The therapeutic prospects of N-acetylgalactosamine-siRNA conjugates

Delivery Strategies of siRNA Therapeutics for Hair Loss Therapy

Therapeutic needs for hair loss are intended to find small interfering ribonucleic acid (siRNA) therapeutics for breakthrough. Since naked siRNA is restricted to meet a druggable target in clinic,, delivery systems are indispensable to overcome intrinsic and pathophysiological barriers, enhancing targetability and persistency to ensure safety, efficacy, and effectiveness. Diverse carriers repurposed from small molecules to siRNA can be systematically or locally employed in hair loss therapy, followed by the adoption of new compositions associated with structural and environmental modification. The siRNA delivery systems have been extensively studied via conjugation or nanoparticle formulation to improve their fate in vitro and in vivo. In this review, we introduce clinically tunable siRNA delivery systems for hair loss based on design principles, after analyzing clinical trials in hair loss and currently approved siRNA therapeutics. We further discuss a strategic research framework for optimized siRNA delivery in hair loss from the scientific perspective of clinical translation.

Injectable long-acting formulations (ILAFs) and manufacturing techniques

INTRODUCTION

Most therapeutics delivered using short-acting formulations need repeated administration, which can harm patient compliance and raise failure risks related to inconsistent treatment. Injectable long-acting formulations (ILAFs) are controlled/sustained-release formulations fabricated to deliver active pharmaceutical ingredients (APIs) and extend their half-life over days to months. Longer half-lives of ILAFs minimize the necessity for frequent doses, increase patient compliance, and reduce the risk of side effects from intravenous (IV) infusions. Using ILAF technologies, the immediate drug release can also be controlled, thereby minimizing potential adverse effects due to high initial drug blood concentrations.

AREA COVERED

In this review, we have discussed various ILAFs, their physiochemical properties, fabrication technologies, advantages, and practical issues, as well as address some major challenges in their application. Especially, the approved ILAFs are highlighted.

EXPERT OPINION

ILAFs are sustained-release formulations with extended activity, which can improve patient compliance. ILAFs are designed to deliver APIs like proteins and peptides and extend their half-life over days to months. The specific properties of each ILAF preparation, such as extended-release and improved drug targeting capabilities, make them an effective approach for precise and focused therapy. Furthermore, this is especially helpful for biopharmaceuticals with short biological half-lives and low stability since most environmental conditions can protect them from sustained-release delivery methods.

Exploring nonreplacement therapies' impact on hemophilia and other rare bleeding disorders

The management of hemophilia, von Willebrand disease (VWD), and rare coagulation disorders traditionally relied on replacement therapies, such as factor concentrates, to address clotting factor deficiencies. However, in recent years, the emergence of nonreplacement therapies has shown promise as an adjunctive approach, especially in hemophilia, and also for patients with VWD and rare bleeding disorders. This review article offers an overview of nonreplacement therapies, such as FVIII-mimicking agents and drugs aimed at rebalancing hemostasis by inhibiting natural anticoagulants, particularly in the management of hemophilia. The utilization of nonreplacement therapies in VWD and rare bleeding disorders has recently attracted attention, as evidenced by presentations at the International Society on Thrombosis and Haemostasis 2023 Congress. Nonreplacement therapies provide alternative methods for preventing bleeding episodes and enhancing patients' quality of life, as many of them are administered subcutaneously and allow longer infusion intervals, resulting in improved quality of life and comfort for patients.

Targeted Protein Degraders- The Druggability Perspective

Targeted Protein degraders (TPDs) show promise in harnessing cellular machinery to eliminate disease-causing proteins, even those previously considered undruggable. Especially if protein turnover is low, targeted protein removal bestows lasting therapeutic effect over typical inhibition. The demonstrated safety and efficacy profile of clinical candidates has fueled the surge in the number of potential candidates across different therapeutic areas. As TPDs often do not comply with Lipinski's rule of five, developing novel TPDs and unlocking their full potential requires overcoming solubility, permeability and oral bioavailability challenges. Tailored in-vitro assays are key to precise profiling and optimization, propelling breakthroughs in targeted protein degradation.

Nanoparticles and siRNA: A new era in therapeutics?

Since its discovery in 1998, the use of small interfering RNA (siRNA) has been increasing in biomedical studies because of its ability to very selectively inhibit the expression of any target gene. Thus, siRNAs can be used to generate therapeutic compounds for different diseases, including those that are currently 'undruggable'. This has led siRNA-based therapeutic compounds to break into clinical settings, with them holding the promise to potentially revolutionise therapeutic approaches. To date, the United States Food and Drug Administration (FDA) have approved 5 compounds for treating different diseases including hypercholesterolemia, transthyretin-mediated amyloidosis (which leads to polyneuropathy), hepatic porphyria, and hyperoxaluria. This current article presents an overview of the molecular mechanisms involved in the selective pharmacological actions of siRNA-based compounds. It also describes the ongoing clinical trials of siRNA-based therapeutic compounds for hepatic diseases, pulmonary diseases, atherosclerosis, hypertriglyceridemia, transthyretin-mediated amyloidosis, and hyperoxaluria, kidney diseases, and haemophilia, as well as providing a description of FDA-approved siRNA therapies. Because of space constraints and to provide an otherwise comprehensive review, siRNA-based compounds applied to cancer therapies have been excluded. Finally, we discuss how the use of lipid-based nanoparticles to deliver siRNAs holds promise for selectively targeting mRNA-encoding proteins associated with the genesis of different diseases. Thus, siRNAs can help reduce the cellular levels of these proteins, thereby contributing to disease treatment. As consequence, a marked increase in the number of marketed siRNA-based medicines is expected in the next two decades, which will likely open up a new era of therapeutics.

Drug conjugates for targeting regulatory T cells in the tumor microenvironment: guided missiles for cancer treatment

Within the tumor microenvironment (TME), regulatory T cells (Tregs) play a key role in suppressing anticancer immune responses; therefore, various strategies targeting Tregs are becoming important for tumor therapy. To prevent the side effects of nonspecific Treg depletion, such as immunotherapy-related adverse events (irAEs), therapeutic strategies that specifically target Tregs in the TME are being investigated. Tumor-targeting drug conjugates are efficient drugs in which a cytotoxic payload is assembled into a carrier that binds Tregs via a linker. By allowing the drug to act selectively on target cells, this approach has the advantage of increasing the therapeutic effect and minimizing the side effects of immunotherapy. Antibody-drug conjugates, immunotoxins, peptide-drug conjugates, and small interfering RNA conjugates are being developed as Treg-targeting drug conjugates. In this review, we discuss key themes and recent advances in drug conjugates targeting Tregs in the TME, as well as future design strategies for successful use of drug conjugates for Treg targeting in immunotherapy.

Development of nucleic acid medicines based on chemical technology

Oligonucleotide-based therapeutics have attracted attention as an emerging modality that includes the modulation of genes and their binding proteins related to diseases, allowing us to take action on previously undruggable targets. Since the late 2010s, the number of oligonucleotide medicines approved for clinical uses has dramatically increased. Various chemistry-based technologies have been developed to improve the therapeutic properties of oligonucleotides, such as chemical modification, conjugation, and nanoparticle formation, which can increase nuclease resistance, enhance affinity and selectivity to target sites, suppress off-target effects, and improve pharmacokinetic properties. Similar strategies employing modified nucleobases and lipid nanoparticles have been used for developing coronavirus disease 2019 mRNA vaccines. In this review, we provide an overview of the development of chemistry-based technologies aimed at using nucleic acids for developing therapeutics over the past several decades, with a specific emphasis on the structural design and functionality of chemical modification strategies.

Peptide-Based Nanoparticles for Systemic Extrahepatic Delivery of Therapeutic Nucleotides

Peptide-based nanoparticles (PBN) for nucleotide complexation and targeting of extrahepatic diseases are gaining recognition as potent pharmaceutical vehicles for fine-tuned control of protein production (up- and/or down-regulation) and for gene delivery. Herein, we review the principles and mechanisms underpinning self-assembled formation of PBN, cellular uptake, endosomal release, and delivery to extrahepatic disease sites after systemic administration. Selected examples of PBN that have demonstrated recent proof of concept in disease models in vivo are summarized to offer the reader a comparative view of the field and the possibilities for clinical application.