EGFR-Targeted Adenovirus Dendrimer Coating for Improved Systemic Delivery of the Theranostic NIS Gene

Vaccinia virus and peptide-receptor radiotherapy synergize to improve treatment of peritoneal carcinomatosis

Tumor-specific overexpression of receptors enables a variety of targeted cancer therapies, exemplified by peptide-receptor radiotherapy (PRRT) for somatostatin receptor (SSTR)-positive neuroendocrine tumors. While effective, PRRT is restricted to tumors with SSTR overexpression. To overcome this limitation, we propose using oncolytic vaccinia virus (vvDD)-mediated receptor gene transfer to permit molecular imaging and PRRT in tumors without endogenous SSTR overexpression, a strategy termed radiovirotherapy. We hypothesized that vvDD-SSTR combined with a radiolabeled somatostatin analog could be deployed as radiovirotherapy in a colorectal cancer peritoneal carcinomatosis model, producing tumor-specific radiopeptide accumulation. Following vvDD-SSTR and ¹⁷⁷Lu-DOTATOC treatment, viral replication and cytotoxicity, as well as biodistribution, tumor uptake, and survival, were evaluated. Radiovirotherapy did not alter virus replication or biodistribution, but synergistically improved vvDD-SSTR-induced cell killing in a receptor-dependent manner and significantly increased the tumor-specific accumulation and tumor-to-blood ratio of ¹⁷⁷Lu-DOTATOC, making tumors imageable by microSPECT/CT and causing no significant toxicity. ¹⁷⁷Lu-DOTATOC significantly improved survival over virus alone when combined with vvDD-SSTR but not control virus. We have therefore demonstrated that vvDD-SSTR can convert receptor-negative tumors into receptor-positive tumors and facilitate molecular imaging and PRRT using radiolabeled somatostatin analogs. Radiovirotherapy represents a promising treatment strategy with potential applications in a wide range of cancers.

Toward the Development of GE11-Based Radioligands for Imaging of Epidermal Growth Factor Receptor-Positive Tumors

The epidermal growth factor receptor (EGFR) is closely associated with tumor development and progression and thus an important target structure for imaging and therapy of various tumors. As a result of its important role in malignancies of various origins and the fact that antibody-based compounds targeting the EGFR have significant drawbacks in terms of in vivo pharmacokinetics, several attempts have been made within the last five years to develop peptide-based EGFR-specific radioligands based on the GE11 scaffold. However, none of these approaches have shown convincing results so far, which has been proposed to be attributed to different potential challenges associated with the GE11 lead structure: first, an aggregation of radiolabeled peptides, which might prevent their interaction with their target receptor, or second, a relatively low affinity of monomeric GE11, necessitating its conversion into a multimeric or polymeric form to achieve adequate EGFR-targeting properties. In the present work, we investigated if these aforementioned points are indeed critical and if the EGFR-targeting ability of GE11 can be improved by choosing an appropriate hydrophilic molecular design or a peptide multimer system to obtain a promising radiopeptide for the visualization of EGFR-overexpressing malignancies by positron emission tomography (PET). For this purpose, we developed several monovalent ⁶⁸Ga-labeled GE11-based agents, a peptide homodimer and a homotetramer to overcome the challenges associated with GE11. The developed ligands were successfully labeled with ⁶⁸Ga³⁺ in high radiochemical yields of ≥97% and molar activities of 41-104 GBq/μmol. The resulting radiotracers presented log _D(7.4) values between -2.17 ± 0.21 and -3.79 ± 0.04 as well as a good stability in human serum with serum half-lives of 112 to 217 min for the monovalent radiopeptides and 84 and 62 min for the GE11 homodimer and homotetramer, respectively. In the following in vitro studies, none of the ⁶⁸Ga-labeled radiopeptides demonstrated a considerable EGF receptor-specific uptake in EGFR-positive A431 cells. Moreover, none of the agents was able to displace [¹²⁵I]I-EGF from the EGFR in competitive displacement assays in the same cell line in concentrations of up to 1 mM, whereas the endogenous receptor ligand hEGF demonstrated a high affinity of 15.2 ± 3.3 nM. These results indicate that it is not the aggregation of the GE11 sequence that seems to be the factor limiting the usefulness of the peptide as basis for radiotracer design but the limited affinity of monovalent and small homomultivalent GE11-based radiotracers to the EGFR. This highlights that the development of small-molecule GE11-based radioligands is not promising.

Oncolytic virus delivery modulated immune responses toward cancer therapy: Challenges and perspectives

Oncolytic viruses (OVs) harness the hallmarks of tumor cells and cancer-related immune responses for the lysis of malignant cells, modulation of the tumor microenvironment, and exertion of vaccine-like activities. However, efficient clinical exploitation of these potent therapeutic modules requires their systematic administration, especially against metastatic and solid tumors. Therefore, developing methods for shielding a virus from the neutralizing environment of the bloodstream while departing toward tumor sites is a must. This paper reports the latest advancements in the employment of chemical and biological compounds aimed at safe and efficient delivery of OVs to target tissues or tumor deposits within the host.

Nanobugs as Drugs: Bacterial Derived Nanomagnets Enhance Tumor Targeting and Oncolytic Activity of HSV-1 Virus

The survival strategies of infectious organisms have inspired many therapeutics over the years. Indeed the advent of oncolytic viruses (OVs) exploits the uncontrolled replication of cancer cells for production of their progeny resulting in a cancer-targeting treatment that leaves healthy cells unharmed. Their success against inaccessible tumors however, is highly variable due to inadequate tumor targeting following systemic administration. Coassembling herpes simplex virus (HSV1716) with biocompatible magnetic nanoparticles derived from magnetotactic bacteria enables tumor targeting from circulation with magnetic guidance, protects the virus against neutralizing antibodies and thereby enhances viral replication within tumors. This approach additionally enhances the intratumoral recruitment of activated immune cells, promotes antitumor immunity and immune cell death, thereby inducing tumor shrinkage and increasing survival in a syngeneic mouse model of breast cancer by 50%. Exploiting the properties of such a nanocarrier, rather than tropism of the virus, for active tumor targeting offers an exciting, novel approach for enhancing the bioavailability and treatment efficacy of tumor immunotherapies for disseminated neoplasms.

Coating an adenovirus with functionalized gold nanoparticles favors uptake, intracellular trafficking and anti-cancer therapeutic efficacy

Adenoviral (Ad) vectors have proven to be important tools for gene and cell therapy, although some issues still need to be addressed, such as undesired interactions with blood components and off-target sequestration that ultimately hamper efficacy. In the past years, several organic and inorganic materials have been developed to reduce immunogenicity and improve biodistribution of Ad vectors. Here we investigated the influence of the functionalization of 14 nm PEGylated gold nanoparticles (AuNPs) with quaternary ammonium groups and an arginine-glycine-aspartic acid (RGD)-motif on the uptake and biodistribution of Ad vectors. We report the formation of Ad@AuNPs complexes that promote cell attachment and uptake, independently of the presence of the coxsackievirus and adenovirus receptor (CAR) and α_vβ₃ and α_vβ₅ integrins, significantly improving transduction without limiting Ad bioactivity. Besides, the presence of the RGD peptide favors tumor targeting and decreases Ad sequestration in the liver. Additionally, tumor delivery of a coated Ad vector expressing the human sodium iodide symporter (hNIS) by mesenchymal stem cells induces increased accumulation of radioactive iodine (¹³¹I) and tumor volume reduction compared to naked Ad-hNIS, highlighting the promising potential of our coating formulation in cancer gene therapy. STATEMENT OF SIGNIFICANCE: Modification of adenoviral vectors with lipids and polymers can reduce interactions with blood components and increase tumor accumulation; however, increased toxicity and reduced transduction efficiency were indicated. Coating with gold nanoparticles has proven to be a successful strategy for increasing the efficiency of transduction of receptor-defective cell lines. Here we explore the contribution of cell surface receptors on the mechanisms of entry of Ad vectors coated with gold nanoparticles in cell lines with varying degrees of resistance to infection. The enhancement of the anti-tumoral effect shown in this work provides new evidence for the potential of our formulation.

Dendrimer Architectonics to Treat Cancer and Neurodegenerative Diseases with Implications in Theranostics and Personalized Medicine

Integration of diagnostic and therapeutic functions in a single platform namely theranostics has become a cornerstone for personalized medicine. Theranostics platform facilitates noninvasive detection and treatment while allowing the monitoring of disease progression and therapeutic efficacy in case of chronic conditions of cancer and Alzheimer's disease (AD). Theranostic tools function by themselves or with the aid of carrier, viz. liposomes, micelles, polymers, or dendrimers. The dendrimer architectures (DA) are well-characterized molecular nanoobjects with a large number of terminal functional groups to enhance solubility and offer multivalency and multifunctional properties. Various noninvasive diagnostic tools like magnetic resonance imaging (MRI), computed tomography (CT), gamma scintigraphy, and optical techniques have been accomplished utilizing DAs for simultaneous imaging and drug delivery. Obstacles in the formulation design, drug loading, payload delivery, biocompatibility, overcoming cellular membrane and blood-brain barrier (BBB), and systemic circulation remain a bottleneck in translational efforts. This review focuses on the diagnostic, therapeutic and theranostic potential of DA-based nanocarriers in treating cancer and neurodegenerative disorders like AD and Parkinson's disease (PD), among others. In view of the inverse relationship between cancer and AD, designing suitable DA-based theranostic nanodrug with high selectivity has tremendous implications in personalized medicine to treat cancer and neurodegenerative disorders.

Radiolabeled Peptide Probes for Liver Cancer Imaging

Liver cancer/Hepatocellular Carcinoma (HCC) is a leading cause of cancer death and represents an important cause of mortality worldwide. Several biomarkers are overexpressed in liver cancer, such as Glypican 3 (GPC3) and Epidermal Growth Factor Receptor (EGFR). These biomarkers play important roles in the progression of tumors and could serve as imaging and therapeutic targets for this disease. Peptides with adequate stability, receptor binding properties, and biokinetic behavior have been intensively studied for liver cancer imaging. A great variety of them have been radiolabeled with clinically relevant radionuclides for liver cancer diagnosis, and many are promising imaging and therapeutic candidates for clinical translation. Herein, we summarize the advancement of radiolabeled peptides for the targeted imaging of liver cancer.

Virotheranostics, a double-barreled viral gun pointed toward cancer; ready to shoot?

Compared with conventional cancer treatments, the main advantage of oncolytic virotherapy is its tumor-selective replication followed by the destruction of malignant cells without damaging healthy cells. Accordingly, this kind of biological therapy can potentially be used as a promising approach in the field of cancer management. Given the failure of traditional monitoring strategies (such as immunohistochemical analysis (in providing sufficient safety and efficacy necessary for virotherapy and continual pharmacologic monitoring to track pharmacokinetics in real-time, the development of alternative strategies for ongoing monitoring of oncolytic treatment in a live animal model seems inevitable. Three-dimensional molecular imaging methods have recently been considered as an attractive approach to overcome the limitations of oncolytic therapy. These noninvasive visualization systems provide real-time follow-up of viral progression within the cancer tissue by the ability of engineered oncolytic viruses (OVs) to encode reporter transgenes based on recombinant technology. Human sodium/iodide symporter (hNIS) is considered as one of the most prevalent nuclear imaging reporter transgenes that provides precise information regarding the kinetics of gene expression, viral biodistribution, toxicity, and therapeutic outcomes using the accumulation of radiotracers at the site of transgene expression. Here, we provide an overview of pre-clinical and clinical applications of hNIS-based molecular imaging to evaluate virotherapy efficacy. Moreover, we describe different types of reporter genes and their potency in the clinical trials.

Effective control of tumor growth through spatial and temporal control of theranostic sodium iodide symporter (NIS) gene expression using a heat-inducible gene promoter in engineered mesenchymal stem cells

Purpose: The tumor homing characteristics of mesenchymal stem cells (MSCs) make them attractive vehicles for the tumor-specific delivery of therapeutic agents, such as the sodium iodide symporter (NIS). NIS is a theranostic protein that allows non-invasive monitoring of the in vivo biodistribution of functional NIS expression by radioiodine imaging as well as the therapeutic application of ¹³¹I. To gain local and temporal control of transgene expression, and thereby improve tumor selectivity, we engineered MSCs to express the NIS gene under control of a heat-inducible HSP70B promoter (HSP70B-NIS-MSCs).

Experimental Design: NIS induction in heat-treated HSP70B-NIS-MSCs was verified by ¹²⁵I uptake assay, RT-PCR, Western blot and immunofluorescence staining. HSP70B-NIS-MSCs were then injected i.v. into mice carrying subcutaneous hepatocellular carcinoma HuH7 xenografts, and hyperthermia (1 h at 41°C) was locally applied to the tumor. 0 - 72 h later radioiodine uptake was assessed by ¹²³I-scintigraphy. The most effective uptake regime was then selected for ¹³¹I therapy.

Results: The HSP70B promoter showed low basal activity in vitro and was significantly induced in response to heat. In vivo, the highest tumoral iodine accumulation was seen 12 h after application of hyperthermia. HSP70B-NIS-MSC-mediated ¹³¹I therapy combined with hyperthermia resulted in a significantly reduced tumor growth with prolonged survival as compared to control groups.

Conclusions: The heat-inducible HSP70B promoter allows hyperthermia-induced spatial and temporal control of MSC-mediated theranostic NIS gene radiotherapy with efficient tumor-selective and temperature-dependent accumulation of radioiodine in heat-treated tumors.

Radiation-Induced Amplification of TGFB1-Induced Mesenchymal Stem Cell-Mediated Sodium Iodide Symporter (NIS) Gene 131I Therapy

PURPOSE

The innate tumor homing potential of mesenchymal stem cells (MSCs) has been used for a targeted delivery of the theranostic sodium iodide symporter (NIS) transgene into solid tumors. We have previously shown that external beam radiotherapy (EBRT) results in the enhanced recruitment of NIS-expressing MSCs into human hepatocellular carcinoma (HuH7). In parallel, the tumor-associated cytokine TGFB1 becomes strongly upregulated in HuH7 tumors in response to EBRT.

EXPERIMENTAL DESIGN

We therefore evaluated the effects of combining focused EBRT (5 Gy) with MSC-mediated systemic delivery of the theranostic NIS transgene under control of a synthetic TGFB1-inducible SMAD-responsive promoter (SMAD-NIS-MSCs) using ¹²³I-scintigraphy followed by ¹³¹I therapy in CD1 nu/nu mice harboring subcutaneous human hepatocellular carcinoma (HuH7).

RESULTS

Following tumor irradiation and SMAD-NIS-MSC application, tumoral iodide uptake monitored in vivo by ¹²³I-scintigraphy was enhanced as compared with nonirradiated tumors. Combination of EBRT and SMAD-NIS-MSC-mediated ¹³¹I therapy resulted in a significantly improved delay in tumor growth and prolonged survival in therapy mice as compared with the combined therapy using CMV-NIS-MSCs or to control groups receiving EBRT or saline only, or EBRT together with SMAD-NIS-MSCs and saline applications.

CONCLUSIONS

MSC-based NIS-mediated ¹³¹I therapy after EBRT treatment dramatically enhanced therapeutic efficacy when a TGFB1-inducible SMAD-responsive promoter was used to drive NIS expression in adoptively applied MSCs. The remarkable therapeutic effect seen is thought to be linked in large part to the enhanced TGFB1 produced in this context, which leads to a highly selective and focused amplification of MSC-based NIS expression within the tumor milieu.

Systemic administration of human mesenchymal stromal cells infected with polymer-coated oncolytic adenovirus induces efficient pancreatic tumor homing and infiltration

Oncolytic adenovirus (oAd)-mediated gene therapy is a promising approach for cancer treatment because of its cancer cell-restricted replication and therapeutic gene expression. However, systemic administration of oAd is severely restricted by their immunogenic nature and poor tumor homing ability, thus oAd cannot be utilized to treat disseminated metastases. In this study, human bone marrow-derived mesenchymal stromal cell (hMSCs) was used as a viral replication-permissive carrier for oAd with an aim to improve the systemic delivery of the virus to tumor tissues. To overcome the poor delivery of oAd into hMSCs, a relaxin (RLX)-expressing oncolytic Ad (oAd/RLX), which degrades dense tumor extracellular matrix of highly desmoplastic pancreatic cancer, was complexed with biodegradable polymer (poly (ethyleneimine)-conjugated poly(CBA-DAH); PCDP), generating oAd/RLX-PCDP complex. oAd/RLX-PCDP complex enhanced the internalization of oAd into hMSC, leading to superior viral production and release from hMSCs, along with high RLX expression. Furthermore, systemic administration of oAd/RLX-PCDP-treated hMSCs elicited more potent antitumor effect compared to naked oAd/RLX or oAd/RLX-treated hMSC in pancreatic tumor model. This potent antitumor effect of systemically administered oAd/RLX-PCDP-treated hMSCs was achieved by superior viral replication in tumor tissues than any other treatment group. In conclusion, these results demonstrate that hMSCs are effective carriers for the systemic delivery of oAd to tumor sites and treatment of pancreatic cancer.

Dual-targeted NIS polyplexes-a theranostic strategy toward tumors with heterogeneous receptor expression

Tumor heterogeneity, within and between tumors, may have severe implications for tumor therapy, especially for targeted gene therapy, where single-targeted approaches often result in limited efficacy and therapy resistance. Polymer-formulated nonviral vectors provide a potent delivery platform for cancer therapy. To improve applicability for future clinical use in a broad range of patients and cancer types, a dual-targeting approach was performed. Synthetic LPEI-PEG2kDa-based polymer backbones were coupled to two tumor-specific peptide ligands GE11 (EGFR-targeting) and cMBP (cMET-targeting). The dual-targeting approach was used to deliver the theranostic sodium iodide symporter (NIS) gene to hepatocellular cancer. NIS as auspicious theranostic gene allows noninvasive imaging of functional NIS gene expression and effective anticancer radioiodide therapy. Enhanced tumor-specific transduction efficiency of dual-targeted polyplexes compared to single-targeted polyplexes was demonstrated in vitro using tumor cell lines with different EGFR and cMET expression and in vivo by 124I-PET-imaging. Therapeutic efficacy of the bispecific concept was mirrored by significantly reduced tumor growth and perfusion, which was associated with prolonged animal survival. In conclusion, the dual-targeting approach highlights the benefits of a bifunctional strategy for a future clinical translation of the bioimaging-based NIS-mediated radiotherapy allowing efficient targeting of heterogeneic tumors with variable receptor expression levels.

Nano-engineered delivery systems for cancer imaging and therapy: Recent advances, future direction and patent evaluation

Cancer is the second highest cause of death worldwide. Several therapeutic approaches, such as conventional chemotherapy, antibodies and small molecule inhibitors and nanotherapeutics have been employed in battling cancer. Amongst them, nanotheranostics is an example of successful personalized medicine bearing dual role of early diagnosis and therapy to cancer patients. In this review, we have focused on various types of theranostic polymer and metal nanoparticles for their role in cancer therapy and imaging concerning their limitation, future application such as dendritic cell cancer vaccination, gene delivery, T-cell activation and immune modulation. Also, some of the recorded patent applications and clinical trials have been illustrated. The impact of the biological microenvironment on the biodistribution and accumulation of nanoparticles have been discussed.

A Novel Approach for Image-Guided 131I Therapy of Pancreatic Ductal Adenocarcinoma Using Mesenchymal Stem Cell-Mediated NIS Gene Delivery

The sodium iodide symporter (SLC5A5/NIS) as theranostic gene would allow for non-invasive imaging of functional NIS expression and therapeutic radioiodine application. Genetically engineered mesenchymal stem cells (MSC), based on their tumor-homing abilities, show great promise as tumor-selective NIS gene delivery vehicles for non-thyroidal tumors. As a next step towards clinical application, tumor specificity and efficacy of MSCs were investigated in an advanced genetically engineered mouse model of pancreatic ductal adenocarcinoma (PDAC). Syngeneic murine MSCs were stably transfected with a NIS-expressing plasmid driven by the CMV-promoter (NIS-MSC). In vivo ¹²³I-scintigraphy and ¹²⁴I-PET revealed significant perchlorate-sensitive NIS-mediated radioiodide accumulation in PDAC after systemic injection of NIS-MSCs. Active MSC recruitment into the tumor stroma was confirmed using NIS immunohistochemistry (IHC). A therapeutic strategy, consisting of three cycles of systemic MSC-mediated NIS delivery, followed by ¹³¹I application, resulted in a significant delay and reduction in tumor growth as compared to controls. Furthermore, IHC analysis of α-SMA and Ki67 revealed differences in the amount and behavior of activated fibroblasts in tumors of mice injected with NIS-MSCs as compared with saline-treated mice. Taken together, MSCs as NIS gene delivery vehicles in this advanced endogenous PDAC mouse model demonstrated high stromal targeting of NIS by selective recruitment of NIS-MSCs after systemic application resulting in an impressive ¹³¹I therapeutic effect. IMPLICATIONS: These data expand the prospect of MSC-mediated radioiodine imaging-guided therapy of pancreatic cancer using the sodium iodide symporter as a theranostic gene in a clinical setting.

Exploring pitfalls of 64Cu-labeled EGFR-targeting peptide GE11 as a potential PET tracer

The epidermal growth factor receptor (EGFR) represents an important molecular target for both radiotracer-based diagnostic imaging and radionuclide therapy of various cancer entities. For the delivery of radionuclides to the tumor, peptides hold great potential as a transport vehicle. With respect to EGFR, the peptide YHWYGYTPQNVI (GE11) has been reported to bind the receptor with high specificity and affinity. In the present study, GE11 with β-alanine (β-Ala-GE11) was conjugated to the chelating agent p-SCN-Bn-NOTA and radiolabeled with ⁶⁴Cu for the first radio pharmacological evaluation as a potential probe for positron emission tomography (PET)-based cancer imaging. For better water solubility, an ethylene glycol-based linker was introduced between the peptide's N terminus and the radionuclide chelator. The stability of the ⁶⁴Cu-labeled peptide conjugate and its binding to EGFR-expressing tumor cells was investigated in vitro and in vivo, and then compared with the ⁶⁴Cu-labeled EGFR-targeting antibody conjugate NOTA-cetuximab. The GE11 peptide conjugate [⁶⁴Cu]Cu-NOTA-linker-β-Ala-GE11 ([⁶⁴Cu]Cu-1) was stable in a buffer solution for at least 24 h but only 50% of the original compound was detected after 24 h of incubation in human serum. Stability could be improved by amidation of the peptide's C terminus (β-Ala-GE11-NH₂ (2)). Binding assays with both conjugates, [⁶⁴Cu]Cu-1 and [⁶⁴Cu]Cu-2, using the EGFR-expressing tumor cell lines A431 and FaDu showed no specific binding. A pilot small animal PET investigation in FaDu tumor-bearing mice revealed only low tumor uptake (standard uptake value (SUV) < 0.2) for both conjugates. The best tumor-to-muscle ratio determined was 3.75 for [⁶⁴Cu]Cu-1, at 1 h post injection. In conclusion, the GE11 conjugates in its present form are not suitable for further biological investigations, since they presumably form aggregates.

External Beam Radiation Therapy Enhances Mesenchymal Stem Cell-Mediated Sodium-Iodide Symporter Gene Delivery

The tumor-homing properties of mesenchymal stem cells (MSC) have led to their development as delivery vehicles for the targeted delivery of therapeutic genes such as the sodium-iodide symporter (NIS) to solid tumors. External beam radiation therapy may represent an ideal setting for the application of engineered MSC-based gene therapy, as tumor irradiation may enhance MSC recruitment into irradiated tumors through the increased production of select factors linked to MSC migration. In the present study, the irradiation of human liver cancer cells (HuH7; 1-10 Gy) showed a strong dose-dependent increase in steady-state mRNA levels of CXCL8, CXCL12, FGF2, PDGFB, TGFB1, THBS1, and VEGF (0-48 h), which was verified for most factors at the protein level (after 48 h). Radiation effects on directed MSC migration were tested in vitro using a live cell tracking migration assay and supernatants from control and irradiated HuH7 cells. A robust increase in mean forward migration index, mean center of mass, and mean directionality of MSCs toward supernatants was seen from irradiated as compared to non-irradiated tumor cells. Transferability of this effect to other tumor sources was demonstrated using the human breast adenocarcinoma cell line (MDA-MB-231), which showed a similar behavior to radiation as seen with HuH7 cells in quantitative polymerase chain reaction and migration assay. To evaluate this in a more physiologic in vivo setting, subcutaneously growing HuH7 xenograft tumors were irradiated with 0, 2, or 5 Gy followed by CMV-NIS-MSC application 24 h later. Tumoral iodide uptake was monitored using ¹²³I-scintigraphy. The results showed increased tumor-specific dose-dependent accumulation of radioiodide in irradiated tumors. The results demonstrate that external beam radiation therapy enhances the migratory capacity of MSCs and may thus increase the therapeutic efficacy of MSC-mediated NIS radionuclide therapy.

An Ethylenediamine-based Switch to Render the Polyzwitterion Cationic at Tumorous pH for Effective Tumor Accumulation of Coated Nanomaterials

Polyzwitterions are employed as coating polymers for biomaterials to induce an antifouling property on the surface. Fine-tuning the betaine structure switches the antifouling property to be interactive with anionic tissue constituents in response to a tumorous pH gradient. The ethylenediamine moiety in the carboxybetaine enabled stepwise protonation and initiated the di-protonation process around tumorous pH (6.5). The net charge of the developed polyzwitterion (PGlu(DET-Car)) was thus neutral at pH 7.4 for antifouling, but was cationic at pH 6.5 for interaction with anionic constituents. Quantum dots coated with PGlu(DET-Car) exhibited comparable stealth and enhanced tumor accumulation relative to the PEG system. The present study provides a novel design of smart switchable polyzwitterion based on a precise control of the net charge.

Systemic tumor-targeted sodium iodide symporter (NIS) gene therapy of hepatocellular carcinoma mediated by B6 peptide polyplexes

BACKGROUND

Nonviral polymer-based gene transfer represents an adaptable system for tumor-targeted gene therapy because various design strategies of shuttle systems, together with the mechanistic concept of active tumor targeting, lead to improved gene delivery vectors resulting in higher tumor specificity, efficacy and safety.

METHODS

Using the sodium iodide symporter (NIS) as a theranostic gene, nonviral gene delivery vehicles based on linear polyethylenimine (LPEI), polyethylene glycol (PEG) and coupled to the synthetic peptide B6 (LPEI-PEG-B6), which specifically binds to tumor cells, were investigated in a hepatocellular carcinoma xenograft model for tumor selectivity and transduction efficiency.

RESULTS

In vitro incubation of three different tumor cell lines with LPEI-PEG-B6/NIS resulted in significant increase in iodide uptake activity compared to untargeted and empty vectors. After establishment of subcutaneous HuH7 tumors, NIS-conjugated nanoparticles were injected intravenously followed by analysis of radioiodide biodistribution using ¹²³ I-scintigraphy showing significant perchlorate-sensitive iodide accumulation in tumors of LPEI-PEG-B6/NIS-treated mice (8.0 ± 1.5% ID/g ¹²³ I; biological half-life of 4 h). After four cycles of repetitive polyplex/¹³¹ I applications, a significant delay of tumor growth was observed, which was associated with markedly improved survival in the therapy group.

CONCLUSIONS

These results clearly demonstrate that systemic in vivo NIS gene transfer using nanoparticle vectors coupled to B6 tumor targeting ligand is capable of inducing tumor-specific radioiodide uptake. This promising gene therapy approach opens the exciting prospect of NIS-mediated radionuclide therapy in metastatic cancer, together with the possibility of combining several targeting ligands to enhance selective therapeutic efficacy in a broad field of cancer types with various receptor expression profiles.

Oncolytic Viruses for Tumor Precision Imaging and Radiotherapy

In 2003 in China, Peng et al. invented the recombinant adenovirus expressing p53 (Gendicine) for clinical tumor virotherapy. This was the first clinically approved gene therapy and tumor virotherapy drug in the world. An oncolytic herpes simplex virus expressing granulocyte-macrophage colony-stimulating factor (Talimogene laherparepvec) was approved for melanoma treatment in the United States in 2015. Since then, oncolytic viruses have been attracting more and more attention in the field of oncology, and may become novel significant modalities of tumor precision imaging and radiotherapy after further improvement. Oncolytic viruses carrying reporter genes can replicate and express genes of interest selectively in tumor cells, thus improving in vivo noninvasive precision molecular imaging and radiotherapy. Here, the latest developments and molecular mechanisms of tumor imaging and radiotherapy using oncolytic viruses are reviewed, and perspectives are given for further research. Various types of tumors are discussed, and special attention is paid to gastrointestinal tumors.

Reintroducing the Sodium-Iodide Symporter to Anaplastic Thyroid Carcinoma

BACKGROUND

Anaplastic thyroid carcinoma (ATC), the most aggressive form of thyroid cancer, is unresponsive to radioiodine therapy. The current study aimed to extend the diagnostic and therapeutic application of radioiodine beyond the treatment of differentiated thyroid cancer by targeting the functional sodium-iodide symporter (NIS) to ATC.

METHODS

The study employed nanoparticle vectors (polyplexes) based on linear polyethylenimine (LPEI), shielded by polyethylene glycol (PEG) and coupled to the synthetic peptide GE11 as an epidermal growth factor receptor (EGFR)-specific ligand in order to target a NIS-expressing plasmid (LPEI-PEG-GE11/NIS) to EGFR overexpressing human thyroid carcinoma cell lines. Using ATC xenograft mouse models, transfection efficiency by ¹²³I scintigraphy and potential for systemic radioiodine therapy after systemic polyplex application were evaluated.

RESULTS

In vitro iodide uptake studies in SW1736 and Hth74 ATC cells, and, for comparison, in more differentiated follicular (FTC-133) and papillary (BCPAP) thyroid carcinoma cells demonstrated high transfection efficiency and EGFR-specificity of LPEI-PEG-GE11/NIS that correlated well with EGFR expression levels. After systemic polyplex injection, in vivo ¹²³I gamma camera imaging revealed significant tumor-specific accumulation of radioiodine in an SW1736 and an Hth74 xenograft mouse model. Radioiodine accumulation was found to be higher in SW1736 tumors, reflecting in vitro results, EGFR expression levels, and results from ex vivo analysis of NIS staining. Administration of ¹³¹I in LPEI-PEG-GE11/NIS-treated SW1736 xenograft mice resulted in significantly reduced tumor growth associated with prolonged survival compared to control animals.

CONCLUSIONS

The data open the exciting prospect of NIS-mediated radionuclide imaging and therapy of ATC after non-viral reintroduction of the NIS gene. The high tumor specificity after systemic application makes the strategy an attractive alternative for the treatment of highly metastatic ATC.

Oncolytic virus delivery: from nano-pharmacodynamics to enhanced oncolytic effect

With the advancement of a growing number of oncolytic viruses (OVs) to clinical development, drug delivery is becoming an important barrier to overcome for optimal therapeutic benefits. Host immunity, tumor microenvironment and abnormal vascularity contribute to inefficient vector delivery. A number of novel approaches for enhanced OV delivery are under evaluation, including use of nanoparticles, immunomodulatory agents and complex viral–particle ligands along with manipulations of the tumor microenvironment. This field of OV delivery has quickly evolved to bioengineering of complex nanoparticles that could be deposited within the tumor using minimal invasive image-guided delivery. Some of the strategies include ultrasound (US)-mediated cavitation-enhanced extravasation, magnetic viral complexes delivery, image-guided infusions with focused US and targeting photodynamic virotherapy. In addition, strategies that modulate tumor microenvironment to decrease extracellular matrix deposition and increase viral propagation are being used to improve tumor penetration by OVs. Some involve modification of the viral genome to enhance their tumoral penetration potential. Here, we highlight the barriers to oncolytic viral delivery, and discuss the challenges to improving it and the perspectives of establishing new modes of active delivery to achieve enhanced oncolytic effects.

EGFR-targeted nonviral NIS gene transfer for bioimaging and therapy of disseminated colon cancer metastases

Liver metastases present a serious problem in the therapy of advanced colorectal cancer (CRC), as more than 20% of patients have distant metastases at the time of diagnosis with less than 5% being cured. Consequently, new therapeutic approaches are of major need together with high-resolution imaging methods that allow highly specific detection of small metastases.

The unique combination of reporter and therapy gene function of the sodium iodide symporter (NIS) may represent a promising theranostic strategy for CRC liver metastases allowing non-invasive imaging of functional NIS expression and therapeutic application of ¹³¹I.

For targeted NIS gene transfer polymers containing linear polyethylenimine (LPEI), polyethylene glycol (PEG) and the epidermal growth factor receptor (EGFR)-specific ligand GE11 were complexed with human NIS DNA (LPEI-PEG-GE11/NIS). Tumor specificity and transduction efficiency were examined in high EGFR-expressing LS174T metastases by non-invasive imaging using ¹⁸F-tetrafluoroborate (¹⁸F-TFB) as novel NIS PET tracer. Mice that were injected with LPEI-PEG-GE11/NIS 48 h before ¹⁸F-TFB application showed high tumoral levels (4.8±0.6% of injected dose) of NIS-mediated radionuclide uptake in comparison to low levels detected in mice that received untargeted control polyplexes. Three cycles of intravenous injection of EGFR-targeted NIS polyplexes followed by therapeutic application of 55.5 MBq ¹³¹I resulted in marked delay in metastases spread, which was associated with improved animal survival.

In conclusion, these preclinical data confirm the enormous potential of EGFR-targeted synthetic polymers for systemic NIS gene delivery in an advanced multifocal CRC liver metastases model and open the exciting prospect of NIS-mediated radionuclide therapy in metastatic disease.

EGFR Targeting and Shielding of pDNA Lipopolyplexes via Bivalent Attachment of a Sequence-Defined PEG Agent

For successful nonviral gene delivery, cationic polymers are promising DNA carrier, which need to comprise several functionalities. The current work focuses on the postincorporation of epidermal growth factor receptor (EGFR) targeted PEGylation agents onto lipopolyplexes for pDNA delivery. T-shaped lipo-oligomers are previously found to be effective sequence-defined carriers for pDNA and siRNA. Here, the bis-oleoyl-oligoaminoethanamide 454 containing tyrosine trimer-cysteine ends is applied for complex formation with pDNA coding for luciferase or sodium iodide symporter (NIS). In a second step, the lipopolyplexes are modified via disulfide formation with sequence-defined monovalent or bivalent PEGylation agents containing one or two 3-nitro-2-pyridinesulfenyl (NPys)-activated cysteines, respectively. For targeting, the polyethylene glycol (PEG) agents comprise the EGFR targeting peptide GE11. In comparison of all transfection complexes, 454 lipopolyplexes modified with the bidentate PEG-GE11 agent show the best, EGFR-dependent uptake as well as luciferase and NIS gene expression into receptor-positive tumor cells.

Imaging and targeted therapy of pancreatic ductal adenocarcinoma using the theranostic sodium iodide symporter (NIS) gene

The theranostic sodium iodide symporter (NIS) gene allows detailed molecular imaging of transgene expression and application of therapeutic radionuclides. As a crucial step towards clinical application, we investigated tumor specificity and transfection efficiency of epidermal growth factor receptor (EGFR)-targeted polyplexes as systemic NIS gene delivery vehicles in an advanced genetically engineered mouse model of pancreatic ductal adenocarcinoma (PDAC) that closely reflects human disease. PDAC was induced in mice by pancreas-specific activation of constitutively active KrasG12D and deletion of Trp53. We used tumor-targeted polyplexes (LPEI-PEG-GE11/NIS) based on linear polyethylenimine, shielded by polyethylene glycol and coupled with the EGFR-specific peptide ligand GE11, to target a NIS-expressing plasmid to high EGFR-expressing PDAC. In vitro iodide uptake studies in cell explants from murine EGFR-positive and EGFR-ablated PDAC lesions demonstrated high transfection efficiency and EGFR-specificity of LPEI-PEG-GE11/NIS. In vivo 123I gamma camera imaging and three-dimensional high-resolution 124I PET showed significant tumor-specific accumulation of radioiodide after systemic LPEI-PEG-GE11/NIS injection. Administration of 131I in LPEI-PEG-GE11/NIS-treated mice resulted in significantly reduced tumor growth compared to controls as determined by magnetic resonance imaging, though survival was not significantly prolonged. This study opens the exciting prospect of NIS-mediated radionuclide imaging and therapy of PDAC after systemic non-viral NIS gene delivery.

99mTc-radiolabeled GE11-modified peptide for ovarian tumor targeting

Background

Ovarian cancer is a serious threat for women health and the early diagnosis of this cancer might improves the survival rate of patients. The use of the targeted radiopharmaceuticals could be a non-invasive and logical method for tumor imaging. The aim of this study was to radiolabel GE11 peptide as a new specific probe for imaging of ovarian tumor.

Methods

HYNIC-SSS-GE11 peptide was labeled with ^99mTc using tricine as a coligand. The ^99mTc-tricine-HYNIC-SSS-GE11 peptide was evaluated for specific cellular binding in three cell lines with different levels of EGFR expression. Tumor targeting was assessed in SKOV3 tumor bearing mice.

Results

By using tricine as a coligand, labeling yield was more than 98% and the stability of the radiolabelled peptide in human serum up to 4 h was 96%. The in vitro cell uptake test showed that this radiolabeled peptide had a good affinity to SKOV3 cells with dissociation constant of 73 nM. The in vivo results showed a tumor/muscle ratio of 3.2 at 4 h following injection of ^99mTc-tricine-HYNIC-SSS-GE11 peptide.

Conclusions

Results of this study showed that ^99mTc-tricine-HYNIC-SSS-GE11 peptide could be a promising tool for diagnosis and staging of ovarian cancer.

Graphical Abstract

^99mTc-tricine-HYNIC-SSS-GE11, a novl targeted agent for ovarian tumor imaging

Designing and building oncolytic viruses

Oncolytic viruses (OVs) are engineered and/or evolved to propagate selectively in cancerous tissues. They have a dual mechanism of action; direct killing of infected cancer cells cross-primes anticancer immunity to boost the killing of uninfected cancer cells. The goal of the field is to develop OVs that are easily manufactured, efficiently delivered to disseminated sites of cancer growth, undergo rapid intratumoral spread, selectively kill tumor cells, cause no collateral damage and pose no risk of transmission in the population. Here we discuss the many virus engineering strategies that are being pursued to optimize delivery, intratumoral spread and safety of OVs derived from different virus families. With continued progress, OVs have the potential to transform the paradigm of cancer care.

Radiolabelled Polymeric Materials for Imaging and Treatment of Cancer: Quo Vadis?

Owing to their tunable blood circulation time and suitable plasma stability, polymer-based nanomaterials hold a great potential for designing and utilising multifunctional nanocarriers for efficient imaging and effective treatment of cancer. When tagged with appropriate radionuclides, they may allow for specific detection (diagnosis) as well as the destruction of tumours (therapy) or even customization of materials, aiming to both diagnosis and therapy (theranostic approach). This review provides an overview of recent developments of radiolabelled polymeric nanomaterials (natural and synthetic polymers) for molecular imaging of cancer, specifically, applying nuclear techniques such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT). Different approaches to radiolabel polymers are evaluated from the methodical radiochemical point of view. This includes new bifunctional chelating agents (BFCAs) for radiometals as well as novel labelling methods. Special emphasis is given to eligible strategies employed to evade the mononuclear phagocytic system (MPS) in view of efficient targeting. The discussion encompasses promising strategies currently employed as well as emerging possibilities in radionuclide-based cancer therapy. Key issues involved in the clinical translation of radiolabelled polymers and future scopes of this intriguing research field are also discussed.

Dendrimers as Innovative Radiopharmaceuticals in Cancer Radionanotherapy

Radiotherapy is one of the most commonly used cancer treatments, with an estimate of 40% success that could be improved further if more efficient targeting and retention of radiation at the tumor site were achieved. This review focuses on the use of dendrimers in radionanotherapy, an emerging technology aimed to improve the efficiency of radiotherapy by implementing nanovectorization, an already established praxis in drug delivery and diagnosis. The labeling of dendrimers with radionuclides also aims to reduce the dose of radiolabeled materials and, hence, their toxicity and tumor resistance. Examples of radiolabeled dendrimers with alpha, beta, and Auger electron emitters are commented, along with the use of dendrimers in boron neutron capture therapy (BNCT). The conjugation of radiolabeled dendrimers to monoclonal antibodies for a more efficient targeting and the application of dendrimers in gene delivery radiotherapy are also covered.

Recent progress in protein-protein interaction study for EGFR-targeted therapeutics

INTRODUCTION

Epidermal growth factor receptor (EGFR) expression is upregulated in many tumors and its aberrant signaling drives progression of many cancer types. Consequently, EGFR has become a clinically validated target as extracellular tumor marker for antibodies as well as for tyrosine kinase inhibitors. Within the last years, new mechanistic insights were uncovered and, based on clinical experience as well as progress in protein engineering, novel bio-therapeutic approaches were developed and tested.

AREAS COVERED

The potential therapeutic targeting arsenal in the fight against cancer now encompasses bispecific or biparatopic antibodies, DARPins, Adnectins, Affibodies, peptides and combinations of these binding molecules with viral- and nano-particles. We review past and recent binding proteins from the literature and include a brief description of the various targeting approaches. Special attention is given to the binding modes with the EGFR. Expert commentary: Clinical data from the three approved anti EGFR antibodies indicate that there is room for improved therapeutic efficacy. Having choices in size, affinity, avidity and the mode of EGFR binding as well as the possibility to combine various effector functions opens the possibility to rationally design more effective therapeutics.

Design of virus-based nanomaterials for medicine, biotechnology, and energy

This review provides an overview of recent developments in "chemical virology." Viruses, as materials, provide unique nanoscale scaffolds that have relevance in chemical biology and nanotechnology, with diverse areas of applications. Some fundamental advantages of viruses, compared to synthetically programmed materials, include the highly precise spatial arrangement of their subunits into a diverse array of shapes and sizes and many available avenues for easy and reproducible modification. Here, we will first survey the broad distribution of viruses and various methods for producing virus-based nanoparticles, as well as engineering principles used to impart new functionalities. We will then examine the broad range of applications and implications of virus-based materials, focusing on the medical, biotechnology, and energy sectors. We anticipate that this field will continue to evolve and grow, with exciting new possibilities stemming from advancements in the rational design of virus-based nanomaterials.

Sequence-defined cMET/HGFR-targeted Polymers as Gene Delivery Vehicles for the Theranostic Sodium Iodide Symporter (NIS) Gene

The sodium iodide symporter (NIS) as well-characterized theranostic gene represents an outstanding tool to target different cancer types allowing noninvasive imaging of functional NIS expression and therapeutic radioiodide application. Based on its overexpression on the surface of most cancer types, the cMET/hepatocyte growth factor receptor serves as ideal target for tumor-selective gene delivery. Sequence-defined polymers as nonviral gene delivery vehicles comprising polyethylene glycol (PEG) and cationic (oligoethanoamino) amide cores coupled with a cMET-binding peptide (cMBP2) were complexed with NIS-DNA and tested for receptor-specificity, transduction efficiency, and therapeutic efficacy in hepatocellular cancer cells HuH7. In vitro iodide uptake studies demonstrated high transduction efficiency and cMET-specificity of NIS-encoding polyplexes (cMBP2-PEG-Stp/NIS) compared to polyplexes without targeting ligand (Ala-PEG-Stp/NIS) and without coding DNA (cMBP2-PEG-Stp/Antisense-NIS). Tumor recruitment and vector biodistribution were investigated in vivo in a subcutaneous xenograft mouse model showing high tumor-selective iodide accumulation in cMBP2-PEG-Stp/NIS-treated mice (6.6 ± 1.6% ID/g (123)I, biological half-life 3 hours) by (123)I-scintigraphy. Therapy studies with three cycles of polyplexes and (131)I application resulted in significant delay in tumor growth and prolonged survival. These data demonstrate the enormous potential of cMET-targeted sequence-defined polymers combined with the unique theranostic function of NIS allowing for optimized transfection efficiency while eliminating toxicity.

Incorporation of Peptides Targeting EGFR and FGFR1 into the Adenoviral Fiber Knob Domain and Their Evaluation as Targeted Cancer Therapies

Oncolytic virotherapies based on adenovirus 5 (Ad5) hold promise as adjunctive cancer therapies; however, their efficacy when delivered systemically is hampered by poor target cell specificity and preexisting anti-Ad5 immunity. Ovarian cancer represents a promising target for virotherapy, since the virus can be delivered locally into the peritoneal cavity. Both epidermal growth factor receptor (EGFR) and fibroblast growth factor receptor 1 (FGFR1) are overexpressed in the majority of human tumors, including ovarian cancer. To generate adenoviral vectors with improved tumor specificity, we generated a panel of Ad5 vectors with altered tropism for EGFR and FGFR, rather than the natural Ad5 receptor, hCAR. We have included mutations within AB loop of the viral fiber knob (KO1 mutation) to preclude interaction with hCAR, combined with insertions in the HI loop to incorporate peptides that bind either EGFR (peptide YHWYGYTPQNVI, GE11) or FGFR1 (peptides MQLPLAT, M*, and LSPPRYP, LS). Viruses were produced to high titers, and the integrity of the fiber protein was validated by Western blotting. The KO1 mutation efficiently ablated hCAR interactions, and significantly increased transduction was observed in hCAR^low/EGFR^high cell lines using Ad5.GE11, while transduction levels using Ad5.M* or Ad5.LS were not increased. In the presence of physiological concentrations of human blood clotting factor X (hFX), significantly increased levels of transduction via the hFX-mediated pathway were observed in cell lines, but not in primary tumor cells derived from epithelial ovarian cancer (EOC) ascites samples. Ad5-mediated transduction of EOC cells was completely abolished by the presence of 2.5% serum from patients, while, surprisingly, incorporation of the GE11 peptide resulted in significant evasion of neutralization in the same samples. We thus speculate that incorporation of the YHWYGYTPQNVI dodecapeptide within the fiber knob domain may provide a novel means of circumventing preexisting Ad5 immunity that warrants further investigation.

Advances in Functional Assemblies for Regenerative Medicine

The ability to synthesise bioresponsive systems and selectively active biochemistries using polymer-based materials with supramolecular features has led to a surge in research interest directed towards their development as next generation biomaterials for drug delivery, medical device design and tissue engineering.

Polymeric oncolytic adenovirus for cancer gene therapy

Oncolytic adenovirus (Ad) vectors present a promising modality to treat cancer. Many clinical trials have been done with either naked oncolytic Ad or combination with chemotherapies. However, the systemic injection of oncolytic Ad in clinical applications is restricted due to significant liver toxicity and immunogenicity. To overcome these issues, Ad has been engineered physically or chemically with numerous polymers for shielding the Ad surface, accomplishing extended blood circulation time and reduced immunogenicity as well as hepatotoxicity. In this review, we describe and classify the characteristics of polymer modified oncolytic Ad following each strategy for cancer treatment. Furthermore, this review concludes with the highlights of various polymer-coated Ads and their prospects, and directions for future research.

Establishment of an Effective Radioiodide Thyroid Ablation Protocol in Mice

Due to the high variance in available protocols on iodide-131 ((131)I) ablation in rodents, we set out to establish an effective method to generate a thyroid-ablated mouse model that allows the application of the sodium iodide symporter (NIS) as a reporter gene without interference with thyroidal NIS. We tested a range of (131)I doses with and without prestimulation of thyroidal radioiodide uptake by a low-iodine diet and thyroid-stimulating hormone (TSH) application. Efficacy of induction of hypothyroidism was tested by measurement of serum T4 concentrations, pituitary TSHβ and liver deiodinase type 1 (DIO1) mRNA expression, body weight analysis, and (99m)Tc-pertechnetate scintigraphy. While 200 µCi (7.4 MBq) (131)I alone was not sufficient to abolish thyroidal T4 production, 500 µCi (18.5 MBq) (131)I combined with 1 week of a low-iodine diet decreased serum concentrations below the detection limit. However, the high (131)I dose resulted in severe side effects. A combination of 1 week of a low-iodine diet followed by injection of bovine TSH before the application of 150 µCi (5.5 MBq) (131)I decreased serum T4 concentrations below the detection limit and significantly increased pituitary TSHβ concentrations. The systemic effects of induced hypothyroidism were shown by growth arrest and a decrease in liver DIO1 expression below the detection limit. (99m)Tc-pertechnetate scintigraphy revealed absence of thyroidal (99m)Tc-pertechnetate uptake in ablated mice. In summary, we report a revised protocol for radioiodide ablation of the thyroid gland in the mouse to generate an in vivo model that allows the study of thyroid hormone action using NIS as a reporter gene.

Dendrimers for theranostic applications

Recently, there have been tremendous advances in the development of various nanotechnology-based platforms for diagnosis and therapy. These nanoplatforms, which include liposomes, micelles, polymers, and dendrimers, comprise highly integrated nanoparticles that provide multiple functions, such as targeting, imaging, and therapy. This review focuses on dendrimer-based nanocarriers that have recently been developed for ‘theranostics (or theragnosis)’, a combination of therapy and diagnostics. We discuss the in vitro and in vivo applications of these nanocarriers in strategies against diseases including cancer. We also explore the use of dendrimers as imaging agents for fluorescence imaging, magnetic resonance imaging, X-ray computed tomography, and nuclear medical imaging.

Active targeted drug delivery for microbes using nano-carriers

Although vaccines and antibiotics could kill or inhibit microbes, many infectious diseases remain difficult to treat because of acquired resistance and adverse side effects. Nano-carriers-based technology has made significant progress for a long time and is introducing a new paradigm in drug delivery. However, it still has some challenges like lack of specificity toward targeting the infectious site. Nanocarriers utilized targeting ligands on their surface called 'active target' provide the promising way to solve the problems like accelerating drug delivery to infectious areas and preventing toxicity or side-effects. In this mini review, we demonstrate the recent studies using the active targeted strategy to kill or inhibit microbes. The four common nano-carriers (e.g. liposomes, nanoparticles, dendrimers and carbon nanotubes) delivering encapsulated drugs are introduced.

Polymeric multifunctional nanomaterials for theranostics

Various applications of polymeric multifunctional nanomaterials for theranostics.

Current advances in polymer-based nanotheranostics for cancer treatment and diagnosis

Nanotheranostics is a relatively new, fast-growing field that combines the advantages of treatment and diagnosis via a single nanoscale carrier. The ability to bundle both therapeutic and diagnostic capabilities into one package offers exciting prospects for the development of novel nanomedicine. Nanotheranostics can deliver treatment while simultaneously monitoring therapy response in real-time, thereby decreasing the potential of over- or under-dosing patients. Polymer-based nanomaterials, in particular, have been used extensively as carriers for both therapeutic and bioimaging agents and thus hold great promise for the construction of multifunctional theranostic formulations. Herein, we review recent advances in polymer-based systems for nanotheranostics, with a particular focus on their applications in cancer research. We summarize the use of polymer nanomaterials for drug delivery, gene delivery, and photodynamic therapy, combined with imaging agents for magnetic resonance imaging, radionuclide imaging, and fluorescence imaging.

Gene therapy and imaging in preclinical and clinical oncology: recent developments in therapy and theranostics

In the case of disseminated cancer, current treatment options reach their limit. Gene theranostics emerge as an innovative route in the treatment and diagnosis of cancer and might pave the way towards development of an efficacious treatment of currently incurable cancer. Various gene vectors have been developed to realize tumor-specific nucleic acid delivery and are considered crucial for the successful application of cancer gene therapy. By adding reporter genes and imaging agents, these systems gain an additional diagnostic function, thereby advancing the theranostic paradigm into cancer gene therapy. Numerous preclinical studies have demonstrated the feasibility of combined tumor gene therapy and diagnostic imaging, and clinical trials in human and veterinary oncology have been executed with partly encouraging results.

Viruses exploit the function of epidermal growth factor receptor

Epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that regulates cellular homeostatic processes. Following ligand binding, EGFR activates different downstream signalling cascades that promote cell survival, proliferation, motility, and angiogenesis and induces F-actin-dependent EGFR endocytosis, which relocalises the activated receptors for degradation or recycling. The responses that are induced by ligand binding to EGFR, including cell signalling activation, protein kinase phosphorylation and cytoskeletal network rearrangement, resemble those induced by virus infection. Increasing evidence demonstrates that many viruses usurp EGFR endocytosis or EGFR-mediated signalling for entry, replication, inflammation, and viral antagonism to the host antiviral system. In addition, viruses have acquired sophisticated mechanisms to regulate EGFR functions by interrupting the EGFR-recycling process and modulating EGFR expression. In this review, we provide an overview of the mechanisms by which viruses alter EGFR signalling in favour of their continued survival.