Injectables and Depots to Prolong Drug Action of Proteins and Peptides

Construction Strategy of Functionalized Liposomes and Multidimensional Application

Liposomes are widely used in the biological field due to their good biocompatibility and surface modification properties. With the development of biochemistry and material science, many liposome structures and their surface functional components have been modified and optimized one by one, pushing the liposome platform from traditional to functionalized and intelligent, which will better satisfy and expand the needs of scientific research. However, a main limiting factor effecting the efficiency of liposomes is the complicated environmental conditions in the living body. Currently, in order to overcome the above problem, functionalized liposomes have become a very promising strategy. In this paper, binding strategies of liposomes with four main functional elements, namely nucleic acids, antibodies, peptides, and stimuli-responsive motif have been summarized for the first time. In addition, based on the construction characteristics of functionalized liposomes, such as drug-carrying, targeting, long-circulating, and stimulus-responsive properties, a comprehensive overview of their features and respective research progress are presented. Finally, the paper critically presents the limitations of these functionalized liposomes in the current applications and also prospectively suggests the future development directions, aiming to accelerate realization of their industrialization.

Unlocking nature's arsenal: Nanotechnology for targeted delivery of venom toxins in cancer therapy

AIM

The aim of the present review is to shed light on the nanotechnological approaches adopted to overcome the shortcomings associated with the delivery of venom peptides which possess inherent anti-cancer properties.

BACKGROUND

Venom peptides although have been reported to demonstrate anti-cancer effects, they suffer from several disadvantages such as in vivo instability, off-target adverse effects, limited drug loading and low bioavailability. This review presents a comprehensive compilation of different classes of nanocarriers while underscoring their advantages, disadvantages and potential to carry such peptide molecules for in vivo delivery. It also discusses various nanotechnological aspects such as methods of fabrication, analytical tools to assess these nanoparticulate formulations, modulation of nanocarrier polymer properties to enhance loading capacity, stability and improve their suitability to carry toxic peptide drugs.

CONCLUSION

Nanotechnological approaches bear great potential in delivering venom peptide-based molecules as anticancer agents by enhancing their bioavailability, stability, efficacy as well as offering a spatiotemporal delivery approach. However, the challenges associated with toxicity and biocompatibility of nanocarriers must be duly addressed.

PERSPECTIVES

The everlasting quest for new breakthroughs for safer delivery of venom peptides in human subjects is fuelled by unmet clinical needs in the current landscape of chemotherapy. In addition, exhaustive efforts are required in obtaining and purifying the venom peptides followed by designing and optimizing scale up technologies.

Polyethylene Glycol-Based Polymer-Drug Conjugates: Novel Design and Synthesis Strategies for Enhanced Therapeutic Efficacy and Targeted Drug Delivery

Due to their potential to enhance therapeutic results and enable targeted drug administration, polymer-drug conjugates that use polyethylene glycol (PEG) as both the polymer and the linker for drug conjugation have attracted much research. This study seeks to investigate recent developments in the design and synthesis of PEG-based polymer-drug conjugates, emphasizing fresh ideas that fill in existing knowledge gaps and satisfy the increasing need for more potent drug delivery methods. Through an extensive review of the existing literature, this study identifies key challenges and proposes innovative strategies for future investigations. The paper presents a comprehensive framework for designing and synthesizing PEG-based polymer-drug conjugates, including rational molecular design, linker selection, conjugation methods, and characterization techniques. To further emphasize the importance and adaptability of PEG-based polymer-drug conjugates, prospective applications are highlighted, including cancer treatment, infectious disorders, and chronic ailments.

Biological importance of arginine: A comprehensive review of the roles in structure, disorder, and functionality of peptides and proteins

Arginine shows Jekyll and Hyde behavior in several respects. It participates in protein folding via ionic and H-bonds and cation-pi interactions; the charge and hydrophobicity of its side chain make it a disorder-promoting amino acid. Its methylation in histones; RNA binding proteins; chaperones regulates several cellular processes. The arginine-centric modifications are important in oncogenesis and as biomarkers in several cardiovascular diseases. The cross-links involving arginine in collagen and cornea are involved in pathogenesis of tissues but have also been useful in tissue engineering and wound-dressing materials. Arginine is a part of active site of several enzymes such as GTPases, peroxidases, and sulfotransferases. Its metabolic importance is obvious as it is involved in production of urea, NO, ornithine and citrulline. It can form unusual functional structures such as molecular tweezers in vitro and sprockets which engage DNA chains as part of histones in vivo. It has been used in design of cell-penetrating peptides as drugs. Arginine has been used as an excipient in both solid and injectable drug formulations; its role in suppressing opalescence due to liquid-liquid phase separation is particularly very promising. It has been known as a suppressor of protein aggregation during protein refolding. It has proved its usefulness in protein bioseparation processes like ion-exchange, hydrophobic and affinity chromatographies. Arginine is an amino acid, whose importance in biological sciences and biotechnology continues to grow in diverse ways.

Bioconjugation Techniques for Enhancing Stability and Targeting Efficiency of Protein and Peptide Therapeutics

Bioconjugation techniques have emerged as powerful tools for enhancing the stability and targeting efficiency of protein and peptide therapeutics. This review provides a comprehensive analysis of the various bioconjugation strategies employed in the field. The introduction highlights the significance of bioconjugation techniques in addressing stability and targeting challenges associated with protein and peptide-based drugs. Chemical and enzymatic bioconjugation methods are discussed, along with crosslinking strategies for covalent attachment and site-specific conjugation approaches. The role of bioconjugation in improving stability profiles is explored, showcasing case studies that demonstrate successful stability enhancement. Furthermore, bioconjugation techniques for ligand attachment and targeting are presented, accompanied by examples of targeted protein and peptide therapeutics. The review also covers bioconjugation approaches for prolonging circulation and controlled release, focusing on strategies to extend half-life, reduce clearance, and design-controlled release systems. Analytical characterization techniques for bioconjugates, including the evaluation of conjugation efficiency, stability, and assessment of biological activity and targeting efficiency, are thoroughly examined. In vivo considerations and clinical applications of bioconjugated protein and peptide therapeutics, including pharmacokinetic and pharmacodynamic considerations, as well as preclinical and clinical developments, are discussed. Finally, the review concludes with an overview of future perspectives, emphasizing the potential for novel conjugation methods and advanced targeting strategies to further enhance the stability and targeting efficiency of protein and peptide therapeutics.

Advanced Formulation Approaches for Proteins

Proteins and peptides are highly desirable as therapeutic agents, being highly potent and specific. However, there are myriad challenges with processing them into patient-friendly formulations: they are often unstable and have a tendency to aggregate or degrade upon storage. As a result, the vast majority of protein actives are delivered parenterally as solutions, which has a number of disadvantages in terms of cost, accessibility, and patient experience. Much work has been undertaken to develop new delivery systems for biologics, but to date this has led to relatively few products on the market. In this chapter, we review the challenges faced when developing biologic formulations, discuss the technologies that have been explored to try to overcome these, and consider the different delivery routes that can be applied. We further present an overview of the currently marketed products and assess the likely direction of travel in the next decade.

Stimuli-Responsive Hydrogels for Protein Delivery

Proteins and peptides are potential therapeutic agents, but their physiochemical properties make their use as drug substances challenging. Hydrogels are hydrophilic polymeric networks that can swell and retain high amounts of water or biological fluids without being dissolved. Due to their biocompatibility, their porous structure, which enables the transport of various peptides and proteins, and their protective effect against degradation, hydrogels have gained prominence as ideal carriers for these molecules' delivery. Particularly, stimuli-responsive hydrogels exhibit physicochemical transitions in response to subtle modifications in the surrounding environment, leading to the controlled release of entrapped proteins or peptides. This review is focused on the application of these hydrogels in protein and peptide delivery, including a brief overview of therapeutic proteins and types of stimuli-responsive polymers.

Recent advances in lipid-based long-acting injectable depot formulations

Long-acting injectable (LAIs) delivery systems sustain the drug therapeutic action in the body, resulting in reduced dosage regimen, toxicity, and improved patient compliance. Lipid-based depots are biocompatible, provide extended drug release, and improve drug stability, making them suitable for systemic and localized treatment of various chronic ailments, including psychosis, diabetes, hormonal disorders, arthritis, ocular diseases, and cancer. These depots include oil solutions, suspensions, oleogels, liquid crystalline systems, liposomes, solid lipid nanoparticles, nanostructured lipid carriers, phospholipid phase separation gel, vesicular phospholipid gel etc. This review summarizes recent advancements in lipid-based LAIs for delivering small and macromolecules, and their potential in managing chronic diseases. It also provides an overview of the lipid depots available in market or clinical phase, as well as patents for lipid-based LAIs. Furthermore, this review critically discusses the current scenario of using in vitro release methods to establish IVIVC and highlights the challenges involved in developing lipid-based LAIs.

Alginate-Based Oral Delivery Systems to Enhance Protection, Release, and Absorption of Catalase

Oxidative stress, overproduction of reactive oxygen species (ROS), plays an important role in the development of inflammatory bowel diseases. Catalase has great therapeutic potential by scavenging hydrogen peroxide, one of the ROSs produced in cellular metabolisms. However, in vivo application to scavenge ROS is currently limited especially in oral administrations. Here, we introduced an alginate-based oral drug delivery system that effectively protected catalase from the simulated harsh conditions of the gastrointestinal (GI) tract, released it in the small intestine mimicked condition, and enhanced its absorption via M cells, highly specialized epithelium cells in the small intestine. First of all, catalase was encapsulated in alginate-based microparticles with different amounts of polygalacturonic acid or pectin, which achieved an encapsulation efficiency of more than 90%. It was further shown that catalase was released from alginate-based microparticles in a pH-dependent manner. Results indicated that alginate-polygalacturonic acid microparticles (60 wt % Alg:40 wt % Gal) released 79.5 ± 2.4% of encapsulated catalase at pH 9.1 in 3 h, while they only released 9.2 ± 1.5% of encapsulated catalase at pH 2.0. Even when catalase was encapsulated in microparticles (60 wt % Alg:40 wt % Gal) and exposed to pH 2.0 followed by pH 9.1, it still retained 81.0 ± 11.3% enzyme activity compared to that in microparticles prior to the pH treatment. We then investigated the efficiency of RGD conjugation to catalase on the catalase uptake by M-like cells, the coculturing of human epithelial colorectal adenocarcinoma; Caco-2 cells and B lymphocyte; Raji cells. RGD-catalase protected M-cells more efficiently from the cytotoxicity of H₂O₂, a typical ROS. RGD conjugation to catalase enhanced the uptake by M-cells with 87.6 ± 0.8% RGD-catalase, whereas 11.5 ± 9.2% of RGD-free catalase passed across M-cells. From the results of protection, release, and absorption of model therapeutic proteins from the harsh pH conditions, alginate-based oral drug delivery systems will have numerous applications for the controlled release of drugs that are easily degradable in the GI tract.

Non-Covalent Albumin Ligands in FDA-Approved Therapeutic Peptides and Proteins

An increasing number of drugs that consist of a therapeutic peptide or protein linked to an albumin-binding structure are being approved. In this perspective, the pharmacokinetic data of currently marketed drugs of this type will be presented. Acylation with fatty acids or fatty α,ω-dicarboxylic acids has been used successfully to prepare long-acting analogs of insulin, GLP-1, and other peptides but not of larger proteins. With a tetrazole-sulfonylamide fatty acid bioisostere, it has now been possible to prepare a long-acting analog of human growth hormone (191 amino acids), which is suitable for once-weekly administration.

Co-delivery of an HIV prophylactic and contraceptive using PGSU as a long-acting multipurpose prevention technology

OBJECTIVES

Poly(glycerol sebacate) urethane (PGSU) elastomers formulated with 4'-ethynyl-2-fluoro-2'-deoxyadenosine (EFdA), levonorgestrel (LNG), or a combination thereof can function as multipurpose prevention technology implants for prophylaxis against HIV and unintended pregnancies. For these public health challenges, long-acting drug delivery technologies may improve patient experience and adherence. Traditional polymers encounter challenges delivering multiple drugs with dissimilar physiochemical properties. PGSU offers an alternative option that successfully delivers hydrophilic EFdA alongside hydrophobic LNG.

METHODS

This article presents the formulation, design, and characterization of PGSU implants, highlighting the impact of API loading, dimensions, and individual- versus combination-loading on release rates.

RESULTS

Co-delivery of hydrophilic EFdA alongside hydrophobic LNG acted as a porogen to accelerate LNG release. Increasing the surface area of LNG-only implants increased LNG release. All EFdA-LNG, EFdA-only, and LNG-only formulated implants demonstrated low burst release and linear release kinetics over 245 or 122 days studied to date.

CONCLUSION

PGSU co-delivers two APIs for HIV prevention and contraception at therapeutically relevant concentrations in vitro from a single bioresorbable, elastomeric implant. A new long-acting polymer technology, PGSU demonstrates linear-release kinetics, dual delivery of APIs with disparate physiochemical properties, and biocompatibility through long-term subcutaneous implantation. PGSU can potentially meet the demands of complex MPT or fixed-dose combination products, where better solutions can serve and empower patients.

Advanced Strategies of Drug Delivery via Oral, Topical, and Parenteral Administration Routes: Where Do Equine Medications Stand?

While the global market for veterinary products has been expanding rapidly, there is still a lack of specialist knowledge of equine pharmaceutics. In many cases, the basic structure of the gastrointestinal tract (GIT) and integumentary system of the horse shares similarities with those of humans. Generally, the dosage form developed for humans can be repurposed to deliver equine medications; however, due to physiological variation, the therapeutic outcomes can be unpredictable. This is an area that requires more research, as there is a clear deficiency in literature precedence on drug delivery specifically for horses. Through a careful evaluation of equine anatomy and physiology, novel drug delivery systems (NDDSs) can be developed to adequately address many of the medical ailments of the horse. In addition to this, there are key considerations when delivering oral, topical, and parenteral drugs to horses, deriving from age and species variation. More importantly, NDDSs can enhance the duration of action of active drugs in animals, significantly improving owner compliance; and ultimately, enhancing the convenience of product administration. To address the knowledge gap in equine pharmaceutical formulations, this paper begins with a summary of the anatomy and physiology of the equine gastrointestinal, integumentary, and circulatory systems. A detailed discussion of potential dosage-form related issues affecting horses, and how they can be overcome by employing NDDSs is presented.

Basic Salt Additives Modulate the Acidic Microenvironment Around In Situ Forming Implants

There is a growing number of protein drugs, yet their limited oral bioavailability requires that patients receive frequent, high dose injections. In situ forming implants (ISFIs) for controlled release of biotherapeutics have the potential to greatly reduce the injection frequency and improve patient compliance. However, protein release from ISFIs is a challenge due to their proclivity for instability. Specifically, factors such as the acidic microclimate within ISFIs can lead to protein aggregation and denaturation. Basic salts have been shown in PLGA microparticle and microcylinder formulations to significantly reduce protein instability by neutralizing this acidic environment. The overall objective of the study was to demonstrate that basic salts can be used with an ISFI system to neutralize the implant acidification. To this end, the basic salts MgCO3 and Mg(OH)2 were added to a protein-releasing ISFI and the effect on drug release, pH, implant swelling, implant diffusivity, and implant erosion were evaluated. Either salt added at 3 wt% neutralized the acidic environment surrounding the implants, keeping the pH at 6.64 ± 0.03 (MgCO₃) and 6.46 ± 0.11 (Mg(OH)₂) after 28 day compared to 3.72 ± 0.05 with no salts added. The salts initially increased solution uptake into the implants but delayed implant degradation and erosion. The 3 wt% Mg(OH)₂ formulation also showed slightly improved drug release with a lower burst and increased slope. We showed that salt additives can be an effective way to modulate the pH in the ISFI environment, which can improve protein stability and ultimately improve the capacity of ISFIs for delivering pH-sensitive biomolecules. Such a platform represents a low-cost method of improving overall patient compliance and reducing the overall healthcare burden.

Translational aspect in peptide drug discovery and development: An emerging therapeutic candidate

In the last two decades, protein-protein interactions (PPIs) have been used as the main target for drug development. However, with larger or superficial binding sites, it has been extremely difficult to disrupt PPIs with small molecules. On the other hand, intracellular PPIs cannot be targeted by antibodies that cannot penetrate the cell membrane. Peptides that have a combination of conformational rigidity and flexibility can be used to target difficult binding interfaces with appropriate binding affinity and specificity. Since the introduction of insulin nearly a century ago, more than 80 peptide drugs have been approved to treat a variety of diseases. These include deadly diseases such as cancer and human immunodeficiency virus infection. It is also useful against diabetes, chronic pain, and osteoporosis. Today, more research is being done on these drugs as lessons learned from earlier approaches, which are still valid today, complement newer approaches such as peptide display libraries. At the same time, integrated genomics and peptide display libraries are new strategies that open new avenues for peptide drug discovery. The purpose of this review is to examine the problems in elucidating the peptide-protein recognition mechanism. This is important to develop peptide-based interventions that interfere with endogenous protein interactions. New approaches are being developed to improve the binding affinity and specificity of existing approaches and to develop peptide agents as potentially useful drugs. We also highlight the key challenges that must be overcome in peptide drug development to realize their potential and provide an overview of recent trends in peptide drug development. In addition, we take an in-depth look at early efforts in human hormone discovery, smart medicinal chemistry and design, natural peptide drugs, and breakthrough advances in molecular biology and peptide chemistry.

Nanomedicine based potentially transformative strategies for colon targeting of peptides: State-of-the-art

Recently, peptides have attracted tremendous attention among researchers attributed to their high target specificity and efficacy compared to conventional therapeutics. The ease of self-administration and non-invasiveness confers oral as the most desirable route. However, numerous challenges associated with peptide delivery through the oral route like harsh gastrointestinal environment, enzymatic degradation, and absorption barriers hinder its clinical translation. Protease activity is more pronounced in the proximal segments of the gastrointestinal tract (GIT). Distal segments like the colon possess lower proteolytic activity, enhanced retention time, etc. which could facilitate easy absorption. However, traversing of the upper segments to reach the colon requires the circumvention of the pitfalls of the GIT. The advent of nanomedicine strategies could help in overcoming the said challenges associated with oral delivery, colon-specific targeting, and improving stability and bioavailability at the active site. Furthermore, the classification of peptides and various nanomedicine strategies for oral delivery of peptides to the colon has been conveyed. Regulatory hurdles and ways to accomplish clinical translation have been addressed.

Recombinant Spider Silk Bioinks for Continuous Protein Release by Encapsulated Producer Cells

Targeted therapies using biopharmaceuticals are of growing clinical importance in disease treatment. Currently, there are several limitations of protein-based therapeutics (biologicals), including suboptimal biodistribution, lack of stability, and systemic side effects. A promising approach to overcoming these limitations could be a therapeutic cell-loaded 3D construct consisting of a suitable matrix component that harbors producer cells continuously secreting the biological of interest. Here, the recombinant spider silk proteins eADF4(C16), eADF4(C16)-RGD, and eADF4(C16)-RGE have been processed together with HEK293 producer cells stably secreting the highly traceable reporter biological TNFR2-Fc-GpL, a fusion protein consisting of the extracellular domain of TNFR2, the Fc domain of human IgG1, and the luciferase of Gaussia princeps as a reporter domain. eADF4(C16) and eADF4(C16)-RGD hydrogels provide structural and mechanical support, promote HEK293 cell growth, and allow fusion protein production by the latter. Bioink-captured HEK293 producer cells continuously release functional TNFR2-Fc-GpL over 14 days. Thus, the combination of biocompatible, printable spider silk bioinks with drug-producing cells is promising for generating implantable 3D constructs for continuous targeted therapy.

Subcutaneous Catabolism of Peptide Therapeutics: Bioanalytical Approaches and ADME Considerations

Many peptide drugs such as insulin and glucagon-like peptide (GLP-1) analogues are successfully administered subcutaneously (SC). Following SC injection, peptides may undergo catabolism in the SC compartment before entering systemic circulation, which could compromise their bioavailability and in turn affect their efficacy.This review will discuss how both technology and strategy have evolved over the past years to further elucidate peptide SC catabolism.Modern bioanalytical technologies (particularly liquid chromatography-high-resolution mass spectrometry) and bioinformatics platforms for data mining has prompted the development of in silico, in vitro and in vivo tools for characterizing peptide SC catabolism to rapidly address proteolytic liabilities and, ultimately, guide the design of peptides with improved SC bioavailability.More predictive models able to recapitulate the interplay between SC catabolism and other factors driving SC absorption are highly desirable to improve in vitro/in vivo correlations.We envision the routine incorporation of in vitro and in vivo SC catabolism studies in ADME screening funnels to develop more effective peptide drugs for SC delivery.

Application of Elastin-Like Polypeptide in Tumor Therapy

Simple Summary

Elastin-like Polypeptide (ELP) are widely applied in protein purification, drug delivery, tissue engineering, and even tumor therapy. Recent studies show that usage of ELP has made great progress in combination with peptide drugs or antibody drugs. The combination of ELP and photosensitizer in cancer therapy or imaging has made more progress and needs to be summarized. In this review, we summarize the specific application of ELP in cancer therapy, especially the latest developments in the combined use of ELP with photosensitizers. We seek to provide the most recent understanding of ELP and its new application in combination with Photosensitizer.

Abstract

Elastin-like polypeptides (ELPs) are stimulus-responsive artificially designed proteins synthesized from the core amino acid sequence of human tropoelastin. ELPs have good biocompatibility and biodegradability and do not systemically induce adverse immune responses, making them a suitable module for drug delivery. Design strategies can equip ELPs with the ability to respond to changes in temperature and pH or the capacity to self-assemble into nanoparticles. These unique tunable biophysicochemical properties make ELPs among the most widely studied biopolymers employed in protein purification, drug delivery, tissue engineering and even in tumor therapy. As a module for drug delivery and as a carrier to target tumor cells, the combination of ELPs with therapeutic drugs, antibodies and photo-oxidation molecules has been shown to result in improved pharmacokinetic properties (prolonged half-life, drug targeting, cell penetration and controlled release) while restricting the cytotoxicity of the drug to a confined infected site. In this review, we summarize the latest developments in the application methods of ELP employed in tumor therapy, with a focus on its conjugation with peptide drugs, antibodies and photosensitizers.

The industrial design, translation, and development strategies for long-acting peptide delivery

INTRODUCTION

Peptides are widely recognized as therapeutic agents in the treatment of a wide range of diseases, such as cancer, diabetes etc. However, their use has been limited by their short half-life, due to significant metabolism by exo- and endo-peptidases as well as their inherent poor physical and chemical stability. Research with the aim of improving their half-life in the body, and thus improving patient compliance (by decreasing the frequency of injections) has gained significant attention.

AREAS COVERED

This review outlines the current landscape and industrial approaches to achieve extended peptide exposure and reduce dosing frequency. Emphasis is placed on identifying challenges in drug product manufacturing and desirable critical quality attributes that are essential for activity and safety, providing insights into chemistry and design aspects impacting peptide release, and summarizing important considerations for CMC developability assessments of sustained release peptide drugs.

EXPERT OPINION

Bring the patient and disease perspective early into development. Substantial advances have been made in the field of sustained delivery of peptides despite their complexity. The article will also highlight considerations for early-stage product design and development, providing an industrial perspective on risk mitigation in developing sustained release peptide drug products.

Hyaluronic Acid-Based Nanomaterials as a New Approach to the Treatment and Prevention of Bacterial Infections

Bacterial contamination of medical devices is a great concern for public health and an increasing risk for hospital-acquired infections. The ongoing increase in antibiotic-resistant bacterial strains highlights the urgent need to find new effective alternatives to antibiotics. Hyaluronic acid (HA) is a valuable polymer in biomedical applications, partly due to its bactericidal effects on different platforms such as contact lenses, cleaning solutions, wound dressings, cosmetic formulations, etc. Because the pure form of HA is rapidly hydrolyzed, nanotechnology-based approaches have been investigated to improve its clinical utility. Moreover, a combination of HA with other bactericidal molecules could improve the antibacterial effects on drug-resistant bacterial strains, and improve the management of hard-to-heal wound infections. This review summarizes the structure, production, and properties of HA, and its various platforms as a carrier in drug delivery. Herein, we discuss recent works on numerous types of HA-based nanoparticles to overcome the limitations of traditional antibiotics in the treatment of bacterial infections. Advances in the fabrication of controlled release of antimicrobial agents from HA-based nanosystems can allow the complete eradication of pathogenic microorganisms.

Matrikines as mediators of tissue remodelling

Extracellular matrix (ECM) proteins confer biomechanical properties, maintain cell phenotype and mediate tissue repair (via release of sequestered cytokines and proteases). In contrast to intracellular proteomes, where proteins are monitored and replaced over short time periods, many ECM proteins function for years (decades in humans) without replacement. The longevity of abundant ECM proteins, such as collagen I and elastin, leaves them vulnerable to damage accumulation and their host organs prone to chronic, age-related diseases. However, ECM protein fragmentation can potentially produce peptide cytokines (matrikines) which may exacerbate and/or ameliorate age- and disease-related ECM remodelling. In this review, we discuss ECM composition, function and degradation and highlight examples of endogenous matrikines. We then critically and comprehensively analyse published studies of matrix-derived peptides used as topical skin treatments, before considering the potential for improvements in the discovery and delivery of novel matrix-derived peptides to skin and internal organs. From this, we conclude that while the translational impact of matrix-derived peptide therapeutics is evident, the mechanisms of action of these peptides are poorly defined. Further, well-designed, multimodal studies are required.

A New Approach to Supramolecular Structure Determination in Pharmaceutical Preparation of Self-Assembling Peptides: A Case Study of Lanreotide Autogel

The supramolecular structure in peptides’ prolonged-released gel formulations is the most critical parameter for the determination of the pharmaceutical profile of the drug. Here, we report our investigation on lanreotide Autogel as a case study. For the first time, we describe the use of the pulsed field gradient (PFG) diffusion-ordered spectroscopy (DOSY) magic-angle spinning NMR to characterize the supramolecular self-assembly and molecular mobility of different samples of lanreotide Autogel formulations prepared according to different formulation protocols. The diffusion coefficient was used to calculate the hydrodynamic radii of supramolecular assemblies and build relative molecular models. DOSY data were integrated with NMR imaging (MRI) measurements and atomic force microscopy (AFM) imaging.

Metronomic Anti-Cancer Therapy: A Multimodal Therapy Governed by the Tumor Microenvironment

Simple Summary

Metronomic chemotherapy with different mechanisms of action against cancer cells and their microenvironment represents an exceptional holistic cancer treatment. Each type of tumor has its own characteristics, including each individual tumor in each patient. Understanding the complexity of the dynamic interactions that take place between tumor and stromal cells and the microenvironment in tumor progression and metastases, as well as the response of the host and the tumor itself to anticancer therapy, will allow therapeutic actions with long-lasting effects to be implemented using metronomic regimens. This study aims to highlight the complexity of cellular interactions in the tumor microenvironment and summarize some of the preclinical and clinical results that explain the multimodality of metronomic therapy, which, together with its low toxicity, supports an inhibitory effect on the primary tumor and metastases. We also highlight the possible use of nano-therapeutic agents as good partners for metronomic chemotherapy.

Abstract

The concept of cancer as a systemic disease, and the therapeutic implications of this, has gained special relevance. This concept encompasses the interactions between tumor and stromal cells and their microenvironment in the complex setting of primary tumors and metastases. These factors determine cellular co-evolution in time and space, contribute to tumor progression, and could counteract therapeutic effects. Additionally, cancer therapies can induce cellular and molecular responses in the tumor and host that allow them to escape therapy and promote tumor progression. In this study, we describe the vascular network, tumor-infiltrated immune cells, and cancer-associated fibroblasts as sources of heterogeneity and plasticity in the tumor microenvironment, and their influence on cancer progression. We also discuss tumor and host responses to the chemotherapy regimen, at the maximum tolerated dose, mainly targeting cancer cells, and a multimodal metronomic chemotherapy approach targeting both cancer cells and their microenvironment. In a combination therapy context, metronomic chemotherapy exhibits antimetastatic efficacy with low toxicity but is not exempt from resistance mechanisms. As such, a better understanding of the interactions between the components of the tumor microenvironment could improve the selection of drug combinations and schedules, as well as the use of nano-therapeutic agents against certain malignancies.

Nanocarriers for oral delivery of biologics: small carriers for big payloads

Macromolecular therapeutics of biological origin, also known as biologics, have become one of the fastest-growing classes of drugs for management of a range of chronic and acute conditions. The majority of approved biologics are administered via the parenteral route and are thus expensive, have low patient compliance, and have high systemic toxicity. Therefore, tremendous efforts have been devoted to the development of carriers for oral delivery of biologics. This review evaluates key chemical (e.g. pH and enzymes) and physiological challenges to oral biologics delivery. We review the conventional formulation strategies and their limitations, followed by a detailed account of the progress on the use of nanocarriers used for oral biologics delivery, covering organic and inorganic nanocarriers. Lastly, we discuss limitations and opportunities presented by these emerging nanomaterials in oral biologics delivery.

Attenuation of the Reaction of Michael Acceptors with Biologically Important Nucleophiles

β-Elimination of drugs tethered to macromolecular carbamates provides a platform for drug half-life extension. However, the macromolecular Michael acceptor products formed upon drug release can potentially react with biological amines and thiols and may raise concerns about safety. We desired to mitigate this possibility by developing linkers that have predictable rates of β-elimination but suppressed rates of nucleophilic addition to their Michael acceptor products. We prepared Michael acceptor products of β-eliminative linkers that contained a methyl group at the Cβ carbon or a gem-dimethyl group at the Cγ carbon and studied the kinetics of their reactions with the most prevalent biological nucleophiles-amine and thiol groups. Aza-Michael reactions with glycine are slowed about 20-fold by methylation of the β-carbon and 175-fold with a gem-dimethyl group at the γ-carbon. Likewise, addition of the glutathione thiol to γ-gem-dimethyl Michael acceptors was retarded 7-24-fold compared to parent unsubstituted linkers. It was estimated that in an in vivo environment of ∼0.5 mM macromolecular thiols or ∼20 mM macromolecular amines-as in plasma-the reaction half-life of a typical Michael acceptor with a γ-gem-dimethyl linker could exceed 3 years for thiols or 25 years for amines. We also prepared a large series of γ-gem-dimethyl β-eliminative linkers and showed excellent structure-activity relationships of elimination rates with corresponding unsubstituted parent linkers. Finally, we compared the first-generation unsubstituted and new gem-dimethyl β-eliminative linkers in a once-monthly drug delivery system of a 39 amino acid peptide. Both linkers provided the desired half-life extension of the peptide, but the Michael acceptor formed from the gem-dimethyl linker was much less reactive. We conclude that the γ-gem-dimethyl β-eliminative linkers provide high flexibility and greatly reduce potential reactions of Michael acceptor products with biologically important nucleophiles.