Oral non-viral gene delivery platforms for therapeutic applications

Since gene therapy can regulate gene and protein expression directly, it has a great potential to prevent or treat a variety of genetic or acquired diseases through vaccines such as viral infections, cystic fibrosis, and cancer. Owing to their high efficacy, in vivo gene therapy trials are usually conducted intravenously, which is usually costly and invasive. There are several advantages to oral drug administration over intravenous injections, such as better patient compliance, ease of use, and lower cost. However, gene therapy is successful if the oligonucleotides can cross the cell membrane easily and reach the nucleus after the endosomal escape. In order to accomplish this task and deliver the cargo to the intended location, appropriate delivery systems should be introduced. This review summarizes oral delivery systems developed for effective gene delivery, vaccination, and treatment of various diseases. Studies have also shown that oral delivery approaches are potentially applicable to treat various diseases, especially inflammatory bowel disease, stomach, and colorectal cancers. Also, the current review provides an update overview on the development of non-viral and oral gene delivery techniques for gene therapy and vaccination purposes.

Absence of QTc Prolongation with Sodium N-(8-[2-Hydroxybenzoyl] Amino) Caprylate (SNAC), an Absorption Enhancer Co-Formulated with the GLP-1 Analogue Semaglutide for Oral Administration

INTRODUCTION

Oral delivery of proteins, including glucagon-like peptide 1 (GLP-1) receptor agonists, is impeded by low gastrointestinal permeation. Oral semaglutide has been developed for once-daily oral administration by co-formulation of the GLP-1 analogue semaglutide with an absorption enhancer, sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (SNAC, 300 mg). A randomised, partially double-blind, placebo-controlled thorough QT/corrected QT (QTc) trial was conducted to confirm the absence of unacceptable QTc interval prolongation with SNAC. QT is defined as interval on the electrocardiogram, measured from the start of the QRS complex to the end of the T wave.

METHODS

Part A of the study sought to identify an appropriate dose of SNAC (which was substantially higher than that used in the oral semaglutide co-formulation) for QTc assessment. Three sequential healthy volunteer cohorts were randomised to escalating single oral doses of SNAC (1.2, 2.4 or 3.6 g) or placebo. Following identification of an appropriate dose, a cross-over trial was conducted (Part B). Healthy volunteers received one of four treatment sequences, including single oral doses of SNAC, moxifloxacin (positive control) and placebo. Primary objectives were to (1) assess adverse events (AEs) with escalating SNAC doses and (2) confirm that SNAC does not cause unacceptable QTc interval prolongation versus placebo, using the Fridericia heart rate-corrected QT interval (QTcF).

RESULTS

All subjects completed Part A (N = 36) and 46 subjects completed Part B. In Part A, all AEs were mild to moderate in severity; no relationship was identified between AE incidence and SNAC dose. SNAC 3.6 g, the maximum investigated SNAC dose, was selected for Part B. There was no unacceptable prolongation of the QTcF interval with SNAC 3.6 g, and assay sensitivity was demonstrated with moxifloxacin as the positive control. There was no significant exposure-response relationship between SNAC concentration and QTcF interval, and no instances of QTc interval > 450 ms or increases > 30 ms.

CONCLUSION

This QT/QTc trial demonstrates that SNAC doses 12-fold higher than the 300 mg dose used in the oral formulation of semaglutide do not cause unacceptable prolongation of the QTcF interval.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT02911870.

Challenges of peptide and protein drug delivery by oral route: Current strategies to improve the bioavailability

Advancement in biotechnology provided a notable expansion of peptide and protein therapeutics, used as antigens, vaccines, hormones. It has a prodigious potential to treat a broad spectrum of diseases such as cancer, metabolic disorders, bone disorders, and so forth. Protein and peptide therapeutics are administered parenterally due to their poor bioavailability and stability, restricting their use. Hence, research focuses on the oral delivery of peptides and proteins for the ease of self-administration. In the present review, we first address the main obstacles in the oral delivery system in addition to approaches used to enhance the stability and bioavailability of peptide/protein. We describe the physiochemical parameters of the peptides and proteins influencing bioavailability in the systemic circulation. It encounters, many barriers affecting its stability, such as poor cellular membrane permeability at the GIT site, enzymatic degradation (various proteases), and first-pass hepatic metabolism. Then describe the current approaches to overcome the challenges mentioned above by the use of absorption enhancers or carriers, structural modification, formulation and advance technology.

Oral GLP1 Gene Delivery by an Antibody-Guided Nanomaterial to Treat Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a chronic and progressive hyperglycemic condition. Glucagon-like peptide-1 (GLP1) is an incretin secreted from pancreatic β-cells and helps to produce insulin to balance the blood glucose level without the risk of hypoglycemia. However, the therapeutic application of GLP1 is limited by its intrinsic short half-life and rapid metabolic clearance in the body. To enhance the antidiabetic effect of GLP1, we designed a human cysteine-modified IgG1-Fc antibody-mediated oral gene delivery vehicle, which helps to produce GLP1 sustainably in the target site with the help of increased half-life of the Fc-conjugated nanocarrier, protects GLP1 from acidic and enzymatic degradation in the gastrointestinal (GI) tract, uptakes and transports the GLP1 formulation through the neonatal Fc receptor (FcRn), and helps to release the GLP1 gene in the intestine. Our formulation could reduce the blood glucose from about an average of 320 mg/dL (hyperglycemic) to 150 mg/dL (normal blood glucose concentration) in diabetic mice, which is about 50% reduction of the total blood glucose concentration. GLP1 (500 μg) complexed with the IgG1-Fc carrier was proven to be the optimal dose for a complete reduction of hyperglycemic conditions in diabetic mice. A significant amount of insulin production and the presence of GLP1 peptide were observed in the pancreatic islets of oral GLP1 formulation-treated diabetic mice in immunohistochemistry analysis compared to nontreated diabetic mice. The orally given formulation was completely nontoxic according to the histopathology analysis of mice organ tissues, and no mice death was observed. Our antibody-mediated oral gene delivery system is a promising tool for various oral therapeutic gene delivery applications to treat diseases like diabetes.

Encapsulation in Polymeric Nanoparticles Enhances the Enzymatic Stability and the Permeability of the GLP-1 Analog, Liraglutide, Across a Culture Model of Intestinal Permeability

The potential of poly (lactic-co-glycolic acid) nanoparticles (PLGA NPs) to overcome the intestinal barrier that limits oral liraglutide delivery was evaluated. Liraglutide-loaded PLGA NPs were prepared by the double emulsion solvent evaporation method. In vitro release kinetics and enzymatic degradation studies were conducted, mimicking the gastrointestinal environment. The permeability of liraglutide solution, liraglutide-loaded PLGA NPs, and liraglutide in the presence of the absorption enhancer PN159 peptide was tested on the Caco-2 cell model. Liraglutide release from PLGA NPs showed a biphasic release pattern with a burst effect of less than 15%. The PLGA nanosystem protected the encapsulated liraglutide from the conditions simulating the gastric environment. The permeability of liraglutide encapsulated in PLGA NPs was 1.5-fold higher (24 × 10⁻⁶ cm/s) across Caco-2 cells as compared to liraglutide solution. PLGA NPs were as effective at elevating liraglutide penetration as the tight junction-opening PN159 peptide. No morphological changes were seen in the intercellular junctions of Caco-2 cells after treatment with liraglutide-PLGA NPs, confirming the lack of a paracellular component in the transport mechanism. PLGA NPs, by protecting liraglutide from enzyme degradation and enhancing its permeability across intestinal epithelium, hold great potential as carriers for oral GLP-1 analog delivery.

Cardiovascular safety of oral semaglutide in patients with type 2 diabetes: Rationale, design and patient baseline characteristics for the PIONEER 6 trial

AIMS

To assess the cardiovascular (CV) safety of oral semaglutide, the first tablet formulation of a glucagon-like peptide-1 receptor agonist.

MATERIALS AND METHODS

PIONEER 6 is a multinational, randomized, placebo-controlled, double-blind trial in patients with type 2 diabetes at high risk of CV events (defined as being aged ≥50 years and having established CV disease [CVD] or moderate [stage 3] chronic kidney disease [CKD], or being aged ≥60 years with ≥1 other CV risk factor). Patients were randomized to once-daily oral semaglutide (up to 14 mg) or placebo added to standard of care. The primary composite endpoint is time to first occurrence of CV death or non-fatal myocardial infarction or non-fatal stroke. The primary hypothesis was to exclude an excess in CV risk with oral semaglutide by assessing non-inferiority versus placebo for the primary endpoint (non-inferiority margin of 1.8 for the upper boundary of the 95% confidence interval of the hazard ratio). PIONEER 6 is event-driven, with follow-up continuing until accrual of at least 122 primary outcome events. There is no pre-defined minimal duration.

RESULTS

Overall, 3183 patients have been enrolled (mean age 66.1 years, 31.6% females) in 214 sites across 21 countries. At baseline, the mean duration of diabetes was 14.9 years, mean glycated haemoglobin concentration was 66 mmol/mol (8.2%), and 84.6% of patients had established CVD/moderate CKD.

CONCLUSIONS

PIONEER 6 will provide evidence regarding the CV safety of oral semaglutide in patients with type 2 diabetes and high CV risk.