides. We also review in silico identification of peptides and the most salient non-peptidic ligands in clinical stages. We later focus the attention on the current validated ligands available to target different tumor compartments: blood vessels, extracelullar matrix, and tumor associated macrophages. The clinical advances and failures of these ligands and their therapeutic conjugates will be discussed. We aim to present the reader with the state-of-the-art in targeting tumors, by using low Mw molecules, and the tools to identify new ligands.

Antitumor Activity of Thermosensitive Hydrogels Packaging Gambogic Acid Nanoparticles and Tumor-Penetrating Peptide iRGD Against Gastric Cancer

Introduction

Gambogic acid (GA) is proved to have anti-tumor effects on gastric cancer. Due to poor solubility, non-specific biological distribution, toxicity to normal tissues and short half-life, it is hard to be applied into the clinic. To overcome these issues, we developed a thermosensitive and injectable hydrogel composed of hydroxypropyl cellulose, silk fibroin and glycerol, with short gelling time, good compatibility and sustained release, and demonstrated that the hydrogel packaged with gambogic acid nanoparticles (GA-NPs) and tumor-penetrating peptide iRGD could improve the anti-tumor activity.

Methods

The Gelling time and micropore size of the hydrogels were regulated through different concentrations of glycerol. Controlled release characteristics of the hydrogels were evaluated with a real-time near-infrared fluorescence imaging system. Location of nanoparticles from different carriers was traced by confocal laser scanning microscopy. The in vivo antitumor activity of the hydrogels packaging GA-NPs and iRGD was evaluated by investigating tumor volume and tumor size.

Results

The thermo-sensitive properties of hydrogels were characterized by 3-4 min, 37°C, when glycerol concentration was 20%. The hydrogels physically packaged with GA-NPs and iRGD showed higher fluorescence intensity than other groups. The in vivo study indicated that the co-administration of GA-NPs and iRGD by hydrogels had higher antitumor activity than the GA-loaded hydrogels and free GA combining with iRGD. Free GA group showed few antitumor effects. Compared with the control group, the body weight in other groups had no obvious change, and the count of leukocytes and hemoglobin was slightly decreased.

Discussion

The hydrogel constructed iRGD and GA-NPs exerted an effective anti-tumor effect possibly due to retention effect, local administration and continuous sustained release of iRGD promoting the penetration of nanoparticles into a deep part of tumors. The delivery system showed little systemic toxicity and would provide a promising strategy to improve anti-gastric cancer efficacy.

Nanotechnology in cancer diagnosis: progress, challenges and opportunities

In the fight against cancer, early detection is a key factor for successful treatment. However, the detection of cancer in the early stage has been hindered by the intrinsic limits of conventional cancer diagnostic methods. Nanotechnology provides high sensitivity, specificity, and multiplexed measurement capacity and has therefore been investigated for the detection of extracellular cancer biomarkers and cancer cells, as well as for in vivo imaging. This review summarizes the latest developments in nanotechnology applications for cancer diagnosis. In addition, the challenges in the translation of nanotechnology-based diagnostic methods into clinical applications are discussed.

Recent insights into apoptosis and toxic autophagy: The roles of MDA-7/IL-24, a multidimensional anti-cancer therapeutic

Apoptosis and autophagy play seminal roles in maintaining organ homeostasis. Apoptosis represents canonical type I programmed cell death. Autophagy is viewed as pro-survival, however, excessive autophagy can promote type II cell death. Defective regulation of these two obligatory cellular pathways is linked to various diseases, including cancer. Biologic or chemotherapeutic agents, which can reprogram cancer cells to undergo apoptosis- or toxic autophagy-mediated cell death, are considered effective tools for treating cancer. Melanoma differentiation associated gene-7 (mda-7) selectively promotes these effects in cancer cells. mda-7 was identified more than two decades ago by subtraction hybridization showing elevated expression during induction of terminal differentiation of metastatic melanoma cells following treatment with recombinant fibroblast interferon and mezerein (a PKC activating agent). MDA-7 was classified as a member of the IL-10 gene family based on its chromosomal location, and the presence of an IL-10 signature motif and a secretory sequence, and re-named interleukin-24 (MDA-7/IL-24). Multiple studies have established MDA-7/IL-24 as a potent anti-cancer agent, which when administered at supra-physiological levels induces growth arrest and cell death through apoptosis and toxic autophagy in a wide variety of tumor cell types, but not in corresponding normal/non-transformed cells. Furthermore, in a phase I/II clinical trial, MDA-7/IL-24 administered by means of a non-replicating adenovirus was well tolerated and displayed significant clinical activity in patients with multiple advanced cancers. This review examines our current comprehension of the role of MDA-7/IL-24 in mediating cancer-specific cell death via apoptosis and toxic autophagy.

iRGD: A Promising Peptide for Cancer Imaging and a Potential Therapeutic Agent for Various Cancers

Poor penetration into the tumor parenchyma and the reduced therapeutic efficacy of anticancer drugs and other medications are the major problems in tumor treatment. A new tumor-homing and penetrating peptide, iRGD (CRGDK/RGPD/EC), can be effectively used to combine and deliver imaging agents or anticancer drugs into tumors. The different “vascular zip codes” expressed in different tissues can serve as targets for docking-based (synaptic) delivery of diagnostic and therapeutic molecules. αv-Integrins are abundantly expressed in the tumor vasculature, where they are recognized by peptides containing the RGD integrin recognition motif. The iRGD peptide follows a multistep tumor-targeting process: First, it is proteolytically cleaved to generate the CRGDK fragment by binding to the surface of cells expressing αv integrins (αvβ3 and αvβ5). Then, the fragment binds to neuropilin-1 and penetrates the tumor parenchyma more deeply. Compared with conventional RGD peptides, the affinity of iRGD for αv integrins is in the mid to low nanomolar range, and the CRGDK fragment has a stronger affinity for neuropilin-1 than that for αv integrins because of the C-terminal exposure of a conditional C-end Rule (CendR) motif (R/KXXR/K), whose receptor proved to be neuropilin-1. Consequently, these advantages facilitate the transfer of CRGDK fragments from integrins to neuropilin-1 and consequently deeper penetration into the tumor. Due to its specific binding and strong affinity, the iRGD peptide can deliver imaging agents and anticancer drugs into tumors effectively and deeply, which is useful in detecting the tumor, blocking tumor growth, and inhibiting tumor metastasis. This review aims to focus on the role of iRGD in the imaging and treatment of various cancers.

Radiation-Induced Targeted Nanoparticle-Based Gene Delivery for Brain Tumor Therapy

Targeted therapy against the programmed cell death ligand-1 (PD-L1) blockade holds considerable promise for the treatment of different tumor types; however, little effect has been observed against gliomas thus far. Effective glioma therapy requires a delivery vehicle that can reach tumor cells in the central nervous system, with limited systemic side effect. In this study, we developed a cyclic peptide iRGD (CCRGDKGPDC)-conjugated solid lipid nanoparticle (SLN) to deliver small interfering RNAs (siRNAs) against both epidermal growth factor receptor (EGFR) and PD-L1 for combined targeted and immunotherapy against glioblastoma, the most aggressive type of brain tumors. Building on recent studies showing that radiation therapy alters tumors for enhanced nanotherapeutic delivery in tumor-associated macrophage-dependent fashion, we showed that low-dose radiation primes targeted SLN uptake into the brain tumor region, leading to enhanced downregulation of PD-L1 and EGFR. Bioluminescence imaging revealed that radiation therapy followed by systemic administration of targeted SLN leads to a significant decrease in glioblastoma growth and prolonged mouse survival. This study combines radiation therapy to prime the tumor for nanoparticle uptake along with the targeting effect of iRGD-conjugated nanoparticles to yield a straightforward but effective approach for combined EGFR inhibition and immunotherapy against glioblastomas, which can be extended to other aggressive tumor types.

Lipoprotein-inspired penetrating nanoparticles for deep tumor-targeted shuttling of indocyanine green and enhanced photo-theranostics

Biomimetic iRGD-rHDL/ICG nanoparticles exhibited deep tumor targeted shuttling of indocyanine green and enhanced phototherapy.

Bioselection Reveals miR-99b and miR-485 as Enhancers of Adenoviral Oncolysis in Pancreatic Cancer

Oncolytic viruses are designed for cancer treatment. Cell-virus interactions are key determinants for successful viral replication. Therefore, the extensive reprogramming of gene expression that occurs in tumor cells might create a hurdle for viral propagation. We used a replication-based approach of a microRNA (miRNA) adenoviral library encoding up to 243 human miRNAs as a bioselection strategy to identify miRNAs that facilitate adenoviral oncolytic activity in pancreatic ductal adenocarcinoma. We identify two miRNAs, miR-99b and miR-485, that function as enhancers of adenoviral oncolysis by improving the intra- and extracellular yield of mature virions. An increased adenoviral activity is the consequence of enhanced E1A and late viral protein expression, which is probably mediated by the downregulation of the transcriptional repressors ELF4, MDM2, and KLF8, which we identify as miR-99b or miR-485 target genes. Arming the oncolytic adenovirus ICOVIR15 with miR-99b or miR-485 enhances its fitness and its antitumoral activity. Our results demonstrate the potential of this strategy to improve oncolytic adenovirus potency, and they highlight miR-99b and miR-485 as sensitizers of adenoviral replication.

Competition of charge-mediated and specific binding by peptide-tagged cationic liposome-DNA nanoparticles in vitro and in vivo

Cationic liposome-nucleic acid (CL-NA) complexes, which form spontaneously, are a highly modular gene delivery system. These complexes can be sterically stabilized via PEGylation [PEG: poly (ethylene glycol)] into nanoparticles (NPs) and targeted to specific tissues and cell types via the conjugation of an affinity ligand. However, there are currently no guidelines on how to effectively navigate the large space of compositional parameters that modulate the specific and nonspecific binding interactions of peptide-targeted NPs with cells. Such guidelines are desirable to accelerate the optimization of formulations with novel peptides. Using PEG-lipids functionalized with a library of prototypical tumor-homing peptides, we varied the peptide density and other parameters (binding motif, peptide charge, CL/DNA charge ratio) to study their effect on the binding and uptake of the corresponding NPs. We used flow cytometry to quantitatively assess binding as well as internalization of NPs by cultured cancer cells. Surprisingly, full peptide coverage resulted in less binding and internalization than intermediate coverage, with the optimum coverage varying between cell lines. In, addition, our data revealed that great care must be taken to prevent nonspecific electrostatic interactions from interfering with the desired specific binding and internalization. Importantly, such considerations must take into account the charge of the peptide ligand as well as the membrane charge density and the CL/DNA charge ratio. To test our guidelines, we evaluated the in vivo tumor selectivity of selected NP formulations in a mouse model of peritoneally disseminated human gastric cancer. Intraperitoneally administered peptide-tagged CL-DNA NPs showed tumor binding, minimal accumulation in healthy control tissues, and preferential penetration of smaller tumor nodules, a highly clinically relevant target known to drive recurrence of the peritoneal cancer.

Tumor target amplification: Implications for nano drug delivery systems

Tumor cells overexpress surface markers which are absent from normal cells. These tumor-restricted antigenic signatures are a fundamental basis for distinguishing on-target from off-target cells for ligand-directed targeting of cancer cells. Unfortunately, tumor heterogeneity impedes the establishment of a solid expression pattern for a given target marker, leading to drastic changes in quality (availability) and quantity (number) of the target. Consequently, a subset of cancer cells remains untargeted during the course of treatment, which subsequently promotes drug-resistance and cancer relapse. Since target inefficiency is only problematic for cancer treatment and not for treatment of other pathological conditions such as viral/bacterial infections, target amplification or the generation of novel targets is key to providing eligible antigenic markers for effective targeted therapy. This review summarizes the limitations of current ligand-directed targeting strategies and provides a comprehensive overview of tumor target amplification strategies, including self-amplifying systems, dual targeting, artificial markers and peptide modification. We also discuss the therapeutic and diagnostic potential of these approaches, the underlying mechanism(s) and established methodologies, mostly in the context of different nanodelivery systems, to facilitate more effective ligand-directed cancer cell monitoring and targeting.

Evidence of Anti-tumoral Efficacy in an Immune Competent Setting with an iRGD-Modified Hyaluronidase-Armed Oncolytic Adenovirus

To enhance adenovirus-mediated oncolysis, different approaches that tackle the selectivity, tumor penetration, and spreading potential of oncolytic adenoviruses have been reported. We have previously demonstrated that insertion of the internalizing Arginine-Glycine-Aspartic (iRGD) tumor-penetrating peptide at the C terminus of the fiber or transgenic expression of a secreted hyaluronidase can improve virus tumor targeting and spreading. Here we report a new oncolytic adenovirus ICOVIR17K-iRGD in which both modifications have been incorporated. In xenografted A549 tumors in nude mice, ICOVIR17K-iRGD shows higher efficacy than the non-iRGD counterpart. To gain insights into the role of the immune system in oncolysis, we have studied ICOVIR17K-iRGD in the tumor isograft mouse model CMT64.6, partially permissive to human adenovirus 5 replication, in immunodeficient or immunocompetent mice. Whereas no efficacy was observed in the immunodeficient setting due to insufficient viral replication, partial efficacy and a polymorphonuclear and CD8+ T cell infiltrate were observed in the immunocompetent mice. The results indicate that the elicitation of a virus-induced anti-tumoral immune response is responsible for the observed partial anti-tumoral effect.

An iRGD peptide conjugated heparin nanocarrier for gastric cancer therapy

The cis-diamminedichloroplatinum(ii) (DDP, cisplatin) is an important antitumor drug for the therapy of gastric cancer in clinics, but it is limited by its nonspecific tissue distribution and severe side effects. Here, an integrin targeted drug delivery system iRGD-heparin nanocarrier (iHP) was successfully synthesized. The iHP has several unique properties. First, this nanocarrier has excellent biodegradation due to its heparin biopolymer frame. Second, it is biocompatible because succinic anhydride-modified heparin has no anticoagulant activity and cell toxicity. We proved that from anticoagulant function evaluation and a cytotoxicity test. Third, iRGD was conjugated to the nanoparticles as an integrin-targeting ligand. Our results showed that iHP has precise targeting to integrin-overexpressed human gastric cancer cells MKN-45P in vitro and tumor tissues in vivo. Hence, we synthesized targeted nanoparticles iHP-DDP (iHDDP) and untargeted nanoparticles HP-DDP (HDDP). In our result, iHDDP showed higher antitumor efficacy than HDDP in vitro and in vivo. And in comparison with free DDP, the iHDDP nanoparticle delivery system showed satisfactory antitumor activity of DDP without weight loss or liver and kidney damage in nude mice bearing MKN-45P tumors.

A nontoxic, low immunogenic and high specific drug delivery system for gastric cancer.

Peptides as drug delivery vehicles across biological barriers

Peptides are small biological molecules that are attractive in drug delivery and materials engineering for applications including therapeutics, molecular building blocks and cell-targeting ligands. Peptides are small but can possess complexity and functionality as larger proteins. Due to their intrinsic properties, peptides are able to overcome the physiological and transport barriers presented by diseases. In this review, we discuss the progress of identifying and using peptides to shuttle across biological barriers and facilitate transport of drugs and drug delivery systems for improved therapy. Here, the focus of this review is on rationally designed, phage display peptides, and even endogenous peptides as carriers to penetrate biological barriers, specifically the blood-brain barrier(BBB), the gastrointestinal tract (GI), and the solid tumor microenvironment (T). We will discuss recent advances of peptides as drug carriers in these biological environments. From these findings, challenges and potential opportunities to iterate and improve peptide-based approaches will be discussed to translate their promise towards the clinic to deliver drugs for therapeutic efficacy.

Seek & Destroy, use of targeting peptides for cancer detection and drug delivery

Accounting for 16 million new cases and 9 million deaths annually, cancer leaves a great number of patients helpless. It is a complex disease and still a major challenge for the scientific and medical communities. The efficacy of conventional chemotherapies is often poor and patients suffer from off-target effects. Each neoplasm exhibits molecular signatures - sometimes in a patient specific manner - that may completely differ from the organ of origin, may be expressed in markedly higher amounts and/or in different location compared to the normal tissue. Although adding layers of complexity in the understanding of cancer biology, this cancer-specific signature provides an opportunity to develop targeting agents for early detection, diagnosis, and therapeutics. Chimeric antibodies, recombinant proteins or synthetic polypeptides have emerged as excellent candidates for specific homing to peripheral and central nervous system cancers. Specifically, peptide ligands benefit from their small size, easy and affordable production, high specificity, and remarkable flexibility regarding their sequence and conjugation possibilities. Coupled to imaging agents, chemotherapies and/or nanocarriers they have shown to increase the on-site delivery, thus allowing better tumor mass contouring in imaging and increased efficacy of the chemotherapies associated with reduced adverse effects. Therefore, some of the peptides alone or in combination have been tested in clinical trials to treat patients. Peptides have been well-tolerated and shown absence of toxicity. This review aims to offer a view on tumor targeting peptides that are either derived from natural peptide ligands or identified using phage display screening. We also include examples of peptides targeting the high-grade malignant tumors of the central nervous system as an example of the complex therapeutic management due to the tumor's location. Peptide vaccines are outside of the scope of this review.

Human Menstrual Blood-Derived Mesenchymal Stem Cells as Potential Cell Carriers for Oncolytic Adenovirus

Antitumor efficacy of systemically administered oncolytic adenoviruses (OAdv) is limited due to diverse factors such as liver sequestration, neutralizing interactions in blood, elimination by the immune system, and physical barriers in tumors. It is therefore of clinical relevance to improve OAdv bioavailability and tumor delivery. Among the variety of tumor-targeting strategies, the use of stem cells and specifically bone marrow-derived mesenchymal stem cells (BM-MSCs) is of particular interest due to their tumor tropism and immunomodulatory properties. Nonetheless, the invasive methods to obtain these cells, the low number of MSCs present in the bone marrow, and their restricted in vitro expansion represent major obstacles for their use in cancer treatments, pointing out the necessity to identify an alternative source of MSCs. Here, we have evaluated the use of menstrual blood-derived mesenchymal stem cells (MenSCs) as cell carriers for regional delivery of an OAdv in the tumor. Our results indicate that MenSCs can be isolated without invasive methods, they have an increased proliferation rate compared to BM-MSCs, and they can be efficiently infected with different serotype 5-based capsid-modified adenoviruses, leading to viral replication and release. In addition, our in vivo studies confirmed the tumor-homing properties of MenSCs after regional administration.

Nonviral cancer gene therapy: Delivery cascade and vector nanoproperty integration

Gene therapy represents a promising cancer treatment featuring high efficacy and limited side effects, but it is stymied by a lack of safe and efficient gene-delivery vectors. Cationic polymers and lipid-based nonviral gene vectors have many advantages and have been extensively explored for cancer gene delivery, but their low gene-expression efficiencies relative to viral vectors limit their clinical translations. Great efforts have thus been devoted to developing new carrier materials and fabricating functional vectors aimed at improving gene expression, but the overall efficiencies are still more or less at the same level. This review analyzes the cancer gene-delivery cascade and the barriers, the needed nanoproperties and the current strategies for overcoming these barriers, and outlines PEGylation, surface-charge, size, and stability dilemmas in vector nanoproperties to efficiently accomplish the cancer gene-delivery cascade. Stability, surface, and size transitions (3S Transitions) are proposed to resolve those dilemmas and strategies to realize these transitions are comprehensively summarized. The review concludes with a discussion of the future research directions to design high-performance nonviral gene vectors.

iRGD as a tumor‑penetrating peptide for cancer therapy (Review)

As a tumor-targeting and ‑penetrating peptide, iRGD binds to αv integrins and neuropilin‑1 receptors, which are expressed at high levels on tumor cells and the surfaces of vasculature. Subsequently, iRGD penetrates deep into the tumor parenchyma with antitumor drugs, imaging agents, immune modulators and biological products. These substances are either chemically linked to the peptide or co‑injected with the peptide. The iRGD peptide can be readily synthesized, exhibits significantly improved penetration, compared with traditional peptides, and can effectively inhibit tumor metastasis. Therefore, the peptide is now used widely for the diagnosis and treatment of cancer. However, whether the peptide is able to promote the entry of drugs into non‑targeted cells remains to be fully elucidated. In this review, an overview of iRGD is presented, focusing on its identification, mechanism of action and previous studies on its roles in various types of cancer. Studies in previous years have demonstrated the potential of the iRGD protein for tumors diagnosis and targeted treatment, which warrants further investigation.

Tumor penetrating peptides for improved drug delivery

In vivo screening of phage libraries in tumor-bearing mice has been used to identify peptides that direct phage homing to a tumor. The power of in vivo phage screening is illustrated by the recent discovery of peptides with unique tumor-penetrating properties. These peptides activate an endocytic transport pathway related to but distinct from macropinocytosis. They do so through a complex process that involves binding to a primary, tumor-specific receptor, followed by a proteolytic cleavage, and binding to a second receptor. The second receptor, neuropilin-1 (or neuropilin-2) activates the transport pathway. This trans-tissue pathway, dubbed the C-end Rule (CendR) pathway, mediates the extravasation transport through extravascular tumor tissue of payloads ranging from small molecule drugs to nanoparticles. The CendR technology provides a solution to a major problem in tumor therapy, poor penetration of drugs into tumors. Targeted delivery with tumor-penetrating peptides has been shown to specifically increase the accumulation of drugs, antibodies and nanotherapeutics in experimental tumors in vivo, and in human tumors ex vivo. Remarkably the payload does not have to be coupled to the peptide; the peptide activates a bulk transport system that sweeps along a drug present in the blood. Treatment studies in mice have shown improved anti-tumor efficacy and less damage to normal tissues with drugs ranging from traditional chemotherapeutics to antibodies, and to nanoparticle drugs.

Oncolytic Adenoviral Delivery of an EGFR-Targeting T-cell Engager Improves Antitumor Efficacy

Antiviral immune responses present a major hurdle to the efficacious use of oncolytic adenoviruses as cancer treatments. Despite the existence of a highly immunosuppressive tumor environment, adenovirus-infected cells can nonetheless be efficiently cleared by infiltrating cytotoxic T lymphocytes (CTL) without compromising tumor burden. In this study, we tested the hypothesis that tumor-infiltrating T cells could be more effectively activated and redirected by oncolytic adenoviruses that were armed with bispecific T-cell-engager (BiTE) antibodies. The oncolytic adenovirus ICOVIR-15K was engineered to express an EGFR-targeting BiTE (cBiTE) antibody under the control of the major late promoter, leading to generation of ICOVIR-15K-cBiTE, which retained its oncolytic properties in vitro cBiTE expression and secretion was detected in supernatants from ICOVIR-15K-cBiTE-infected cells, and the secreted BiTEs bound specifically to both CD3⁺ and EGFR⁺ cells. In cell coculture assays, ICOVIR-15K-cBiTE-mediated oncolysis resulted in robust T-cell activation, proliferation, and bystander cell-mediated cytotoxicity. Notably, intratumoral injection of this cBiTE-expressing adenovirus increased the persistence and accumulation of tumor-infiltrating T cells in vivo, compared with the parental virus lacking such effects. Moreover, in two distinct tumor xenograft models, combined delivery of ICOVIR-15K-cBiTE with peripheral blood mononuclear cells or T cells enhanced the antitumor efficacy achieved by the parental counterpart. Overall, our results show how arming oncolytic adenoviruses with BiTE can overcome key limitations in oncolytic virotherapy. Cancer Res; 77(8); 2052-63. ©2017 AACR.

Development of a multi-target peptide for potentiating chemotherapy by modulating tumor microenvironment

Finding effective cures against aggressive malignancy remains a major challenge in cancer chemotherapy. Here, we report a "tadpole"-like peptide by covalently conjugating the alanine-alanine-asparagine "tail" residual to the cyclic tumor homing peptide iRGD (CCRGDKGPDC) to afford nRGD, which significantly enhanced tumoricidal effects of doxorubicin, by either co-administered as a physical mixture or as a targeting ligand covalently conjugated to the liposomal carrier. Given twice at an equivalent dose of 5 mg/kg, doxorubicin loaded liposomes modified with nRGD (nRGD-Lipo-Dox) showed excellent antitumor efficacy in 4T1 breast cancer mice, of which 44.4% remained alive for over 90 days without recurrence during the period of investigation. The dramatic improvement in antitumor efficacy was attributed to nRGD-Lipo-Dox which appeared to specifically interact with tumor vascular endothelial cells to achieve efficient tumor penetration, and modulate tumor microenvironment with depletion of tumor associated macrophages.

Biodistribution and evaluation of 131 I-labeled neuropilin-binding peptide for targeted tumor imaging

Neuropilin-1 (NRP-1) is overexpressed in several kinds of cancer cell and contributes to tumor aggressiveness. Recently, the arginine/lysine-rich peptide with C-terminal motifs (R/K)XX(R/K) indicated promising penetrating and transporting capability into NRP-1 positive cancer cells. In the present study, we describe a ¹³¹ I-labeled C-end rule motif peptide conjugate, Tyr-tLyp-1, for NRP-1 positive tumor targeting and imaging properties. Briefly, a truncated Lyp-1 peptide was designed to expose its C-end motif and conjugated to tyrosine for radiolabeling after structural modification. The peptide indicated specific binding to A549 cancer cells at 2 μM concentration, and its binding was dependent on NRP-1 expression and could be inhibited by other NRP-1-binding peptides. In vivo imaging of ¹³¹ I-labeled Tyr-tLyp-1peptide showed that a subcutaneous A549 xenograft tumor could be visualized using a SPECT/CT scanner. The tumor uptake of ¹³¹ I-Tyr-tLyp-1 was 4.77 times higher than the uptake in muscles by SPECT/CT software quantification at 6 h post injection. Together, this study indicated that truncated Lyp-1 peptide could specifically localize in NRP-1 positive tumors and successfully mediate the ¹³¹ I radionuclide diagnosis, indicating promising targeted imaging capability for NRP-1 positive tumors. Copyright © 2016 John Wiley & Sons, Ltd.

pH-Switch Nanoprecipitation of Polymeric Nanoparticles for Multimodal Cancer Targeting and Intracellular Triggered Delivery of Doxorubicin

Theranostic nanoparticles are emerging as potent tools for noninvasive diagnosis, treatment, and monitoring of solid tumors. Herein, an advanced targeted and multistimuli responsive theranostic platform is presented for the intracellular triggered delivery of doxorubicin. The system consists of a polymeric-drug conjugate solid nanoparticle containing encapsulated superparamagnetic iron oxide nanoparticles (IO@PNP) and decorated with a tumor homing peptide, iRGD. The production of this nanosystem is based on a pH-switch nanoprecipitation method in organic-free solvents, making it ideal for biomedical applications. The nanosystem shows sufficient magnetization saturation for magnetically guided therapy along with reduced cytotoxicity and hemolytic effects. IO@PNP are largely internalized by endothelial and metastatic cancer cells and iRGD decorated IO@PNP moderately enhance their internalization into endothelial cells, while no enhancement is found for the metastatic cancer cells. Poly(ethylene glycol)-block-poly(histidine) with pH-responsive and proton-sponge properties promotes prompt lysosomal escape once the nanoparticles are endocyted. In addition, the polymer-doxorubicin conjugate solid nanoparticles show both intracellular lysosomal escape and efficient translocation of doxorubicin to the nuclei of the cells via cleavage of the amide bond. Overall, IO@PNP-doxorubicin and the iRGD decorated counterpart demonstrate to enhance the toxicity of doxorubicin in cancer cells by improving the intracellular delivery of the drug carried in the IO@PNP.

iRGD peptide conjugation potentiates intraperitoneal tumor delivery of paclitaxel with polymersomes

Polymersomes are versatile nanoscale vesicles that can be used for cytoplasmic delivery of payloads. Recently, we demonstrated that pH-sensitive polymersomes exhibit an intrinsic selectivity towards intraperitoneal tumor lesions. A tumor homing peptide, iRGD, harbors a cryptic C-end Rule (CendR) motif that is responsible for neuropilin-1 (NRP-1) binding and for triggering extravasation and tumor penetration of the peptide. iRGD functionalization increases tumor selectivity and therapeutic efficacy of systemic drug-loaded nanoparticles in many tumor models. Here we studied whether intraperitoneally administered paclitaxel-loaded iRGD-polymersomes show improved efficacy in the treatment of peritoneal carcinomatosis. First, we demonstrated that the pH-sensitive polymersomes functionalized with RPARPAR (a prototypic CendR peptide) or iRGD internalize in the cells that express NRP-1, and that internalized polymersomes release their cargo inside the cytosol. CendR-targeted polymersomes loaded with paclitaxel were more cytotoxic on NRP-1-positive cells than on NRP-1-negative cells. In mice bearing peritoneal tumors of gastric (MKN-45P) or colon (CT26) origin, intraperitoneally administered RPARPAR and iRGD-polymersomes showed higher tumor-selective accumulation and penetration than untargeted polymersomes. Finally, iRGD-polymersomes loaded with paclitaxel showed improved efficacy in peritoneal tumor growth inhibition and in suppression of local dissemination compared to the pristine paclitaxel-polymersomes or Abraxane. Our study demonstrates that iRGD-functionalization improves efficacy of paclitaxel-polymersomes for intraperitoneal treatment of peritoneal carcinomatosis.

iRGD peptide as effective transporter of CuInZnxS2+x quantum dots into human cancer cells

In this paper, iRGD peptide-mediated quantum dots (QDs) delivery was studied. In the first step, dodecanethiol-capped CuInZnxS2+x (ZCIS) QDs were prepared and subsequently transferred into water using a standard and facile ligand exchange approach involving 3-mercaptopropionic acid (MPA). ZCIS@MPA nanocrystals possess a photoluminescence quantum yield (PL QY) of 25%, a PL emission centered at ca. 640nm and low distributions in size and shape. Next, the iRGD peptide was electrostatically associated to ZCIS@MPA QDs. After cytotoxicity evaluation, the tumor-targeting and penetrating activities of the iRGD/QD assembly were investigated by confocal microscopy. The experiments performed on various cancer cell lines revealed a high penetration ability of the assembly, while the bare QDs were not internalized. Additionally, imaging experiments were conducted on three-dimensional multicellular tumor spheroids in order to mimic the tumor microenvironment in vivo. iRGD/QD assemblies were found to be evenly distributed throughout the whole HeLa spheroid contrary to normal cells where they were not present. Therefore, iRGD/QD assemblies have a great potential to be used as targeted imaging agents and/or nanocarriers specific to cancer cells.

iRGD decorated lipid-polymer hybrid nanoparticles for targeted co-delivery of doxorubicin and sorafenib to enhance anti-hepatocellular carcinoma efficacy

The combination of doxorubicin (DOX) with sorafenib (SOR) has proven an effective strategy to enhance anti-hepatocellular carcinoma (HCC) efficacy. However, respective in vivo pharmacokinetic profiles and different endocytosis capacities of these two drugs greatly hinder their current application. Herein, the tumor-targeting peptide iRGD decorated lipid-polymer hybrid nanoparticles (NPs) with a shell-core structure were developed for co-delivery of DOX and SOR (DOX+SOR/iRGD NPs). After the drug ratio was optimized, the stabilized DOX+SOR/iRGD NPs were prepared. Through the iRGD-integrin recognition, DOX+SOR/iRGD NPs showed synergistic cytotoxicity, pro-apoptotic ability and enhanced internalization rate in human liver cancer HepG2 cells. In vivo pharmacokinetic result demonstrated that an extended circulation and bioavailability of DOX+SOR/iRGD NPs than free drugs. More importantly, DOX+SOR/iRGD NPs significantly enhanced antitumor efficiency in HCC xenograft mouse models. Overall, this study describes a promising nanoparticulate drug co-delivery strategy to combine clinical anticancer drugs and enhance anti-HCC efficacy.

Tumor-penetrating peptide modified and pH-sensitive polyplexes for tumor targeted siRNA delivery

The pH-sensitive copolymer enhanced the lysosome escape of polyplexes and modification of iRGD endowed the polyplexes with effective intratumoral delivery and high transfection efficiency.