Clinical experiences with systemically administered siRNA-based therapeutics in cancer

Tumor-Associated Fibronectin Targeted Liposomal Nanoplatform for Cyclophilin A siRNA Delivery and Targeted Malignant Glioblastoma Therapy

Malignant glioblastoma (GBM) is the most aggressive brain cancer that has a very low survival rate. With the rapid development of nanotechnology in the past few decades, the use of nanoparticles (NPs) for nucleic acid delivery is expected to have a revolutionary impact on GBM therapy. However, clinical success in GBM therapy remains a formidable challenge, mainly due to suboptimal in vivo delivery of therapeutics to glioma cells. Herein, we developed an aptamer-like peptide (aptide)-decorated liposomal nanoplatform for systemic small interfering RNA (siRNA) delivery and targeted GBM therapy. This nanoplatform is mainly composed of the following key components: (i) classic liposome structure with an aqueous core that can encapsulate therapeutic siRNA; (ii) hydrophilic polyethylene glycol (PEG) chains on the outer shell to prolong blood circulation; and (iii) surface-encoded aptide to specifically target the extra-domain B (EDB) of fibronectin that over-expressed on glioma cells. After systemic administration of these new siRNA delivery NPs, they can target the glioma cells and efficiently inhibit the GBM tumor growth by silencing the expression of cyclophilin A (CypA), which is up-regulated in brain cancer and plays an important role in malignant transformation of brain cancer and maintaining glioma cell stemness. These results suggest that the reported RNA interference (RNAi) NP platform herein could become an effective tool for targeted GBM therapy.

Fluorinated Oligoethylenimine Nanoassemblies for Efficient siRNA-Mediated Gene Silencing in Serum-Containing Media by Effective Endosomal Escape

Efficient small interfering RNA (siRNA) delivery in the presence of serum is of crucial importance for effective gene therapy. Fluorinated vectors are considered to be attractive candidates for siRNA-mediated gene therapy because of their delivery efficacy in serum-containing media. However, the mechanisms driving the superior gene transfection behavior of fluorinated vectors are still not well-understood, and comprehensive investigations are warranted. Herein, we fabricated a library of perfluorooctanoyl fluoride-fluorinated (PFF-fluorinated) oligoethylenimines (f _xOEIs, x is the PFF:OEI feeding ratio), which can readily form nanoassemblies (f _xOEI NAs) capable of efficient siRNA delivery in cells cultured in medium both devoid of and supplemented with fetal bovine serum (FBS). The gene silencing test in serum-containing medium revealed that the f_0.7OEI/siRNA NAs achieved a luciferase silencing of ∼88.4% in Luc-HeLa cells cultured in FBS-containing medium, which was almost 2-fold greater than the silencing efficacy of siRNA delivered by the commercially available vector Lipo 2000 (∼48.8%). High levels of apolipoprotein B silencing were also achieved by f_0.7OEI/siRNA NAs in vivo. For an assessment of the underlying mechanisms of the efficacy of gene silencing of fluorinated vectors, two alkylated OEIs, aOEI-C8 and aOEI-C12, were fabricated as controls with similar molecular structure and hydrophobicity to that of f_0.7OEI, respectively. In vitro investigations showed that the superior gene delivery exhibited by f_0.7OEI NAs derived from the potent endosomal disruption capability of fluorinated vectors in the presence of serum, which was essentially attributed to the serum protein adsorption resistance of the f_0.7OEI NAs. Therefore, this work provides an innovative approach to siRNA delivery as well as insights into fluorine-associated serum resistance.

Nanoparticle-Based Delivery of CRISPR/Cas9 Genome-Editing Therapeutics

The recent progress in harnessing the efficient and precise method of DNA editing provided by CRISPR/Cas9 is one of the most promising major advances in the field of gene therapy. However, the development of safe and optimally efficient delivery systems for CRISPR/Cas9 elements capable of achieving specific targeting of gene therapy to the location of interest without off-target effects is a primary challenge for clinical therapeutics. Nanoparticles (NPs) provide a promising means to meet such challenges. In this review, we present the most recent advances in developing innovative NP-based delivery systems that efficiently deliver CRISPR/Cas9 constructs and maximize their effectiveness.

Redox-Responsive Nanoparticle-Mediated Systemic RNAi for Effective Cancer Therapy

Biodegradable polymeric nanoparticles (NPs) have demonstrated significant potential to improve the systemic delivery of RNA interference (RNAi) therapeutics, such as small interfering RNA (siRNA), for cancer therapy. However, the slow and inefficient siRNA release inside tumor cells generally observed for most biodegradable polymeric NPs may result in compromised gene silencing efficacy. Herein, a biodegradable and redox-responsive NP platform, composed of a solid poly(disulfide amide) (PDSA)/cationic lipid core and a lipid-poly(ethylene glycol) (lipid-PEG) shell for systemic siRNA delivery to tumor cells, is developed. This newly generated NP platform can efficiently encapsulate siRNA under extracellular environments and can respond to the highly concentrated glutathione (GSH) in the cytoplasm to induce fast intracellular siRNA release. By screening a library of PDSA polymers with different structures and chain lengths, the optimized NP platform shows the unique features of i) long blood circulation, ii) high tumor accumulation, iii) fast GSH-triggered intracellular siRNA release, and iv) exceptionally effective gene silencing. Together with the facile polymer synthesis technique and robust NP formulation enabling scale-up, this new redox-responsive NP platform may become an effective tool for RNAi-based cancer therapy.

Biomedical applications of mRNA nanomedicine

As an attractive alternative to plasmid DNA, messenger RNA (mRNA) has recently emerged as a promising class of nucleic acid therapeutics for biomedical applications. Advances in addressing the inherent shortcomings of mRNA and in the development of nanoparticle-based delivery systems have prompted the development and clinical translation of mRNA-based medicines. In this review, we discuss the chemical modification strategies of mRNA to improve its stability, minimize immune responses, and enhance translational efficacy. We also highlight recent progress in nanoparticle-based mRNA delivery. Considerable attention is given to the increasingly widespread applications of mRNA nanomedicine in the biomedical fields of vaccination, protein-replacement therapy, gene editing, and cellular reprogramming and engineering.

Using two-fluid nozzle for spray freeze drying to produce porous powder formulation of naked siRNA for inhalation

Spray freeze drying is an attractive technology to produce powder formulation for inhalation. It can be used to generate large porous particles which tend to aerosolize efficiently and do not aggregate readily. It also avoids material to be exposed to elevated temperature. In this study, we reported the use of two-fluid nozzle to produce spray freeze dried powder of small interfering RNA (siRNA). The effect of atomization gas flow rate and liquid feed rate were inspected initially using herring sperm DNA (hsDNA) as nucleic acid model. The atomization gas flow rate was found to have a major impact on the aerosol properties. The higher the atomization gas flow rate, the smaller the particle size, the higher the fine particle fraction (FPF). In contrast, the liquid feed rate had very minor effect. Subsequently, spray freeze dried siRNA powder was produced at various atomization gas flow rates. The particles produced were highly porous as examined with the scanning electron microscopy, and the structural integrity of the siRNA was demonstrated with gel electrophoresis. The gene-silencing effect of the siRNA was also successfully preserved in vitro. The best performing siRNA formulation was prepared at the highest atomization gas flow rate investigated with a moderate FPF of 30%. However, this was significantly lower than that obtained with the corresponding hsDNA counterparts (FPF ∼57%). A direct comparison between the hsDNA and siRNA formulations revealed that the former exhibited a lower density, hence a smaller aerodynamic diameter despite similar geometric size.

Exosome-Mediated Small RNA Delivery: A Novel Therapeutic Approach for Inflammatory Lung Responses

Exosomes (EXOs) are a type of extracellular nanovesicles released from living cells. Accumulating evidence suggests that EXOs are involved in the pathogenesis of human diseases, including lung conditions. In recent years, the potential of EXO-mediated drug delivery has gained increasing interest. In this report, we investigated whether inhaled EXOs serve as an efficient and practical delivery vehicle to activate or inhibit alveolar macrophages (AMs), subsequently modulating pulmonary immune responses. We first identified the recipient cells of the inhaled EXOs, which were labeled with PKH26. We found that only lung macrophages efficiently take up intratracheally instilled EXOs in vivo. Using modified calcium chloride-mediated transformation, we manipulated small RNA molecules in serum-derived EXOs, including siRNAs, microRNA (miRNA) mimics, and miRNA inhibitors. Via intratracheal instillation, we successfully delivered siRNA and miRNA mimics or inhibitors into lung macrophages using the serum-derived EXOs as vehicles. Furthermore, EXO siRNA or miRNA molecules are functional in modulating LPS-induced lung inflammation in vivo. Beneficially, serum-derived EXOs themselves do not trigger lung immune responses, adding more favorable features to serve as drug delivery agents. Collectively, we developed a novel protocol using serum-derived EXOs to deliver designated small RNA molecules into lung macrophages in vivo, potentially shedding light on future gene therapy of human lung diseases.

Biologically Targeted Magnetic Hyperthermia: Potential and Limitations

Hyperthermia, the mild elevation of temperature to 40–43°C, can induce cancer cell death and enhance the effects of radiotherapy and chemotherapy. However, achievement of its full potential as a clinically relevant treatment modality has been restricted by its inability to effectively and preferentially heat malignant cells. The limited spatial resolution may be circumvented by the intravenous administration of cancer-targeting magnetic nanoparticles that accumulate in the tumor, followed by the application of an alternating magnetic field to raise the temperature of the nanoparticles located in the tumor tissue. This targeted approach enables preferential heating of malignant cancer cells whilst sparing the surrounding normal tissue, potentially improving the effectiveness and safety of hyperthermia. Despite promising results in preclinical studies, there are numerous challenges that must be addressed before this technique can progress to the clinic. This review discusses these challenges and highlights the current understanding of targeted magnetic hyperthermia.

Nucleic acid nanomedicines in Phase II/III clinical trials: translation of nucleic acid therapies for reprogramming cells

This review presents an integrated analysis of the current-state-of-the-art in nucleic acid nanotherapies and highlights the importance of nanotechnology in the delivery of nucleic acid therapies. While there is no one dominant nanodesign, the diversity of nanodesigns and delivery of different siRNAs, miRNA and DNA to inhibit more than 20 targets in seven disease states in Phase II/III clinical trials reflects the potential of nucleic acid therapies to treat intractable diseases and non-druggable targets. We provide benchmarks to aid in comparing the design, proof-of-concept studies and clinical trials. From this, we demonstrate the importance of generating a strategic framework for integrating clinical 'wish lists' for a means to treat intractable diseases with engineering 'design checklists' for nucleic acid nanotherapies.

PEI-Coated Fe₃O₄ Nanoparticles Enable Efficient Delivery of Therapeutic siRNA Targeting REST into Glioblastoma Cells

Glioblastomas (GBM) are the most frequent brain tumors lacking efficient treatment. The increasingly elucidated gene targets make siRNA-based gene therapy a promising anticancer approach, while an efficient delivery system is urgently needed. Here, polyethyleneimine (PEI)-coated Fe₃O₄ nanoparticles (NPs) have been developed and applied for siRNA delivery into GBM cells to silence repressor element 1-silencing transcription factor (REST). The prepared PEI-coated Fe₃O₄ NPs were characterized as magnetic nanoparticles with a positive charge, by transmission electronic microscopy, dynamic light-scattering analysis and a magnetometer. By gel retardation assay, the nanoparticles were found to form complexes with siRNA and the interaction proportion of NP to siRNA was 2.8:1. The cellular uptake of NP/siRNA complexes was verified by prussian blue staining, fluorescence labeling and flow cytometry in U-87 and U-251 GBM cells. Furthermore, the REST silencing examined by realtime polymerase chain reaction (PCR) and Western blotting presented significant reduction of REST in transcription and translation levels. Upon the treatment of NP/siRNA targeting REST, the GBM cell viabilities were inhibited and the migration capacities were repressed remarkably, analyzed by cell counting kit-8 and transwell assay separately. In this study, we demonstrated the PEI-coated Fe₃O₄ nanoparticle as a vehicle for therapeutic siRNA delivery, at an appropriate NP/siRNA weight ratio for REST silencing in GBM cells, inhibiting cell proliferation and migration efficiently. These might represent a novel potential treatment strategy for GBM.

Recent Progress in Metal-Based Nanoparticles Mediated Photodynamic Therapy

Photodynamic therapy (PDT) is able to non-invasively treat and diagnose various cancers and nonmalignant diseases by combining light, oxygen, and photosensitizers (PSs). However, the application of PDT is hindered by poor water solubility and limited light-penetration depth of the currently available photosensitizers (PSs). Water solubility of PSs is crucial for designing pharmaceutical formulation and administration routes. Wavelength of light source at visible range normally has therapeutic depth less than 1 mm. In this review, focus is on the recent research progress of metal-based nanoparticles being applied in PDT. The potential toxicity of these nanoscales and future directions are further discussed.

Self-assembly of affinity-controlled nanoparticles via host-guest interactions for drug delivery

There has been increasing interest in constructing affinity-based drug delivery systems via different non-covalent interactions. Herein we report a host-guest interaction-based strategy to develop effective drug delivery systems using cyclodextrin-containing copolymers. Hydrophilic copolymers with one polyethylene glycol block and another block containing either α-cyclodextrin or β-cyclodextrin were synthesized. Using poly(β-benzyl l-aspartate) and pyrene as model guest compounds, we demonstrated the nanoparticle formation by host-guest interaction-mediated self-assembly. When an antioxidant and anti-inflammatory drug Tempol was used, the formation of well-defined spherical nanoparticles and therapeutic loading can be simultaneously realized. The obtained nanotherapy showed affinity-controlled drug release. In vitro cell culture experiments suggested that the host-guest nanotherapy exhibited desirable antioxidant and anti-inflammatory effects in macrophages. In a mouse model of an inflammatory disease ulcerative colitis, the orally administered host-guest nanoparticle can be effectively accumulated in the inflamed colonic tissue. Oral treatment of mice bearing colitis with the nanotherapy led to significantly improved efficacy in comparison with free drugs. A good in vivo safety profile was also observed for the developed host-guest nanotherapy. Accordingly, these types of affinity nanoparticles based on CD-containing copolymers can function as effective nanoplatforms for targeted treatment of a plethora of diseases.

Tau-targeting therapies for Alzheimer disease

Alzheimer disease (AD) is the most common form of dementia. Pathologically, AD is characterized by amyloid plaques and neurofibrillary tangles in the brain, with associated loss of synapses and neurons, resulting in cognitive deficits and eventually dementia. Amyloid-β (Aβ) peptide and tau protein are the primary components of the plaques and tangles, respectively. In the decades since Aβ and tau were identified, development of therapies for AD has primarily focused on Aβ, but tau has received more attention in recent years, in part because of the failure of various Aβ-targeting treatments in clinical trials. In this article, we review the current status of tau-targeting therapies for AD. Initially, potential anti-tau therapies were based mainly on inhibition of kinases or tau aggregation, or on stabilization of microtubules, but most of these approaches have been discontinued because of toxicity and/or lack of efficacy. Currently, the majority of tau-targeting therapies in clinical trials are immunotherapies, which have shown promise in numerous preclinical studies. Given that tau pathology correlates better with cognitive impairments than do Aβ lesions, targeting of tau is expected to be more effective than Aβ clearance once the clinical symptoms are evident. With future improvements in diagnostics, these two hallmarks of the disease might be targeted prophylactically.

Self-assembled dual fluorescence nanoparticles for CD44-targeted delivery of anti-miR-27a in liver cancer theranostics

Despite the vital role miRNA-27a plays in driving the development and progress of liver cancer, miRNA-based inhibition therapy is hampered due to its undesired degradation and off-target effects. Herein, a multifunctional nanoparticle for noninvasive tracking of targeted delivery of anti-miR-27a oligonucleotides against liver cancer was constructed.

Methods: Dual-fluorescent conjugates (QD-HA-PEI) were first fabricated through crosslinking hyaluronic acid (HA), polyethyleneimine (PEI) and near-infrared (NIR) fluorescent quantum dots (QDs) via a facile one-pot approach. Antisense oligonucleotide was then encapsulated by QD-HA-PEI to form anti-miR-27a/QD-HA-PEI via electrostatic interactions. Targeting, biodistribution, bioimaging, in vitro cytotoxicity and in vivo anti-tumor effects were evaluated and the underlying mechanism was studied.

Results: The NIR fluorescence of anti-miR-27a/QD-HA-PEI could be employed to monitor CD44 receptor-targeted cellular uptake and tumor accumulation. Importantly, the intrinsic fluorescence of anti-miR-27a/QD-HA-PEI remained in the “ON” state in extracellular or blood environment, but switched to the “OFF” state in the intracellular environment, indicating pH-responsive oligonucleotide release. Furthermore, anti-miR-27a/QD-HA-PEI exhibited effective and selective anti-cancer effects in vitro and in vivo with fewer side effects via the direct down-regulation of oncogenic transcription factors FOXO1 and PPAR-γ.

Conclusion: Our findings validate the dual-fluorescent nanoparticles as delivery vectors of therapeutic miRNA, capable of simultaneous tumor imaging and tracking of miRNA-based modulation therapy, thereby providing an efficient and safe approach for liver cancer theranostics.

Lipidation of polyethylenimine-based polyplex increases serum stability of bioengineered RNAi agents and offers more consistent tumoral gene knockdown in vivo

Recently we have established a novel approach to produce bioengineered noncoding RNA agents (BERAs) in living cells that carry target RNAi molecules (e.g., siRNA and miRNA) and thus act as "prodrugs". Using GFP-siRNA-loaded BERA (BERA/GFP-siRNA) as a model molecule, this study was to define the in vitro and in vivo knockdown efficiency of BERAs delivered by liposome-polyethylenimine nanocomplex (lipopolyplex or LPP). Compared to in vivo-jetPEI® (IVJ-PEI) and polyplex formulations, LPP offered greater protection of BERA/GFP-siRNA against degradation by serum RNases. Particle sizes and zeta potentials of LPP nanocomplex remained stable over 28 days when stored at 4 °C. Furthermore, comparable levels of BERA/GFP-siRNA were delivered by LPP and IVJ-PEI to luciferase/GFP-expressing human SK-Hep1-Luc-GFP or A549-Luc-GFP cells, which were selectively processed into target GFP-siRNA and subsequently knocked down GFP mRNA and protein levels. In addition, LPP-carried BERA/GFP-siRNA was successfully delivered into xenograft tumors and offered more consistent knockdown of tumoral GFP mRNA level in an orthotopic hepatocellular carcinoma (HCC) SK-Hep1-Luc-GFP xenograft mouse model, while IVJ-PEI formulation showed larger variation. These findings demonstrated that lipidation of polyplexes improved serum stability of biologic RNAi molecules, which was efficiently delivered to orthotopic HCC tissues to knock down target gene expression.

RNA Therapeutics in Oncology: Advances, Challenges, and Future Directions

RNA-based therapeutic technologies represent a rapidly expanding class of therapeutic opportunities with the power to modulate cellular biology in ways never before possible. With RNA-targeted therapeutics, inhibitors of previously undruggable proteins, gene expression modulators, and even therapeutic proteins can be rationally designed based on sequence information alone, something that is not possible with other therapeutic modalities. The most advanced RNA therapeutic modalities are antisense oligonucleotides (ASOs) and small interfering RNAs. Particularly with ASOs, recent clinical data have demonstrated proof of mechanism and clinical benefit with these approaches across several nononcology disease areas by multiple routes of administration. In cancer, next-generation ASOs have recently demonstrated single-agent activity in patients with highly refractory cancers. Here we discuss advances in RNA therapeutics for the treatment of cancer and the challenges that remain to solidify these as mainstay therapeutic modalities to bridge the pharmacogenomic divide that remains in cancer drug discovery.

Negative regulation of cationic nanoparticle-induced inflammatory toxicity through the increased production of prostaglandin E2 via mitochondrial DNA-activated Ly6C+ monocytes

Rationale: Cationic nanocarriers present with well-known toxicities, including inflammatory toxicity, which limit their clinical application. How the cationic nanocarrier-induced inflammatory response is negatively regulated is unknown. Herein, we found that following a sublethal dose of cationic nanocarriers, the induced inflammatory response is characterized by early neutrophil infiltration and spontaneous resolution within 1 week.

Methods: C57BL/6 mice were intravenously injected with a dosage of 1-100 mg/kg cationic DOTAP liposomes as well as other cationic materials. Cell necrosis was detected by flow cytometry. Release of mitochondrial DNA was quantified by qPCR via Taqman probes. Signal proteins were detected by Western blotting. PGE₂ production in the supernatant was quantitated using an enzyme immunoassay (EIA). The infiltrated inflammatory cells were observed in WT mice, Ccr2^-/- mice, Sting^-/-mice and Tlr9^-/-mice.

Results: The early stage (24-48 h) inflammatory neutrophil infiltration was followed by an increasing percentage of monocytes; and, compared with WT mice, Ccr2^-/- mice presented with more severe pulmonary inflammation. A previously uncharacterized population of regulatory monocytes expressing both inflammatory and immunosuppressive cytokines was identified in this model. The alteration in monocyte phenotype was directly induced by mtDNA release from cationic nanocarrier-induced necrotic cells via a STING- or TLR9-dependent pathway. Neutrophil activation was specifically inhibited by PGE2 from Ly6C⁺ inflammatory monocytes, and intravenous injections of dual-phenotype monocytes beneficially modified the immune response; this inhibitory effect was abolished after treatment with indomethacin. Moreover, we provide clear evidence that mitochondrial DNA activated Ly6C⁺ monocytes and increased PGE2 production through TLR9- or STING-mediated MAPK-NF-κB-COX2 pathways.

Conclusion: Our findings suggest that Ly6C⁺ monocytes and mtDNA-induced Ly6C⁺ monocyte PGE2 production may be part of a feedback mechanism that contributes to the resolution of cationic nanocarrier-induced inflammatory toxicity and may have important implications for understanding nanoparticle biocompatibility and designing better, safer drug delivery systems.

Co-Delivery of Doxorubicin and Anti-BCL-2 siRNA by pH-Responsive Polymeric Vector to Overcome Drug Resistance in In Vitro and In Vivo HepG2 Hepatoma Model

Drug resistance, developed through multiple mechanisms, is a major hindrance to successful chemotherapy of tumor. Combination therapy of chemotherapeutic drugs and siRNA represents an emerging strategy which may improve anticancer effect by synergistic actions. In this study, triblock copolymer of poly(ethylene glycol)- block-poly(l-lysine)- block-poly aspartyl ( N-( N', N'-diisopropylaminoethyl)) (PEG-PLL-PAsp(DIP)) was synthesized for the first time to enable the codelivery of BCL-2 siRNA and DOX. The system is supposed to not only bypass drug efflux but also down-regulate the antiapoptotic gene and consequently confronting against chemoresistance as well. Moreover, the pH responsive ability of the codelivery system can prevent drug leakage during circulation and guarantee swift drug release at tumors. The codelivered siRNA serves to suppress the expression of antiapoptotic BCL-2 and hence sensitize the cancer cells to anticancer drugs and produce improved therapeutic effect. Consequently, the codelivery of BCL-2 siRNA and anticancer drug DOX serves as a promising strategy against drug resistance in chemotherapy.

Supramolecular functional assemblies: dynamic membrane transporters and peptide nanotubular composites

The fabrication of functional molecular devices constitutes one of the most important current challenges for chemical sciences. The complex processes accomplished by living systems continuously demand the assistance of non-covalent interactions between molecular building blocks. Additionally, these building blocks (proteins, membranes, nucleotides) are also constituted by self-assembled structures. Therefore, supramolecular chemistry is the discipline required to understand the properties of the minimal self-assembled building blocks of living systems and to develop new functional smart materials. In the first part of this feature article, we highlight selected examples of the preparation of supramolecular membrane transporters with special emphasis on the application of dynamic covalent bonds. In the second section of the paper we review recent breakthroughs in the preparation of peptide nanotube hybrids with functional applications. The development of these devices constitutes an exciting process from where we can learn how to understand and manipulate supramolecular functional assemblies.

Targeting Accessories to the Crime: Nanoparticle Nucleic Acid Delivery to the Tumor Microenvironment

Nucleic acid delivery for cancer holds extraordinary promise. Increasing expression of tumor suppressor genes or inhibition of oncogenes in cancer cells has important therapeutic potential. However, several barriers impair progress in cancer gene delivery. These include effective delivery to cancer cells and relevant intracellular compartments. Although viral gene delivery can be effective, it has the disadvantages of being immuno-stimulatory, potentially mutagenic and lacking temporal control. Various nanoparticle (NP) platforms have been developed to overcome nucleic acid delivery hurdles, but several challenges still exist. One such challenge has been the accumulation of NPs in non-cancer cells within the tumor microenvironment (TME) as well as the circulation. While uptake by these cancer-associated cells is considered to be an off-target effect in some contexts, several strategies have now emerged to utilize NP-mediated gene delivery to intentionally alter the TME. For example, the similarity of NPs in shape and size to pathogens promotes uptake by antigen presenting cells, which can be used to increase immune stimulation and promote tumor killing by T-lymphocytes. In the era of immunotherapy, boosting the ability of the immune system to eliminate cancer cells has proven to be an exciting new area in cancer nanotechnology. Given the importance of cancer-associated cells in tumor growth and metastasis, targeting these cells in the TME opens up new therapeutic applications for NPs. This review will cover evidence for non-cancer cell accumulation of NPs in animal models and patients, summarize characteristics that promote NP delivery to different cell types, and describe several therapeutic strategies for gene modification within the TME.

Polysaccharide-Based Controlled Release Systems for Therapeutics Delivery and Tissue Engineering: From Bench to Bedside

Polysaccharides or polymeric carbohydrate molecules are long chains of monosaccharides that are linked by glycosidic bonds. The naturally based structural materials are widely applied in biomedical applications. This article covers four different types of polysaccharides (i.e., alginate, chitosan, hyaluronic acid, and dextran) and emphasizes their chemical modification, preparation approaches, preclinical studies, and clinical translations. Different cargo fabrication techniques are also presented in the third section. Recent progresses in preclinical applications are then discussed, including tissue engineering and treatment of diseases in both therapeutic and monitoring aspects. Finally, clinical translational studies with ongoing clinical trials are summarized and reviewed. The promise of new development in nanotechnology and polysaccharide chemistry helps clinical translation of polysaccharide-based drug delivery systems.

Journey of siRNA: Clinical Developments and Targeted Delivery

Since the evolutionary discovery of RNA interference and its utilization for gene knockdown in mammalian cell, a remarkable progress has been achieved in small interfering RNA (siRNA) therapeutics. siRNA is a promising tool, utilized as therapeutic agent against various diseases. Despite its significant potential benefits, safe, efficient, and target oriented delivery of siRNA is one of the major challenges in siRNA therapeutics. This review covers major achievements in clinical trials and targeted delivery of siRNAs using various targeting ligand-receptor pair. Local and systemically administered siRNA drug candidates at various phases in clinical trials are described in this review. This review also provides a deep insight in development of targeted delivery of siRNA. Various targeting ligand-siRNA pair with complexation and conjugation approaches are discussed in this review. This will help to achieve further optimization and development in targeted delivery of siRNAs to achieve higher gene silencing efficiency with lowest siRNA dose availability.

Engineering functional inorganic-organic hybrid systems: advances in siRNA therapeutics

Cancer treatment still faces a lot of obstacles such as tumor heterogeneity, drug resistance and systemic toxicities. Beyond the traditional treatment modalities, exploitation of RNA interference (RNAi) as an emerging approach has immense potential for the treatment of various gene-caused diseases including cancer. The last decade has witnessed enormous research and achievements focused on RNAi biotechnology. However, delivery of small interference RNA (siRNA) remains a key challenge in the development of clinical RNAi therapeutics. Indeed, functional nanomaterials play an important role in siRNA delivery, which could overcome a wide range of sequential physiological and biological obstacles. Nanomaterial-formulated siRNA systems have potential applications in protection of siRNA from degradation, improving the accumulation in the target tissues, enhancing the siRNA therapy and reducing the side effects. In this review, we explore and summarize the role of functional inorganic-organic hybrid systems involved in the siRNA therapeutic advancements. Additionally, we gather the surface engineering strategies of hybrid systems to optimize for siRNA delivery. Major progress in the field of inorganic-organic hybrid platforms including metallic/non-metallic cores modified with organic shells or further fabrication as the vectors for siRNA delivery is discussed to give credit to the interdisciplinary cooperation between chemistry, pharmacy, biology and medicine.

CK2 targeted RNAi therapeutic delivered via malignant cell-directed tenfibgen nanocapsule: dose and molecular mechanisms of response in xenograft prostate tumors

CK2, a protein serine/threonine kinase, promotes cell proliferation and suppresses cell death. This essential-for-survival signal demonstrates elevated expression and activity in all cancers examined, and is considered an attractive target for cancer therapy. Here, we present data on the efficacy of a tenfibgen (TBG) coated nanocapsule which delivers its cargo of siRNA (siCK2) or single stranded RNA/DNA oligomers (RNAi-CK2) simultaneously targeting CK2α and α' catalytic subunits. Intravenous administration of TBG-siCK2 or TBG-RNAi-CK2 resulted in significant xenograft tumor reduction at low doses in PC3-LN4 and 22Rv1 models of prostate cancer. Malignant cell uptake and specificity in vivo was verified by FACS analysis and immunofluorescent detection of nanocapsules and PCR detection of released oligomers. Dose response was concordant with CK2αα' RNA transcript levels and the tumors demonstrated changes in CK2 protein and in markers of proliferation and cell death. Therapeutic response corresponded to expression levels for argonaute and GW proteins, which function in oligomer processing and translational repression. No toxicity was detected in non-tumor tissues or by serum chemistry. Tumor specific delivery of anti-CK2 RNAi via the TBG nanoencapsulation technology warrants further consideration of translational potential.

Targeted co-delivery of Beclin 1 siRNA and FTY720 to hepatocellular carcinoma by calcium phosphate nanoparticles for enhanced anticancer efficacy

Purpose

FTY720, known as fingolimod, is a new immunosuppressive agent with effective anticancer properties. Although it was recently confirmed that FTY720 inhibits cancer cell proliferation, FTY720 can also induce protective autophagy and reduce cytotoxicity. Blocking autophagy with Beclin 1 siRNA after treatment with FTY720 promotes apoptosis. The objective of this study was to enhance the anticancer effect of FTY720 in hepatocellular carcinoma (HCC) by targeted co-delivery of FTY720 and Beclin 1 siRNA using calcium phosphate (CaP) nanoparticles (NPs).

Materials and methods

First, the siRNA was encapsulated within the CaP core. To form an asymmetric lipid bilayer structure, we then used an anionic lipid for the inner leaflet and a cationic lipid for the outer leaflet; after removing chloroform by rotary evaporation, these lipids were dispersed in a saline solution with FTY720. The NPs were analyzed by transmission electron microscopy, dynamic light scattering and ultraviolet–visible spectrophotometry. Cancer cell viability and cell death were analyzed by MTT assays, fluorescence-activated cell sorting analysis and Western blotting. In addition, the in vivo effects of the NPs were investigated using an athymic nude mouse subcutaneous transplantation tumor model.

Results

When the CaP NPs, called LCP-II NPs, were loaded with FTY720 and siRNA, they exhibited the expected size and were internalized by cells. These NPs were stable in systemic circulation. Furthermore, co-delivery of FTY720 and Beclin 1 siRNA significantly increased cytotoxicity in vitro and in vivo compared with that caused by treatment with the free drug alone.

Conclusion

The CaP NP system can be further developed for co-delivery of FTY720 and Beclin 1 siRNA to treat HCC, enhancing the anticancer efficacy of FTY720. Our findings provide a new insight into HCC treatment with co-delivered small molecules and siRNA, and these results can be readily translated into cancer clinical trials.

Polymer-Mediated Inhibition of Pro-invasive Nucleic Acid DAMPs and Microvesicles Limits Pancreatic Cancer Metastasis

Nucleic acid binding polymers (NABPs) have been extensively used as vehicles for DNA and RNA delivery. More recently, we discovered that a subset of these NABPs can also serve as anti-inflammatory agents by capturing pro-inflammatory extracellular nucleic acids and associated protein complexes that promote activation of toll-like receptors (TLRs) in diseases such as lupus erythematosus. Nucleic-acid-mediated TLR signaling also facilitates tumor progression and metastasis in several cancers, including pancreatic cancer (PC). In addition, extracellular DNA and RNA circulate on or within lipid microvesicles, such as microparticles or exosomes, which also promote metastasis by inducing pro-tumorigenic signaling in cancer cells and pre-conditioning secondary sites for metastatic establishment. Here, we explore the use of an NABP, the 3^rd generation polyamidoamine dendrimer (PAMAM-G3), as an anti-metastatic agent. We show that PAMAM-G3 not only inhibits nucleic-acid-mediated activation of TLRs and invasion of PC tumor cells in vitro, but can also directly bind extracellular microvesicles to neutralize their pro-invasive effects as well. Moreover, we demonstrate that PAMAM-G3 dramatically reduces liver metastases in a syngeneic murine model of PC. Our findings identify a promising therapeutic application of NABPs for combating metastatic disease in PC and potentially other malignancies.

Engineering Multifunctional RNAi Nanomedicine To Concurrently Target Cancer Hallmarks for Combinatorial Therapy

Cancer hallmarks allow the complexity and heterogeneity of tumor biology to be better understood, leading to the discovery of various promising targets for cancer therapy. An amorphous iron oxide nanoparticle (NP)-based RNAi strategy is developed to co-target two cancer hallmarks. The NP technology can modulate the glycolysis pathway by silencing MCT4 to induce tumor cell acidosis, and concurrently exacerbate oxidative stress in tumor cells via the Fenton-like reaction. This strategy has the following features for systemic siRNA delivery: 1) siRNA encapsulation within NPs for improving systemic stability; 2) effective endosomal escape through osmotic pressure and/or endosomal membrane oxidation; 3) small size for enhancing tumor tissue penetration; and 4) triple functions (RNAi, Fenton-like reaction, and MRI) for combinatorial therapy and in vivo tracking.

Using Genome Sequence to Enable the Design of Medicines and Chemical Probes

Rapid progress in genome sequencing technology has put us firmly into a postgenomic era. A key challenge in biomedical research is harnessing genome sequence to fulfill the promise of personalized medicine. This Review describes how genome sequencing has enabled the identification of disease-causing biomolecules and how these data have been converted into chemical probes of function, preclinical lead modalities, and ultimately U.S. Food and Drug Administration (FDA)-approved drugs. In particular, we focus on the use of oligonucleotide-based modalities to target disease-causing RNAs; small molecules that target DNA, RNA, or protein; the rational repurposing of known therapeutic modalities; and the advantages of pharmacogenetics. Lastly, we discuss the remaining challenges and opportunities in the direct utilization of genome sequence to enable design of medicines.

Chemical modifications of nucleic acid drugs and their delivery systems for gene-based therapy

Gene-based therapy is one of essential therapeutic strategies for precision medicine through targeting specific genes in specific cells of target tissues. However, there still exist many problems that need to be solved, such as safety, stability, selectivity, delivery, as well as immunity. Currently, the key challenges of gene-based therapy for clinical potential applications are the safe and effective nucleic acid drugs as well as their safe and efficient gene delivery systems. In this review, we first focus on current nucleic acid drugs and their formulation in clinical trials and on the market, including antisense oligonucleotide, siRNA, aptamer, and plasmid nucleic acid drugs. Subsequently, we summarize different chemical modifications of nucleic acid drugs as well as their delivery systems for gene-based therapeutics in vivo based on nucleic acid chemistry and nanotechnology methods.

Amphiphilic nanocarrier-induced modulation of PLK1 and miR-34a leads to improved therapeutic response in pancreatic cancer

The heterogeneity of pancreatic ductal adenocarcinoma (PDAC) suggests that successful treatment might rely on simultaneous targeting of multiple genes, which can be achieved by RNA interference-based therapeutic strategies. Here we show a potent combination of microRNA and siRNA delivered by an efficient nanocarrier to PDAC tumors. Using proteomic-microRNA profiles and survival data of PDAC patients from TCGA, we found a novel signature for prolonged survival. Accordingly, we used a microRNA-mimic to increase miR-34a together with siRNA to silence PLK1 oncogene. For in vivo dual-targeting of this combination, we developed a biodegradable amphiphilic polyglutamate amine polymeric nanocarrier (APA). APA-miRNA-siRNA polyplexes systemically administered to orthotopically inoculated PDAC-bearing mice showed no toxicity and accumulated at the tumor, resulting in an enhanced antitumor effect due to inhibition of MYC oncogene, a common target of both miR-34a and PLK1. Taken together, our findings warrant this unique combined polyplex's potential as a novel nanotherapeutic for PDAC.

RNA-Peptide nanoplexes drug DNA damage pathways in high-grade serous ovarian tumors

DNA damaging chemotherapy is a cornerstone of current front-line treatments for advanced ovarian cancer (OC). Despite the fact that a majority of these patients initially respond to therapy, most will relapse with chemo-resistant disease; therefore, adjuvant treatments that synergize with DNA-damaging chemotherapy could improve treatment outcomes and survival in patients with this deadly disease. Here, we report the development of a nanoscale peptide-nucleic acid complex that facilitates tumor-specific RNA interference therapy to chemosensitize advanced ovarian tumors to frontline platinum/taxane therapy. We found that the nanoplex-mediated silencing of the protein kinase, MK2, profoundly sensitized mouse models of high-grade serous OC to cytotoxic chemotherapy by blocking p38/MK2-dependent cell cycle checkpoint maintenance. Combined RNAi therapy improved overall survival by 37% compared with platinum/taxane chemotherapy alone and decreased metastatic spread to the lungs without observable toxic side effects. These findings suggest (a) that peptide nanoplexes can serve as safe and effective delivery vectors for siRNA and (b) that combined inhibition of MK2 could improve treatment outcomes in patients currently receiving frontline chemotherapy for advanced OC.

Redox-sensitive dendrimersomes assembled from amphiphilic Janus dendrimers for siRNA delivery

A cationic redox-sensitive Janus dendrimer (ssJD) that self-assembles into redox-sensitive dendrimersomes (RSDs) to complex with siRNA can readily deliver siRNA into tumor cells, and then rapidly release siRNA in a reductive environment to down-regulate a targeted gene.

Clusterin inhibition mediates sensitivity to chemotherapy and radiotherapy in human cancer

Since its discovery in 1983, the protein clusterin (CLU) has been isolated from almost all human tissues and fluids and linked to the development of different physiopathological processes, including carcinogenesis and tumor progression. During the last few years, several studies have shown the cytoprotective role of secretory CLU in tumor cells, inhibiting their apoptosis and enhancing their resistance to conventional treatments including hormone depletion, chemotherapy, and radiotherapy. In an effort to determine the therapeutic potential that the inhibition of this protein could have on the development of new strategies for cancer treatment, numerous studies have been carried out in this field, with results, in most cases, satisfactory but sometimes contradictory. In this document, we summarize for the first time the current knowledge of the effects that CLU inhibition has on sensitizing tumor cells to conventional cancer treatments and discuss its importance in the development of new strategies against cancer.

Recurrent ubiquitin B silencing in gynecological cancers establishes dependence on ubiquitin C

Transcriptional repression of ubiquitin B (UBB) is a cancer-subtype-specific alteration that occurs in a substantial population of patients with cancers of the female reproductive tract. UBB is 1 of 2 genes encoding for ubiquitin as a polyprotein consisting of multiple copies of ubiquitin monomers. Silencing of UBB reduces cellular UBB levels and results in an exquisite dependence on ubiquitin C (UBC), the second polyubiquitin gene. UBB is repressed in approximately 30% of high-grade serous ovarian cancer (HGSOC) patients and is a recurrent lesion in uterine carcinosarcoma and endometrial carcinoma. We identified ovarian tumor cell lines that retain UBB in a repressed state, used these cell lines to establish orthotopic ovarian tumors, and found that inducible expression of a UBC-targeting shRNA led to tumor regression, and substantial long-term survival benefit. Thus, we describe a recurrent cancer-specific lesion at the level of ubiquitin production. Moreover, these observations reveal the prognostic value of UBB repression and establish UBC as a promising therapeutic target for ovarian cancer patients with recurrent UBB silencing.

Targeted Delivery of siRNA Therapeutics to Malignant Tumors

Over the past 20 years, a diverse group of ligands targeting surface biomarkers or receptors has been identified with several investigated to target siRNA to tumors. Many approaches to developing tumor-homing peptides, RNA and DNA aptamers, and single-chain variable fragment antibodies by using phage display, in vitro evolution, and recombinant antibody methods could not have been imagined by researchers in the 1980s. Despite these many scientific advances, there is no reason to expect that the ligand field will not continue to evolve. From development of ligands based on novel or existing biomarkers to linking ligands to drugs and gene and antisense delivery systems, several fields have coalesced to facilitate ligand-directed siRNA therapeutics. In this review, we discuss the major categories of ligand-targeted siRNA therapeutics for tumors, as well as the different strategies to identify new ligands.

Exploring the pH Sensitivity of Poly(allylamine) Phosphate Supramolecular Nanocarriers for Intracellular siRNA Delivery

Silencing RNA (siRNA) technologies emerge as a promising therapeutic tool for the treatment of multiple diseases. An ideal nanocarrier (NC) for siRNAs should be stable at physiological pH and release siRNAs in acidic endosomal pH, fulfilling siRNA delivery only inside cells. Here, we show a novel application of polyamine phosphate NCs (PANs) based on their capacity to load negatively charged nucleic acids and their pH stability. PANs are fabricated by complexation of phosphate anions from phosphate buffer solution (PB) with the amine groups of poly(allylamine) hydrochloride as carriers for siRNAs. PANs are stable in a narrow pH interval, from 7 to 9, and disassemble at pH's higher than 9 and lower than 6. siRNAs are encapsulated by complexation with poly(allylamine) hydrochloride before or after PAN formation. PANs with encapsulated siRNAs are stable in cell media. Once internalized in cells following endocytic pathways, PANs disassemble at the low endosomal pH and release the siRNAs into the cytoplasm. Confocal laser scanning microscopy (CLSM) images of Rhodamine Green labeled PANs (RG-PANs) with encapsulated Cy3-labeled siRNA in A549 cells show that siRNAs are released from the PANs. Colocalization experiments with labeled endosomes and either labeled siRNAs prove the translocation of siRNAs into the cytosol. As a proof of concept, it is shown that PANs with encapsulated green fluorescence protein (GFP) siRNAs silence GFP in A549 cells expressing this protein. Silencing efficacy was evaluated by flow cytometry, CLSM, and Western blot assays. These results open the way for the use of poly(allylamine) phosphate nanocarriers for the intracellular delivery of genetic materials.

Engineering and physical sciences in oncology: challenges and opportunities

The principles of engineering and physics have been applied to oncology for nearly 50 years. Engineers and physical scientists have made contributions to all aspects of cancer biology, from quantitative understanding of tumour growth and progression to improved detection and treatment of cancer. Many early efforts focused on experimental and computational modelling of drug distribution, cell cycle kinetics and tumour growth dynamics. In the past decade, we have witnessed exponential growth at the interface of engineering, physics and oncology that has been fuelled by advances in fields including materials science, microfabrication, nanomedicine, microfluidics, imaging, and catalysed by new programmes at the National Institutes of Health (NIH), including the National Institute of Biomedical Imaging and Bioengineering (NIBIB), Physical Sciences in Oncology, and the National Cancer Institute (NCI) Alliance for Nanotechnology. Here, we review the advances made at the interface of engineering and physical sciences and oncology in four important areas: the physical microenvironment of the tumour and technological advances in drug delivery; cellular and molecular imaging; and microfluidics and microfabrication. We discussthe research advances, opportunities and challenges for integrating engineering and physical sciences with oncology to develop new methods to study, detect and treat cancer, and we also describe the future outlook for these emerging areas.

Virus-Mimicking Chimaeric Polymersomes Boost Targeted Cancer siRNA Therapy In Vivo

Small interfering RNA (siRNA) offers a highly selective and effective pharmaceutical for various life-threatening diseases, including cancers. The clinical translation of siRNA is, however, challenged by its short plasma life, poor cell uptake, and cumbersome intracellular trafficking. Here, cNGQGEQc peptide-functionalized reversibly crosslinked chimaeric polymersomes (cNGQ/RCCPs) is shown to mediate high-efficiency targeted delivery of Polo-like kinase1 specific siRNA (siPLK1) to orthotopic human lung cancer in nude mice. Strikingly, siRNA is completely and tightly loaded into the aqueous lumen of the polymersomes at an unprecedentedly low N/P ratio of 0.45. cNGQ/RCCPs loaded with firefly luciferase specific siRNA (siGL3) or siPLK1 are efficiently taken up by α₃ β₁ -integrin-overexpressing A549 lung cancer cells and quickly release the payloads to the cytoplasm, inducing highly potent and sequence-specific gene silencing in vitro. The in vivo studies using nude mice bearing orthotopic A549 human lung tumors reveal that siPLK1-loaded cNGQ/RCCPs boost long circulation, superb tumor accumulation and selectivity, effective suppression of tumor growth, and significantly improved survival time. These virus-mimicking chimaeric polymersomes provide a robust and potent platform for targeted cancer siRNA therapy.

Amide linkages mimic phosphates in RNA interactions with proteins and are well tolerated in the guide strand of short interfering RNAs

While the use of RNA interference (RNAi) in molecular biology and functional genomics is a well-established technology, in vivo applications of synthetic short interfering RNAs (siRNAs) require chemical modifications. We recently found that amides as non-ionic replacements for phosphodiesters may be useful modifications for optimization of siRNAs. Herein, we report a comprehensive study of systematic replacement of a single phosphate with an amide linkage throughout the guide strand of siRNAs. The results show that amides are surprisingly well tolerated in the seed and central regions of the guide strand and increase the silencing activity when placed between nucleosides 10 and 12, at the catalytic site of Argonaute. A potential explanation is provided by the first crystal structure of an amide-modified RNA-DNA with Bacillus halodurans RNase H1. The structure reveals how small changes in both RNA and protein conformation allow the amide to establish hydrogen bonding interactions with the protein. Molecular dynamics simulations suggest that these alternative binding modes may compensate for interactions lost due to the absence of a phosphodiester moiety. Our results suggest that an amide can mimic important hydrogen bonding interactions with proteins required for RNAi activity and may be a promising modification for optimization of biological properties of siRNAs.