Randomized clinical study of safety, pharmacokinetics, and pharmacodynamics of RIPK1 inhibitor GSK2982772 in healthy volunteers

Discovery of phenylisoxazolidine analogs targeting receptor interacting protein kinase 1 with anti-inflammatory activity

Receptor Interacting Protein Kinase1 (RIPK1) is a key regulator of necroptosis and plays an important role in various inflammatory signaling and cell death processes. GSK963 has been reported to inhibit RIPK1 with limited anti-necroptotic effect. We designed and prepared a series of phenylisoxazolidine analogs based on GSK963 to improve their anti-necroptotic activity. After several turns of structure activity relationship (SAR) studies, compound 22, encoded with KWML-22, was found to have good anti-necroptotic activity (EC50 = 30.0 nM) and enzymatic activity (IC50 = 6.9 nM) against RIPK1. In a TNF-α-induced inflammation in vivo model, a dose of 10 mg/kg protected mice from hypothermia and death. Our results suggest that 22 is a promising lead compound for the study of inflammatory diseases.

Safety, Pharmacokinetics and Target Engagement of a Novel Brain Penetrant RIPK1 Inhibitor (SIR9900) in Healthy Adults and Elderly Participants

Receptor-interacting serine/threonine kinase 1 (RIPK1) regulates inflammatory signaling and induces apoptosis and necroptosis. Pharmacological inhibition of RIPK1 kinase activity has demonstrated efficacy in animal models of neurodegenerative, autoimmune and inflammatory diseases. SIR9900 is a potent and selective novel small molecule RIPK1 inhibitor. This first-in-human, phase I, randomized, double-blind, placebo-controlled study evaluated the safety, pharmacokinetics, and pharmacodynamics of single (3-200 mg) and multiple (3-60 mg daily for 10 days) ascending oral doses of SIR9900 in healthy adult (18-64 years, n = 80) and elderly participants (≥ 65 years, multiple doses 30 mg, n = 8). The study included a food effect component. Overall, SIR9900 was safe and well tolerated with no concerning dose-dependent trends in safety observed. SIR9900 was rapidly absorbed with a plasma maximum concentration time (Tmax) of 3.0-4.0 h and plasma half-life (t1/2) of 31.92-37.75 h following single doses. Similar Tmax and t1/2 results were observed following multiple doses. Systemic exposure to SIR9900 increased in a dose-proportional manner and was similar between adult and elderly participants. No appreciable food effect was observed. The cerebrospinal fluid to unbound plasma ratio was 1.15. A robust pharmacodynamic effect was demonstrated with approximately 90% peripheral target engagement at 3 h post-dose, and sustained RIPK1 inhibition over the 10-day treatment period. The promising safety, pharmacokinetic, and pharmacodynamic profile of SIR9900 with central nervous system penetrating potential in healthy adult and elderly participants supports its further clinical development in patients with inflammatory and degenerative diseases, particularly in the central nervous system.

RIPK1 expression and inhibition in tauopathies: implications for neuroinflammation and neuroprotection

Tauopathies are a group of neurodegenerative diseases characterized by the alteration/aggregation of TAU protein. One of the main challenges of these diseases is that they have neither biomarkers nor pharmacological targets to stop the neurodegenerative process. Apart from the neurodegenerative process, tauopathies are also characterized by a chronic low-grade neuroinflammation process, where the receptor-interacting protein kinase 1 (RIPK1) protein plays an essential role. Our research aimed to explore the role of RIPK1 in various tauopathies. We examined mouse models of frontotemporal dementia (FTD), as well as brain tissue samples from patients with progressive supranuclear palsy (PSP), a primary form of 4R tauopathy, and Alzheimer's disease (AD), which is considered a secondary tauopathy. Our findings show elevated levels of RIPK1 mRNA levels across various forms of tauopathies, in both mouse models and human tissue samples associated with primary and secondary TAU-related disorders. Furthermore, we investigated the potential of using a RIPK1 inhibitor, known as GSK2982772, in a mouse model as a novel treatment strategy for FTD. The data showed that GSK2982772 treatment effectively reduced the reactive astrocyte response triggered by TAUP301L overexpression. However, this RIPK1 inhibitor failed to protect against the neurodegeneration caused by elevated TAUP301L levels in the hippocampal region. These results suggest that although inhibiting RIPK1 activity may help reduce TAU-related astrogliosis in the brain, the complexity of the inflammatory pathways involved could explain the absence of neuroprotective effects against TAU-induced neurodegeneration.

Unraveling the role of RIPKs in diabetic kidney disease and its therapeutic perspectives

Nephropathy is the microvascular complication of diabetes mellitus and is the leading cause of chronic kidney disease. This review discusses the implications of receptor-interacting protein kinase (RIPK) family members and their regulation of inflammation and cell death pathways in the initiation and progression of diabetic kidney disease. Hyperglycemia leads to reactive oxygen species (ROS) generation and RIPK1 overexpression, the first regulator of necroptosis. Further, RIPK1 can form complex I to promote nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB) and mitogen-activated protein kinase (MAPK) pathway activation or complex II to cause programmed cell death in the kidneys. The rise in RIPK1 level upon ROS generation declines the apoptosis regulators' level while the necroptosis regulators' level is boosted. Necroptosis is a programmed or controlled necrosis-type cell death pathway executed by RIPK1, RIPK3, and mixed lineage kinase domain-like (MLKL) proteins, and recent research suggests its importance in diabetic nephropathy. In necroptosis, RIPK1 and RIPK3 interrelate with their RIP homotypic interaction motif (RHIM) domains and cause the recruitment of MLKL. Next, MLKL gets oligomerized, migrate towards the plasma membrane, and causes its rupture. We emphasized different research studies on drugs highlighting the nephroprotective effects via regulating the RIPKs. We hope that the conclusions of this review may provide new strategies for diabetic kidney disease treatment and promising targets for drug development based on necroptosis.

Search for New Compounds with Anti-Inflammatory Activity Among 1,2,4-Triazole Derivatives

Compounds containing the 1,2,4-triazole moiety in their structure exhibit broad biological activities. Many of these compounds demonstrate anti-inflammatory activity in vitro through various mechanisms, such as inhibiting COX-1/COX-2 and LOX, modulating pro-inflammatory cytokine levels, or having effects on other specific enzymes. Some also display activities in vivo. In many publications, the activities of new 1,2,4-triazole-based compounds exceed those of the reference drugs, suggesting their promising potential as new therapeutic agents. This review of active 1,2,4-triazole derivatives with anti-inflammatory activity is based on literature published from 2015-2024.

Targeted Degradation of Receptor-Interacting Protein Kinase 1 to Modulate the Necroptosis Pathway

Necroptosis is a highly regulated form of necrotic cell death that plays an essential role in pathogen defense and tissue homeostasis. Abnormal regulation of the necroptotic pathway has been implicated in the pathogenesis of various human diseases, including cancer, inflammatory, and neurodegenerative diseases. Receptor-interacting protein kinase 1 (RIPK1) serves as a crucial regulator of the necroptotic signaling pathway and has been identified as a potential therapeutic target. Mechanistically, RIPK1 serves as both a protein kinase and a scaffolding protein, fulfilling its dual function through a combination of kinase activity-dependent and kinase activity-independent mechanisms. Thus, employing a targeted RIPK1 knockdown strategy is a highly effective means of inhibiting RIPK1 functions. To achieve a targeted RIPK1 knockdown, we generated a RIPK1-PROTAC, MS2031, by connecting the ZB-R-55 RIPK1 binder to the VHL ligand, thereby recruiting the CUL2-RING-VHL (CRL2VHL) E3 ubiquitin ligase complex for targeted degradation of RIPK1 through the 26S proteasome. Notably, MS2031 treatment effectively reduced the abundance of RIPK1 protein in the nanomolar range in various cell lines we examined, including HT-29 and T47D cells, and modulated the necroptosis signaling pathway. These results suggest that MS2031 may hold potential for the treatment of human diseases resulting from aberrant regulation of RIPK1.

The role of autophagy in RIP1 mediated cell death and intestinal inflammation

Autophagy, a highly conserved catabolic process that targets various types of cellular cargoes to lysosomal degradation, is one of the most important biological mechanisms critical for cellular homeostasis. Components of these cellular cargoes can range from individual proteins to invading pathogens, and degrading these materials is important for maintaining organismal health and survival. The process of autophagy is carried out by complex molecular mechanisms, and a growing body of evidence indicates that these mechanisms intersect with those involved in the cell death pathways. In this review, we examine several emerging studies elucidating the role of autophagy in RIP1-mediated cell death signaling, with particular emphasis on impaired autophagy caused by ATG16L1 deficiency. We also discuss how autophagy in RIP1-mediated cell death affects intestinal homeostasis in preclinical models, and the implications of the intersection between RIP1 and autophagy for understanding the intestinal pathologies associated with inflammatory bowel disease (IBD). Finally, we highlight the potential benefits of therapeutic targeting of RIP1 and autophagy proteins, while also proposing areas of research that will likely elucidate new links between autophagy and cell death signaling.

Encoding and display technologies for combinatorial libraries in drug discovery: The coming of age from biology to therapy

Drug discovery is a sophisticated process that incorporates scientific innovations and cutting-edge technologies. Compared to traditional bioactivity-based screening methods, encoding and display technologies for combinatorial libraries have recently advanced from proof-of-principle experiments to promising tools for pharmaceutical hit discovery due to their high screening efficiency, throughput, and resource minimization. This review systematically summarizes the development history, typology, and prospective applications of encoding and displayed technologies, including phage display, ribosomal display, mRNA display, yeast cell display, one-bead one-compound, DNA-encoded, peptide nucleic acid-encoded, and new peptide-encoded technologies, and examples of preclinical and clinical translation. We discuss the progress of novel targeted therapeutic agents, covering a spectrum from small-molecule inhibitors and nonpeptidic macrocycles to linear, monocyclic, and bicyclic peptides, in addition to antibodies. We also address the pending challenges and future prospects of drug discovery, including the size of screening libraries, advantages and disadvantages of the technology, clinical translational potential, and market space. This review is intended to establish a comprehensive high-throughput drug discovery strategy for scientific researchers and clinical drug developers.

A phase I randomized study to evaluate safety, pharmacokinetics, and pharmacodynamics of SIR2446M, a selective RIPK1 inhibitor, in healthy participants

Activation of receptor-interacting protein kinase 1 (RIPK1), a broadly expressed serine/threonine protein kinase, by pro-inflammatory cytokines and pathogens can result in apoptosis, necroptosis, or inflammation. RIPK1 inhibition has been shown to reduce inflammation and cell damage in preclinical studies and may have therapeutic potential for degenerative and inflammatory diseases. SIR2446 is a potent and selective novel small molecule RIPK1 kinase inhibitor. This phase I, randomized, double-blind, placebo-controlled study in Australia (ACTRN12621001621808) evaluated the safety (primary objective), pharmacokinetics, and pharmacodynamics of single (3-600 mg) and multiple (5-400 mg for 10 days) ascending oral doses of SIR2446M (SIR2446 magnesium salt form) in healthy adults from Nov 24, 2021, until May 01, 2023. All treatment-emergent adverse events (TEAEs) were mild/moderate. The most reported TEAEs were vascular access site pain, headache, and rash morbilliform. SIR2446M plasma half-lives ranged from 11 to 19 h and there were no major deviations from dose proportionality for maximum concentration and area under the curve across doses. Renal excretion of unchanged SIR2446 was minimal. No marked accumulation was observed (mean accumulation ratio, 1.2-1.6) after multiple daily doses. A high-fat meal mildly reduced the exposure but was not considered clinically significant. SIR2446M had a rapid and sustained inhibitory effect on the activity of RIPK1, with an overall 90% target engagement at repeated doses ranging from 30 to 400 mg in peripheral blood mononuclear cells ex vivo stimulated to undergo necroptosis. The favorable safety, pharmacokinetic, and pharmacodynamic profile of SIR2446M in healthy participants supports its further clinical development in patients with degenerative and inflammatory diseases.

Protein phosphorylation and kinases: Potential therapeutic targets in necroptosis

Necroptosis is a pivotal contributor to the pathogenesis of various human diseases, including those affecting the nervous system, cardiovascular system, pulmonary system, and kidneys. Extensive investigations have elucidated the mechanisms and physiological ramifications of necroptosis. Among these, protein phosphorylation emerges as a paramount regulatory process, facilitating the activation or inhibition of specific proteins through the addition of phosphate groups to their corresponding amino acid residues. Currently, the targeting of kinases has gained recognition as a firmly established and efficacious therapeutic approach for diverse diseases, notably cancer. In this comprehensive review, we elucidate the intricate role of phosphorylation in governing key molecular players in the necroptotic pathway. Moreover, we provide an in-depth analysis of recent advancements in the development of kinase inhibitors aimed at modulating necroptosis. Lastly, we deliberate on the prospects and challenges associated with the utilization of kinase inhibitors to modulate necroptotic processes.

Practical Three-Component Regioselective Synthesis of Drug-Like 3-Aryl(or heteroaryl)-5,6-dihydrobenzo[h]cinnolines as Potential Non-Covalent Multi-Targeting Inhibitors To Combat Neurodegenerative Diseases

Neurodegenerative diseases (NDs) are one of the prominent health challenges facing contemporary society, and many efforts have been made to overcome and (or) control it. In this research paper, we described a practical one-pot two-step three-component reaction between 3,4-dihydronaphthalen-1(2H)-one (1), aryl(or heteroaryl)glyoxal monohydrates (2a-h), and hydrazine monohydrate (NH2NH2•H2O) for the regioselective preparation of some 3-aryl(or heteroaryl)-5,6-dihydrobenzo[h]cinnoline derivatives (3a-h). After synthesis and characterization of the mentioned cinnolines (3a-h), the in silico multi-targeting inhibitory properties of these heterocyclic scaffolds have been investigated upon various Homo sapiens-type enzymes, including hMAO-A, hMAO-B, hAChE, hBChE, hBACE-1, hBACE-2, hNQO-1, hNQO-2, hnNOS, hiNOS, hPARP-1, hPARP-2, hLRRK-2(G2019S), hGSK-3β, hp38α MAPK, hJNK-3, hOGA, hNMDA receptor, hnSMase-2, hIDO-1, hCOMT, hLIMK-1, hLIMK-2, hRIPK-1, hUCH-L1, hPARK-7, and hDHODH, which have confirmed their functions and roles in the neurodegenerative diseases (NDs), based on molecular docking studies, and the obtained results were compared with a wide range of approved drugs and well-known (with IC50, EC50, etc.) compounds. In addition, in silico ADMET prediction analysis was performed to examine the prospective drug properties of the synthesized heterocyclic compounds (3a-h). The obtained results from the molecular docking studies and ADMET-related data demonstrated that these series of 3-aryl(or heteroaryl)-5,6-dihydrobenzo[h]cinnolines (3a-h), especially hit ones, can really be turned into the potent core of new drugs for the treatment of neurodegenerative diseases (NDs), and/or due to the having some reactionable locations, they are able to have further organic reactions (such as cross-coupling reactions), and expansion of these compounds (for example, with using other types of aryl(or heteroaryl)glyoxal monohydrates) makes a new avenue for designing novel and efficient drugs for this purpose.

Small-molecule agents for treating skin diseases

Skin diseases are a class of common and frequently occurring diseases that significantly impact daily lives. Currently, the limited effective therapeutic drugs are far from meeting the clinical needs; most drugs typically only provide symptomatic relief rather than a cure. Developing small-molecule drugs with improved efficacy holds paramount importance for treating skin diseases. This review aimed to systematically introduce the pathogenesis of common skin diseases in daily life, list related drugs applied in the clinic, and summarize the clinical research status of candidate drugs and the latest research progress of candidate compounds in the drug discovery stage. Also, it statistically analyzed the number of publications and global attention trends for the involved skin diseases. This review might provide practical information for researchers engaged in dermatological drugs and further increase research attention to this disease area.

Discovery of novel biaryl benzoxazepinones as dual-mode receptor-interacting protein kinase-1 (RIPK1) inhibitors

Systemic inflammatory response syndrome (SIRS), an exaggerated defense response of the organism to a noxious stressor, involves a massive inflammatory cascade that ultimately leads to reversible or irreversible end-organ dysfunction and even death. Suppressing RIPK1, a key protein in necroptosis pathway, has been proven to be an effective therapeutic strategy for inflammation and SIRS. In this study, a series of novel biaryl benzoxazepinone RIPK1 inhibitors were designed and synthesized by introducing different aryl substituents at the C7 position of benzoxazepinone. As a result, p-cyanophenyl substituted analog 19 exhibited the most potent in vitro anti-necroptotic effect in HT-29 cells (EC50 = 1.7 nM) and superior protection against temperature loss and death in mice in the TZ-induced SIRS model compared to GSK'772. What's more, in vivo analysis of the levels of inflammatory factors in mice also revealed that compound 19 had better anti-inflammatory activity than GSK'772.

RIPK1 inhibitors: A key to unlocking the potential of necroptosis in drug development

Within the field of medical science, there is a great deal of interest in investigating cell death pathways in the hopes of discovering new drugs. Over the past two decades, pharmacological research has focused on necroptosis, a cell death process that has just been discovered. Receptor-interacting protein kinase 1 (RIPK1), an essential regulator in the cell death receptor signalling pathway, has been shown to be involved in the regulation of important events, including necrosis, inflammation, and apoptosis. Therefore, researching necroptosis inhibitors offers novel ways to treat a variety of disorders that are not well-treated by the therapeutic medications now on the market. The research and medicinal potential of RIPK1 inhibitors, a promising class of drugs, are thoroughly examined in this study. The journey from the discovery of Necrostatin-1 (Nec-1) to the recent advancements in RIPK1 inhibitors is marked by significant progress, highlighting the integration of traditional medicinal chemistry approaches with modern technologies like high-throughput screening and DNA-encoded library technology. This review presents a thorough exploration of the development and therapeutic potential of RIPK1 inhibitors, a promising class of compounds. Simultaneously, this review highlights the complex roles of RIPK1 in various pathological conditions and discusses potential inhibitors discovered through diverse pathways, emphasizing their efficacy against multiple disease models, providing significant guidance for the expansion of knowledge about RIPK1 and its inhibitors to develop more selective, potent, and safe therapeutic agents.

Necroptosis inhibitors: mechanisms of action and therapeutic potential

Necroptosis is a type of programmed cell death that is morphologically similar to necrosis. This type of cell death is involved in various pathophysiological disorders, including inflammatory, neurodegenerative, infectious, and malignant diseases. Receptor-interacting protein kinase 1 (RIPK1), RIPK3, and mixed lineage kinase domain-like protein (MLKL) pseudokinase constitute the core components of the necroptosis signaling pathway and are considered the most promising targets for therapeutic intervention. The discovery and characterization of necroptosis inhibitors not only accelerate our understanding of the necroptosis signaling pathway but also provide important drug candidates for the treatment of necroptosis-related diseases. Here, we will review recent research progress on necroptosis inhibitors, mechanisms of action and their potential applications for disease treatment.

Inhibition of Receptor-Interacting Protein Kinase 1 in Chronic Plaque Psoriasis: A Multicenter, Randomized, Double-Blind, Placebo-Controlled Study

INTRODUCTION

Receptor-interacting protein kinase 1 (RIPK1), a key mediator of inflammation through necroptosis and proinflammatory cytokine production, may play a role in the pathogenesis of immune-mediated inflammatory diseases such as chronic plaque psoriasis. An experimental medicine study of RIPK1 inhibition with GSK2982772 immediate-release formulation at doses up to 60 mg three times daily in mild to moderate plaque psoriasis indicated that efficacy may be improved with higher trough concentrations of GSK2982772.

METHODS

This multicenter, randomized, double-blind, placebo-controlled, repeat-dose study (NCT04316585) assessed the efficacy, safety, pharmacokinetics, and pharmacodynamics of 960 mg GSK2982772 (once-daily modified-release formulation) in patients with moderate to severe plaque psoriasis. Twenty-nine patients were randomized 2:1 to GSK2982772 (N = 19) or placebo (N = 10) for 12 weeks.

RESULTS

GSK2982772 was well tolerated with trough concentrations greater than tenfold higher than the previous phase 1 study with immediate release. Despite near complete RIPK1 target engagement in blood and modest reduction in circulating inflammatory cytokines, the proportion of patients achieving 75% improvement from baseline in Psoriasis Area Severity Index score at week 12 was similar between GSK2982772 and placebo (posterior median 1.8% vs 4.9%, respectively), with an estimated median treatment difference of - 2.3%. This analysis incorporated historical placebo data through the use of an informative prior distribution on the placebo arm. Week 4 changes in skin biopsy gene expression suggested sufficient local drug exposure to elicit a pharmacodynamic response.

CONCLUSION

Administration of the RIPK1 inhibitor GSK2982772 to patients with moderate to severe plaque psoriasis did not translate into meaningful clinical improvements.

From Hit to Lead: Structure-Based Optimization of Novel Selective Inhibitors of Receptor-Interacting Protein Kinase 1 (RIPK1) for the Treatment of Inflammatory Diseases

Receptor-interacting protein kinase 1 (RIPK1) is a key regulator of cellular necroptosis, which is considered as an important therapeutic target for necroptosis-related indications. Herein, we report the structural optimization and structure-activity relationship investigations of a series of eutectic 5-substituted-indole-3-carboxamide derivatives. The prioritized compound 10b exhibited low nanomolar IC50 values against RIPK1 and showed good kinase selectivity. Based on its eutectic structure, 10b occupied both the allosteric and ATP binding pockets of RIPK1, making it a potent dual-mode inhibitor of RIPK1. In vitro, 10b had a potent protective effect against necroptosis in cells. Compound 10b also provided robust protection in a TNFα-induced systemic inflammatory response syndrome (SIRS) model and imiquimod (IMQ)-induced psoriasis model. It also showed good pharmacokinetic properties and low toxicity. Overall, 10b is a promising lead compound for drug discovery targeting RIPK1 and warrants further study.

Safety, pharmacokinetics, and target engagement of a brain penetrant RIPK1 inhibitor, SAR443820 (DNL788), in healthy adult participants

SAR443820 (DNL788) is a selective, orally bioavailable, brain penetrant inhibitor of receptor-interacting serine/threonine protein kinase 1 (RIPK1). This phase I first-in-human healthy participant study (NCT05795907) was comprised of three parts: randomized, double-blind, placebo-controlled single ascending dose (SAD; part 1a); 14-day multiple ascending dose (MAD; part 2) parts that evaluated safety, tolerability, pharmacokinetics (PK), and pharmacodynamics of SAR443820; and a separate open-label, single-dose part 1b (PK-cerebrospinal fluid [CSF]) to assess SAR443820 levels in CSF. SAR443820 was well-tolerated in healthy participants, and no treatment discontinuation related to an adverse event (AE) occurred. Most common AEs were dizziness and headache. No clinically meaningful changes were noted in laboratory values, vital signs, or electrocardiogram parameters. SAR443820 had a favorable PK profile, with plasma half-lives (geometric mean) ranged between 5.7-8.0 h and 7.2-8.9 h after single and repeated doses, respectively. There were no major deviations from dose proportionality for maximum concentration and area under the curve across SAR443820 doses. Mean CSF-to-unbound plasma concentration ratio ranged from 0.8 to 1.3 over time (assessed up to 10 h postdose), indicating high brain penetrance. High levels of inhibition of activated RIPK1, as measured by decrease in pS166-RIPK1, were achieved in both SAD and MAD parts, with a maximum median inhibition from baseline close to 90% at predose (Ctrough ) after multiple dosing in MAD, reflecting a marked RIPK1 target engagement at the peripheral level. These results support further development of SAR443820 in phase II trials in amyotrophic lateral sclerosis (NCT05237284) and multiple sclerosis (NCT05630547).

Therapeutic potential of PANoptosis: innate sensors, inflammasomes, and RIPKs in PANoptosomes

The innate immune system initiates cell death pathways in response to pathogens and cellular stress. Cell death can be either non-lytic (apoptosis) or lytic (PANoptosis, pyroptosis, and necroptosis). PANoptosis has been identified as an inflammatory, lytic cell death pathway driven by caspases and RIPKs that is regulated by PANoptosome complexes, making it distinct from other cell death pathways. Several PANoptosome complexes (including ZBP1-, AIM2-, RIPK1-, and NLRP12-PANoptosomes) have been characterized to date. Furthermore, PANoptosis is implicated in infectious and inflammatory diseases, cancers, and homeostatic perturbations. Therefore, targeting its molecular components offers significant potential for therapeutic development. This review covers PANoptosomes and their assembly, PANoptosome-mediated cell death mechanisms, and ongoing progress in developing therapeutics that target PANoptosis.

Mechanisms of PANoptosis and relevant small-molecule compounds for fighting diseases

Pyroptosis, apoptosis, and necroptosis are mainly programmed cell death (PCD) pathways for host defense and homeostasis. PANoptosis is a newly distinct inflammatory PCD pathway that is uniquely regulated by multifaceted PANoptosome complexes and highlights significant crosstalk and coordination among pyroptosis (P), apoptosis (A), and/or necroptosis(N). Although some studies have focused on the possible role of PANpoptosis in diseases, the pathogenesis of PANoptosis is complex and underestimated. Furthermore, the progress of PANoptosis and related agonists or inhibitors in disorders has not yet been thoroughly discussed. In this perspective, we provide perspectives on PANoptosome and PANoptosis in the context of diverse pathological conditions and human diseases. The treatment targeting on PANoptosis is also summarized. In conclusion, PANoptosis is involved in plenty of disorders including but not limited to microbial infections, cancers, acute lung injury/acute respiratory distress syndrome (ALI/ARDS), ischemia-reperfusion, and organic failure. PANoptosis seems to be a double-edged sword in diverse conditions, as PANoptosis induces a negative impact on treatment and prognosis in disorders like COVID-19 and ALI/ARDS, while PANoptosis provides host protection from HSV1 or Francisella novicida infection, and kills cancer cells and suppresses tumor growth in colorectal cancer, adrenocortical carcinoma, and other cancers. Compounds and endogenous molecules focused on PANoptosis are promising therapeutic strategies, which can act on PANoptosomes-associated members to regulate PANoptosis. More researches on PANoptosis are needed to better understand the pathology of human conditions and develop better treatment.

Molecular and functional characteristics of receptor-interacting protein kinase 1 (RIPK1) and its therapeutic potential in Alzheimer's disease

Inflammation and cell death processes positively control the organ homeostasis of an organism. Receptor-interacting protein kinase 1 (RIPK1), a member of the RIPK family, is a crucial regulator of cell death and inflammation, and control homeostasis at the cellular and tissue level. Necroptosis, a programmed form of necrosis-mediated cell death and tumor necrosis factor (TNF)-induced necrotic cell death, is mostly regulated by RIPK1 kinase activity. Thus, RIPK1 has recently emerged as an upstream kinase that controls multiple cellular pathways and participates in regulating inflammation and cell death. All the major cell types in the central nervous system (CNS) have been found to express RIPK1. Selective inhibition of RIPK1 has been shown to prevent neuronal cell death, which could ultimately lead to a significant reduction of neurodegeneration and neuroinflammation. In addition, the kinase structure of RIPK1 is highly conducive to the development of specific pharmacological small-molecule inhibitors. These factors have led to the emergence of RIPK1 as an important therapeutic target for Alzheimer's disease (AD).

A phase I, randomized, ascending-dose study to assess safety, pharmacokinetics, and activity of GDC-8264, a RIP1 inhibitor, in healthy volunteers

Receptor-interacting protein 1 (RIP1) is a key regulator of multiple signaling pathways that mediate inflammatory responses and cell death. RIP1 kinase activity mediates apoptosis and necroptosis induced by tumor necrosis factor (TNF)-α, Toll-like receptors, and ischemic tissue damage. RIP1 has been implicated in several human pathologies and consequently, RIP1 inhibition may represent a therapeutic approach for diseases dependent on RIP1-mediated inflammation and cell death. GDC-8264 is a potent, selective, and reversible small molecule inhibitor of RIP1 kinase activity. This phase I, randomized, placebo-controlled, double-blinded trial examined safety, pharmacokinetics (PKs), and pharmacodynamics (PDs) of single- (5-225 mg) and multiple- (50 and 100 mg once daily, up to 14 days) ascending oral doses of GDC-8264 in healthy volunteers, and also tested the effect of food on the PKs of GDC-8264. All adverse events in GDC-8264-treated subjects in both stages were mild. GDC-8264 exhibited dose-proportional increases in systemic exposure; the mean terminal half-life ranged from 10-13 h, with limited accumulation on multiple dosing (accumulation ratio [AR] ~ 1.4); GDC-8264 had minimal renal excretion at all doses. A high-fat meal had no significant effect on the PKs of GDC-8264. In an ex vivo stimulation assay of whole blood, GDC-8264 rapidly and completely inhibited release of CCL4, a downstream marker of RIP1 pathway activation, indicating a potent pharmacological effect. Based on PK-PD modeling, the GDC-8264 half-maximal inhibitory concentration for the inhibition of CCL4 release was estimated to be 0.58 ng/mL. The favorable safety, PKs, and PDs of GDC-8264 support its further development for treatment of RIP1-driven diseases.

Necroptosis in Organ Transplantation: Mechanisms and Potential Therapeutic Targets

Organ transplantation remains the only treatment option for patients with end-stage organ dysfunction. However, there are numerous limitations that challenge its clinical application, including the shortage of organ donations, the quality of donated organs, injury during organ preservation and reperfusion, primary and chronic graft dysfunction, acute and chronic rejection, infection, and carcinogenesis in post-transplantation patients. Acute and chronic inflammation and cell death are two major underlying mechanisms for graft injury. Necroptosis is a type of programmed cell death involved in many diseases and has been studied in the setting of all major solid organ transplants, including the kidney, heart, liver, and lung. It is determined by the underlying donor organ conditions (e.g., age, alcohol consumption, fatty liver, hemorrhage shock, donation after circulatory death, etc.), preservation conditions and reperfusion, and allograft rejection. The specific molecular mechanisms of necroptosis have been uncovered in the organ transplantation setting, and potential targeting drugs have been identified. We hope this review article will promote more clinical research to determine the role of necroptosis and other types of programmed cell death in solid organ transplantation to alleviate the clinical burden of ischemia-reperfusion injury and graft rejection.

Small-molecule discovery through DNA-encoded libraries

The development of bioactive small molecules as probes or drug candidates requires discovery platforms that enable access to chemical diversity and can quickly reveal new ligands for a target of interest. Within the past 15 years, DNA-encoded library (DEL) technology has matured into a widely used platform for small-molecule discovery, yielding a wide variety of bioactive ligands for many therapeutically relevant targets. DELs offer many advantages compared with traditional screening methods, including efficiency of screening, easily multiplexed targets and library selections, minimized resources needed to evaluate an entire DEL and large library sizes. This Review provides accounts of recently described small molecules discovered from DELs, including their initial identification, optimization and validation of biological properties including suitability for clinical applications.

Scaffold hopping derived novel benzoxazepinone RIPK1 inhibitors as anti-necroptosis agents

Receptor-interacting protein kinase 1 (RIPK1)-mediated necroptosis is believed to have a significant role in contributing to inflammatory diseases. Inhibiting RIPK1 has shown promise in effectively alleviating the inflammation process. In our current study, we employed scaffold hopping to develop a series of novel benzoxazepinone derivatives. Among these derivatives, compound o1 displayed the most potent antinecroptosis activity (EC50=16.17±1.878nM) in cellular assays and exhibited the strongest binding affinity to the target site. Molecular docking analyses further elucidated the mechanism of action of o1, revealing its ability to fully occupy the protein pocket and form hydrogen bonds with the amino acid residue Asp156. Our findings highlight that o1 specifically inhibits necroptosis, rather than apoptosis, by impeding the RIPK1/Receptor-interacting protein kinase 3 (RIPK3)/mixed-lineage kinase domain-like (MLKL) pathway's phosphorylation, triggered by TNFα, Smac mimetic, and z-VAD (TSZ). Additionally, o1 demonstrated dose-dependent improvements in the survival rate of mice with Systemic Inflammatory Response Syndrome (SIRS), surpassing the protective effect observed with GSK'772.

Necroptosis in the pathophysiology of preeclampsia

Necroptosis is a newly-identified form of gene-regulated cell necrosis that is increasingly considered to be a pathway associated with human pathophysiological conditions. Cells undergoing necroptosis exhibit necrotic phenotypes, including disruption of the plasma membrane integrity, organelle swelling, and cytolysis. Accumulating evidence suggests that trophoblast necroptosis plays a complex role in preeclampsia (PE). However, the exact pathogenesis remains unclear. Its unique mechanisms of action in various diseases are expected to provide prospects for the treatment of PE. Therefore, it is necessary to further explore its molecular mechanism in PE in order to identify potential therapeutic options. This review examines the current knowledge regarding the role and mechanisms of necroptosis in PE and provides a theoretical basis for new therapeutic targets for PE.

Discovery of Sibiriline derivatives as novel receptor-interacting protein kinase 1 inhibitors

Receptor-interacting protein kinase 1 (RIPK1), a vital protein of the necroptosis pathway, plays a pivotal role in various inflammatory diseases. Sibiriline has been reported to be a potent ATP-competitive RIPK1 inhibitor, but its anti-necroptotic effects are limited. A series of structural analogues of Sibiriline were synthesized and evaluated for their anti-necroptotic activity. Comprehensive structure-activity relationship (SAR) was performed to left azaindole and right substituents of benzene of Sibiriline, respectively. The optimal compound KWCN-41, specifically inhibiting cell necroptosis but not apoptosis, protects cell survival by blocking the necroptotic pathway, which inhibits the phosphorylation of essential proteins of the necroptosis. It also prevented the development of inflammation and reduced the level of inflammatory factors in mice. KWCN-41 is expected to be a lead compound for further studies in inflammatory diseases.

Role of necroptosis in kidney health and disease

Cell death, particularly that of tubule epithelial cells, contributes critically to the pathophysiology of kidney disease. A body of evidence accumulated over the past 15 years has ascribed a central pathophysiological role to a particular form of regulated necrosis, termed necroptosis, to acute tubular necrosis, nephron loss and maladaptive renal fibrogenesis. Unlike apoptosis, which is a non-immunogenic process, necroptosis results in the release of cellular contents and cytokines, which triggers an inflammatory response in neighbouring tissue. This necroinflammatory environment can lead to severe organ dysfunction and cause lasting tissue injury in the kidney. Despite evidence of a link between necroptosis and various kidney diseases, there are no available therapeutic options to target this process. Greater understanding of the molecular mechanisms, triggers and regulators of necroptosis in acute and chronic kidney diseases may identify shortcomings in current approaches to therapeutically target necroptosis regulators and lead to the development of innovative therapeutic approaches.

A new perspective on the potential application of RIPK1 in the treatment of sepsis

RIPK1 is a global cellular sensor that can determine the survival of cells. Generally, RIPK1 can induce cell apoptosis and necroptosis through TNF, Fas and lipopolysaccharide stimulation, while its scaffold function can sense the fluctuation of cellular energy and promote cell survival. Sepsis is a nonspecific disease that seriously threatens human health. There is some dispute in the literature about the role of RIPK1 in sepsis. In this review, the authors attempt to comprehensively discuss the differential results for RIPK1 in sepsis by summarizing the underlying molecular mechanism and putting forward a tentative idea as to whether RIPK1 can serve as a biomarker for the monitoring of treatment and progression in sepsis.

From PERK to RIPK1: Design, synthesis and evaluation of novel potent and selective necroptosis inhibitors

Receptor-Interacting serine/threonine-Protein Kinase 1 (RIPK1) emerged as an important driver of inflammation and, consequently, inflammatory pathologies. The enzymatic activity of RIPK1 is known to indirectly promote inflammation by triggering cell death, in the form of apoptosis, necroptosis and pyroptosis. Small molecule Receptor-Interacting serine/threonine-Protein Kinase 1 inhibitors have therefore recently entered clinical trials for the treatment of a subset of inflammatory pathologies. We previously identified GSK2656157 (GSK'157), a supposedly specific inhibitor of protein kinase R (PKR)-like ER kinase (PERK), as a much more potent type II Receptor-Interacting serine/threonine-Protein Kinase 1 inhibitor. We now performed further structural optimisation on the GSK'157 scaffold in order to develop a novel class of more selective Receptor-Interacting serine/threonine-Protein Kinase 1 inhibitors. Based on a structure-activity relationship (SAR) reported in the literature, we anticipated that introducing a substituent on the para-position of the pyridinyl ring would decrease the interaction with PERK. Herein, we report a series of novel GSK'157 analogues with different para-substituents with increased selectivity for Receptor-Interacting serine/threonine-Protein Kinase 1. The optimisation led to UAMC-3861 as the best compound of this series in terms of activity and selectivity for Receptor-Interacting serine/threonine-Protein Kinase 1 over PERK. The most selective compounds were screened in vitro for their ability to inhibit RIPK1-dependent apoptosis and necroptosis. With this work, we successfully synthesised a novel series of potent and selective type II Receptor-Interacting serine/threonine-Protein Kinase 1 inhibitors based on the GSK'157 scaffold.

A Transversal Approach Combining In Silico, In Vitro and In Vivo Models to Describe the Metabolism of the Receptor Interacting Protein 1 Kinase Inhibitor Sibiriline

Sibiriline is a novel drug inhibiting receptor-interacting protein 1 kinase (RIPK1) and necroptosis, a regulated form of cell death involved in several disease models. In this study, we aimed to investigate the metabolic fate of sibiriline in a cross-sectional manner using an in silico prediction, coupled with in vitro and in vivo experiments. In silico predictions were performed using GLORYx and Biotransformer 3.0 freeware; in vitro incubation was performed on differentiated human HepaRG cells, and in vivo experiments including a pharmacokinetic study were performed on mice treated with sibiriline. HepaRG culture supernatants and mice plasma samples were analyzed with ultra-high-performance liquid chromatography, coupled with tandem mass spectrometry (LC-HRMS/MS). The molecular networking bioinformatics tool applied to LC-HRMS/MS data allowed us to visualize the sibiriline metabolism kinetics. Overall, 14 metabolites, mostly produced by Phase II transformations (glucuronidation and sulfation) were identified. These data provide initial reassurance regarding the toxicology of this new RIPK1 inhibitor, although further studies are required.

Necroptosis Blockade Potentiates the Neuroprotective Effect of Hypothermia in Neonatal Hypoxic-Ischemic Encephalopathy

Neonatal encephalopathy (NE) caused by hypoxia-ischemia (HI) affects around 1 per 1000 term newborns and is the leading cause of acquired brain injury and neurodisability. Despite the use of hypothermia (HT) as a standard of care, the incidence of NE and its devastating outcomes remains a major issue. Ongoing research surrounding add-on neuroprotective strategies against NE is important as HT effects are limited, leaving 50% of treated patients with neurological sequelae. Little is known about the interaction between necroptotic blockade and HT in neonatal HI. Using a preclinical Lewis rat model of term human NE induced by HI, we showed a neuroprotective effect of Necrostatin-1 (Nec-1: a compound blocking necroptosis) in combination with HT. The beneficial effect of Nec-1 added to HT against NE injuries was observed at the mechanistic level on both pMLKL and TNF-α, and at the anatomical level on brain volume loss visualized by magnetic resonance imaging (MRI). HT alone showed no effect on activated necroptotic effectors and did not preserve the brain MRI volume. This study opens new avenues of research to understand better the specific cell death mechanisms of brain injuries as well as the potential use of new therapeutics targeting the necroptosis pathway.

Regulated Necrosis in Atherosclerosis

During atherosclerosis, lipid-rich plaques are formed in large- and medium-sized arteries, which can reduce blood flow to tissues. This situation becomes particularly precarious when a plaque develops an unstable phenotype and becomes prone to rupture. Despite advances in identifying and treating vulnerable plaques, the mortality rate and disability caused by such lesions remains the number one health threat in developed countries. Vulnerable, unstable plaques are characterized by a large necrotic core, implying a prominent role for necrotic cell death in atherosclerosis and plaque destabilization. Necrosis can occur accidentally or can be induced by tightly regulated pathways. Over the past decades, different forms of regulated necrosis, including necroptosis, ferroptosis, pyroptosis, and secondary necrosis, have been identified, and these may play an important role during atherogenesis. In this review, we describe several forms of necrosis that may occur in atherosclerosis and how pharmacological modulation of these pathways can stabilize vulnerable plaques. Moreover, some challenges of targeting necrosis in atherosclerosis such as the presence of multiple death-inducing stimuli in plaques and extensive cross-talk between necrosis pathways are discussed. A better understanding of the role of (regulated) necrosis in atherosclerosis and the mechanisms contributing to plaque destabilization may open doors to novel pharmacological strategies and will enable clinicians to tackle the residual cardiovascular risk that remains in many atherosclerosis patients.

Necroptosis: A Pathogenic Negotiator in Human Diseases

Over the past few decades, mechanisms of programmed cell death have attracted the scientific community because they are involved in diverse human diseases. Initially, apoptosis was considered as a crucial mechanistic pathway for programmed cell death; recently, an alternative regulated mode of cell death was identified, mimicking the features of both apoptosis and necrosis. Several lines of evidence have revealed that dysregulation of necroptosis leads to pathological diseases such as cancer, cardiovascular, lung, renal, hepatic, neurodegenerative, and inflammatory diseases. Regulated forms of necrosis are executed by death receptor ligands through the activation of receptor-interacting protein kinase (RIPK)-1/3 and mixed-lineage kinase domain-like (MLKL), resulting in the formation of a necrosome complex. Many papers based on genetic and pharmacological studies have shown that RIPKs and MLKL are the key regulatory effectors during the progression of multiple pathological diseases. This review focused on illuminating the mechanisms underlying necroptosis, the functions of necroptosis-associated proteins, and their influences on disease progression. We also discuss numerous natural and chemical compounds and novel targeted therapies that elicit beneficial roles of necroptotic cell death in malignant cells to bypass apoptosis and drug resistance and to provide suggestions for further research in this field.

Necroptosis at a glance

Necroptosis, or programmed necrosis, is an inflammatory form of cell death with important functions in host defense against pathogens and tissue homeostasis. The four cytosolic receptor-interacting protein kinase homotypic interaction motif (RHIM)-containing adaptor proteins RIPK1, RIPK3, TRIF (also known as TICAM1) and ZBP1 mediate necroptosis induction in response to infection and cytokine or innate immune receptor activation. Activation of the RHIM adaptors leads to phosphorylation, oligomerization and membrane targeting of the necroptosis effector protein mixed lineage kinase domain-like (MLKL). Active MLKL induces lesions on the plasma membrane, leading to the release of pro-inflammatory damage-associated molecular patterns (DAMPs). Thus, activities of the RHIM adaptors and MLKL are tightly regulated by posttranslational modifications to prevent inadvertent release of immunogenic contents. In this Cell Science at a Glance article and the accompanying poster, we provide an overview of the regulatory mechanisms of necroptosis and its biological functions in tissue homeostasis, pathogen infection and other inflammatory diseases.

Cell death in skin function, inflammation, and disease

Cell death is an essential process that plays a vital role in restoring and maintaining skin homeostasis. It supports recovery from acute injury and infection and regulates barrier function and immunity. Cell death can also provoke inflammatory responses. Loss of cell membrane integrity with lytic forms of cell death can incite inflammation due to the uncontrolled release of cell contents. Excessive or poorly regulated cell death is increasingly recognised as contributing to cutaneous inflammation. Therefore, drugs that inhibit cell death could be used therapeutically to treat certain inflammatory skin diseases. Programmes to develop such inhibitors are already underway. In this review, we outline the mechanisms of skin-associated cell death programmes; apoptosis, necroptosis, pyroptosis, NETosis, and the epidermal terminal differentiation programme, cornification. We discuss the evidence for their role in skin inflammation and disease and discuss therapeutic opportunities for targeting the cell death machinery.

AZ-628 delays osteoarthritis progression via inhibiting the TNF-α-induced chondrocyte necroptosis and regulating osteoclast formation

As a degenerative disease, the pathogenesis and treatment of osteoarthritis (OA) are still being studied. The prevailing view is that articular cartilage dysfunction plays an essential role in the development of osteoarthritis. Similarly, dynamic bone remodeling dramatically influences the development of osteoarthritis. The inflammatory response is caused by the overexpression of inflammatory factors, among which tumor necrosis factor-α is one of the main causes of OA, and its sources include the secretion of chondrocytes themselves and osteoclast secretion of subchondral bone. Moreover, TNF-α-induced activation of RIP1, RIP3, and MLKL has been shown to play an important role in cell necroptosis and inflammatory responses. In vitro, AZ-628 alleviates chondrocyte inflammation and necroptosis by inhibiting the NF-κB signaling pathway and RIP3 activation instead of RIP1 activation. AZ-628 also reduces osteoclast activity, proliferation and differentiation, and release of inflammatory substances by inhibiting autophagy, MAPK, and NF-κB pathways. Similarly, the in vivo study demonstrated that AZ-628 could inhibit chondrocyte breakdown and lower osteoclast formation and bone resorption, thereby slowing down subchondral bone changes induced by dynamic bone remodeling and reversing the progression of osteoarthritis in mice. The results of this study indicate that AZ-628 could be used to treat OA byinhibiting chondrocyte necroptosis and regulating osteoclast formation.

Emerging therapies to target CNS pathophysiology in multiple sclerosis

The rapidly evolving therapeutic landscape of multiple sclerosis (MS) has contributed to paradigm shifts in our understanding of the biological mechanisms that contribute to CNS injury and in treatment philosophies. Opportunities remain to further improve treatment of relapsing-remitting MS, but two major therapeutic gaps are the limiting of progressive disease mechanisms and the repair of CNS injury. In this Review, we provide an overview of selected emerging therapies that predominantly target processes within the CNS that are thought to be involved in limiting non-relapsing, progressive disease injury or promoting tissue repair. Among these, we consider agents that modulate adaptive and innate CNS-compartmentalized inflammation, which can be mediated by infiltrating immune cells and/or resident CNS cells, including microglia and astrocytes. We also discuss agents that target degenerative disease mechanisms, agents that might confer neuroprotection, and agents that create a more favourable environment for or actively contribute to oligodendrocyte precursor cell differentiation, remyelination and axonal regeneration. We focus on agents that are novel for MS, that are known to or are presumed to penetrate the CNS, and that have already entered early stages of development in MS clinical trials.

Safety, pharmacokinetics and target engagement of novel RIPK1 inhibitor SAR443060 (DNL747) for neurodegenerative disorders: Randomized, placebo-controlled, double-blind phase I/Ib studies in healthy subjects and patients

RIPK1 is a master regulator of inflammatory signaling and cell death and increased RIPK1 activity is observed in human diseases, including Alzheimer’s disease (AD) and amyotrophic lateral sclerosis (ALS). RIPK1 inhibition has been shown to protect against cell death in a range of preclinical cellular and animal models of diseases. SAR443060 (previously DNL747) is a selective, orally bioavailable, central nervous system (CNS)–penetrant, small‐molecule, reversible inhibitor of RIPK1. In three early‐stage clinical trials in healthy subjects and patients with AD or ALS (NCT03757325 and NCT03757351), SAR443060 distributed into the cerebrospinal fluid (CSF) after oral administration and demonstrated robust peripheral target engagement as measured by a reduction in phosphorylation of RIPK1 at serine 166 (pRIPK1) in human peripheral blood mononuclear cells compared to baseline. RIPK1 inhibition was generally safe and well‐tolerated in healthy volunteers and patients with AD or ALS. Taken together, the distribution into the CSF after oral administration, the peripheral proof‐of‐mechanism, and the safety profile of RIPK1 inhibition to date, suggest that therapeutic modulation of RIPK1 in the CNS is possible, conferring potential therapeutic promise for AD and ALS, as well as other neurodegenerative conditions. However, SAR443060 development was discontinued due to long‐term nonclinical toxicology findings, although these nonclinical toxicology signals were not observed in the short duration dosing in any of the three early‐stage clinical trials. The dose‐limiting toxicities observed for SAR443060 preclinically have not been reported for other RIPK1‐inhibitors, suggesting that these toxicities are compound‐specific (related to SAR443060) rather than RIPK1 pathway‐specific.

Synthesis of [11C]carbonyl-labeled cyclohexyl (5-(2-acetamidobenzo[d]thiazol-6-yl)-2-methylpyridin-3-yl)carbamate ([11C-carbonyl]PK68) as a potential PET tracer for receptor-interacting protein 1 kinase

Background

Receptor-interacting protein 1 kinase (RIPK1) is a key enzyme in the regulation of cellular necroptosis. Recently, cyclohexyl (5-(2-acetamidobenzo[d]thiazol-6-yl)-2-methylpyridin-3-yl)carbamate (PK68, 5) has been developed as a potent inhibitor of RIPK1. Herein, we synthesized [¹¹C]carbonyl-labeled PK68 ([¹¹C-carbonyl]PK68, [¹¹C]PK68) as a potential PET tracer for imaging RIPK1 and evaluated its brain uptake in vivo.

Results

We synthesized [¹¹C]PK68 by reacting amine precursor 14 with [¹¹C]acetyl chloride. At the end of synthesis, we obtained [¹¹C]PK68 of 1200–1790 MBq with a radiochemical yield of 9.1 ± 5.9% (n = 10, decay-corrected to the end of irradiation) and radiochemical purity of > 99%, and a molar activity of 37–99 GBq/μmol starting from 18–33 GBq of [¹¹C]CO₂. The fully automated synthesis took 30 min from the end of irradiation. In a small-animal PET study, [¹¹C]PK68 was rapidly distributed in the liver and kidneys of healthy mice after injection, and subsequently cleared from their bodies via hepatobiliary excretion and the intestinal reuptake pathway. Although there was no obvious specific binding of RIPK1 in the PET study, [¹¹C]PK68 demonstrated relatively high stability in vivo and provided useful structural information further candidate development.

Conclusions

In the present study, we successfully radiosynthesized [¹¹C]PK68 as a potential PET tracer and evaluated its brain uptake. We are planning to optimize the chemical structure of [¹¹C]PK68 and conduct further PET studies on it using pathological models.

Development of a Once-Daily Modified-Release Formulation for the Short Half-Life RIPK1 Inhibitor GSK2982772 using DiffCORE Technology

Purpose

GSK2982772 is a selective inhibitor of receptor-interacting protein kinase-1 (RIPK1) with a short 2- to 3-h half-life. In a previous modified-release (MR) study, a matrix monolithic formulation (80% GSK2982772 released over 12 h) provided a once-daily (QD) pharmacokinetic (PK) profile in the fasted state; however, it was susceptible to food effects. The current study evaluated the safety and PK of MR formulations using GSK proprietary DiffCORE™ technology.

Methods

Part A evaluated PK following single-dose (240 mg) fasted and fed (high-fat meal) administration of three DiffCORE MR formulations within pre-defined in vitro extremes of 80% GSK2982772 released over 12 h (MR-12 h) to 80% GSK2982772 released over 18 h (MR-18 h) versus an immediate-release formulation. Part B evaluated MR-16 h (120–960 mg) in different prandial states.

Results

Pharmacokinetic profiles for all MR formulations and doses tested in the fasted and fed states were consistent with QD dosing.

Conclusions

The DiffCORE technology overcame the food effect vulnerability observed with the matrix monolithic formulation. The MR-16 h formulation was selected for further clinical development as a QD dosing regimen (NCT03649412 September 26, 2018).

Supplementary Information

The online version contains supplementary material available at 10.1007/s11095-021-03124-7.

Cell Death in Hepatocellular Carcinoma: Pathogenesis and Therapeutic Opportunities

Simple Summary

The progression of liver tumors is highly influenced by the interactions between cancer cells and the surrounding environment, and, consequently, can determine whether the primary tumor regresses, metastasizes, or establishes micrometastases. In the context of liver cancer, cell death is a double-edged sword. On one hand, cell death promotes inflammation, fibrosis, and angiogenesis, which are tightly orchestrated by a variety of resident and infiltrating host cells. On the other hand, targeting cell death in advanced hepatocellular carcinoma could represent an attractive therapeutic approach for limiting tumor growth. Further studies are needed to investigate therapeutic strategies combining current chemotherapies with novel drugs targeting either cell death or the tumor microenvironment.

Abstract

Hepatocellular carcinoma (HCC) is the most prevalent primary liver cancer and the third leading cause of cancer death worldwide. Closely associated with liver inflammation and fibrosis, hepatocyte cell death is a common trigger for acute and chronic liver disease arising from different etiologies, including viral hepatitis, alcohol abuse, and fatty liver. In this review, we discuss the contribution of different types of cell death, including apoptosis, necroptosis, pyroptosis, or autophagy, to the progression of liver disease and the development of HCC. Interestingly, inflammasomes have recently emerged as pivotal innate sensors with a highly pathogenic role in various liver diseases. In this regard, an increased inflammatory response would act as a key element promoting a pro-oncogenic microenvironment that may result not only in tumor growth, but also in the formation of a premetastatic niche. Importantly, nonparenchymal hepatic cells, such as liver sinusoidal endothelial cells, hepatic stellate cells, and hepatic macrophages, play an important role in establishing the tumor microenvironment, stimulating tumorigenesis by paracrine communication through cytokines and/or angiocrine factors. Finally, we update the potential therapeutic options to inhibit tumorigenesis, and we propose different mechanisms to consider in the tumor microenvironment field for HCC resolution.

Biologic and pathologic aspects of osteocytes in the setting of medication-related osteonecrosis of the jaw (MRONJ)

Medication-related osteonecrosis of the jaw (MRONJ) is a potentially severe, debilitating condition affecting patients with cancer and patients with osteoporosis who have been treated with powerful antiresorptives (pARs) or angiogenesis inhibitors (AgIs). Oral risk factors associated with the development of MRONJ include tooth extraction and inflammatory dental disease (e.g., periodontitis, periapical infection). In bone tissues, osteocytes play a bidirectional role in which they not only act as the "receiver" of systemic signals from blood vessels, such as hormones and drugs, or local signals from the mineralized matrix as it is deformed, but they also play a critical role as "transmitter" of signals to the cells that execute bone modeling and remodeling (osteoclasts, osteoblasts and lining cells). When the survival capacity of osteocytes is overwhelmed, they can die. Osteocyte death has been associated with several pathological conditions. Whereas the causes and mechanisms of osteocyte death have been studied in conditions like osteonecrosis of the femoral head (ONFH), few studies of the causes and mechanisms of osteocyte death have been done in MRONJ. The three forms of cell death that affect most of the different cells in the body (apoptosis, autophagy, and necrosis) have been recognized in osteocytes. Notably, necroptosis, a form of regulated cell death with "a necrotic cell death phenotype," has also been identified as a form of cell death in osteocytes under certain pathologic conditions. Improving the understanding of osteocyte death in MRONJ may be critical for preventing disease and developing treatment approaches. In this review, we intend to provide insight into the biology of osteocytes, cell death, in general, and osteocyte death, in particular, and discuss hypothetical mechanisms involved in osteocyte death associated with MRONJ.

Necroptosis in Pulmonary Diseases: A New Therapeutic Target

In the past decades, apoptosis has been the most well-studied regulated cell death (RCD) that has essential functions in tissue homeostasis throughout life. However, a novel form of RCD called necroptosis, which requires receptor-interacting protein kinase-3 (RIPK3) and mixed-lineage kinase domain-like pseudokinase (MLKL), has recently been receiving increasing scientific attention. The phosphorylation of RIPK3 enables the recruitment and phosphorylation of MLKL, which oligomerizes and translocates to the plasma membranes, ultimately leading to plasma membrane rupture and cell death. Although apoptosis elicits no inflammatory responses, necroptosis triggers inflammation or causes an innate immune response to protect the body through the release of damage-associated molecular patterns (DAMPs). Increasing evidence now suggests that necroptosis is implicated in the pathogenesis of several human diseases such as systemic inflammation, respiratory diseases, cardiovascular diseases, neurodegenerative diseases, neurological diseases, and cancer. This review summarizes the emerging insights of necroptosis and its contribution toward the pathogenesis of lung diseases.

N-3-oxododecanoyl homoserine lactone exacerbates endothelial cell death by inducing receptor-interacting protein kinase 1-dependent apoptosis

Endothelial dysfunction is associated with the initiation of sepsis-associated organ failure. Bacterial quorum-sensing molecules act as pathogen-associated molecular patterns; however, the effects of quorum-sensing molecules on endothelial cells remain less understood. This study investigated the molecular mechanisms of quorum-sensing molecule-induced cell death and their interaction with lipopolysaccharide (LPS) in human umbilical vein endothelial cells. Endothelial cells were treated with N-3-oxododecanoyl homoserine lactone (3OC12-HSL) and LPS derived from Pseudomonas aeruginosa. Treatment with 3OC12-HSL reduced cell viability in a dose-dependent manner, and cotreatment with 3OC12-HSL and LPS enhanced cell death. Terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling assay revealed an increase in apoptotic cell death following 3OC12-HSL treatment; furthermore, cotreatment with 3OC12-HSL and LPS enhanced apoptosis. Western blotting revealed that treatment with 3OC12-HSL activated the receptor-interacting protein kinase 1 (RIPK1) pathway, leading to an increase in the levels of cleaved caspase 8 and 3. In addition, we found that treatment with necrostatin-1, an RIPK1 inhibitor, reduced cell death and ameliorated the activation of the RIPK1-dependent apoptotic pathway in 3OC12-HSL-treated cells. In conclusion, 3OC12-HSL induced endothelial cell apoptosis via the activation of the RIPK1 pathway, independent of LPS toxicity. Inhibition of RIPK1 may act as a therapeutic option for preserving endothelial cell integrity in patients with sepsis by disrupting the mechanism by which quorum-sensing molecules mediate their toxicity.

A randomised, placebo-controlled study of RIPK1 inhibitor GSK2982772 in patients with active ulcerative colitis

OBJECTIVE

Tumour necrosis factor signalling via the receptor-interacting protein kinase 1 (RIPK1) pathway regulates colonic inflammation suggesting that RIPK1 inhibition may be a potential therapeutic target in ulcerative colitis (UC). This phase IIa, randomised, double-blind experimental medicine study investigated the safety, pharmacokinetics (PK), pharmacodynamics (PD) and preliminary efficacy of the RIPK1 inhibitor GSK2982772 in patients with active UC.

DESIGN

In part A, prior to a protocol amendment, one patient was randomised to receive GSK2982772 60 mg twice daily for 42 days. After the amendment, patients were randomised 2:1 to receive GSK2982772 60 mg or placebo three times daily for 42 days. In part B, all patients switched to open-label GSK2982772 60 mg three times daily for 42 days. Safety, PK, PD biomarkers, histological disease activity, clinical efficacy and quality of life were assessed at days 43 and 85.

RESULTS

Thirty-six patients were randomised (n=12, placebo/open-label GSK2982772; n=24, GSK2982772/open-label GSK2982772). Most adverse events were mild, with headache reported the most frequently across groups (placebo/open-label GSK2982772, n=2 (17%); GSK2982772/open-label GSK2982772, n=8 (33%)). GSK2982772 was well distributed into colonic tissue, with generally higher concentrations in colonic biopsy samples versus plasma. No apparent differences between treatment groups were observed for PD, histological disease activity, clinical disease activity or quality-of-life measures. At screening, all patients had Mayo endoscopic scores of 2 or 3. At day 43, no patients in the placebo/open-label GSK2982772 group achieved Mayo endoscopic scores of 0 or 1 vs 3/24 (13%) for GSK2982772/open-label GSK2982772. At day 85, 1/9 (11%) achieved scores of 0 or one for placebo/open-label GSK2982772 vs 3/22 (14%) for GSK2982772/open-label GSK2982772.

CONCLUSION

GSK2982772 was generally well tolerated, with no treatment-related safety concerns identified. However, no significant differences in efficacy were observed between treatment groups, suggesting that GSK2982772 as monotherapy is not a promising treatment for patients with active UC.

TRIAL REGISTRATION NUMBER

NCT02903966.

Small molecule therapeutics for neuroinflammation-mediated neurodegenerative disorders

Chronically activated microglia and the resulting cascade of neuroinflammatory mechanisms have been postulated to play a critical role in neurodegenerative disorders. Microglia are the main component of the brain's innate immune system and become activated by infection, injury, misfolded proteins or a multitude of other stimuli. Activated microglia release pro-inflammatory and cytotoxic factors that can damage neurons and transform astrocytes to become toxic to neurons as well. Therapeutic approaches aiming to modulate microglia activation may be beneficial to mitigate the progression of inflammatory-mediated neurodegenerative diseases. In this literature review, we provide an overview of recent progress on key microglia targets and discovery of small molecule compounds advancing in clinical trials to minimize neuroinflammation.

Development of a Prototype, Once-Daily, Modified-Release Formulation for the Short Half-Life RIPK1 Inhibitor GSK2982772

PURPOSE

GSK2982772 is a selective inhibitor of receptor-interacting protein kinase-1, with a 2-3 h half-life. This study evaluated if a once-daily modified-release formulation of GSK2982772 could be developed with no significant food effect.

METHODS

Part A evaluated the pharmacokinetics of GSK2982772 following fasted single-dose (120 mg) administration of two matrix minitab formulations (MT-8 h and MT-12 h) vs 120 mg immediate release (IR) and MT-12 h with a high-fat meal. Part B evaluated once-daily MT-12 h for 3 days at three dose levels. Part C evaluated a matrix monolithic (MM-12 h) formulation at two dose levels in different prandial states.

RESULTS

All modified-release formulations dosed in the fasted state reduced maximum plasma concentration (Cmax), delayed time to C_max, and decreased area under the curve (AUC) vs IR. When MT-12 h or MM-12 h were co-administered with a meal (standard or high-fat) C_max and AUC increased. Dosing MM-12 h 1 h before a standard or high-fat meal had minimal impact on exposure vs fasted.

CONCLUSIONS

MT-12 h and MM-12 h provided a QD pharmacokinetic profile in the fasted state, however when MT-12 h was dosed with a high-fat meal a QD profile was not maintained. ( ClinicalTrials.gov Identifier: NCT03266172).