Dual-Domain Antibodies with Engineered Fc-FcRn Affinity Modulation

A major asset of many monoclonal antibody (mAb)-based biologics is their persistence in circulation. The MHC class I family Fc receptor, FCGRT, is primarily responsible for this extended pharmacokinetic behavior. Engagement of FCGRT with the crystallizable fragment (Fc) domain protects IgG from catabolic elimination, thereby extending the persistence and bioavailability of IgG and related Fc-based biologics. There is a need for reliable in vivo models to facilitate the preclinical development of novel IgG-based biologics. FcRn-humanized mice have been widely accepted as translationally relevant surrogates for IgG-based biologics evaluations. Although such FCGRT-humanized mice, especially the mouse strain, B6.Cg-Fcgrttm1Dcr Tg(FCGRT)32Dcr (abbreviated Tg32), have been substantially validated for modeling humanized IgG-based biologics, there is a recognized caveat - they lack an endogenous source of human IgG that typifies the human competitive condition. Here, we used CRISPR/Cas9-mediated homology-directed repair to equip the hFCGRT Tg32 strain with a human IGHG1 Fc domain. This replacement now results in mice that produce human IgG1 Fc-mouse IgG Fab2 chimeric antibodies at physiologically relevant levels, which can be further heightened by immunization. This endogenous chimeric IgG1 significantly dampens the serum half-life of administered humanized mAbs in an hFCGRT-dependent manner. Thus, such IgG1-Fc humanized mice may provide a more physiologically relevant competitive hF

Neonatal Fc receptor (FcRn) plays an important role in regulating IgG homeostasis in the body. Changes in FcRn expression levels or activity caused by genetic polymorphisms of FCGRT, which encodes FcRn, may lead to interindividual differences in pharmacokinetics of therapeutic antibodies. In this study, we sequenced the 5'-flanking region, all exons and their flanking regions of FCGRT from 126 Japanese subjects. Thirty-three genetic variations, including 17 novel ones, were found. Of these, two novel non-synonymous variations, 629G>A (R210Q) and 889T>A (S297T), were found as heterozygous variations. We next assessed the functional significance of the two novel non-synonymous variations by expressing wild-type and variant proteins in HeLa cells. Both variant proteins showed similar intracellular localization as well as antibody recycling efficiencies. These results suggested that at least no common functional polymorphic site with amino acid change was present in the FCGRT of our Japanese population.

Rhesus macaque is an important animal model for studies testing interventions like antibody therapeutics; as such knowledge of inter-individual variations in function of genes affecting antibody recycling is important for optimal experimental design. Neonatal Fc receptor (FcRn), a heterodimer composed of FCGRT and β2-m chains, plays critical role in extending catabolic half-life of IgG. We studied genomic polymorphisms in rhesus macaque FcRn and asked if they are functional by assessing correlations with serum IgG or β2-m levels. We tested 75 animals and report the presence of a VNTR polymorphism in promoter of FcRn as well as a single nucleotide polymorphism in the signal peptide of β2-m. A VNTR minor allele was associated with lower levels of serum IgG. This polymorphism may account for inter-animal variation in antibody levels and has relevance for effective design of rhesus macaque studies investigating vaccine-induced antibody responses and passive immunizations.

IgG-based therapeutic antibodies are increasingly adopted for diverse human diseases, such as cancer and autoimmune disorders displaying remarkable therapeutic performance. A key factor in their success lies in the extended half-life of IgG molecules, which is regulated by the pH-dependent interaction between IgG and neonatal Fc receptor (FcRn). This interaction prevents lysosomal degradation of IgG. Despite the frequent use of humanized rodent models expressing human FcRn (hFcRn) in preclinical studies, these models often fail to accurately replicate human antibody pharmacokinetics (PK) due to the use of non-native promoters that influence FcRn expression. To overcome this limitation, we developed an innovative humanized FcRn knock-in (hiFcRn) mouse model using CRISPR/Cas9 technology. This model integrates hFcRn cDNA into the endogenous locus of the mouse Fcgrt gene, completely replacing native mouse FcRn (mFcRn) expression. The hiFcRn mouse model offers a more human-relevant platform for the preclinical evaluation of therapeutic antibodies and Fc-fusion proteins.

SARS-CoV-2 is primarily transmitted through droplets and airborne aerosols, and in order to prevent infection and reduce viral spread vaccines should elicit protective immunity in the airways. The neonatal Fc receptor (FcRn) transfers IgG across epithelial barriers and can enhance mucosal delivery of antigens. Here we explore FcRn-mediated respiratory delivery of SARS-CoV-2 spike (S). A monomeric IgG Fc was fused to a stabilized spike; the resulting S-Fc bound to S-specific antibodies and FcRn. Intranasal immunization of mice with S-Fc and CpG significantly induced antibody responses compared to the vaccination with S alone or PBS. Furthermore, we intranasally immunized mice or hamsters with S-Fc. A significant reduction of virus replication in nasal turbinate, lung, and brain was observed following nasal challenges with SARS-CoV-2 and its variants. Intranasal immunization also significantly reduced viral airborne transmission in hamsters. Nasal IgA, neutralizing antibodies, lung-resident memory T cells, and bone-marrow S-specific plasma cells mediated protection. Hence, FcRn delivers an S-Fc antigen effectively into the airway and induces protection against SARS-CoV-2 infection and transmission.

Efficient delivery of therapeutic antibodies into the central nervous system (CNS) remains severely limited by the restrictive nature of the blood-brain barrier (BBB). Receptor-mediated transcytosis (RMT) has emerged as a promising strategy to enhance antibody transport across the BBB. In this Viewpoint, we highlight recent advances in RMT-based antibody delivery, focusing specifically on three representative BBB receptors: transferrin receptor (TfR), insulin receptor (InsR), and neonatal Fc receptor (FcRn). By comparing antibody engineering strategies that target these receptors, we summarize current progress, discuss critical limitations, and suggest directions for advancing CNS-targeted therapeutic antibodies. This Viewpoint provides valuable insights for selecting appropriate RMT targets and optimizing antibody-based therapies for CNS diseases.

Background: Transferrin receptor-targeting monoclonal antibodies (TfRMAbs) enhance brain drug delivery by facilitating TfR-mediated transcytosis across the blood-brain barrier (BBB). Data suggest that chronic TfRMAb dosing reduces their plasma exposure in a dose- and fusion partner-dependent manner; however, the underlying mechanisms remain unclear. The neonatal Fc receptor (FcRn) extends IgG half-life via recycling, but its saturation after repeated doses may alter the pharmacokinetics (PK) of IgG fusion proteins. This study evaluated the role of the FcRn on the PK and biodistribution of TfRMAb fusion proteins. Methods: We examined TfRMAb alone and TfRMAb fused to erythropoietin (TfRMAb-EPO) or TNFα receptor (TfRMAb-TNFR) in wild-type (WT) and FcRn knockout (KO) mice following acute (single dose) or chronic (3× weekly for 4 weeks) subcutaneous administration at 3 mg/kg. Plasma levels, tissue biodistribution, and FcRn binding were measured using immunoassays. Results: Our results show that fusion partners influenced FcRn-mediated recycling and PK of TfRMAb fusion proteins. After acute dosing, TfRMAb-TNFR exhibited the greatest reduction in plasma exposure in FcRn KO versus WT mice, compared with TfRMAb and TfRMAb-EPO. Chronic dosing reduced the plasma persistence of all fusion proteins in WT mice. In FcRn KO mice, plasma exposure of TfRMAb and TfRMAb-EPO decreased with chronic dosing, whereas TfRMAb-TNFR showed no further reduction. Differences in FcRn binding affinity likely

Monoclonal antibody (mAb) engineering that optimizes binding to receptors present on brain vascular endothelial cells has enabled them to cross through the blood-brain barrier (BBB) and access the brain parenchyma to treat neurological diseases. However, once in the brain the extent to which receptor-mediated reverse transcytosis clears mAb from the brain is unknown. The aim of this study was to determine the contribution of the neonatal Fc-receptor (FcRn) in rat brain efflux employing two different in vivo drug delivery models. Two mAb variants with substantially different affinities to FcRn, and no known neuronal targets, (IgG1 N434A and H435A) were administered to rats via intranasal-to-central nervous system (CNS) and intra-cranial dosing techniques. Levels of full-length IgG were quantified in serum and brain hemispheres by a sensitive enzyme-linked immunosorbent assay (ELISA). Following intra-nasal delivery, low cerebral hemisphere levels of variants were obtained at 20min, with a trend towards faster clearance of the high FcRn binder (N434A); however, the relatively higher serum levels confounded analysis of brain FcRn contribution to efflux. Using stereotaxic coordinates, we optimized the timing and dosing regimen for injection of mAb into the cortex. Levels of N434A, but not H435A, decreased in the cerebral hemispheres following bilateral injection into the rat cortex and higher levels of N434A were detected in serum compared to H435A after 24h. Immunohistochemical s

Monoclonal antibodies have therapeutic potential for treating diseases of the central nervous system, but their accumulation in the brain is limited by the blood-brain barrier (BBB). Here, we show that reducing the affinity of an antibody for the transferrin receptor (TfR) enhances receptor-mediated transcytosis of the anti-TfR antibody across the BBB into the mouse brain where it reaches therapeutically relevant concentrations. Anti-TfR antibodies that bind with high affinity to TfR remain associated with the BBB, whereas lower-affinity anti-TfR antibody variants are released from the BBB into the brain and show a broad distribution 24 hours after dosing. We designed a bispecific antibody that binds with low affinity to TfR and with high affinity to the enzyme β-secretase (BACE1), which processes amyloid precursor protein into amyloid-β (Aβ) peptides including those associated with Alzheimer's disease. Compared to monospecific anti-BACE1 antibody, the bispecific antibody accumulated in the mouse brain and led to a greater reduction in brain Aβ after a single systemic dose. TfR-facilitated transcytosis of this bispecific antibody across the BBB may enhance its potency as an anti-BACE1 therapy for treating Alzheimer's disease.

The emerging class of bispecific antibodies represents a significant advancement in Alzheimer's disease (AD) immunotherapy by addressing the limited brain concentrations achieved with conventional monoclonal antibodies. The majority of bispecific antibodies developed for AD treatment utilize transferrin receptor (TfR1)-mediated transcytosis to enhance blood-brain barrier (BBB) penetration, resulting in higher and more uniform brain concentrations compared to conventional antibodies. This improved delivery has demonstrated superior efficacy in reducing brain amyloid-beta (Aβ) burden. Additionally, TfR1-mediated delivery may help mitigate adverse effects such as amyloid-related imaging abnormalities (ARIA). This is likely achieved by a reduction in antibody accumulation at vascular Aβ deposits, resulting from the combined effects of lower dosing and a different brain entry route when using bispecific antibodies. Besides targeting Aβ, bispecific antibodies have been engineered to address other key pathological features of AD, including tau pathology and neuroinflammatory targets, which are critical drivers of disease progression. These antibodies also show promise in diagnostic applications, particularly as radioligands for antibody-based positron emission tomography (immunoPET), leveraging their rapid brain delivery and efficient and specific target engagement. Moreover, the principles of bispecific antibody technology have been adapted for use beyond immunotherapy. The incorpo

Understanding the biological mechanisms underlying the pH-dependent nature of FcRn binding, as well as the various factors influencing the affinity to FcRn, was concurrent with the arrival of the first recombinant IgG monoclonal antibodies (mAbs) and IgG Fc-fusion proteins in clinical practice. IgG Fc-FcRn became a central subject of interest for the development of these drugs for the comfort of patients and good clinical responses. In this review, we describe (i) mAb mutations close to and outside the FcRn binding site, increasing the affinity for FcRn at acidic pH and leading to enhanced mAb half-life and biodistribution, and (ii) mAb mutations increasing the affinity for FcRn at acidic and neutral pH, blocking FcRn binding and resulting, in vivo, in endogenous IgG degradation. Mutations modifying FcRn binding are discussed in association with pH-dependent modulation of antigen binding and (iii) anti-FcRn mAbs, two of the latest innovations in anti-FcRn mAbs leading to endogenous IgG depletion. We discuss the pharmacological effects, the biological consequences, and advantages of targeting IgG-FcRn interactions and their application in human therapeutics.

We have engineered the Fc region of a human immunoglobulin G (IgG) to generate a mutated antibody that modulates the concentrations of endogenous IgGs in vivo. This has been achieved by targeting the activity of the Fc receptor, FcRn, which serves through its IgG salvage function to maintain and regulate IgG concentrations in the body. We show that an IgG whose Fc region was engineered to bind with higher affinity and reduced pH dependence to FcRn potently inhibits FcRn-IgG interactions and induces a rapid decrease of IgG levels in mice. Such FcRn blockers (or 'Abdegs,' for antibodies that enhance IgG degradation) may have uses in reducing IgG levels in antibody-mediated diseases and in inducing the rapid clearance of IgG-toxin or IgG-drug complexes.

The neonatal Fc receptor (FcRn) is expressed by cells of epithelial, endothelial and myeloid lineages and performs multiple roles in adaptive immunity. Characterizing the FcRn/IgG interaction is fundamental to designing therapeutic antibodies because IgGs with moderately increased binding affinities for FcRn exhibit superior serum half-lives and efficacy. It has been hypothesized that 2 FcRn molecules bind an IgG homodimer with disparate affinities, yet their affinity constants are inconsistent across the literature. Using surface plasmon resonance biosensor assays that eliminated confounding experimental artifacts, we present data supporting an alternate hypothesis: 2 FcRn molecules saturate an IgG homodimer with identical affinities at independent sites, consistent with the symmetrical arrangement of the FcRn/Fc complex observed in the crystal structure published by Burmeister et al. in 1994. We find that human FcRn binds human IgG1 with an equilibrium dissociation constant (KD) of 760 ± 60 nM (N = 14) at 25°C and pH 5.8, and shows less than 25% variation across the other human subtypes. Human IgG1 binds cynomolgus monkey FcRn with a 2-fold higher affinity than human FcRn, and binds both mouse and rat FcRn with a 10-fold higher affinity than human FcRn. FcRn/IgG interactions from multiple species show less than a 2-fold weaker affinity at 37°C than at 25°C and appear independent of an IgG's variable region. Our in vivo data in mouse and rat models demonstrate that both affi

The treatment of neurological disorders with large-molecule biotherapeutics requires that the therapeutic drug be transported across the blood-brain barrier (BBB). However, recombinant biotherapeutics, such as neurotrophins, enzymes, decoy receptors, and monoclonal antibodies (MAb), do not cross the BBB. These biotherapeutics can be re-engineered as brain-penetrating bifunctional IgG fusion proteins. These recombinant proteins comprise two domains, the transport domain and the therapeutic domain, respectively. The transport domain is an MAb that acts as a molecular Trojan horse by targeting a BBB-specific endogenous receptor that induces receptor-mediated transcytosis into the brain, such as the human insulin receptor (HIR) or the transferrin receptor (TfR). The therapeutic domain of the IgG fusion protein exerts its pharmacological effect in the brain once across the BBB. A generation of bifunctional IgG fusion proteins has been engineered using genetically engineered MAbs directed to either the BBB HIR or TfR as the transport domain. These IgG fusion proteins were validated in animal models of lysosomal storage disorders; acute brain conditions, such as stroke; or chronic neurodegeneration, such as Parkinson's disease and Alzheimer's disease. Human phase I-III clinical trials were also completed for Hurler MPSI and Hunter MPSII using brain-penetrating IgG-iduronidase and -iduronate-2-sulfatase fusion protein, respectively.

Almost 50 million people worldwide are affected by Alzheimer's disease (AD), the most common neurodegenerative disorder. Development of disease-modifying therapies would benefit from reliable, non-invasive positron emission tomography (PET) biomarkers for early diagnosis, monitoring of disease progression, and assessment of therapeutic effects. Traditionally, PET ligands have been based on small molecules that, with the right properties, can penetrate the blood-brain barrier (BBB) and visualize targets in the brain. Recently a new class of PET ligands based on antibodies have emerged, mainly in applications related to cancer. While antibodies have advantages such as high specificity and affinity, their passage across the BBB is limited. Thus, to be used as brain PET ligands, antibodies need to be modified for active transport into the brain. Here, we review the development of radioligands based on antibodies for visualization of intrabrain targets. We focus on antibodies modified into a bispecific format, with the capacity to undergo transferrin receptor 1 (TfR1)-mediated transcytosis to enter the brain and access pathological proteins, e.g. amyloid-beta. A number of such antibody ligands have been developed, displaying differences in brain uptake, pharmacokinetics, and ability to bind and visualize the target in the brain of transgenic mice. Potential pathological changes related to neurodegeneration, e.g. misfolded proteins and neuroinflammation, are suggested as future tar

Antisense oligonucleotides (ASOs) have emerged as one of the most innovative new genetic drug modalities. However, their high molecular weight limits their bioavailability for otherwise-treatable neurological disorders. We investigated conjugation of ASOs to an antibody against the murine transferrin receptor, 8D3130, and evaluated it via systemic administration in mouse models of the neurodegenerative disease spinal muscular atrophy (SMA). SMA, like several other neurological and neuromuscular diseases, is treatable with single-stranded ASOs that modulate splicing of the survival motor neuron 2 (SMN2) gene. Administration of 8D3130-ASO conjugate resulted in elevated levels of bioavailability to the brain. Additionally, 8D3130-ASO yielded therapeutic levels of SMN2 splicing in the central nervous system of adult human SMN2-transgenic (hSMN2-transgenic) mice, which resulted in extended survival of a severely affected SMA mouse model. Systemic delivery of nucleic acid therapies with brain-targeting antibodies offers powerful translational potential for future treatments of neuromuscular and neurodegenerative diseases.

Neurological disorders are a diverse group of conditions that pose an increasing health burden worldwide. There is a general lack of effective therapies due to multiple reasons, of which a key obstacle is the presence of the blood-brain barrier, which limits drug delivery to the central nervous system, and generally restricts the pool of candidate drugs to small, lipophilic molecules. However, in many cases, these are unable to target key pathways in the pathogenesis of neurological disorders. As a group, RNA therapies have shown tremendous promise in treating various conditions because they offer unique opportunities for specific targeting by leveraging Watson-Crick base pairing systems, opening up possibilities to modulate pathological mechanisms that previously could not be addressed by small molecules or antibody-protein interactions. This potential paradigm shift in disease management has been enabled by recent advances in synthesizing, purifying, and delivering RNA. This review explores the use of RNA-based therapies specifically for central nervous system disorders, where we highlight the inherent limitations of RNA therapy and present strategies to augment the effectiveness of RNA therapeutics, including physical, chemical, and biological methods. We then describe translational challenges to the widespread use of RNA therapies and close with a consideration of future prospects in this field.

Recent advancements in gene expression modulation and RNA delivery systems have underscored the immense potential of nucleic acid-based therapies (NA-BTs) in biological research. However, the blood-brain barrier (BBB), a crucial regulatory structure that safeguards brain function, presents a significant obstacle to the delivery of drugs to glial cells and neurons. The BBB tightly regulates the movement of substances from the bloodstream into the brain, permitting only small molecules to pass through. This selective permeability poses a significant challenge for effective therapeutic delivery, especially in the case of NA-BTs. Extracellular vesicles, particularly exosomes, are recognized as valuable reservoirs of potential biomarkers and therapeutic targets. They are also gaining significant attention as innovative drug and nucleic acid delivery (NAD) carriers. Their unique ability to safeguard and transport genetic material, inherent biocompatibility, and capacity to traverse physiological barriers highlight their potential as drug carriers. This review provides a comprehensive overview of current strategies to enhance NAD to the brain, focusing on the emerging potential of exosomes as biocompatible and efficient nanocarriers. It synthesizes recent advances in the use of exosomes for NA-BTs in neurological disorders, comparing their advantages with those of conventional nanodelivery systems and cell-based therapies. Additionally, the review highlights innovative exosome engin

The convergence of peptides and nanoparticles through bionanoconjugation has emerged as a transformative strategy to address the persistent challenges in treating neurodegenerative disorders. Peptides, particularly short sequences (< 45 amino acids), offer unique advantages as protein mimetics, including structural flexibility, target specificity and blood-brain barrier permeability. Their clinical translation is hindered by rapid enzymatic degradation, short half-life, and poor bioavailability. Conjugation with nanoparticles, overcomes these limitations by enhancing stability, prolonging circulation, and enabling precise targeting. Peptide-nanoparticle conjugates, including TAT-functionalized gold nanoparticles and RGD-decorated polymeric systems, have shown significant improvements in blood brain barrier penetration. These advancements are associated with a reduction in amyloid-beta aggregation and the inhibition of tau hyperphosphorylation in preclinical models. These hybrids leverage peptides dual roles as therapeutic agents and drug carriers, often exploiting receptor-mediated transport for brain delivery. This review critically evaluates covalent and noncovalent conjugation strategies, such as carbodiimide chemistry, ligand exchange, and click reactions, highlighting their impact on structural stability and bioactivity. We further discuss advances in peptide classes, including cell-penetrating peptides, nuclear localization signals, targeting peptides and bioactive pept

Excessive reactive oxygen species (ROS)-induced nigrostriatal dopaminergic neuron degeneration is a cardinal pathological feature of Parkinson's disease (PD). Although icariin, a natural antioxidant capable of scavenging ROS, shows therapeutic potential, it remains underutilized in clinical settings. This translational gap primarily stems from two pharmacological limitations: (1) inadequate blood-brain barrier (BBB) penetration that prevents effective delivery of icariin to the brain, and (2) the lack of targeted drug release at pathological sites, thereby diminishing its local neuroprotective efficacy against ROS-mediated neurodegeneration. To overcome these challenges, we developed a ROS-responsive selenocysteamine-alginate nanogel (ASeNG-ICA) that bypasses the BBB via nose-to-brain delivery and enables pathology-triggered drug release through diselenide bond cleavage in the high-ROS microenvironments characteristic of PD. In vitro studies demonstrated that the nanogels undergo ROS-responsive disintegration, resulting in sustained icariin release under oxidative conditions. Following intranasal administration in mice, ASeNG-ICA achieved rapid brain biodistribution. In a PD mouse model, this delivery system significantly reduced striatal malondialdehyde (MDA) levels, regulated antioxidant enzymes (HO-1, SOD) expression, alleviated oxidative stress and improved behavioral disorders, surpassing conventional free icariin therapy. Overall, ASeNG-ICA resolves critical delivery ba

Although biotherapeutics have vast potential for treating brain disorders, their use has been limited due to low exposure across the blood-brain barrier (BBB). We report that by manipulating the binding mode of an antibody fragment to the transferrin receptor (TfR), we have developed a Brain Shuttle module, which can be engineered into a standard therapeutic antibody for successful BBB transcytosis. Brain Shuttle version of an anti-Aβ antibody, which uses a monovalent binding mode to the TfR, increases β-Amyloid target engagement in a mouse model of Alzheimer's disease by 55-fold compared to the parent antibody. We provide in vitro and in vivo evidence that the monovalent binding mode facilitates transcellular transport, whereas a bivalent binding mode leads to lysosome sorting. Enhanced target engagement of the Brain Shuttle module translates into a significant improvement in amyloid reduction. These findings have major implications for the development of biologics-based treatment of brain disorders.

The blood-brain barrier (BBB) poses a major challenge for developing effective antibody therapies for neurological diseases. Using transcriptomic and proteomic profiling, we searched for proteins in mouse brain endothelial cells (BECs) that could potentially be exploited to transport antibodies across the BBB. Due to their limited protein abundance, neither antibodies against literature-identified targets nor BBB-enriched proteins identified by microarray facilitated significant antibody brain uptake. Using proteomic analysis of isolated mouse BECs, we identified multiple highly expressed proteins, including basigin, Glut1, and CD98hc. Antibodies to each of these targets were significantly enriched in the brain after administration in vivo. In particular, antibodies against CD98hc showed robust accumulation in brain after systemic dosing, and a significant pharmacodynamic response as measured by brain Aβ reduction. The discovery of CD98hc as a robust receptor-mediated transcytosis pathway for antibody delivery to the brain expands the current approaches available for enhancing brain uptake of therapeutic antibodies.

Myasthenia gravis (MG) is a chronic, fluctuating, antibody-mediated autoimmune disorder directed against the post-synaptic neuromuscular junctions of skeletal muscles, resulting in a wide spectrum of manifestations ranging from mild to potentially fatal. Given its unique natural course, designing an ideal trial design for MG has been wrought with difficulties and evidence in favour of several of the conventional agents is weak as per current standards. Despite this, acetylcholinesterases and corticosteroids have remained the cornerstones of treatment for several decades with intravenous immunoglobulins (IVIG) and therapeutic plasma exchange (PLEX) offering rapid treatment response, especially in crises. However, the treatment of MG entails long-term immunosuppression and conventional agents are viable options but take longer to act and have a number of class-specific adverse effects. Advances in immunology, translational medicine and drug development have seen the emergence of several newer biological agents which offer selective, target-specific immunotherapy with fewer side effects and rapid onset of action. Eculizumab is one of the newer agents that belong to the class of complement inhibitors and has been approved for the treatment of refractory general MG. Zilucoplan and ravulizumab are other agents in this group in clinical trials. Neisseria meningitis is a concern with all complement inhibitors, mandating vaccination. Neonatal Fc receptor (FcRn) inhibitors prevent immu

Background: Thyroid eye disease (TED) is a rare autoimmune orbital disorder predominantly associated with Graves' disease. It is characterized by orbital inflammation, tissue remodeling, and potential visual morbidity. Conventional therapies, particularly systemic glucocorticoids, offer only partial symptomatic relief, failing to reverse chronic structural changes such as proptosis and diplopia, and are associated with substantial adverse effects. This review aims to synthesize recent developments in understandings of TED pathogenesis and to critically evaluate emerging therapeutic strategies. Methods: A systematic literature review was conducted using MEDLINE, Embase, and international clinical trial registries focusing on pivotal clinical trials and investigational therapies targeting core molecular pathways involved in TED. Results: Current evidence suggests that TED pathogenesis is primarily driven by the autoimmune activation of orbital fibroblasts (OFs) through thyrotropin receptor (TSH-R) and insulin-like growth factor-1 receptor (IGF-1R) signaling. Teprotumumab, a monoclonal IGF-1R inhibitor and the first therapy approved by the U.S. Food and Drug Administration for TED, has demonstrated substantial clinical benefit, including improvements in proptosis, diplopia, and quality of life. However, concerns remain regarding relapse rates and treatment-associated adverse events, particularly hearing impairment. Investigational therapies, including next-generation IGF-1R inhi

Prostate cancer remains a prevalent and lethal malignancy across the globe. Despite ongoing advances in therapeutic approaches, these remain ineffective, and new treatments are drastically needed. Prostate-specific membrane antigen (PSMA)-targeted radionuclide therapy is a well-developed approach for prostate cancer treatment; however, current small molecule and antibody carriers for molecular radiotherapy each have drawbacks in their biodistribution and consequent side effects as highlighted in current clinical trials. To address this, we developed an approach to bioengineer the well clinically validated antibody carrier HuJ591 to yield an engineered, full-length antibody construct that achieves the beneficial fast pharmacokinetic profile of small molecule carriers alongside the enhanced tumor targeting and reduced renal toxicity of antibody carriers. We report here a rational design process to produce a novel humanized PSMA-targeting antibody designed for the delivery of radiation with abrogated FcRn recycling that aims to reduce blood circulation time and minimize systemic exposure. We demonstrate that these IgG-based constructs retain the favorable properties of HuJ591, such as inherent protein stability, expression in systems compatible with industrial manufacture, and comparable, highly specific PSMA-binding characteristics. We then radiolabeled constructs with the diagnostic radionuclide 64Cu as a surrogate for therapeutic radionuclide payloads and undertook a proof-of