Conjugation to albumin-binding molecule tags as a strategy to improve both efficacy and pharmacokinetic properties of the complement inhibitor compstatin

Smart delivery of poly-peptide composite for effective cancer therapy

In the past decade, multifunctional peptides have attracted increasing attention in the biomedical field. Peptides possess many impressive advantages, such as high penetration ability, low cost, and etc. However, the short half-life and instability of peptides limit their application. In this study, a poly-peptide drug loading system (called HKMA composite) was designed based on the different functionalities of four peptides. The peptide compositions of HKMA composite from N-terminal to C-terminal were HCBP1, KLA, matrix metalloproteinase-2 (MMP-2)-cleavable peptide and albumin-binding domain. The targeting and lethality of HKMA to NSCLC cell line H460 sphere cells and the half-life of the system were measuredin vivo. The results showed that the HKMA composite had a long half-life and specific killing effect on H460 sphere cellsin vitroandin vivo. Our result proposed smart peptide drug loading system and provided a potential methodology for effective cancer treatment.

Compstatins: the dawn of clinical C3-targeted complement inhibition

Despite the growing recognition of the complement system as a major contributor to a variety of clinical conditions, the therapeutic arsenal has remained scarce. The introduction of an anti-C5 antibody in 2007 raised confidence in complement-targeted therapy. However, it became apparent that inhibition of late-stage effector generation might not be sufficient in multifactorial complement disorders. Upstream intervention at the level of C3 activation has therefore been considered promising. The approval of pegcetacoplan, a C3 inhibitor of the compstatin family, in 2021 served as critical validation of C3-targeted treatment. This review delineates the evolution of the compstatin family from its academic origins to the clinic and highlights current and potential future applications of this promising drug class in complement diseases.

Targeted Delivery of C/EBPα-saRNA by RNA Aptamers Shows Anti-tumor Effects in a Mouse Model of Advanced PDAC

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive malignancies; it preferentially metastasizes to the liver and is the main cause of death from this disease. In previous studies, small activating RNA against CCAAT/enhancer-binding protein-α (C/EBPα-saRNA) demonstrated efficacy of PDAC in a local subcutaneous tumor model. In this study, we focused on the efficacy of C/EBPα-saRNA in advanced stage PDAC. For targeted delivery, we selected a new anti-transferrin receptor aptamer (TR14), which demonstrated a high binding affinity to target proteins. The TR14 aptamer was internalized with clathrin-mediated endocytosis, distributed in early endosome, late endosome, and lysosome subcellularly. To investigate its anti-tumor effects to advanced PDAC, we conjugated C/EBPα-saRNA to TR14. Treatment of pancreatic cancer cells with the conjugates upregulated expression of C/EBPα and its downstream target p21, and inhibited cell proliferation. For in vivo assays, we established an advanced PDAC mouse model by engrafting luciferase reporter-PANC-1 cells directly into the livers of non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice. After treatment of aptamer-C/EBPα conjugates, we observed significant reduction of tumor growth in this advanced PDAC mouse model. Combinational treatment of the conjugates with gemcitabine also demonstrated enhanced anti-tumor effects in advanced PDAC. This suggests that aptamer-C/EBPα conjugates could be used as an adjuvant, along with other conventional anti-cancer drugs in advanced PDAC. In conclusion, targeted delivery of C/EBPα-saRNAs by aptamers might have potential therapeutic effects in advanced PDAC.

New Analogs of the Complement C3 Inhibitor Compstatin with Increased Solubility and Improved Pharmacokinetic Profile

Improper regulation of complement is associated with various pathologies, and the clinical demand for compounds that can regulate complement activation is therefore imperative. Cp40, an analog of the peptide compstatin, inhibits all complement pathways at the level of the central component C3. We have further developed Cp40, using either PEGylation at the N-terminus or insertion of charged amino acids at the C-terminus. The PEGylated analogs are highly soluble and retained their inhibitory activity, with C3b binding affinity dependent on the length of the PEG chain. The addition of two or three residues of lysine, in turn, not only improved the peptide's solubility but also increased the binding affinity for C3b while retaining its inhibitory potency. Three of the new derivatives showed improved pharmacokinetic profiles in vivo in non-human primates. Given their compelling solubility and pharmacokinetic profiles, these new Cp40 analogs should broaden the spectrum of administration routes, likely reducing dosing frequency during chronic treatment and potentially expanding their range of clinical application.

Evolution of compstatin family as therapeutic complement inhibitors

INTRODUCTION

Therapeutic modulation of complement activation is considered as a promising approach for the treatment of host tissue damage in several inflammatory and autoimmune diseases. Complement component protein C3 is a particularly attractive drug target for complement inhibitors, due to its central role in three pathways of complement activation cascade. Areas covered: The author provides a comprehensive review on compstatin family peptides which have been discovered and optimized as potent and selective C3 inhibitors via a combination of chemical, biophysical and computational approaches. New generations of the compstatin family with improved potency and therapeutic properties have been developed in recent years. Over two decades, compstatin demonstrated therapeutic potential as a first-of-its-kind complement inhibitor in a series of disease models, with encouraging efforts in clinical trials. Expert opinion: Compstatin holds promise for new therapeutic implications in blocking the effect of the complement cascade in a variety of disease conditions. The development of cost-effective treatment options with suitable dosing route and schedule will be critical for patients with complement mediated chronic diseases.

Complement component C3 - The "Swiss Army Knife" of innate immunity and host defense

As a preformed defense system, complement faces a delicate challenge in providing an immediate, forceful response to pathogens even at first encounter, while sparing host cells in the process. For this purpose, it engages a tightly regulated network of plasma proteins, cell surface receptors, and regulators. Complement component C3 plays a particularly versatile role in this process by keeping the cascade alert, acting as a point of convergence of activation pathways, fueling the amplification of the complement response, exerting direct effector functions, and helping to coordinate downstream immune responses. In recent years, it has become evident that nature engages the power of C3 not only to clear pathogens but also for a variety of homeostatic processes ranging from tissue regeneration and synapse pruning to clearing debris and controlling tumor cell progression. At the same time, its central position in immune surveillance makes C3 a target for microbial immune evasion and, if improperly engaged, a trigger point for various clinical conditions. In our review, we look at the versatile roles and evolutionary journey of C3, discuss new insights into the molecular basis for C3 function, provide examples of disease involvement, and summarize the emerging potential of C3 as a therapeutic target.

From orphan drugs to adopted therapies: Advancing C3-targeted intervention to the clinical stage

Complement dysregulation is increasingly recognized as an important pathogenic driver in a number of clinical disorders. Complement-triggered pathways intertwine with key inflammatory and tissue destructive processes that can either increase the risk of disease or exacerbate pathology in acute or chronic conditions. The launch of the first complement-targeted drugs in the clinic has undeniably stirred the field of complement therapeutic design, providing new insights into complement's contribution to disease pathogenesis and also helping to leverage a more personalized, comprehensive approach to patient management. In this regard, a rapidly expanding toolbox of complement therapeutics is being developed to address unmet clinical needs in several immune-mediated and inflammatory diseases. Elegant approaches employing both surface-directed and fluid-phase inhibitors have exploited diverse components of the complement cascade as putative points of therapeutic intervention. Targeting C3, the central hub of the system, has proven to be a promising strategy for developing biologics as well as small-molecule inhibitors with clinical potential. Complement modulation at the level of C3 has recently shown promise in preclinical primate models, opening up new avenues for therapeutic intervention in both acute and chronic indications fueled by uncontrolled C3 turnover. This review highlights recent developments in the field of complement therapeutics, focusing on C3-directed inhibitors and alternative pathway (AP) regulator-based approaches. Translational perspectives and considerations are discussed, particularly with regard to the structure-guided drug optimization and clinical advancement of a new generation of C3-targeted peptidic inhibitors.

New milestones ahead in complement-targeted therapy

The complement system is a powerful effector arm of innate immunity that typically confers protection from microbial intruders and accumulating debris. In many clinical situations, however, the defensive functions of complement can turn against host cells and induce or exacerbate immune, inflammatory, and degenerative conditions. Although the value of inhibiting complement in a therapeutic context has long been recognized, bringing complement-targeted drugs into clinical use has proved challenging. This important milestone was finally reached a decade ago, yet the clinical availability of complement inhibitors has remained limited. Still, the positive long-term experience with complement drugs and their proven effectiveness in various diseases has reinvigorated interest and confidence in this approach. Indeed, a broad variety of clinical candidates that act at almost any level of the complement activation cascade are currently in clinical development, with several of them being evaluated in phase 2 and phase 3 trials. With antibody-related drugs dominating the panel of clinical candidates, the emergence of novel small-molecule, peptide, protein, and oligonucleotide-based inhibitors offers new options for drug targeting and administration. Whereas all the currently approved and many of the proposed indications for complement-targeted inhibitors belong to the rare disease spectrum, these drugs are increasingly being evaluated for more prevalent conditions. Fortunately, the growing experience from preclinical and clinical use of therapeutic complement inhibitors has enabled a more evidence-based assessment of suitable targets and rewarding indications as well as related technical and safety considerations. This review highlights recent concepts and developments in complement-targeted drug discovery, provides an overview of current and emerging treatment options, and discusses the new milestones ahead on the way to the next generation of clinically available complement therapeutics.

Therapeutic control of complement activation at the level of the central component C3

The increasing recognition of the complement system's association with diseases of the inflammatory spectrum and with biomaterial and transplant-related complications has generated growing interest in the therapeutic modulation of this innate immune cascade. As a central functional hub that largely drives the activation, amplification, and effector generation of the complement response, the plasma protein C3 has long been recognized as an attractive target. While pharmacological modulation of C3 activation may offer a powerful opportunity to interfere with or even prevent complement-driven pathologies, the development of C3 inhibitors has often been accompanied by concerns regarding the safety and feasibility of this approach. Although no C3-targeted inhibitors have thus far been approved for clinical use, several promising concepts and candidates have emerged in recent years. At the same time, experiences from preclinical development and clinical trials are slowly providing a more detailed picture of therapeutic complement inhibition at the level of C3. This review highlights the current therapeutic strategies to control C3 activation and discusses the possibilities and challenges on the road to bringing C3-targeted therapeutics to the clinic.

Complement therapeutics in inflammatory diseases: promising drug candidates for C3-targeted intervention

There is increasing appreciation that complement dysregulation lies at the heart of numerous immune-mediated and inflammatory disorders. Complement inhibitors are therefore being evaluated as new therapeutic options in various clinical translation programs and the first clinically approved complement-targeted drugs have profoundly impacted the management of certain complement-mediated diseases. Among the many members of the intricate protein network of complement, the central component C3 represents a 'hot-spot' for complement-targeted therapeutic intervention. C3 modulates both innate and adaptive immune responses and is linked to diverse immunomodulatory systems and biological processes that affect human pathophysiology. Compelling evidence from preclinical disease models has shown that C3 interception may offer multiple benefits over existing therapies or even reveal novel therapeutic avenues in disorders that are not commonly regarded as complement-driven, such as periodontal disease. Using the clinically developed compstatin family of C3 inhibitors and periodontitis as illustrative examples, this review highlights emerging therapeutic concepts and developments in the design of C3-targeted drug candidates as novel immunotherapeutics for oral and systemic inflammatory diseases.

Compstatin: a C3-targeted complement inhibitor reaching its prime for bedside intervention

There is a growing awareness that complement plays an integral role in human physiology and disease, transcending its traditional perception as an accessory system for pathogen clearance and opsonic cell killing. As the list of pathologies linked to dysregulated complement activation grows longer, it has become clear that targeted modulation of this innate immune system opens new windows of therapeutic opportunity for anti-inflammatory drug design. Indeed, the introduction of the first complement-targeting drugs has reignited a vibrant interest in the clinical translation of complement-based inhibitors. Compstatin was discovered as a cyclic peptide that inhibits complement activation by binding C3 and interfering with convertase formation and C3 cleavage. As the convergence point of all activation pathways and a molecular hub for crosstalk with multiple pathogenic pathways, C3 represents an attractive target for therapeutic modulation of the complement cascade. A multidisciplinary drug optimization effort encompassing rational 'wet' and in silico synthetic approaches and an array of biophysical, structural and analytical tools has culminated in an impressive structure-function refinement of compstatin, yielding a series of analogues that show promise for a wide spectrum of clinical applications. These new derivatives have improved inhibitory potency and pharmacokinetic profiles and show efficacy in clinically relevant primate models of disease. This review provides an up-to-date survey of the drug design effort placed on the compstatin family of C3 inhibitors, highlighting the most promising drug candidates. It also discusses translational challenges in complement drug discovery and peptide drug development and reviews concerns related to systemic C3 interception.

Therapeutic C3 inhibitor Cp40 abrogates complement activation induced by modern hemodialysis filters

Approximately 350,000 individuals in the United States rely on maintenance hemodialysis treatment because of end-stage renal disease. Despite improvements in dialysis technology, the mortality rate for patients treated with maintenance dialysis is still exceptionally high, with a 5-year survival rate of only 35%. Many patients succumb to conditions resulting at least in part from the chronic induction of inflammation. Among the triggers of inflammation, the complement system is of particular importance, being a well-appreciated mediator of inflammatory processes that is involved in many pathologic states. Here we used a refined pre-clinical model of hemodialysis in cynomolgus monkeys to confirm that even modern, polymer-based hemodialysis filters activate complement and to evaluate the potential of Cp40, a peptidic C3 inhibitor, to attenuate hemodialysis-induced complement activation. Our data show marked induction of complement activation even after only a single session of hemodialysis. Importantly, complete inhibition of complement activation was achieved in response to two distinct Cp40 treatment regimens. Further, we show that application of Cp40 during hemodialysis resulted in increased levels of the anti-inflammatory cytokine IL-10, indicating that Cp40 may be a potent and cost-effective treatment option for attenuating chronic inflammatory conditions in dialysis-dependent patients.