Cation-Free siRNA Micelles as Effective Drug Delivery Platform and Potent RNAi Nanomedicines for Glioblastoma Therapy

Nanoparticle-based small interfering RNA (siRNA) therapy shows great promise for glioblastoma (GBM). However, charge associated toxicity and limited blood-brain-barrier (BBB) penetration remain significant challenges for siRNA delivery for GBM therapy. Herein, novel cation-free siRNA micelles, prepared by the self-assembly of siRNA-disulfide-poly(N-isopropylacrylamide) (siRNA-SS-PNIPAM) diblock copolymers, are prepared. The siRNA micelles not only display enhanced blood circulation time, superior cell take-up, and effective at-site siRNA release, but also achieve potent BBB penetration. Moreover, due to being non-cationic, these siRNA micelles exert no charge-associated toxicity. Notably, these desirable properties of this novel RNA interfering (RNAi) nanomedicine result in outstanding growth inhibition of orthotopic U87MG xenografts without causing adverse effects, achieving remarkably improved survival benefits. Moreover, as a novel type of polymeric micelle, the siRNA micelle displays effective drug loading ability. When utilizing temozolomide (TMZ) as a model loading drug, the siRNA micelle realizes effective synergistic therapy effect via targeting the key gene (signal transducers and activators of transcription 3, STAT3) in TMZ drug resistant pathways. The authors' results show that this siRNA micelle nanoparticle can serve as a robust and versatile drug codelivery platform, and RNAi nanomedicine and for effective GBM treatment.

A smart multiantenna gene theranostic system based on the programmed assembly of hypoxia-related siRNAs

The systemic therapeutic utilisation of RNA interference (RNAi) is limited by the non-specific off-target effects, which can have severe adverse impacts in clinical applications. The accurate use of RNAi requires tumour-specific on-demand conditional activation to eliminate the off-target effects of RNAi, for which conventional RNAi systems cannot be used. Herein, a tumourous biomarker-activated RNAi platform is achieved through the careful design of RNAi prodrugs in extracellular vesicles (EVs) with cancer-specific recognition/activation features. These RNAi prodrugs are assembled by splitting and reconstituting the principal siRNAs into a hybridisation chain reaction (HCR) amplification machine. EVs facilitate the specific and efficient internalisation of RNAi prodrugs into target tumour cells, where endogenous microRNAs (miRNAs) promote immediate and autonomous HCR-amplified RNAi activation to simultaneously silence multiantenna hypoxia-related genes. With multiple guaranteed cancer recognition and synergistic therapy features, the miRNA-initiated HCR-promoted RNAi cascade holds great promise for personalised theranostics that enable reliable diagnosis and programmable on-demand therapy.

Multifunctional Liposomes Enable Active Targeting and Twinfilin 1 Silencing to Reverse Paclitaxel Resistance in Brain Metastatic Breast Cancer

Paclitaxel (PTX) is a first-line chemotherapeutic drug for breast cancer, but PTX resistance often occurs in metastatic breast cancer. In addition, due to the poor targeting of chemotherapeutic drugs and the presence of the blood-brain barrier (BBB), it is hard to effectively treat brain metastatic breast cancer using paclitaxel. Thus, it is urgent to develop an effective drug delivery system for the treatment of brain metastatic breast cancer. The current study found that TWF1 gene, an epithelial-mesenchymal transition-associated gene, was overexpressed in brain metastatic breast cancer (231-BR) cells and was associated with the PTX resistance of 231-BR cells. Knockdown of TWF1 by small interference RNA (siRNA) in 231-BR cells could effectively increase the sensitivity of brain metastatic breast cancer cells to paclitaxel. Then, a liposome-based drug delivery system was developed for PTX delivery across BBB, enhancing PTX sensitivity and brain metastases targeting via BRBP1 peptide modification. The results showed that BRBP1-modified liposomes could effectively cross the BBB, specifically accumulate in brain metastases, and effectively interfere TWF1 gene expression in vitro and in vivo, and thus they enhanced proliferation inhibition, cell cycle arrest, and apoptosis induction, thereby inhibiting the formation and growth of brain metastases. In summary, our results indicated that BRBP1-modified and PTX- and TWF1 siRNA-loaded liposomes have the potential for the treatment of brain metastatic breast cancer, which lays the foundation for the development of a new targeted drug delivery system.

Programmably tiling rigidified DNA brick on gold nanoparticle as multi-functional shell for cancer-targeted delivery of siRNAs

Small interfering RNA (siRNA) is an effective therapeutic to regulate the expression of target genes in vitro and in vivo. Constructing a siRNA delivery system with high serum stability, especially responsive to endogenous stimuli, remains technically challenging. Herein we develop anti-degradation Y-shaped backbone-rigidified triangular DNA bricks with sticky ends (sticky-YTDBs) and tile them onto a siRNA-packaged gold nanoparticle in a programmed fashion, forming a multi-functional three-dimensional (3D) DNA shell. After aptamers are arranged on the exterior surface, a biocompatible siRNA-encapsulated core/shell nanoparticle, siRNA/Ap-CS, is achieved. SiRNAs are internally encapsulated in a 3D DNA shell and are thus protected from enzymatic degradation by the outermost layer of YTDB. The siRNAs can be released by endogenous miRNA and execute gene silencing within tumor cells, causing cell apoptosis higher than Lipo3000/siRNA formulation. In vivo treatment shows that tumor growth is completely (100%) inhibited, demonstrating unique opportunities for next-generation anticancer-drug carriers for targeted cancer therapies.

Multifunctional Applications of Engineered Extracellular Vesicles in the Treatment of Cancer

Extracellular vesicles (EVs) are key players of intercellular communication in the physiological and pathological setting. In cancer, EVs mediate complex signaling mechanisms between cancer cells and the tumor microenvironment (TME), and can influence tumor progression and the response to existing therapies. Importantly, EVs can be loaded with therapeutic agents and modified to display tumor-targeting molecules. In the field of nanomedicine, EVs have been engineered to serve as therapeutic delivery vehicles for several anticancer agents, including antibodies, chemotherapy, compounds, CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats-associated endonuclease 9), and small interfering RNA (siRNA). Notably, the engineered EVs were shown to suppress malignant features of cancer cells, to elicit antitumor immunity, and to decrease tumor angiogenesis. Here, we review the EV-based therapies designed to target cancer cells and to educate components of the TME to drive antitumor responses. These studies illustrate the multifunctional applications of EVs in the development of anticancer therapies and their translational potential for cancer treatment.

Codelivery of BV6 and anti-IL6 siRNA by hyaluronate-conjugated PEG-chitosan-lactate nanoparticles inhibits tumor progression

AIMS

Increased expression of inhibitor of apoptosis (IAP) genes has been associated with progressive cancer and chemoresistance. Accordingly, blockade of IAPs by BV6 has resulted in ameliorative outcomes. Interleukin (IL)-6 is another important mediator involved in the growth and survival of tumor cells. Therefore, we hypothesized that simultaneous inhibition of IAPs and IL-6 could be a new promising anti-tumor treatment strategy.

MATERIALS AND METHODS

In this study, we generated and characterized hyaluronate-PEG-Chitosan-Lactate (H-PCL) nanoparticles (NPs) to simultaneously deliver IL6-specific siRNA and BV6 to 4T1 (breast cancer) and CT26 (colon cancer) cells, and investigate the anti-tumor properties of this combination therapy both in vitro and in vivo.

KEY FINDINGS

H-PCL NPs exhibited good physicochemical properties leading to efficient transfection of cancer cells and suppression of target molecules. Moreover, combination therapy synergistically increased apoptosis, as well as decreased cell migration, proliferation, colony formation, and angiogenesis in both 4T1 and CT26 cell lines and suppressed cancer progression in tumor-bearing mice that was associated with enhanced survival time.

SIGNIFICANCE

These findings imply the effectiveness of cancer combination therapy by using H-PCL NPs loaded with anti-IL-6 siRNA and BV6.

The chemical structure and phosphorothioate content of hydrophobically modified siRNAs impact extrahepatic distribution and efficacy

Small interfering RNAs (siRNAs) have revolutionized the treatment of liver diseases. However, robust siRNA delivery to other tissues represents a major technological need. Conjugating lipids (e.g. docosanoic acid, DCA) to siRNA supports extrahepatic delivery, but tissue accumulation and gene silencing efficacy are lower than that achieved in liver by clinical-stage compounds. The chemical structure of conjugated siRNA may significantly impact invivo efficacy, particularly in tissues with lower compound accumulation. Here, we report the first systematic evaluation of the impact of siRNA scaffold-i.e. structure, phosphorothioate (PS) content, linker composition-on DCA-conjugated siRNA delivery and efficacy in vivo. We found that structural asymmetry (e.g. 5- or 2-nt overhang) has no impact on accumulation, but is a principal factor for enhancing activity in extrahepatic tissues. Similarly, linker chemistry (cleavable versus stable) altered activity, but not accumulation. In contrast, increasing PS content enhanced accumulation of asymmetric compounds, but negatively impacted efficacy. Our findings suggest that siRNA tissue accumulation does not fully define efficacy, and that the impact of siRNA chemical structure on activity is driven by intracellular re-distribution and endosomal escape. Fine-tuning siRNA chemical structure for optimal extrahepatic efficacy is a critical next step for the progression of therapeutic RNAi applications beyond liver.

A photo-triggerable aptamer nanoswitch for spatiotemporal controllable siRNA delivery

A photo-triggerable aptamer nanoswitch was proposed for spatiotemporal regulation of siRNA delivery. Recognition between AS1411 and nucleolin was effectively blocked by a photo-labile complementary oligonucleotide, which could be reactivated with photo-irradiation, resulting in efficient tumor-targeted siRNA internalization and gene silencing in vitro and in vivo.

Stimuli-Responsive Polysaccharide Enveloped Liposome for Targeting and Penetrating Delivery of survivin-shRNA into Breast Tumor

Silencing the inhibitor of apoptosis (IAP) by RNAi is a promising method for tumor therapy. One of the major challenges lies in how to sequentially overcome the system barriers in the course of the tumor targeting delivery, especially in the tumor accumulation and penetration. Herein we developed a novel stimuli-responsive polysaccharide enveloped liposome carrier, which was constructed by layer-by-layer depositing redox-sensitive amphiphilic chitosan (CS) and hyaluronic acid (HA) onto the liposome and then loading IAP inhibitor survivin-shRNA gene and permeation promoter hyaluronidase (HAase) sequentially. The as-prepared HA/HAase/CS/liposome/shRNA (HCLR) nanocarrier was verified to be stable in blood circulation due to the negative charged HA shield. The tumor targeting recognition and the enhanced tumor accumulation of HCLR were visualized by fluorescence resonance energy transfer (FRET) and in vivo fluorescence biodistribution. The deshielding of HA and the protonizing of CS in slightly acidic tumor extracellular pH environment (pH_e, 6.8-6.5) were demonstrated by ζ potential change from -23.1 to 29.9 mV. The pH_e-responsive HAase release was confirmed in the tumor extracellular mimicking environments, and the intratumoral biodistribution showed that the tumor penetration of HCLR was improved. The cell uptake of HCLR in pH_e environment was significantly enhanced compared with that in physiological pH environment. The increased shRNA release of HCLR was approved in 10 mM glutathione (GSH) and tumor cells. Surprisingly, HCLR suppressed the tumor growth markedly through survivin silencing and meanwhile maintained low toxicity to mice. This study indicates that the novel polysaccharide enveloped HCLR is promising in clinical translation, thanks to the stimuli-triggered tumor accumulation, tumor penetration, cell uptake, and intracellular gene release.

Two Phase 3 Trials of Inclisiran in Patients with Elevated LDL Cholesterol

BACKGROUND

Inclisiran inhibits hepatic synthesis of proprotein convertase subtilisin-kexin type 9. Previous studies suggest that inclisiran might provide sustained reductions in low-density lipoprotein (LDL) cholesterol levels with infrequent dosing.

METHODS

We enrolled patients with atherosclerotic cardiovascular disease (ORION-10 trial) and patients with atherosclerotic cardiovascular disease or an atherosclerotic cardiovascular disease risk equivalent (ORION-11 trial) who had elevated LDL cholesterol levels despite receiving statin therapy at the maximum tolerated dose. Patients were randomly assigned in a 1:1 ratio to receive either inclisiran (284 mg) or placebo, administered by subcutaneous injection on day 1, day 90, and every 6 months thereafter over a period of 540 days. The coprimary end points in each trial were the placebo-corrected percentage change in LDL cholesterol level from baseline to day 510 and the time-adjusted percentage change in LDL cholesterol level from baseline after day 90 and up to day 540.

RESULTS

A total of 1561 and 1617 patients underwent randomization in the ORION-10 and ORION-11 trials, respectively. Mean (±SD) LDL cholesterol levels at baseline were 104.7±38.3 mg per deciliter (2.71±0.99 mmol per liter) and 105.5±39.1 mg per deciliter (2.73±1.01 mmol per liter), respectively. At day 510, inclisiran reduced LDL cholesterol levels by 52.3% (95% confidence interval [CI], 48.8 to 55.7) in the ORION-10 trial and by 49.9% (95% CI, 46.6 to 53.1) in the ORION-11 trial, with corresponding time-adjusted reductions of 53.8% (95% CI, 51.3 to 56.2) and 49.2% (95% CI, 46.8 to 51.6) (P<0.001 for all comparisons vs. placebo). Adverse events were generally similar in the inclisiran and placebo groups in each trial, although injection-site adverse events were more frequent with inclisiran than with placebo (2.6% vs. 0.9% in the ORION-10 trial and 4.7% vs. 0.5% in the ORION-11 trial); such reactions were generally mild, and none were severe or persistent.

CONCLUSIONS

Reductions in LDL cholesterol levels of approximately 50% were obtained with inclisiran, administered subcutaneously every 6 months. More injection-site adverse events occurred with inclisiran than with placebo. (Funded by the Medicines Company; ORION-10 and ORION-11 ClinicalTrials.gov numbers, NCT03399370 and NCT03400800.).

Population Pharmacokinetic-Pharmacodynamic Model of Serum Transthyretin Following Patisiran Administration

Hereditary transthyretin-mediated amyloidosis is an inherited, rapidly progressive, life-threatening disease caused by mutated transthyretin (TTR) protein. Patisiran is a small interfering RNA (siRNA) formulated in a lipid nanoparticle that inhibits hepatic TTR protein synthesis by RNA interference. We have developed an indirect-response pharmacokinetic-pharmacodynamic model relating plasma siRNA (ALN-18328) levels to serum TTR reduction across five clinical studies. A sigmoidal function described this relationship, with estimated Hill coefficient of 0.548, and half maximal inhibitory concentration (IC₅₀), IC₈₀, and IC₉₀ values of 9.45, 118.5, and 520.5 ng/mL, respectively. Following patisiran 0.3 mg/kg every 3 weeks (q3w), steady-state plasma ALN-18328 exposures were between IC₈₀ and IC₉₀, yielding average serum TTR reductions of 80%-90% from baseline. Covariate analysis indicated similar TTR reduction across evaluated intrinsic and extrinsic factors, obviating the need for dose adjustment. Modeling results support the recommended patisiran dosing schedule of 0.3 mg/kg q3w, with a maximum dose of 30 mg for patients weighing ≥100 kg.

Charge Conversional Biomimetic Nanocomplexes as a Multifunctional Platform for Boosting Orthotopic Glioblastoma RNAi Therapy

Nanotechnology-based RNA interference (RNAi) has shown great promise in overcoming the limitations of traditional clinical treatments for glioblastoma (GBM). However, because of the complexity of brain physiology, simple blood-brain barrier (BBB) penetration or tumor-targeting strategies cannot entirely meet the demanding requirements of different therapeutic delivery stages. Herein, we developed a charge conversional biomimetic nanoplatform with a three-layer core-shell structure to programmatically overcome persistent obstacles in siRNA delivery to GBM. The resulting nanocomplex presents good biocompatibility, prolonged blood circulation, high BBB transcytosis, effective tumor accumulation, and specific uptake by tumor cells in the brain. Moreover, red blood cell membrane (RBCm) disruption and effective siRNA release can be further triggered elegantly by charge conversion from negative to positive in the endo/lysosome (pH 5.0-6.5) of tumor cells, leading to highly potent target-gene silencing with a strong anti-GBM effect. Our study provides an intelligent biomimetic nanoplatform tailored for systemically siRNA delivery to GBM, leveraging Angiopep-2 peptide-modified, immune-free RBCm and charge conversional components. Improved therapeutic efficacy, higher survival rates, and minimized systemic side effects were achieved in orthotopic U87MG-luc human glioblastoma tumor-bearing nude mice.

Preparation, Determination of Activity, and Biodistribution of Cholesterol-Containing Nuclease-Resistant siRNAs In Vivo

RNA interference (RNAi) is a powerful tool for suppressing gene expression associated with various diseases that are not amenable to treatment with low molecular weight drugs. Despite significant progress in this area, the potential for therapeutic use of RNAi in humans is limited due to the lack of efficient delivery systems. Bioconjugation is one of the most promising methods for delivering siRNA to cells and tissues, since conjugation of siRNA with molecules capable of penetrating cells through natural transport mechanisms can provide specificity of delivery without toxic effects and unwanted immunostimulation. Here we describe the design, preparation, and in vivo evaluation of cholesterol-containing siRNA conjugates able to accumulate in the tumor, penetrate into cells without a carrier, and suppress the expression of the target genes.

Multifunctional Nanodelivery Platform for Maximizing Nucleic Acids Combination Therapy

The silencing of an oncogene with a small interfering RNA (siRNA) is a promising way for cancer therapy. Its efficacy can be further enhanced by integrating with other therapeutics; however, transporting siRNA and other active ingredients to the same location at the same time is challenging. Here, we report a novel multifunctional nanodelivery platform by sequentially layering several functional ingredients, such as siRNAs, microRNAs, peptides, and targeting ligands, onto a core through charge-charge interaction. The prepared nanovectors effectively and programmably delivered multiple active components to maximize therapeutic combination with minimal off-targeting effects.

Patisiran Pharmacokinetics, Pharmacodynamics, and Exposure-Response Analyses in the Phase 3 APOLLO Trial in Patients With Hereditary Transthyretin-Mediated (hATTR) Amyloidosis

Hereditary transthyretin-mediated (hATTR) amyloidosis is an inherited, rapidly progressive, life-threatening disease caused by deposition of abnormal transthyretin protein. Patisiran is an RNA interference therapeutic comprising a novel, small interfering ribonucleic acid (ALN-18328) formulated in a lipid nanoparticle targeted to inhibit hepatic transthyretin protein synthesis. The lipid nanoparticle also contains 2 novel lipid excipients (DLin-MC3-DMA and PEG2000 -C-DMG). Here we report patisiran pharmacokinetics (PK), pharmacodynamics (PD), and exposure-response analyses from the phase 3 APOLLO trial, in which patients with hATTR amyloidosis with polyneuropathy were randomized 2:1 to receive patisiran 0.3 mg/kg or placebo intravenously every 3 weeks over 18 months. In patisiran-treated patients, mean maximum reduction in serum transthyretin level from baseline was 87.8%. Patisiran PK exposure was stable following chronic dosing. There were no meaningful differences in PK exposure, serum transthyretin reduction, and efficacy (change from baseline in modified Neuropathy Impairment Score+7) across all subgroups analyzed (age, sex, race, body weight, genotype status of valine-to-methionine mutation at position 30 [V30M] and non-V30M, prior use of tetramer stabilizers, mild/moderate renal impairment, and mild hepatic impairment). transthyretin reduction and efficacy were similar across the interpatient PK exposure range for ALN-18328. There was no trend in the incidence of adverse events or serious adverse events across the interpatient PK exposure range for all 3 analytes. Incidence of antidrug antibodies was low (3.4%) and transient, with no impact on PK, PD, efficacy, or safety. The patisiran dosing regimen of 0.3 mg/kg every 3 weeks is appropriate for all patients with hATTR amyloidosis.

PAMAM Dendrimers as a Delivery System for Small Interfering RNA

Polyamidoamine dendrimers (PAMAM) form positively charged nanoparticles that function as nonviral delivery vectors for gene therapy. They protect nucleic acids from enzymatic degradation and facilitate endocytosis and endosomal escape. In this chapter, we describe the preparation and in vitro evaluation of small interfering RNA (siRNA)-PAMAM dendrimers. The physicochemical properties of the designed formulations were evaluated by size and zeta potential assessment and atomic force microscopy (AFM). The binding and release of the siRNA molecules from the PAMAM dendrimers were also assessed. Visualization and quantitative analysis of the siRNA-PAMAM dendrimers in live cells were analyzed by fluorescence microscopy and flow cytometry, respectively. Improving siRNA delivery to human cells through PAMAM dendrimers should accelerate the clinical applications of RNA interference.

Effects of Renal Impairment on the Pharmacokinetics, Efficacy, and Safety of Inclisiran: An Analysis of the ORION-7 and ORION-1 Studies

OBJECTIVE

To investigate the pharmacodynamic properties of inclisiran, a small interfering RNA targeting proprotein convertase subtilisin-kexin type 9 (PCSK9), in individuals with normal renal function and renal impairment (RI).

PATIENTS AND METHODS

The analysis included participants with normal renal function and mild, moderate, and severe RI from the phase 1 ORION-7 renal study (n=31) and the phase 2 ORION-1 study (n=247) who received 300 mg of inclisiran sodium or placebo.

RESULTS

In ORION-7, PCSK9 values were reduced at day 60 in the normal renal function group (68.1%±12.4%), mild RI group (74.2%±12.3%), moderate RI group (79.8%±4.9%), and severe RI group (67.9%±16.4%) (P<.001 vs placebo in all groups). Low-density lipoprotein cholesterol levels were significantly reduced versus placebo: normal renal function, 57.6%±10.7%; mild RI, 35.1%±13.5%; moderate RI, 53.1%±21.3%; severe RI, 49.2%±26.6% (P<.001 for all). In ORION-1, PCSK9 level reductions at day 180 were 48.3% to 58.6% in the 300-mg single-dose groups and 67.3% to 73.0% in the 300-mg 2-dose groups (P<.001 vs placebo in all groups). The corresponding low-density lipoprotein cholesterol level reductions were 35.7% to 40.2% in the 300-mg single-dose groups and 50.9% to 58.0% in the 300 mg 2-dose groups (P<.001 vs placebo in all groups). In ORION-7, exposure to inclisiran was proportionally greater in individuals with increasing RI; inclisiran was undetectable in plasma 48 hours after administration in any group.

CONCLUSION

The pharmacodynamic effects and safety profile of inclisiran were similar in study participants with normal and impaired renal function. Dose adjustments of inclisiran are not required in these patients.

TRIAL REGISTRATION

clinicaltrials.gov Identifiers: NCT02597127 and NCT03159416.

Rekindling RNAi Therapy: Materials Design Requirements for In Vivo siRNA Delivery

With the recent FDA approval of the first siRNA-derived therapeutic, RNA interference (RNAi)-mediated gene therapy is undergoing a transition from research to the clinical space. The primary obstacle to realization of RNAi therapy has been the delivery of oligonucleotide payloads. Therefore, the main aims is to identify and describe key design features needed for nanoscale vehicles to achieve effective delivery of siRNA-mediated gene silencing agents in vivo. The problem is broken into three elements: 1) protection of siRNA from degradation and clearance; 2) selective homing to target cell types; and 3) cytoplasmic release of the siRNA payload by escaping or bypassing endocytic uptake. The in vitro and in vivo gene silencing efficiency values that have been reported in publications over the past decade are quantitatively summarized by material type (lipid, polymer, metal, mesoporous silica, and porous silicon), and the overall trends in research publication and in clinical translation are discussed to reflect on the direction of the RNAi therapeutics field.

Engineered nanoparticles for systemic siRNA delivery to malignant brain tumours

Improved delivery materials are needed to enable siRNA transport across biological barriers, including the blood-brain barrier (BBB), to treat diseases like brain cancer. We engineered bioreducible nanoparticles for systemic siRNA delivery to patient-derived glioblastoma cells in an orthotopic mouse tumor model. We first utilized a newly developed biomimetic in vitro model to evaluate and optimize the performance of the engineered bioreducible nanoparticles at crossing the brain microvascular endothelium. We performed transmission electron microscopy imaging which indicated that the engineered nanoparticles are able to cross the BBB endothelium via a vesicular mechanism. The nanoparticle formulation engineered to best cross the BBB model in vitro led to safe delivery across the BBB to the brain in vivo. The nanoparticles were internalized by human brain cancer cells, released siRNA to the cytosol via environmentally-triggered degradation, and gene silencing was obtained both in vitro and in vivo. This study opens new frontiers for the in vitro evaluation and engineering of nanomedicines for delivery to the brain, and reports a systemically administered biodegradable nanocarrier for oligonucleotide delivery to treat glioma.

Dual-Blockade Immune Checkpoint for Breast Cancer Treatment Based on a Tumor-Penetrating Peptide Assembling Nanoparticle

Cancer immunotherapy can enhance the antitumor effect of drugs through a combinatorial approach in a synergistic manner. However, the effective targeted delivery of various drugs remains a challenge. We generated a peptide assembling tumor-targeted nanodelivery system based on a breast cancer homing and penetrating peptide for the codelivery of a programmed cell death ligand 1 (PD-L1) small interfering RNA (siRNA) (siPD-L1) and an indoleamine 2,3-dioxygenase inhibitor as a dual blockade of an immune checkpoint. The vector is capable of specifically accumulating in the breast cancer tumor site in a way that allows the siRNA to escape from endosomal vesicles after being endocytosed by tumor cells. The drug within these cells then acts to block tryptophan metabolism. The results showed that locally released siPD-L1 and 1-methyl-dl-tryptophan favor the survival and activation of cytotoxic T lymphocytes, resulting in apoptosis of breast cancer cells. Therefore, this study provides a potential approach for treating breast cancer by blocking immunological checkpoints through the assembly of micelles with functional peptides.

Octopus-like Flexible Vector for Noninvasive Intraocular Delivery of Short Interfering Nucleic Acids

Gene therapy is promising for chronic posterior ocular diseases, which are causal factors for severe vision impairment and even blindness worldwide. However, the inherent absorption barriers of the eye restrict intraocular delivery of therapeutic nucleic acids via topical instillation. Safe and efficient nonviral vectors for ocular gene therapy are still unmet clinical desires. Herein, an octopus-like flexible multivalent penetratin (MVP) was designed to facilitate condensation and delivery of therapeutic nucleic acids using multiarm polyethylene glycol (PEG) as a core and conjugating penetratin at each end of the PEG arms as outspread tentacles. Among the MVPs, 8-valent penetratin (8VP) stably compacted nucleic acids into positively charged polyplexes smaller than 100 nm, promoting cellular uptake efficiency (approaching 100%) and transfection rate (over 75%). After being instilled into the conjunctival sac, 8VP enabled rapid (<10 min) and prolonged (>6 h) distribution of nucleic acids in the retina via a noncorneal pathway. In a retinoblastoma-bearing mice model, topical instillation of 8VP/siRNA efficiently inhibited the protein expression of intraocular tumor without toxicity. MVP is advantageous over the commercial transfection reagent in safety and efficiency, and therefore provides a promising vector for noninvasive intraocular gene delivery.

Dendrimer mediated targeting of siRNA against polo-like kinase for the treatment of triple negative breast cancer

Irresponsiveness of triple negative breast cancer (TNBC) toward conventional therapies has drawn attention toward siRNA therapeutics. In gene delivery, dendrimers are gaining significant attention due to their characteristic features and polo-like kinase (PLK1) is reported as a potential target for TNBC. In this work, phosphorus and polyamidoamine dendrimer (generation 3 and 4 of each type) are explored to address delivery challenges of PLK1 siRNA (siPLK1). Dendriplexes were formed and complexation was found at 3:1 N/P ratio for all dendrimers by gel electrophoresis. Complexation was also supported by zeta potential, circular dichroism and intercalation assay. Dendriplexes were found to be stable in presence of ribonuclease and serum. Dendriplexes resulted in enhanced cell uptake of siPLK1 compared to siPLK1 solution in MDA-MB-231 and MCF-7 cells. Dendriplexes caused increased cell arrest in sub-G1 phase compared to solution. These observations suggested phosphorus and polyamidoamine dendrimers as potential carriers for siPLK1 delivery to treat TNBC.

Effectiveness of Small Interfering RNA Delivery via Arginine-Rich Polyethylenimine-Based Polyplex in Metastatic and Doxorubicin-Resistant Breast Cancer Cells

Poor cellular uptake, rapid degradation in the presence of serum, and inefficient transfection are some of the major barriers in achieving therapeutic efficacy of naked small interfering RNAs (siRNAs). We investigated the efficacy of the polyplex formulated using our synthesized polymer, polyethylene glycol (PEG)-modified l-arginine oligo(-alkylaminosiloxane) that is grafted with poly(ethyleneimine) (PEI) for siRNA delivery. We hypothesized that the polyplex formulated using the polymer with a balanced composition of PEI for siRNA condensation and its protection, PEG for polyplex stability and to minimize the PEI-associated toxicity, and with arginine facilitating cellular uptake would overcome the aforementioned issues with siRNA delivery. We tested our hypothesis using antiluciferase siRNA in luciferase-expressing metastatic breast cancer cells (MDA-MB-231-Luc-D3H2LN) and anti-ABCB1 siRNA against an efflux membrane protein, ABCB1, in doxorubicin (DOX)-resistant breast cancer cells (MCF-7/Adr). The results demonstrated that the polyplex at an optimal nucleotide/polymer ratio is stable in the presence of excess polyanions, has no cellular toxicity, and protects siRNA from RNase degradation. Transfection of MDA-MB-231-Luc-D3H2LN cells with antiluciferase siRNA polyplex showed almost complete knockdown of luciferase expression. In MCF-7/Adr cells, transfection with anti-ABCB1 siRNA effectively downregulated its target efflux protein, ABCB1; increased cellular uptake of DOX; and enhanced its cytotoxic effect. However, the cotreatment did not completely overcome drug resistance, suggesting that further optimization is needed and/or a mechanism(s) other than the efflux protein ABCB1 may be involved in drug resistance. In conclusion, our polyplex is effective for siRNA delivery and can be explored for different therapeutic applications.

Mechanistic profiling of the release kinetics of siRNA from lipidoid-polymer hybrid nanoparticles in vitro and in vivo after pulmonary administration

Understanding the release kinetics of siRNA from nanocarriers, their cellular uptake, their in vivo biodistribution and pharmacokinetics is a fundamental prerequisite for efficient optimisation of the design of nanocarriers for siRNA-based therapeutics. Thus, we investigated the influence of composition on the siRNA release from lipid-polymer hybrid nanoparticles (LPNs) consisting of cationic lipidoid 5 (L₅) and poly(DL-lactic-co-glycolic acid) (PLGA) intended for pulmonary administration. An array of siRNA-loaded LPNs was prepared by systematic variation of: (i) the L₅ content (10-20%, w/w), and (ii) the L₅:siRNA ratio (10,1-30:1, w/w). For comparative purposes, L₅-based lipoplexes, L₅-based stable nucleic acid lipid nanoparticles (SNALPs). and dioleoyltrimethylammoniumpropane (DOTAP)-modified LPNs loaded with siRNA were also prepared. Release studies in buffer and lung surfactant-containing medium showed that siRNA release is dependent on the presence of both surfactant and heparin (a displacing agent) in the release medium, since these interact with the lipid shell structure thereby facilitating decomplexation of L₅ and siRNA, as evident from the retarded siRNA release when the L₅ content and the L₅:siRNA ratio were increased. This confirms the hypothesis that siRNA loaded in LPNs is predominantly present as complexes with the cationic lipid and primarily is located near the particle surface. Cellular uptake and tolerability studies in the human macrophage cell line THP-1 and the type I-like human alveolar epithelial cell line hAELVi, which together represents a monolayer-based barrier model of lung epithelium, indicated that uptake of LPNs was much higher in THP-1 cells in agreement with their primary clearance role. In vivo biodistributions of formulations loaded with Alexa Fluor® 750-labelled siRNA after pulmonary administration in mice were compared by using quantitative fluorescence imaging tomography. The L₅-modified LPNs, SNALPs and DOTAP-modified LPNs displayed significantly increased lung retention of siRNA as compared to L₅-based lipoplexes, which had a biodistribution profile comparable to that of non-loaded siRNA, for which >50% of the siRNA dose permeated the air-blood barrier within 6 h and subsequently was excreted via the kidneys. Hence, the enhanced lung retention upon pulmonary administration of siRNA-loaded LPNs represents a promising characteristic that can be used to control the delivery of the siRNA cargo to lung tissue for local management of disease.

Symbiotic Self-Assembly Strategy toward Lipid-Encased Cross-Linked Polymer Nanoparticles for Efficient Gene Silencing

A novel "symbiotic self-assembly" strategy that integrates the advantages of biocompatible lipids with a structurally robust polymer to efficiently encapsulate and deliver siRNAs is reported. The assembly process is considered to be symbiotic because none of the assembling components are capable of self-assembly but can form well-defined nanostructures in the presence of others. The conditions of the self-assembly process are simple but have been chosen such that it offers the ability to arrive at a system that is noncationic for mitigating carrier-based cytotoxicity, efficiently encapsulate siRNA to minimize cargo loss, be effectively camouflaged to protect the siRNA from nuclease degradation, and efficiently escape the endosome to cause gene knockdown. The lipid-siRNA-polymer (L-siP) nanoassembly formation and its disassembly in the presence of an intracellular trigger have been extensively characterized experimentally and through computational modeling. The complexes have been evaluated for the delivery of four different siRNA molecules in six different cell lines, where an efficient gene knockdown is demonstrated. The reported generalized strategy has the potential to make an impact on the development of a safe and effective delivery agent for RNAi-mediated gene therapy that holds the promise of targeting several hard-to-cure diseases.

In vivo rendezvous of small nucleic acid drugs with charge-matched block catiomers to target cancers

Stabilisation of fragile oligonucleotides, typically small interfering RNA (siRNA), is one of the most critical issues for oligonucleotide therapeutics. Many previous studies encapsulated oligonucleotides into ~100-nm nanoparticles. However, such nanoparticles inevitably accumulate in liver and spleen. Further, some intractable cancers, e.g., tumours in pancreas and brain, have inherent barrier characteristics preventing the penetration of such nanoparticles into tumour microenvironments. Herein, we report an alternative approach to cancer-targeted oligonucleotide delivery using a Y-shaped block catiomer (YBC) with precisely regulated chain length. Notably, the number of positive charges in YBC is adjusted to match that of negative charges in each oligonucleotide strand (i.e., 20). The YBC rendezvouses with a single oligonucleotide in the bloodstream to generate a dynamic ion-pair, termed unit polyion complex (uPIC). Owing to both significant longevity in the bloodstream and appreciably small size (~18 nm), the uPIC efficiently delivers oligonucleotides into pancreatic tumour and brain tumour models, exerting significant antitumour activity.

Targeting RNA: A Transformative Therapeutic Strategy

The therapeutic pathways that modulate transcription mechanisms currently include gene knockdown and splicing modulation. However, additional mechanisms may come into play as more understanding of molecular biology and disease etiology emerge. Building on advances in chemistry and delivery technology, oligonucleotide therapeutics is emerging as an established, validated class of drugs that can modulate a multitude of genetic targets. These targets include over 10,000 proteins in the human genome that have hitherto been considered undruggable by small molecules and protein therapeutics. The approval of five oligonucleotides within the last 2 years elicited unprecedented excitement in the field. However, there are remaining challenges to overcome and significant room for future innovation to fully realize the potential of oligonucleotide therapeutics. In this review, we focus on the translational strategies encompassing preclinical evaluation and clinical development in the context of approved oligonucleotide therapeutics. Translational approaches with respect to pharmacology, pharmacokinetics, cardiac safety evaluation, and dose selection that are specific to this class of drugs are reviewed with examples. The mechanism of action, chemical evolution, and intracellular delivery of oligonucleotide therapies are only briefly reviewed to provide a general background for this class of drugs.

Engineered Histidine-Enriched Facial Lipopeptides for Enhanced Intracellular Delivery of Functional siRNA to Triple Negative Breast Cancer Cells

Cytosolic delivery of functional siRNA remains the major challenge to develop siRNA-based therapeutics. Designing clinically safe and effective siRNA transporter to deliver functional siRNA across the plasma and endosomal membrane remains a key hurdle. With the aim of improving endosomal release, we have designed cyclic and linear peptide-based transporters having an Arg-^DHis-Arg template. Computational studies show that the Arg-^DHis-Arg template is also stabilized by the Arg-His side-chain hydrogen bonding interaction at physiological pH, which dissociates at lower pH. The overall atomistic interactions were examined by molecular dynamics simulations, which indicate that the extent of peptide_siRNA assembly formation depends greatly on physicochemical properties of the peptides. Our designed peptides having the Arg-^DHis-Arg template and two lipidic moieties facilitate high yield of intracellular delivery of siRNA. Additionally, unsaturated lipid, linoleic acid moieties were introduced to promote fusogenicity and facilitate endosomal release and cytosolic delivery. Interestingly, such protease-resistant peptides provide serum stability to siRNA and exhibit high efficacy of erk1 and erk2 gene silencing in the triple negative breast cancer (TNBC) cell line. The peptide having two linoleyl moieties demonstrated comparable efficacy with commercial transfection reagent HiPerFect, as evidenced by the erk1 and erk2 gene knockdown experiment. Additionally, our study shows that ERK1/2 silencing siRNA and doxorubicin-loaded gramicidin-mediated combination therapy is more effective than siRNA-mediated gene silencing-based monotherapy for TNBC treatment.

Design of a Novel PEGylated Liposomal Vector for Systemic Delivery of siRNA to Solid Tumors

A small interfering RNA (siRNA) delivery system using dioleylphosphate-diethylenetriamine conjugate (DOP-DETA)-based liposomes (DL) was assessed for systemic delivery of siRNA to tumors. DL carrying siRNA capable of inducing efficient gene silencing with low doses of siRNA were modified with polyethylene glycol (PEG-DL/siRNA) for systemic injection of siRNA. The biodistribution of DL and siRNA in the PEG-DL/siRNA was studied by using radiolabeled DL and fluorescence-labeled siRNA, respectively. DL in the PEG-DL/siRNA showed a high retention in the plasma, accumulation in the tumor, and low accumulation in the liver and spleen after intravenous injection. The in vivo effects of PEGylation were observed only when distearoylphosphatidylethanolamine (DSPE)-PEG but not distearoylglycerol (DSG)-PEG were used. This result suggests that the electrostatic interaction between lipid molecules on the surface of PEG-DL/siRNA was a critical determinant for the in vivo effect of PEGylation. When PEG-DL/siRNA (0.1 mg/kg siRNA) was intravenously injected into tumor-bearing mice, in vivo gene silencing was observed in subcutaneous tumors. These results indicate that PEG-DL/siRNA designed in this study is a promising formulation for systemic use of siRNA.

An Open-Label, Multicenter, Phase I, Dose Escalation Study with Phase II Expansion Cohort to Determine the Safety, Pharmacokinetics, and Preliminary Antitumor Activity of Intravenous TKM-080301 in Subjects with Advanced Hepatocellular Carcinoma

Lessons Learned.

TKM‐080301 showed a favorable toxicity profile at the studied dose.

TKM‐080301 targeting PLK1 through small interfering RNA mechanism did not demonstrate improved overall survival in patients with advanced hepatocellular carcinoma compared with historical control. Preliminary antitumor activity as shown in this early‐phase study does not support further evaluation as a single agent.

Background.

Polo‐like kinase 1 (PLK1) is overexpressed in hepatocellular carcinoma (HCC). Knockdown of PLK1 expression by PLK1 small interfering RNA (siRNA) in an HCC cell line showed reduced expression in RNA‐induced silencing complex and a reduction in cell proliferation.

Methods.

A 3 + 3 dose escalation plus expansion cohort at the maximum tolerated dose (MTD) was implemented. Patients with HCC, Eastern Cooperative Oncology Group (ECOG) performance status ≤2, and Child‐Pugh score A received TKM‐080301 as an intravenous infusion once every week for 3 consecutive weeks, repeated every 28 days.

Results.

The study enrolled 43 patients. The starting dose of TKM‐080301 was 0.3 mg/kg, and MTD was declared at 0.75 mg/kg. Following the development of grade 4 thrombocytopenia in two subjects on the expansion cohort, the MTD was redefined at 0.6 mg/kg. Four patients did not have any evaluable postbaseline scan. Of the other 39 subjects who had received at least 0.3 mg/kg, 18 subjects (46.2%) had stable disease (SD) by independent RECIST 1.1 criteria. By Choi criteria, eight subjects (23.1%) had a partial response (PR). For 37 assessable subjects, with 2 subjects censored, median progression‐free survival (PFS) was 2.04 months. Median survival for the whole study population was 7.5 months.

Conclusion.

TKM‐080301 was generally well tolerated. In this early‐phase study, antitumor effect for TKM 080301 was limited. Further evaluation as a single agent in large randomized trials is not warranted.

Boosting RNAi therapy for orthotopic glioblastoma with nontoxic brain-targeting chimaeric polymersomes

Glioblastoma with intracranial infiltrative growth remains an incurable disease mainly owing to existence of blood brain barrier (BBB) and off-target drug toxicity. RNA interference (RNAi) with a high specificity and low toxicity emerges as a new treatment modality for glioblastoma. The clinical application of RNAi technology is, however, hampered by the absence of safe and brain-targeting transfection agents. Here, we report on angiopep-2 peptide-decorated chimaeric polymersomes (ANG-CP) as a nontoxic and brain-targeting non-viral vector to boost the RNAi therapy for human glioblastoma in vivo. ANG-CP shows excellent packaging and protection of anti-PLK1 siRNA (siPLK1) in its lumen while quickly releasing payloads in a cytoplasmic reductive environment. Notably, in vitro experiments demonstrate that ANG-CP can effectively permeate the bEnd.3 monolayer, transport siRNA into the cytosol of U-87 MG glioblastoma cells via the LRP-1-mediated pathway, and significantly silence PLK1 mRNA and corresponding oncoprotein in U-87 MG cells. ANG-CP greatly prolongs the siPLK1 circulation time and enhances its accumulation in glioblastoma. RNAi with siPLK1 induces a strong anti-glioblastoma effect and significantly improves the survival time of glioblastoma carrying mice.

Inferring Half-Lives at the Effect Site of Oligonucleotide Drugs

Knowledge of the kinetics of the active drug in biophase, that is, at the effect site, is fundamental to select dose and to reason about safety. Unfortunately, the kinetics is cumbersome to measure in vivo. We describe how dose-response-time (DRT) analysis estimates the biophase and the target-response half-lives from data of the circulating protein of the encoded messenger RNA for seven antisense oligonucleotides (ASOs) and four small interfering RNA (siRNA) drugs. The biophase half-lives were estimated with acceptable precision (relative standard error <26%). For ASOs, the estimates were similar to, or slightly longer than, the reported terminal plasma half-lives. Terminal plasma half-life was reported for only one siRNA, precluding any general comparison. The estimated half-lives of response were 0.5-12 days cross drugs and shorter than the biophase half-lives. We recommend DRT analysis when limited plasma pharmacokinetic data are available, or when the biophase half-life differs from the terminal plasma half-life.

Inhibition of glioma growth by a GOLPH3 siRNA-loaded cationic liposomes

PURPOSE

GOLPH3 has been shown to be involved in glioma proliferation. In this study, we aimed to demonstrate that GOLPH3 can serve as a target for glioma gene therapy.

METHODS

During the experiment, cationic liposomes with angiopep-2 (A2-CL) were used to deliver siGOLPH3 crossing the blood-brain barrier and reaching the glioma.

RESULTS

At the cellular level, the A2-CL/siGOLPH3 could silence GOLPH3 and then effectively inhibited the proliferation of cells. In vivo experiments, using U87-GFP-Luci-bearing BALB/c mouse models, we demonstrated that A2-CL could deliver GOLPH3-siRNA specifically to glioma and effectively inhibit glioma growth.

CONCLUSIONS

This study shows that GOLPH3 has great potential as a target for the gene therapy of glioma and is of great value in precise medical applications.

Sustained delivery of siRNA/mesoporous silica nanoparticle complexes from nanofiber scaffolds for long-term gene silencing

A low toxicity and efficient delivery system is needed to deliver small interfering RNAs (siRNA) in vitro and in vivo. The use of mesoporous silica nanoparticles (MSN) is becoming increasingly common due to its biocompatibility, tunable pore size and customizable properties. However, bolus delivery of siRNA/MSN complexes remains suboptimal, especially when a sustained and long-term administration is required. Here, we utilized electrospun scaffolds for sustained delivery of siRNA/MSN-PEI through surface adsorption and nanofiber encapsulation. As a proof-of-concept, we targeted collagen type I expression to modulate fibrous capsule formation. Surface adsorption of siRNA/MSN-PEI provided sustained availability of siRNA for at least 30 days in vitro. As compared to conventional bolus delivery, such scaffold-mediated transfection provided more effective gene silencing (p < 0.05). On the contrary, a longer sustained release was attained (at least 5 months) when siRNA/MSN-PEI complexes were encapsulated within the electrospun fibers. In vivo subcutaneous implantation and biodistribution analysis of these scaffolds revealed that siRNA remained localized up to ∼290 μm from the implants. Finally, a fibrous capsule reduction of ∼45.8% was observed after 4 weeks in vivo as compared to negative scrambled siRNA treatment. Taken together, these results demonstrate the efficacy of scaffold-mediated sustained delivery of siRNA/MSN-PEI for long-term non-viral gene silencing applications.

STATEMENT OF SIGNIFICANCE

The bolus delivery of siRNA/mesoporous silica nanoparticles (MSN) complexes shows high efficiency to silence protein agonists of tumoral processes as cancer treatments. However, in tissue engineering area, scaffold mediated delivery is desired to achieve a local and sustained release of therapeutics. We showed the feasibility and the efficacy of siRNA/MSN delivered from electrospun scaffolds through surface adsorption and nanofiber encapsulation. We showed that this method enhances siRNA transfection efficiency and sustained targeted proteins silencing in vitro and in vivo. As a proof of concept, in this study, we targeted collagen type I expression to modulate fibrous capsule formation. However this platform can be applied to the release and transfection of siRNA or miRNA in cancer and tissue engineering applications.

NIR-induced spatiotemporally controlled gene silencing by upconversion nanoparticle-based siRNA nanocarrier

Spatiotemporal control over the release or activation of biomacromolecules such as siRNA remains a significant challenge. Light-controlled release has gained popularity in recent years; however, a major limitation is that most photoactivable compounds/systems respond only to UV irradiation, but not near-infrared (NIR) light that offers a deeper tissue penetration depth and better biocompatibility. This paper reports a simple NIR-to-UV upconversion nanoparticle (UCNP)-based siRNA nanocarrier for NIR-controlled gene silencing. siRNA is complexed onto a NaYF4:Yb/Tm/Er UCNP through an azobenzene (Azo)-cyclodextrin (CD) host-guest interaction. The UV emission generated by the NIR-activated UCNP effectively triggers the trans-to-cis photoisomerization of azobenzene, thus leading to the release of siRNA due to unmatched host-guest pairs. The UCNP-siRNA complexes are also functionalized with PEG (i.e., UCNP-(CD/Azo)-siRNA/PEG NPs), targeting ligands (i.e., EGFR-specific GE11 peptide), acid-activatable cell-penetrating peptides (i.e., TH peptide), and imaging probes (i.e., Cy5 fluorophore). The UCNP-(CD/Azo)-siRNA/PEG NPs with both GE11 and TH peptides display a high level of cellular uptake and an excellent endosomal/lysosomal escape capability. More importantly, NIR-controlled spatiotemporal knockdown of GFP expression is successfully achieved in both a 2D monolayer cell model and a 3D multicellular tumor spheroid model. Thus, this simple and versatile nanoplatform has great potential for the selective activation or release of various biomacromolecules.

Lipid-modified cell-penetrating peptide-based self-assembly micelles for co-delivery of narciclasine and siULK1 in hepatocellular carcinoma therapy

Hepatocellular carcinoma (HCC) is the most frequent type of primary liver cancer, and one therapeutic approach is to target both the AMPK and autophagy pathways in order to synergistically promote programmed cell death. Here, a series of amphiphilic, lipid-modified cell-penetrating peptides were synthesized and allowed to self-assemble into micelles loaded with the AMPK activator narciclasine (Narc) and short interfering RNA targeting the unc-51-like kinase 1 (siULK1). The size of these micelles, their efficiency of transfection into cells, and their ability to release drug or siRNA cargo in vitro were pH-sensitive, such that drug release was facilitated in the acidic microenvironment of the tumor. Transfecting the micelles into HCC cells significantly inhibited protective autophagy within tumor cells, and delivering the micelles into mice carrying HCC xenografts induced apoptosis, slowed tumor growth, and inhibited autophagy. Our results indicate that co-delivering Narc and siULK1 in biocompatible micelles can safely inhibit tumor growth and protective autophagy, justifying further studies into this promising therapeutic approach against HCC.

STATEMENT OF SIGNIFICANCE

We have focused on the targeted therapy of HCC via synergistically inhibiting the autophagy and inducing apoptosis. The lipid-modified cell-penetrating peptide can not only aggregate into micelles to load natural product narciclasine and ULK1 siRNA simultaneously, but also facilitate uptake and endosome escape with a pH-sensitive manner in HepG2 cells. HepG2 cell treated with siULK1-M-Narc has increased apoptotic levels and declined autophagy via the targeted regulation of AMPK-ULK1 signaling axis. The in vivo studies have confirmed that siULK1-M-Narc efficiently reduce the growth of tumor on HCC xenograft models with good safety. Thus, we suppose the lipid-modified cell-penetrating peptide has good application prospects in the targeted combinational therapy of HCC.

Synthesis of cationic branched tea polysaccharide derivatives for targeted delivery of siRNA to hepatocytes

The cationic branched tea polysaccharide (CTPSA) derivative bearing N-acylurea and 3-(dimethylamino)-1-propylamine residues was synthesized and characterized using FTIR and ¹H NMR spectroscopy. A nonspecific siRNA (NsiRNA) was used as a model molecule of functional siRNA that could downregulate over-expressed glycometabolism enzymes in the liver. The result from the agarose gel electrophoresis confirmed that the CTPSA and NsiRNA could form stable complexes when their weight ratio was larger than 18. The zeta potentials and sizes of the complexes were in the range of +8-+15 mv and 120-150 nm, respectively. The CTPSA/NsiRNA complex was observed as nanoparticles with a spherical shape of approximately 100 nm using scanning electron microscopy. The CTPSA derivative and the CTPSA/NsiRNA complexes exhibited lower cytotoxicity in HL-7702 cells when compared with the branched PEI (bPEI) and bPEI/NsiRNA complexes assessed by the Cell Counting Kit-8 assay. The results of flow cytometric analysis and laser confocal microscopy indicated that the CTPSA derivative could effectively target the transfer of the NsiRNA to HL-7702 cells. This work provides a potential approach to promote the CTPSA derivative as a nonviral vector for targeted delivery of functional siRNA to hepatocytes.

Synthesis and characterization of a hyperbranched grafting copolymer PEI-g-PLeu for gene and drug co-delivery

L-Leucine (Leu) is a hydrophobic natural amino acid and can polymerize into poly-L-Leucine (PLeu) to be an excellent biocompatible material. In this paper, a hyperbranched copolymer polyethyleneimine-g-poly-L-leucine (PEI-g-PLeu) was synthesized by ring-opening polymerization with leucine NCA as monomer and PEI as initiator, which will be used as drug and gene co-delivery system for cancer therapy. To characterize the transfection efficiency in vitro, pGL3 as the reporter gene was loaded in PEI-g-PLeu to form complexes. Doxorubicin (DOX) with cis-aconitic anhydride linker (CAD) and calf thymus DNA (as model DNA) were co-loaded in PEI-g-PLeu to obtain PEI-g-PLeu/DNA/CAD nanoparticles to measure Zeta potentials and particle sizes. Lastly, CAD and modified Bc12-shRNA(as therapeutic gene) were co-loaded in PEI-g-PLeu to get PEI-g-PLeu/CAD/DNA complexes. Our finding revealed when PEI and PLeu with the molar ratio of 1:240, and PEI-g-PLeu and DNA with the mass ratio of 1:5, PEI-g-PLeu/CAD/DNA had negligible cytotoxicity with equivalent gene transfaction efficiency compared with PEI25k. As a result, PEI-g-PLeu/CAD/DNA was a promising drug and gene co-delivery system.

Liposome-Protamine-DNA Nanoparticle-Mediated Delivery of Short Hairpin RNA Targeting Brachyury Inhibits Chordoma Cell Growth

Recent evidence suggests that brachyury is a crucial molecular driver in the initiation and propagation of chordoma. However, no small molecules have been used to specifically target brachyury. Short hairpin RNA (shRNA) has therapeutic promise for the genetic treatment of cancer, but the usage of shRNA therapeutics is limited by obstacles related to effective delivery into the nuclei of target cancer cells due to their inherent sensitivity to nucleases and large polyanionic characteristics. To overcome instability and low transfection efficiency, liposome-protamine-DNA (LPD) nanoparticles were synthesized and investigated as a non-viral carrier of shRNA targeting brachyury in chordoma cells. The size, zeta potential, affinity and transfection efficiency of LPD-shRNA complexes were characterized, and their biological functions in chordoma cells were evaluated. The transfection efficiency of LPD-shRNA was significant higher than naked shRNA. LPD delivered brachyury shRNA into chordoma cells and inhibited brachyury expression, induced apoptosis, upregulated the epithelial biomarker, E-cadherin, downregulated the mesenchymal biomarker, Snail and Slug, and suppressed cell growth. These data indicate that LPD might be a promising non-viral carrier for shRNA in gene targeted therapy of chordoma.

A Nanoparticle Carrier for Co-Delivery of Gemcitabine and Small Interfering RNA in Pancreatic Cancer Therapy

BACKGROUND: The concept of precision medicine to treat cancer shows promise and a co-delivery carrier for chemotherapy drugs and target genes is the key tool for both basic research and clinical application. To address this, we developed a cancer-targeting nanoparticle vector to transfer gemcitabine (Gem) and small interfering RNA (siRNA) to pancreatic cancer. METHODS: Iron oxide nanoparticles (IONPs) resonant at 15 nm were conjugated with the single chain variable fragment (scFv) against CD44v6 (scFvCD44v6), which has proven pancreatic cancer-targeting specificity as reported in our previous study. Gem was then linked through a lysosomally cleavable tetrapeptide linker, resulting in a scFv-targeted nanoparticle construct, which was subsequently conjugated to siRNA targeting the Bmi-1 oncogene (siBmi-1) to obtain the multifunctional nanoparticle scFv-Gem-siBmi-1-NPs. A series of biological experiments were performed to test its biophysical characterization, gene silencing efficacy and anti-tumor effect in vitro and in vivo. RESULTS: The multifunctional nanoparticle not only possesses an ultra-small size of approximately 80 nm, excellent biocompatibility and biodegradability, but also exerts a synergistic anti-tumor effect both in vitro and in vivo, such as inhibition of tumor cell growth, invasion and migration, reduction of cell cycle progression and promotion of tumor apoptosis. Furthermore, this nanoparticle can efficiently target pancreatic cancer in vivo, resulting in the enhanced bioavailability and efficacy of Gem. CONCLUSION: scFv-Gem-siBmi-1-NPs provide an effective and targeted co-delivery of Gem and siBmi-1 to pancreatic cancer, and exert an efficient and corporate anti-tumor therapeutic effect. This prospective vector shows promise for precise treatment of pancreatic cancer.

Optimization of Transforming Growth Factor-β1 siRNA Loaded Chitosan-Tripolyphosphate Nanoparticles for the Treatment of Colorectal Cancer Hepatic Metastasis in a Mouse Model

Metastatic liver disease is the most frequent complication of colorectal cancer (CRC), and the development of liver-targeted nanoparticles for drug delivery is a promising therapeutic approach. However, to improve the efficacy of passive drug delivery, its release rate at the sites of liver metastases should be maximized while minimizing drug uptake in nontargeted cells. Herein, we report the development and use of tripolyphosphate (TPP) modified chitosan (CS) nanoparticles loaded with small interfering RNA (siRNA) directed against transforming growth factor β1 (TGF-β1), which promotes tumorigenesis in advanced CRC. The nanoparticles efficiently inhibited CRC hepatic metastasis in an animal model. Particles of 300 nm in size and zeta potential at 20 mV showed a more striking liver-targeting effect. A weight ratio of CS/TPP of 8:1 for particles with TGF- β1 siRNA loaded at a concentration of 20 μM at pH 7.5 showed good pH-responsive drug release when exposed to a CRC homogenate at pH 6.5. In vivo, CS-TPP/TGF- β1 siRNA nanoparticles significantly reduced the volume and number of CRC metastatic foci. This was accompanied by the downregulation of TGF- β1 expression in the tumor microenvironment, inhibition of tumor associated macrophage formation, and improvement of the immune microenvironment. These results indicate that it is possible to achieve effective passive liver targeting by optimizing the processing parameters. The design of nanoparticles carrying siRNA against overexpressed oncogenes provides an excellent platform for the development of an efficient liver cancer therapy.

Comparison of partially and fully chemically-modified siRNA in conjugate-mediated delivery in vivo

Small interfering RNA (siRNA)-based drugs require chemical modifications or formulation to promote stability, minimize innate immunity, and enable delivery to target tissues. Partially modified siRNAs (up to 70% of the nucleotides) provide significant stabilization in vitro and are commercially available; thus are commonly used to evaluate efficacy of bio-conjugates for in vivo delivery. In contrast, most clinically-advanced non-formulated compounds, using conjugation as a delivery strategy, are fully chemically modified (100% of nucleotides). Here, we compare partially and fully chemically modified siRNAs in conjugate mediated delivery. We show that fully modified siRNAs are retained at 100x greater levels in various tissues, independently of the nature of the conjugate or siRNA sequence, and support productive mRNA silencing. Thus, fully chemically stabilized siRNAs may provide a better platform to identify novel moieties (peptides, aptamers, small molecules) for targeted RNAi delivery.

A modular platform for targeted RNAi therapeutics

Previous studies have identified relevant genes and signalling pathways that are hampered in human disorders as potential candidates for therapeutics. Developing nucleic acid-based tools to manipulate gene expression, such as short interfering RNAs^1-3 (siRNAs), opens up opportunities for personalized medicine. Yet, although major progress has been made in developing siRNA targeted delivery carriers, mainly by utilizing monoclonal antibodies (mAbs) for targeting^4-8, their clinical translation has not occurred. This is in part because of the massive development and production requirements and the high batch-to-batch variability of current technologies, which rely on chemical conjugation. Here we present a self-assembled modular platform that enables the construction of a theoretically unlimited repertoire of siRNA targeted carriers. The self-assembly of the platform is based on a membrane-anchored lipoprotein that is incorporated into siRNA-loaded lipid nanoparticles that interact with the antibody crystallizable fragment (Fc) domain. We show that a simple switch of eight different mAbs redirects the specific uptake of siRNAs by diverse leukocyte subsets in vivo. The therapeutic potential of the platform is demonstrated in an inflammatory bowel disease model by targeting colon macrophages to reduce inflammatory symptoms, and in a Mantle Cell Lymphoma xenograft model by targeting cancer cells to induce cell death and improve survival. This modular delivery platform represents a milestone in the development of precision medicine.

The Effects of Biological Fluids on Colloidal Stability and siRNA Delivery of a pH-Responsive Micellar Nanoparticle Delivery System

Nanoparticles (NPs) interact with complex protein milieus in biological fluids, and these interactions have profound effects on NP physicochemical properties and function. Surprisingly, most studies neglect the impact of these interactions, especially with respect to NP-mediated siRNA delivery. Here, the effects of serum on colloidal stability and siRNA delivery of a pH-responsive micellar NP delivery system were characterized. Results show cationic NP-siRNA complexes aggregate in ≥2% serum in buffer, but are stable in serum-free media. Furthermore, nonaggregated NP-siRNA delivered in serum-free media result in 4-fold greater siRNA uptake in vitro, compared to aggregated NP-siRNA. Interestingly, pH-responsive membrane lysis behavior, which is required for endosomal escape, and NP-siRNA dissociation, necessary for gene knockdown, are significantly reduced in serum. Consistent with these data, nonaggregated NP-siRNA in serum-free conditions result in highly efficient gene silencing, even at doses as low as 5 nM siRNA. NP-siRNA diameter was measured at albumin and IgG levels mimicking biological fluids. Neither albumin nor IgG alone induces NP-siRNA aggregation, implicating other serum proteins in NP colloidal instability. Finally, as a proof-of-principle that stability is maintained in established in vivo models, transmission electron microscopy reveals NP-siRNA are taken up by ductal epithelial cells in a nonaggregated state when injected retroductally into mouse salivary glands in vivo. Overall, this study shows serum-induced NP-siRNA aggregation significantly diminishes efficiency of siRNA delivery by reducing uptake, pH-responsive membrane lysis activity, and NP-siRNA dissociation. Moreover, these results highlight the importance of local NP-mediated drug delivery and are broadly applicable to other drug delivery systems.

Multifunctional peptide-lipid nanocomplexes for efficient targeted delivery of DNA and siRNA into breast cancer cells

The development of carriers for the delivery of oligonucleotide therapeutics is essential for the successful translation of gene therapies to the clinic. In the present study, a delivery system, which combines the fusogenic lipid 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) with a well-defined synthetic multifunctional peptide, was produced and optimized for gene delivery, with the aim to develop an efficient gene delivery platform for breast cancer cells. For this purpose, a breast cancer-specific cell targeting peptide (CTP) was incorporated into our leading peptide-based gene delivery system (to generate DEN-K(GALA)-TAT-K(STR)-CTP) to improve its cell-specific internalization, and investigated in combination with a formulation approach (DOPE/1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)). DEN-K(GALA)-TAT-K(STR)-CTP alone efficiently complexed with DNA or siRNA, and promoted efficient cellular uptake, but low levels of gene expression. By adding the formulation approach, synergistic improvements in gene expression and silencing were observed compared to the peptide or formulation approaches alone. Of significance, this current system demonstrated more efficient gene knockdown when compared to the leading commercial siRNA delivery agent Lipofectamine® RNAiMAX. The utility of this system was demonstrated through the delivery of BCL2 (B-cell lymphoma 2) siRNA to MCF-7 cells, which led to near complete knockdown of the Bcl-2 protein, and inhibition of MCF-7 cell migration in a wound healing assay. The present peptide/lipid hybrid system is an excellent candidate for the delivery of DNA or siRNA into breast cancer cells.

STATEMENT OF SIGNIFICANCE

The identification of safe and effective delivery systems for DNA and siRNA is of great importance. Herein, we developed a well-defined, multifunctional and cell-specific lipidic peptide DEN-K(GALA)-TAT-K(STR)-CTP as a breast cancer cell targeted gene delivery vector. When combined with a lipid component (DOTAP/DOPE), the peptide/lipid hybrid system demonstrated higher gene expression or knockdown levels compared to the peptide or lipid approach alone when used to deliver pDNA or siRNA respectively, indicating synergistic enhancement of gene delivery efficiency. Importantly, this delivery strategy achieved greater knockdown of the Bcl-2 protein when compared to the leading commercial siRNA delivery system Lipofectamine® RNAiMAX, suggesting its potential utility for the targeted treatment of Bcl-2 overexpressing breast cancers.

Autophagy plays a dual role during intracellular siRNA delivery by lipoplex and polyplex nanoparticles

Growing evidence indicates that autophagy plays a vital role during intracellular DNA delivery mediated by lipoplex and polyplex nanoparticles. However, autophagy in intracellular siRNA delivery has not been well understood. In this study, lipofectamine 2000 and chitosan were used to formulate lipoplex and polyplex with siRNA for systematically investigating the interplay between siRNA delivery and autophagy. After transfection of H1299 cells with lipoplex and polyplex, the number of autophagic vacuoles was increased significantly indicated by the accumulation of monodansylcadaverine (MDC) staining. Western blot revealed that the LC3-II expression was significantly increased after transfection, whereas p-mTOR expression was not influenced apparently. In addition, small-molecule autophagy modulators significantly affected transfection efficiency. Specifically, the mTOR-dependent autophagy inducer rapamycin enhanced the knockdown efficiency of both lipoplex and polyplex, whereas mTOR-dependent autophagy inhibitor 3-methyladenine (3-MA) suppressed their silencing efficiency. On the contrary, mTOR-independent autophagy inducer LiBr decreased whereas mTOR-independent autophagy inhibitor thapsigargin (TG) increased the knockdown efficacy. Immunofluorescence staining showed that siRNA was partially co-localized with autophagosomes and the percentage of co-localized siRNA was significantly affected by autophagy modulators in the opposite trend of gene knockdown efficacy. In conclusion, our study suggests that autophagy plays an important role during the intracellular siRNA trafficking mediated by both lipoplex and polyplex. Modulating autophagy process will result in distinct knockdown efficiency, which may be applied as a potential convenient way for improving siRNA delivery efficacy.

STATEMENT OF SIGNIFICANCE

Although tremendous effects has been made in the development of non-viral siRNA delivery systems, the intracellular siRNA trafficking has not been elucidated clearly. In this study, we systematically investigated the relationship between autophagy and intracellular siRNA delivery. We found that the non-viral siRNA delivery by both lipoplex and polyplex could induce mTOR-independent autophagy response. More interestingly, knockdown efficiency of both lipoplex and polyplex could be modulated with different autophagy regulators. Specifically, the mTOR-dependent autophagy inducer rapamycin enhances the knockdown efficiency of both lipoplex and polyplex, whereas mTOR-dependent autophagy inhibitor 3-methyladenine suppresses their silencing efficiency. On the contrary, mTOR-independent autophagy inducer lithium bromide decreases, whereas mTOR-independent autophagy inhibitor thapsigargin increases the knockdown efficacy. These findings suggest that the mTOR-dependent and -independent autophagy play a distinct role in the intracellular siRNA trafficking. Furthermore, co-administration with proper autophagy regulators could be potential convenient method to modulate siRNA transfection efficacy.

Zwitterionic Nanocarrier Surface Chemistry Improves siRNA Tumor Delivery and Silencing Activity Relative to Polyethylene Glycol

Although siRNA-based nanomedicines hold promise for cancer treatment, conventional siRNA-polymer complex (polyplex) nanocarrier systems have poor pharmacokinetics following intravenous delivery, hindering tumor accumulation. Here, we determined the impact of surface chemistry on the in vivo pharmacokinetics and tumor delivery of siRNA polyplexes. A library of diblock polymers was synthesized, all containing the same pH-responsive, endosomolytic polyplex core-forming block but different corona blocks: 5 kDa (benchmark) and 20 kDa linear polyethylene glycol (PEG), 10 kDa and 20 kDa brush-like poly(oligo ethylene glycol), and 10 kDa and 20 kDa zwitterionic phosphorylcholine-based polymers (PMPC). In vitro, it was found that 20 kDa PEG and 20 kDa PMPC had the highest stability in the presence of salt or heparin and were the most effective at blocking protein adsorption. Following intravenous delivery, 20 kDa PEG and PMPC coronas both extended circulation half-lives 5-fold compared to 5 kDa PEG. However, in mouse orthotopic xenograft tumors, zwitterionic PMPC-based polyplexes showed highest in vivo luciferase silencing (>75% knockdown for 10 days with single IV 1 mg/kg dose) and 3-fold higher average tumor cell uptake than 5 kDa PEG polyplexes (20 kDa PEG polyplexes were only 2-fold higher than 5 kDa PEG). These results show that high molecular weight zwitterionic polyplex coronas significantly enhance siRNA polyplex pharmacokinetics without sacrificing polyplex uptake and bioactivity within tumors when compared to traditional PEG architectures.

Preclinical Mammalian Safety Studies of EPHARNA (DOPC Nanoliposomal EphA2-Targeted siRNA)

To address the need for efficient and biocompatible delivery systems for systemic siRNA delivery, we developed 1,2-Dioleoyl-sn-Glycero-3-Phosphatidylcholine (DOPC) nanoliposomal EphA2-targeted therapeutic (EPHARNA). Here, we performed safety studies of EPHARNA in murine and primate models. Single dosing of EPHARNA was tested at 5 concentrations in mice (N = 15 per group) and groups were sacrificed on days 1, 14, and 28 for evaluation of clinical pathology and organ toxicity. Multiple dosing of EPHARNA was tested in mice and Rhesus macaques twice weekly at two dose levels in each model. Possible effects on hematologic parameters, serum chemistry, coagulation, and organ toxicity were assessed. Following single-dose EPHARNA administration to mice, no gross pathologic or dose-related microscopic findings were observed in either the acute (24 hours) or recovery (14 and 28 days) phases. The no-observed-adverse-effect level (NOAEL) for EPHARNA is considered >225 μg/kg when administered as a single injection intravenously in CD-1 mice. With twice weekly injection, EPHARNA appeared to stimulate a mild to moderate inflammatory response in a dose-related fashion. There appeared to be a mild hemolytic reaction in the female mice. In Rhesus macaques, minimal to moderate infiltration of mononuclear cells was found in some organs including the gastrointestinal tract, heart, and kidney. No differences attributed to EPHARNA were observed. These results demonstrate that EPHARNA is well tolerated at all doses tested. These data, combined with previously published in vivo validation studies, have led to an ongoing first-in-human phase I clinical trial (NCT01591356). Mol Cancer Ther; 16(6); 1114-23. ©2017 AACR.

Co-administration of liposomal l-OHP and PEGylated TS shRNA-lipoplex: A novel approach to enhance anti-tumor efficacy and reduce the immunogenic response to RNAi molecules

Many therapeutic strategies have been applied in efforts to conquer the development and/or progression of cancer. The combination of chemotherapy and an RNAi-based approach has proven to be an efficient anticancer therapy. However, the feasibility of such a therapeutic strategy has been substantially restricted either by the failure to achieve the efficient delivery of RNAi molecules to tumor tissue or by the immunostimulatory response triggered by RNAi molecules. In this study, therefore, we intended to investigate the efficacy of using liposomal oxaliplatin (liposomal l-OHP) to guarantee the efficient delivery of RNAi molecules, namely shRNA against thymidylate synthase (TS shRNA) complexed with cationic liposome (TS shRNA-lipoplex), to solid tumors, and to suppress the immunostimulatory effect of RNAi molecules, TS shRNA, following intravenous administration. Herein, we describe how liposomal l-OHP enhanced the intra-tumor accumulation of TS shRNA-lipoplex and significantly reduced the immunostimulatory response triggered by TS shRNA. Consequently, such enhanced accumulation of TS shRNA-lipoplex along with the cytotoxic effect of liposomal l-OHP led to a remarkable tumor growth suppression (compared to mono-therapy) following systemic administration. Our results, therefore, may have important implications for the provision of a safer and more applicable combination therapy of RNAi molecules and anti-cancer agents that can produce a more reliable anti-tumor effect.

Effects of tripolyphosphate on cellular uptake and RNA interference efficiency of chitosan-based nanoparticles in Raw 264.7 macrophages

Tumor necrosis factor-α (TNF-α) is a major pro-inflammatory cytokine that is mainly secreted by macrophages during inflammation. Here, we synthesized a series of N-(2-hydroxy)propyl-3-trimethyl ammonium chitosan chlorides (HTCCs), and then used a complex coacervation technique or tripolyphosphate (TPP)-assisted ionotropic gelation strategy to complex the HTCCs with TNF-α siRNA (siTNF) to form nanoparticles (NPs). The resultant NPs had a desirable particle size (210-279nm), a slightly positive zeta potential (14-22mV), and negligible cytotoxicity against Raw 264.7 macrophages and colon-26 cells. Subsequent cellular uptake tests demonstrated that the introduction of TPP to the NPs markedly increased their cellular uptake efficiency (to nearly 100%) compared with TPP-free NPs, and yielded a correspondingly higher intracellular concentration of siRNA. Critically, in vitro gene silencing experiments revealed that all of the TPP-containing NPs showed excellent efficiency in inhibiting the mRNA expression level of TNF-α (by approximately 85-92%, which was much higher than that obtained using Oligofectamine/siTNF complexes). Collectively, these results obviously suggest that our non-toxic TPP-containing chitosan-based NPs can be exploited as efficient siTNF carriers for the treatment of inflammatory diseases.