Endolysosomal Pathway Research Articles

Targeted protein degradation through site-specific antibody conjugation with mannose 6-phosphate glycan.

Recent developments in targeted protein degradation have provided great opportunities to eliminating extracellular protein targets using potential therapies with unique mechanisms of action and pharmacology. Among them, Lysosome-Targeting Chimeras (LYTACs) acting through mannose 6-phosphate receptor (M6PR) have been shown to facilitate degradation of several soluble and membrane-associated proteins in lysosomes with high efficiency. Herein we have developed a novel site-specific antibody conjugation approach to generate antibody mannose 6-phosphate (M6P) conjugates. The method uses a high affinity synthetic M6P glycan, bisM6P, that is coupled to an Fc-engineered antibody NNAS. This mutant without any effector function was generated by switching the native glycosylation site from position 297 to 298 converting non-sialylated structures to highly sialylated N-glycans. The sialic acid of the glycans attached to Asn298 in the engineered antibody was selectively conjugated to bisM6P without chemoenzymatic modification, which is often used for site-specific antibody conjugation through glycans. The conjugate is mainly homogeneous by analysis using mass spectrometry, typically with one or two glycans coupled. The M6P-conjugated antibody against a protein of interest (POI) efficiently internalized targeted soluble proteins, such as human tumor necrosis factor (TNF), in both cancer cell lines and human immune cells, through the endo-lysosomal pathway as demonstrated by confocal microscopy and flow cytometry. TNF in cell culture media was significantly depleted after the cells were incubated with the M6P-conjugated antibody. TNF internalization is mediated through M6PR, and it is correlated well with cell surface expression of cation-independent M6PR (CI-MPR) in immune cells. A significant amount of CI-MPR remains on the cell surface, while internalized TNF is degraded in lysosomes. Thus, the antibody-M6P conjugate is highly efficient in inducing internalization and subsequent lysosome-mediated protein degradation. Our platform provides a unique method for producing biologics-based degraders that may be used to treat diseases through event-driven pharmacology, thereby addressing unmet medical needs.

CYpHER: catalytic extracellular targeted protein degradation with high potency and durable effect

Many disease-causing proteins have multiple pathogenic mechanisms, and conventional inhibitors struggle to reliably disrupt more than one. Targeted protein degradation (TPD) can eliminate the protein, and thus all its functions, by directing a cell’s protein turnover machinery towards it. Two established strategies either engage catalytic E3 ligases or drive uptake towards the endolysosomal pathway. Here we describe CYpHER (CatalYtic pH-dependent Endolysosomal delivery with Recycling) technology with potency and durability from a catalytic mechanism that shares the specificity and straightforward modular design of endolysosomal uptake. By bestowing pH-dependent release on the target engager and using the rapid-cycling transferrin receptor as the uptake receptor, CYpHER induces endolysosomal delivery of surface and extracellular targets while re-using drug, potentially yielding increased potency and reduced off-target tissue exposure risks. The TfR-based approach allows targeting to tumors that overexpress this receptor and offers the potential for transport to the CNS. CYpHER function was demonstrated in vitro with EGFR and PD-L1, and in vivo with EGFR in a model of EGFR-driven non-small cell lung cancer.

Tao and Rap2l ensure proper Misshapen activation and levels during Drosophila border cell migration.

Collective cell migration is fundamental in development, wound healing, and metastasis. During Drosophila oogenesis, border cells (BCs) migrate collectively inside the egg chamber, controlled by the Ste20-like kinase Misshapen (Msn). Msn coordinates the restriction of protrusion formation and contractile forces within the cluster. Here, we demonstrate that Tao acts as an upstream activator of Msn in BCs. Depleting Tao significantly impedes BC migration, producing a phenotype similar to Msn loss of function. Furthermore, we show that the localization of Msn relies on its citron homology (CNH) domain, which interacts with the small GTPase Rap2l. Rap2l promotes the trafficking of Msn to the endolysosomal pathway. Depleting Rap2l elevates Msn levels by reducing its trafficking into late endosomes and increases overall contractility. These data suggest that Tao promotes Msn activation, while global Msn protein levels are controlled via Rap2l and the endolysosomal degradation pathway. Thus, two mechanisms ensure appropriate Msn levels and activation in BCs.

Sortilin-mediated translocation of mitochondrial ACSL1 impairs adipocyte thermogenesis and energy expenditure in male mice

Beige fat activation involves a fuel switch to fatty acid oxidation following chronic cold adaptation. Mitochondrial acyl-CoA synthetase long-chain family member 1 (ACSL1) localizes in the mitochondria and plays a key role in fatty acid oxidation; however, the regulatory mechanism of the subcellular localization remains poorly understood. Here, we identify an endosomal trafficking component sortilin (encoded by Sort1) in adipose tissues that shows dynamic expression during beige fat activation and facilitates the translocation of ACSL1 from the mitochondria to the endolysosomal pathway for degradation. Depletion of sortilin in adipocytes results in an increase of mitochondrial ACSL1 and the activation of AMPK/PGC1α signaling, thereby activating beige fat and preventing high-fat diet (HFD)-induced obesity and insulin resistance. Collectively, our findings indicate that sortilin controls adipose tissue fatty acid oxidation by substrate fuel selection during beige fat activation and provides a potential targeted approach for the treatment of metabolic diseases.

The schizophrenia risk gene C4 induces pathological synaptic loss by impairing AMPAR trafficking.

Neuroimmune interactions play a significant role in regulating synaptic plasticity in both the healthy and diseased brain. The complement pathway, an extracellular proteolytic cascade, exemplifies these interactions. Its activation triggers microglia-dependent synaptic elimination via the complement receptor 3 (CR3). Current models of pathological complement activity in the brain propose that accelerated synaptic loss resulting from overexpression of C4 (C4-OE), a gene associated with schizophrenia, follows this pathway. Here, we report that C4-mediated cortical hypoconnectivity is CR3-independent. Instead, C4-OE triggers impaired GluR1 trafficking through an intracellular mechanism involving the endosomal protein SNX27, resulting in pathological synaptic loss. Moreover, C4 circuit alterations in the prefrontal cortex, a brain region associated with neuropsychiatric disorders, were rescued by increasing neuronal levels of SNX27, which we identify as an interacting partner of this neuroimmune protein. Our results link excessive complement activity to an intracellular endo-lysosomal trafficking pathway altering synaptic plasticity.

Suppression of the amyloidogenic metabolism of APP and the accumulation of Aβ by alcadein α in the brain during aging

Generation and accumulation of amyloid-β (Aβ) protein in the brain are the primary causes of Alzheimer’s disease (AD). Alcadeins (Alcs composed of Alcα, Alcβ and Alcγ family) are a neuronal membrane protein that is subject to proteolytic processing, as is Aβ protein precursor (APP), by APP secretases. Previous observations suggest that Alcs are involved in the pathophysiology of Alzheimer’s disease (AD). Here, we generated new mouse AppNL-F (APP-KI) lines with either Alcα- or Alcβ-deficient background and analyzed APP processing and Aβ accumulation through the aging process. The Alcα-deficient APP-KI (APP-KI/Alcα-KO) mice enhanced brain Aβ accumulation along with increased amyloidogenic β-site cleavage of APP through the aging process whereas Alcβ-deficient APP-KI (APP-KI/Alcβ-KO) mice neither affected APP metabolism nor Aβ accumulation at any age. More colocalization of APP and BACE1 was observed in the endolysosomal pathway in neurons of APP-KI/Alcα-KO mice compared to APP-KI and APP-KI/Alcβ-KO mice. These results indicate that Alcα plays an important role in the neuroprotective function by suppressing the amyloidogenic cleavage of APP by BACE1 in the brain, which is distinct from the neuroprotective function of Alcβ, in which p3-Alcβ peptides derived from Alcβ restores the viability in neurons impaired by toxic Aβ.

Endolysosomal channel TMEM175 mediates antitoxin activity of DABMA.

DABMA is a chemical molecule optimized from the parent compound ABMA and exhibits broad-spectrum antipathogenic activity by modulating the host's endolysosomal and autophagic pathways. Both DABMA and ABMA inhibit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in a cellular assay, which further expands their anti-pathogen spectrum in vitro. However, their precise mechanism of action has not yet been resolved. TMEM175 is a newly characterized endolysosomal channel which plays an essential role in the homeostasis of endosomes and lysosomes as well as organelle fusion. Here, we show that DABMA increases the endosomal TMEM175 current through organelle patch clamping with an EC50 of 17.9 μm. Depletion of TMEM175 protein significantly decreases the antitoxin activity of DABMA and affects its action on acidic- and Rab7-positive endosomes as well as on endolysosomal trafficking. Thus, TMEM175 is necessary for DABMA's activity and may represent a druggable target for the development of anti-infective drugs. Moreover, DABMA, as an activator of the TMEM175 channel, may be useful for the in-depth characterization of the physiological and pathological roles of this endolysosomal channel.

Cystatin F Depletion in Mycobacterium tuberculosis-Infected Macrophages Improves Cathepsin C/Granzyme B-Driven Cytotoxic Effects on HIV-Infected Cells during Coinfection.

Cystatin F (CstF) is a protease inhibitor of cysteine cathepsins, including those involved in activating the perforin/granzyme cytotoxic pathways. It is targeted at the endolysosomal pathway but can also be secreted to the extracellular milieu or endocytosed by bystander cells. CstF was shown to be significantly increased in tuberculous pleurisy, and during HIV coinfection, pleural fluids display high viral loads. In human macrophages, our previous results revealed a strong upregulation of CstF in phagocytes activated by interferon γ or after infection with Mycobacterium tuberculosis (Mtb). CstF manipulation using RNA silencing led to increased proteolytic activity of lysosomal cathepsins, improving Mtb intracellular killing. In the present work, we investigate the impact of CstF depletion in macrophages during the coinfection of Mtb-infected phagocytes with lymphocytes infected with HIV. The results indicate that decreasing the CstF released by phagocytes increases the major pro-granzyme convertase cathepsin C of cytotoxic immune cells from peripheral blood-derived lymphocytes. Consequently, an observed augmentation of the granzyme B cytolytic activity leads to a significant reduction in viral replication in HIV-infected CD4+ T-lymphocytes. Ultimately, this knowledge can be crucial for developing new therapeutic approaches to control both pathogens based on manipulating CstF.

Truncated tau interferes with the autophagy and endolysosomal pathway and results in lipid accumulation

The autophagy-lysosomal pathway plays a critical role in the clearance of tau protein aggregates that deposit in the brain in tauopathies, and defects in this system are associated with disease pathogenesis. Here, we report that expression of Tau35, a tauopathy-associated carboxy-terminal fragment of tau, leads to lipid accumulation in cell lines and primary cortical neurons. Our findings suggest that this is likely due to a deleterious block of autophagic clearance and lysosomal degradative capacity by Tau35. Notably, upon induction of autophagy by Torin 1, Tau35 inhibited nuclear translocation of transcription factor EB (TFEB), a key regulator of lysosomal biogenesis. Both cell lines and primary cortical neurons expressing Tau35 also exhibited changes in endosomal protein expression. These findings implicate autophagic and endolysosomal dysfunction as key pathological mechanisms through which disease-associated tau fragments could lead to the development and progression of tauopathy.

Achieving Endo/Lysosomal Escape Using Smart Nanosystems for Efficient Cellular Delivery.

The delivery of therapeutic agents faces significant hurdles posed by the endo-lysosomal pathway, a bottleneck that hampers clinical effectiveness. This comprehensive review addresses the urgent need to enhance cellular delivery mechanisms to overcome these obstacles. It focuses on the potential of smart nanomaterials, delving into their unique characteristics and mechanisms in detail. Special attention is given to their ability to strategically evade endosomal entrapment, thereby enhancing therapeutic efficacy. The manuscript thoroughly examines assays crucial for understanding endosomal escape and cellular uptake dynamics. By analyzing various assessment methods, we offer nuanced insights into these investigative approaches' multifaceted aspects. We meticulously analyze the use of smart nanocarriers, exploring diverse mechanisms such as pore formation, proton sponge effects, membrane destabilization, photochemical disruption, and the strategic use of endosomal escape agents. Each mechanism's effectiveness and potential application in mitigating endosomal entrapment are scrutinized. This paper provides a critical overview of the current landscape, emphasizing the need for advanced delivery systems to navigate the complexities of cellular uptake. Importantly, it underscores the transformative role of smart nanomaterials in revolutionizing cellular delivery strategies, leading to a paradigm shift towards improved therapeutic outcomes.

Quantitative Chemical Imaging of Organelles.

ConspectusDNA nanodevices are nanoscale assemblies, formed from a collection of synthetic DNA strands, that may perform artificial functions. The pioneering developments of a DNA cube by Nadrian Seeman in 1991 and a DNA nanomachine by Turberfield and Yurke in 2000 spawned an entire generation of DNA nanodevices ranging from minimalist to rococo architectures. Since our first demonstration in 2009 that a DNA nanodevice can function autonomously inside a living cell, it became clear that this molecular scaffold was well-placed to probe living systems. Its water solubility, biocompatibility, and engineerability to yield molecularly identical assemblies predisposed it to probe and program biology.Since DNA is a modular scaffold, one can integrate independent or interdependent functionalities onto a single assembly. Work from our group has established a new class of organelle-targeted, DNA-based fluorescent reporters. These reporters comprise three to four oligonucleotides that each display a specific motif or module with a specific function. Given the 1:1 stoichiometry of Watson-Crick-Franklin base pairing, all modules are present in a fixed ratio in every DNA nanodevice. These modules include an ion-sensitive dye or a detection module and a normalizing dye for ratiometry that along with detection module forms a "measuring module". The third module is an organelle-targeting module that engages a cognate protein so that the whole assembly is trafficked to the lumen of a target organelle. Together, these modules allow us to measure free ion concentrations with accuracies that were previously unattainable, in subcellular locations that were previously inaccessible, and at single organelle resolution. By revealing that organelles exist in different chemical states, DNA nanodevices are providing new insights into organelle biology. Further, the ability to deliver molecules with cell-type and organelle level precision in animal models is leading to biomedical applications.This Account outlines the development of DNA nanodevices as fluorescent reporters for chemically mapping or modulating organelle function in real time in living systems. We discuss the technical challenges of measuring ions within endomembrane organelles and show how the unique properties of DNA nanodevices enable organelle targeting and chemical mapping. Starting from the pioneering finding that an autonomous DNA nanodevice could map endolysosomal pH in cells, we chart the development of strategies to target organelles beyond the endolysosomal pathway and expanding chemical maps to include all the major ions in physiology, reactive species, enzyme activity, and voltage. We present a series of vignettes highlighting the new biology unlocked with each development, from the discovery of chemical heterogeneity in lysosomes to identifying the first protein importer of Ca2+ into lysosomes. Finally, we discuss the broader applicability of targeting DNA nanodevices organelle-specifically beyond just reporting ions, namely using DNA nanodevices to modulate organelle state, and thereby cell state, with potential therapeutic applications.

Increasing the Survival of a Neuronal Model of Alzheimer's Disease Using Docosahexaenoic Acid, Restoring Endolysosomal Functioning by Modifying the Interactions between the Membrane Proteins C99 and Rab5.

Docosahexaenoic acid (DHA, C22:6 ω3) may be involved in various neuroprotective mechanisms that could prevent Alzheimer's disease (AD). Its influence has still been little explored regarding the dysfunction of the endolysosomal pathway, known as an early key event in the physiopathological continuum triggering AD. This dysfunction could result from the accumulation of degradation products of the precursor protein of AD, in particular the C99 fragment, capable of interacting with endosomal proteins and thus contributing to altering this pathway from the early stages of AD. This study aims to evaluate whether neuroprotection mediated by DHA can also preserve the endolysosomal function. AD-typical endolysosomal abnormalities were recorded in differentiated human SH-SY5Y neuroblastoma cells expressing the Swedish form of human amyloid precursor protein. This altered phenotype included endosome enlargement, the reduced secretion of exosomes, and a higher level of apoptosis, which confirmed the relevance of the cellular model chosen for studying the associated deleterious mechanisms. Second, neuroprotection mediated by DHA was associated with a reduced interaction of C99 with the Rab5 GTPase, lower endosome size, restored exosome production, and reduced neuronal apoptosis. Our data reveal that DHA may influence protein localization and interactions in the neuronal membrane environment, thereby correcting the dysfunction of endocytosis and vesicular trafficking associated with AD.

An open-label phase 1 study to investigate SGNCEACAM5C/SAR445953 in adults with advanced solid tumors (SGNCEA5C-001).

TPS3160 Background: Patients (pts) with recurrent or metastatic solid tumors, including non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC), colorectal cancer (CRC), gastric adenocarcinoma (GC), and pancreatic ductal adenocarcinoma (PDAC), have limited treatment options with short PFS and OS despite recent advances (1-3). Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) is highly expressed across multiple solid tumors, such as CRC, GC, PDAC, and NSCLC. Restricted normal tissue expression and efficient lysosomal trafficking of CEACAM5 highlight its potential as an anticancer target. SGN-CEACAM5C is a novel investigational antibody-drug conjugate (ADC) directed to CEACAM5 composed of the humanized immunoglobulin G (IgG1) anti-CEACAM5 monoclonal antibody tusamitamab chemically conjugated to 8 molecules of the topoisomerase 1 inhibitor 7-aminomethyl-10,11-methylenedioxycamptothecin (AMDCPT). SGN-CEACAM5C selectively binds to CEACAM5 present on the cell surface and is internalized via the endo-lysosomal pathway, with subsequent release of the payload through enzymatic cleavage. Release of the cytotoxic payload induces DNA damage, cell cycle arrest in S phase, and apoptosis in tumor cells. In vitro bystander activity was observed against tumor cells without CEACAM5 surface expression. SGN-CEACAM5C is highly active in multiple patient-derived xenograft models, including CRC, GC, and NSCLC, across various levels of CEACAM5 expression (4,5). These preclinical findings justify evaluation of SGN-CEACAM5C in a clinical trial setting. Methods: SGNCEA5C-001 (NCT06131840) is a phase 1, open-label, multicenter study designed to characterize the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary antitumor activity of SGN-CEACAM5C in adults with select advanced solid tumors. This study consists of dose escalation (Part A), dose and schedule optimization (Part B), and dose expansion (Part C). Eligible pts are adults ≥18 years of age with confirmed metastatic or unresectable solid tumor malignancy, measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1, an ECOG PS of 0-1, and 1 of the following tumor types: CRC, GC/gastroesophageal junction adenocarcinoma (GEJ), PDAC, NSCLC (squamous/non-squamous), or SCLC. Primary endpoints include incidence of AEs, laboratory abnormalities, dose modifications due to AEs, dose-limiting toxicities, and cumulative safety. Secondary endpoints include estimates of PK parameters, incidence of antidrug antibodies, objective response rate and best response per RECIST v1.1 by investigator, duration of response, PFS, and OS. Safety and antitumor activity endpoints will be summarized using descriptive statistics. Recruitment is ongoing for Part A in North America. 1. Bordry 2021. 2. Chakrabarti 2022. 3. Merle 2022. 4. Baudat 2023. 5. Baudat 2024. Clinical trial information: NCT06131840 .

Intestinal lymphatic transport of Smilax china L. pectic polysaccharide via Peyer's patches and its uptake and transport mechanisms in mononuclear phagocytes

Recently, the intestinal lymphatic transport based on Peyer's patches (PPs) is emerging as a promising absorption pathway for natural polysaccharides. Herein, the aim of this study is to investigate the PP-based oral absorption of a pectic polysaccharide from Smilax china L. (SCLP), as well as its uptake and transport mechanisms in related immune cells. Taking advantages of the traceability of fluorescently labeled SCLP, we confirmed that SCLP could be absorbed into PPs and captured by their mononuclear phagocytes (dendritic cells and macrophages) following oral administration. Subsequently, the systematic in vitro study suggested that the endocytic mechanisms of SCLP by model mononuclear phagocytes (BMDCs and RAW264.7 cells) mainly involved caveolae-mediated endocytosis, macropinocytosis and phagocytosis. More importantly, SCLP directly binds and interacts with toll-like receptor 2 (TLR2) and galectin 3 (Gal-3) receptor, and was taken up by mononuclear phagocytes in receptor-mediated manner. After internalization, SCLP was intracellularly transported primarily through endolysosomal pathway and ultimately localized in lysosomes. In summary, this work reveals novel information and perspectives about the in vivo fate of SCLP, which will contribute to further research and utilization of SCLP and other pectic polysaccharides.

Tumor Protein D52 Regulates Paligenosis in Exocrine Pancreatic Acinar Cells

Background: Paligenosis is a conserved cellular plasticity program in which fully differentiated cells reenter the cell cycle in order to regenerate lost tissue during injury. This process is utilized by cells that have a slow turnover rate and lack dedicated stem cells, as is the case with exocrine pancreatic acinar cells. Acinar cells, which synthesize and secrete digestive enzymes necessary for macronutrient digestion, undergo paligenosis in response to damage induced by the inflammatory disease pancreatitis. During paligenosis, acinar cells first downscale their secretory apparatus by upregulating autophagy, and then take on a mucinous-ductal-progenitor-like identity in a process called acinar to ductal metaplasia (ADM) prior to proliferation. This phenomenon can be recapitulated in rodent models in vivo utilizing repeated episodes of cerulein-induced pancreatitis or in 18-hour suspension culture during which primary isolated acinar cells dedifferentiate to a progenitor-like state. We have previously reported that markers of the endolysosomal secretory pathway in acinar cells are rapidly lost during models of experimental pancreatitis and suspension culture. Tumor Protein D52, which regulates endolysosomal traffcking and secretion in acinar cells, undergoes lysosomal degradation at the onset of experimental pancreatitis; furthermore, restoring D52 expression by adenovirus in isolated acinar cells maintains secretion during experimental pancreatitis as well as maintains acinar differentiation in suspension culture. Hypothesis: Degradation of D52, and loss of the endolysosomal secretory pathway, are pivotal events during the initial stages of paligenosis. Methods: To study the role of D52 and the regulation of paligenosis, we generated tamoxifen-inducible, acinar specific D52 knockout mice (D52KOac), and markers of paligenosis (ADM, proliferation) were assessed by immunoblot, qPCR, and immunostaining. Mice were given tamoxifen at 2-3 months of age to ensure normal pancreatic development, and tissues were harvested 21 days after tamoxifen. Results: Compared to controls, D52KOac exhibited 2.5-fold upregulation of the ductal markers Sox9 and CK19, 50% reduction of Ptf1α, and a 5-fold increase in β-catenin; these markers signify the presence of ADM and cells with progenitor-like characteristics. Cell cycle regulation and proliferation were also observed in D52KOac by a nearly 3-fold increase in cyclin D and increased Ki67+ nuclei. Conclusions: These data support that loss of D52 in pancreatic acinar cells induces spontaneous paligenosis in the absence of cellular injury and inflammation. These findings point to a previously unrecognized role for D52 in the regulation of acinar cell differentiation and plasticity. Given that paligenosis is a key pathway involved in the development of pancreatic neoplasms and adenocarcinoma, studying D52-regulated paligenosis will reveal additional insights into this critical protective mechanism. American Pancreatic Association Foundation Young Investigator Award. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

In vitro and in vivo proof-of-concept studies of extracellular protein degradation using novel M6PR-targeting chimeras (MTACs).

Abstract The mannose-6-phosphate-receptor (M6PR) traffics proteins from extracellular and intracellular locales to late endosomes/lysosomes for degradation and is ubiquitously expressed. This natural endogenous function of the mannose-6-phosphate-receptor (M6PR) may be harnessed for degradation of soluble circulating proteins and cell specific degradation of membrane proteins. Here we describe the design and development of novel M6PR targeting chimeras (MTACs). MTACs are heterobifunctional molecules containing Avilar’s novel, potent, small molecule M6PR-binding ligands conjugated to ligands that bind a target protein of interest for degradation. For proof-of-concept studies, MTACs were designed to target the extracellular protein IgG, the second most abundant circulating protein with a long plasma half-life. Reduction of pathogenic IgG autoantibodies is a clinically validated strategy for treating multiple debilitating autoimmune diseases. In vitro characterization of tridentate and monodentate MTACs revealed potent biochemical binding to M6PR and IgG, and MTAC-mediated cellular uptake and degradation of IgG via the endolysosomal pathway in K562 and LNCaP cells. In vivo MTAC-mediated depletion of human IgG was demonstrated using a heterologous rat PK/PD model.

Limbic-predominant age-related TDP-43 encephalopathy (LATE-NC): Co-pathologies and genetic risk factors provide clues about pathogenesis.

Limbic-predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC) is detectable at autopsy in more than one-third of people beyond age 85 years and is robustly associated with dementia independent of other pathologies. Although LATE-NC has a large impact on public health, there remain uncertainties about the underlying biologic mechanisms. Here, we review the literature from human studies that may shed light on pathogenetic mechanisms. It is increasingly clear that certain combinations of pathologic changes tend to coexist in aging brains. Although "pure" LATE-NC is not rare, LATE-NC often coexists in the same brains with Alzheimer disease neuropathologic change, brain arteriolosclerosis, hippocampal sclerosis of aging, and/or age-related tau astrogliopathy (ARTAG). The patterns of pathologic comorbidities provide circumstantial evidence of mechanistic interactions ("synergies") between the pathologies, and also suggest common upstream influences. As to primary mediators of vulnerability to neuropathologic changes, genetics may play key roles. Genes associated with LATE-NC include TMEM106B, GRN, APOE, SORL1, ABCC9, and others. Although the anatomic distribution of TDP-43 pathology defines the condition, important cofactors for LATE-NC may include Tau pathology, endolysosomal pathways, and blood-brain barrier dysfunction. A review of the human phenomenology offers insights into disease-driving mechanisms, and may provide clues for diagnostic and therapeutic targets.

Abstract CT077: An open-label phase 1 study to investigate SGN-CEACAM5C in adults with advanced solid tumors (SGNCEA5C-001, Trial in Progress)

Abstract Background Patients (pts) with recurrent or metastatic solid tumors, including non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC), colorectal cancer (CRC), gastric adenocarcinoma (GC), and pancreatic ductal adenocarcinoma (PDAC), have limited treatment options with short PFS and OS despite recent advances (Bordry 2021; Chakrabarti 2022; Merle 2022). Carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) is highly expressed across multiple solid tumors, such as CRC, GC, PDAC, and NSCLC. Restricted normal tissue expression and efficient lysosomal trafficking of CEACAM5 highlight its potential as an anticancer target. SGN-CEACAM5C is a novel investigational antibody-drug conjugate (ADC) directed to CEACAM5 composed of the humanized immunoglobulin G (IgG1) anti-CEACAM5 monoclonal antibody tusamitamab chemically conjugated to 8 molecules of the topoisomerase 1 inhibitor 7-aminomethyl-10,11-methylenedioxycamptothecin (AMDCPT). SGN-CEACAM5C selectively binds to CEACAM5 present on the cell surface and is internalized via the endo-lysosomal pathway, with subsequent release of the payload through enzymatic cleavage. Release of the cytotoxic payload induces DNA damage, cell cycle arrest in S phase, and apoptosis in tumor cells. In vitro bystander activity was observed against tumor cells without CEACAM5 surface expression. SGN-CEACAM5C is highly active in multiple patient-derived xenograft models, including CRC, GC, and NSCLC, across various levels of CEACAM5 expression (Baudat 2023; Baudat 2024). These preclinical findings justify evaluation of SGN-CEACAM5C in a clinical trial setting. Methods SGNCEA5C-001 (NCT06131840) is a phase 1, open-label, multicenter study designed to characterize the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary antitumor activity of SGN-CEACAM5C in adults with select advanced solid tumors. This study consists of dose escalation (Part A), dose and schedule optimization (Part B), and dose expansion (Part C). Eligible pts are adults ≥18 years of age with confirmed metastatic or unresectable solid tumor malignancy, measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1, an ECOG PS of 0-1, and 1 of the following tumor types: CRC, GC/gastroesophageal junction adenocarcinoma (GEJ), PDAC, NSCLC (squamous/non-squamous), or SCLC. Primary endpoints include incidence of AEs, laboratory abnormalities, dose modifications due to AEs, dose-limiting toxicities, and cumulative safety. Secondary endpoints include estimates of PK parameters, incidence of antidrug antibodies, objective response rate and best response per RECIST v1.1 by investigator, duration of response, PFS, and OS. Safety and antitumor activity endpoints will be summarized using descriptive statistics. Recruitment is ongoing for Part A in North America. Citation Format: Funda Meric-Bernstam, Cesar A. Perez, Nehal Lakhani, Meredith Pelster, Justin Call, Suzanne McGoldrick, Tianhua Wang, Brigitte Demers, Amita Patnaik. An open-label phase 1 study to investigate SGN-CEACAM5C in adults with advanced solid tumors (SGNCEA5C-001, Trial in Progress) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT077.

Lipid-Based Nanoparticle Functionalization with Coiled-Coil Peptides for In Vitro and In Vivo Drug Delivery.

For the delivery of drugs, different nanosized drug carriers (e.g., liposomes, lipid nanoparticles, and micelles) have been developed in order to treat diseases that afflict society. Frequently, these vehicles are formed by the self-assembly of small molecules to encapsulate the therapeutic cargo of interest. Over decades, nanoparticles have been optimized to make them more efficient and specific to fulfill tailor-made tasks, such as specific cell targeting or enhanced cellular uptake. In recent years, lipid-based nanoparticles in particular have taken center stage; however, off-targeting side effects and poor endosomal escape remain major challenges since therapies require high efficacy and acceptable toxicity.To overcome these issues, many different approaches have been explored to make drug delivery more specific, resulting in reduced side effects, to achieve an optimal therapeutic effect and a lower required dose. The fate of nanoparticles is largely dependent on size, shape, and surface charge. A common approach to designing drug carriers with targeting capability is surface modification. Different approaches to functionalize nanoparticles have been investigated since the attachment of targeting moieties plays a significant role in whether they can later interact with surface-exposed receptors of cells. To this end, various strategies have been used involving different classes of biomolecules, such as small molecules, nucleic acids, antibodies, aptamers, and peptides.Peptides in particular are often used since there are many receptors overexpressed in different specific cell types. Furthermore, peptides can be produced and modified at a low cost, enabling high therapeutic screening. Cell-penetrating peptides (CPPs) and cell-targeting peptides (CTPs) are frequently used for this purpose. Less studied in this context are fusogenic coiled-coil peptides. Lipid-based nanoparticles functionalized with these peptides are able to avoid the endolysosomal pathway; instead such particles can be taken up by membrane fusion, resulting in increased delivery of payload. Furthermore, they can be used for targeting cells/organs but are not directed at surface-exposed receptors. Instead, they recognize complementary peptide sequences, facilitating their uptake into cells.In this Account, we will discuss peptides as moieties for enhanced cytosolic delivery, targeted uptake, and how they can be attached to lipid-based nanoparticles to alter their properties. We will discuss the properties imparted to the particles by peptides, surface modification approaches, and recent examples showing the power of peptides for in vitro and in vivo drug delivery. The main focus will be on the functionalization of lipid-based nanoparticles by fusogenic coiled-coil peptides, highlighting the relevance of this concept for the development of future therapeutics.

Expression of ALS-PFN1 impairs vesicular degradation in iPSC-derived microglia

Microglia play a pivotal role in neurodegenerative disease pathogenesis, but the mechanisms underlying microglia dysfunction and toxicity remain to be elucidated. To investigate the effect of neurodegenerative disease-linked genes on the intrinsic properties of microglia, we studied microglia-like cells derived from human induced pluripotent stem cells (iPSCs), termed iMGs, harboring mutations in profilin-1 (PFN1) that are causative for amyotrophic lateral sclerosis (ALS). ALS-PFN1 iMGs exhibited evidence of lipid dysmetabolism, autophagy dysregulation and deficient phagocytosis, a canonical microglia function. Mutant PFN1 also displayed enhanced binding affinity for PI3P, a critical signaling molecule involved in autophagic and endocytic processing. Our cumulative data implicate a gain-of-toxic function for mutant PFN1 within the autophagic and endo-lysosomal pathways, as administration of rapamycin rescued phagocytic dysfunction in ALS-PFN1 iMGs. These outcomes demonstrate the utility of iMGs for neurodegenerative disease research and implicate microglial vesicular degradation pathways in the pathogenesis of these disorders.