Antibody Targeting Research Articles

Trogocytosis: A potential pathogenic mechanism in immune thrombocytopenia leading to impaired megakaryocyte maturation and reduced platelet production

Immune thrombocytopenia (ITP) is an autoimmune disease due to increased peripheral platelets destruction and inappropriate bone marrow production of platelets by megakaryocytes (MKs). The pathophysiology of ITP is complex and multifactorial, which remains not fully understood. However, the production of antiplatelet autoantibodies and the destruction of antibody-coated platelets through antibody-dependent cellular phagocytosis by macrophages (Mθ) expressing Fc gamma receptor (FcγR) are regarded as the key mechanisms. Glycoprotein (GP) Ⅱb/Ⅲa is the main target of antiplatelet antibodies leading to platelet phagocytosis by splenic Mθ, through interactions with FcγR. As GPⅡb/Ⅲa is normally expressed both on platelets and the MKs from which they are derived, we inferred that partial phagocytosis (definitely trogocytosis) of MKs by bone marrow Mθ might exist, leading to the increased amount of granular MKs (or non-platelets-producing MKs) in ITP. And we further hypothesized that the “bitten” MKs cannot sustain their normal function of maturation. Such trogocytosis mechanism may shed new light on the understanding of morphology alterations, maturation defects and decreased platelets production of MKs in ITP, and provide appealing implications in therapeutic modifications targeting the interplay of MKs and Mθ in bone marrow.

Rapid dual-modal detection of two types of pesticides in fruits using SERS-based immunoassay

Pesticide residue is a harmful chemical residue produced in agricultural production, posing a threat to human health. To detect mixed pesticide residues in food rapidly and simultaneously, we present a dual-channel dual-modal test strip immunoassay. According to the standard colorimetric bar, the naked-eye test can achieve semi-quantitative detection. By collecting the Raman spectra of the signal probes, surface-enhanced Raman scattering (SERS) detection can achieve accurate quantification of pesticide residues. Specifically, a double-layer 4-mercaptobenzoic acid (4-MBA) molecule-labeled bimetallic core-shell material (AuMBA@AgMBA) was conjugated with target antibodies to obtain signal probes. Here, antibody bonding was achieved by the dehydrated condensation of its amino group with the carboxyl group of the outer 4-MBA. In addition, the Au nanoparticles were connected to rabbit IgG by electrostatic adsorption as indicating probes to ensure the normal operation of the test strips. Under the optimal parameters, the detection ranges of acetamiprid and carbendazim were 0.3 - 2μg/kg and 3 - 30μg/kg, respectively. Furthermore, the recovery experiments showed that the results of the SERS method matched well with the high-performance liquid chromatography method. The SERS immunoassay is characterized by high sensitivity, rapidity and reliability, which has potential to simultaneously detect mixed pesticides in the field.

Switching from Dupilumab to Upadacitinib in Adults and Adolescents with Moderate-to-Severe Atopic Dermatitis and Inadequate Response to Dupilumab: Efficacy and Safety Results from the Phase 3b/4 LEVEL UP Study

Atopic dermatitis (AD) is a chronic skin disease characterized by intense itch and eczematous skin lesions. Upadacitinib (UPA), a selective oral Janus kinase (JAK) inhibitor, and dupilumab (DUPI), a monoclonal antibody targeting interleukin-4 and interleukin-13 signaling, are both approved treatments for moderate-to-severe AD. LEVEL UP is a phase 3b/4 efficacy assessor blinded monotherapy study comparing UPA to DUPI for treatment of moderate-to-severe AD in adults and adolescents over a 16-week period (Period 1). Patients not achieving ≥75% improvement in the Eczema Area and Severity Index (EASI 75) from baseline at Week 16 entered an additional 16-week extension phase (Period 2). In Period 2, patients either continued/escalated to UPA 30 mg (UPA/UPA 30) or switched from DUPI to UPA 15 mg (DUPI/UPA), with the potential to escalate to 30 mg based on clinical response. Efficacy for skin and itch outcomes in Period 2 were assessed using observed case analysis while on treatment, without statistical comparisons. Here we report efficacy and safety results for the DUPI/UPA switch group. A total of 355 patients who did not achieve EASI 75 at Week 16 entered Period 2 of the study (DUPI/UPA, N=208). At Week 32, response rates in the DUPI/UPA group were: 79.6%, 58.7%, and 19.9% achieving EASI 75, EASI 90, and EASI 100, respectively; 60.2% achieving WP-NRS improvement ≥4 among those with baseline WP-NRS ≥4; 37.0% achieving WP-NRS 0/1 among those with baseline WP-NRS >1; and 26.8% simultaneously achieving EASI 90 and WP-NRS 0/1 by Week 32. Clinically meaningful outcomes were also observed at an earlier visit (Week 20). No new safety signals through Week 32 were identified compared to the established safety profile of UPA. Most patients with an inadequate response to DUPI at Week 16 experienced clinically meaningful improvements in skin clearance and itch at 4 weeks post-switch to UPA, with additional patients achieving these outcomes by 16 weeks post-switch. These findings suggest that switching from DUPI to UPA is an effective treatment strategy for patients who do not meet moderate or optimal treatment targets with DUPI.

2D4, a humanized monoclonal antibody targeting CD132, is a promising treatment for systemic lupus erythematosus

AbstractCurrent therapies for systemic lupus erythematosus that target a particular factor or cell type exhibit limited effectiveness. To address this limitation, our focus was on CD132, a subunit common to six inflammatory factor receptors implicated in SLE. Our study revealed heightened CD132 expression in SLE patients’ lymphocytes, contributing to the production of pro-inflammatory cytokines and immunoglobulins. We developed a novel humanized anti-CD132 monoclonal antibody, named as 2D4. 2D4 efficiently blocked IL-21 and IL-15, with limited effectiveness against IL-2, thereby suppressing T and B cells without disrupting immune tolerance. In the mouse immunization model, 2D4 virtually inhibited T cell-dependent, antigen-specific B-cell response. In lupus murine models, 2D4 mitigated inflammation by suppressing multiple pro-inflammatory cytokines and anti-dsDNA antibody titers, also diminishing proteinuria and glomerulonephritis. Compared to Belimumab, 2D4 exhibited superior efficacy in ameliorating the inflammatory state and preserving renal function. Moreover, 2D4 exhibited the ability to inhibit the production of pro-inflammatory factors and autoantibodies in PBMCs from individuals with SLE, highlighting its therapeutic potential for SLE individuals. Potent, 2D4 has the potential to significantly improve clinical outcomes in SLE and other complex autoimmune disorders.

The factor XI/XIa antibody abelacimab combined with enoxaparin inhibits filter clotting in hemodialysis circuits ex vivo.

Drugs targeting factor XI may offer an alternative to heparin for preventing blood clotting in extracorporeal circulation. We investigated the effects of abelacimab, a novel monoclonal antibody targeting factor XI. We collected whole blood samples into two bags (each 240ml, control group: enoxaparin 1.2mg, treatment group: enoxaparin 1.2mg plus abelacimab 5mg) and circulated in a hemodialysis device for up to 3h. We performed whole blood aggregation and thromboelastometry at several time points. Time to filter clotting was the primary endpoint. We included 10 volunteers. Each volunteer's blood was split into two bags (containing enoxaparin +/- abelacimab) and used simultaneously on two hemodialysis devices. The treatment group's time to filter clotting was significantly prolonged (treatment: 180min, IQR 180-180 vs. control: 120min, IQR 97-147, p < 0.001), and the transmembrane pressure was significantly lower at the end of the circuit flow (treatment: 13 mmHg vs. control: 65 mmHg, p = 0.001). Fibrinogen levels and median platelet counts were preserved. Platelet aggregation was better preserved in the treatment group for ristocetin (p = 0.015), thrombin receptor activating peptide (p = 0.015), and arachidonic acid (p = 0.001). Thromboelastometry showed prolonged clotting times in the treatment group at the end of the experiment (INTEM, p < 0.001; HEPTEM, p = 0.001). Abelacimab prolonged the time to filter clotting in this ex vivo model of hemodialysis. This is an aggressive model due to the frequent re-circulation of blood and a lack of endothelial cells. These data provide support for testing abelacimab in patients on hemodialysis.

INNV-07. IVOSIDENIB AND BEVACIZUMAB IN HEAVILY PRETREATED PATIENTS WITH IDH1 MUTANT GLIOMAS

Abstract Isocitrate dehydrogenase 1 (IDH1) inhibitors are transforming the treatment of patients with non-enhancing IDH1 mutant gliomas that have only undergone surgical resection. Questions remain on the utility of IDH1 inhibitors in patients that have received prior therapies such as radiation therapy (RT) and chemotherapy (e.g. temozolomide (TMZ)) and have progressive disease. We evaluated the safety and efficacy of ivosidenib, an oral IDH1 inhibitor, in combination with bevacizumab (BEV), a monoclonal antibody targeting VEGF-A, in IDH1 mutant glioma patients that were heavily pretreated. Fourteen patients received combination ivosidenib and bevacizumab starting between February 2021 to July 2023. In our small cohort, patient age range was 26 to 73 years with seven female patients and seven male patients. Diagnoses represented were astrocytoma, IDH1 mutant (n=10) and oligodendroglioma, IDH1 mutant (n=4). At the time of IDH1 therapy initiation, the majority of patients (n=10) had a grade 3 tumor. All patients (n=14) had canonical IDH1 mutation (p.Arg132His) and had enhancing disease. Therapies initiated prior to ivosidenib therapy included: prior RT (n=12), prior TMZ (n=14) and prior BEV (n=10). The median number of progressions prior to initiation of ivosidenib combination therapy was 3 (range 2 to 6). All patients received ivosidenib dosed at 500 mg daily with bevacizumab doses varying from 5 to 15 mg/kg IV dosed every 2 to 3 weeks. Combination therapy was well tolerated with minimal patients experiencing toxicities requiring dose interruptions; diarrhea (n=2), creatine phosphokinase elevations (n=1), QTc prolongation (n=1), and thrombocytopenia (n=1). The median treatment duration on ivosidenib combination therapy was 4.42 months (range 0.69 to 11.4 months). In this cohort, the combination of ivosidenib and bevacizumab was well tolerated. More information is needed on the benefit of ivosidenib in combination with other therapies and in heavily pretreated patients with IDH1 mutant gliomas.

Exploring the Biological Activity of a Humanized Anti-CD99 ScFv and Antibody for Targeting T Cell Malignancies

CD99, a type I transmembrane protein, emerges as a promising therapeutic target due to its heightened expression in T cell acute lymphoblastic leukemia (T-ALL). This characteristic renders it a potential marker for minimal residual disease detection and an appealing target for antibody-based treatments. Previous studies have revealed that a mouse monoclonal antibody, mAb MT99/3, selectively binds to CD99, triggering apoptosis in T-ALL/T-LBL cells while preserving the integrity of healthy cells. By targeting CD99, mAb MT99/3 suppresses antigen presentation and disrupts T cell functions, offering promise for addressing hyperresponsive T cell conditions. To facilitate clinical translation, we developed a humanized ScFv variant of mAb MT99/3, termed HuScFvMT99/3 in “ScFvkh” design. Structural analysis confirms its resemblance to the original antibody, and the immunoreactivity of HuScFvMT99/3 against CD99 is preserved. The fully humanized version of antibody HuMT99/3 was further engineered, exhibiting similar binding affinity at the 10−10 M level and specificity to the CD99 epitope without antigenic shift. HuMT99/3 demonstrates remarkable selectivity, recognizing both malignant and normal T cells but inducing apoptosis only in T-ALL/T-LBL cells, highlighting its potential for safe and targeted therapy.

Characteristics of stem sings of EpCAM-negative and EpCAM-positive tumor cells in primary tumor and 2D and 3D cultures in breast cancer

One of the predictors of adverse prognosis in breast cancer is the overexpression of the EpCAM protein. However, a signifcant part of tumor cells have low or no EpCAM expression. The molecular features and the ability to grow in 2D and 3D cultures, indirectly refecting metastatic potential of tumor cells without EpCAM expression, have not been sufficiently studied.The aim of the study was to compare phenotypic variants of stem cells and EMT depending on the EpCAM expression in the primary tumor of breast cancer and 2D and 3D cultures.Material and Methods. The study included 7 patients with invasive breast carcinoma of no special type. Luminal A subtype was found in 2/7 patients (29 %), and luminal B HER2-negative molecular subtype was found in 5/7 patients (71 %). The patients didn’t have neoadjuvant chemotherapy. Cells from the primary tumor were cultured in 2D and 3D. The primary tumor cells, 2D and 3D cultures were phenotyped using fow cytometry with antibodies targeting: CD45, EpCAM (CD326), CD44, CD24, N-cadherin (CD325), and CD133, CK7/8, EpCAM (CD326).Results. No significant differences were found in the frequency of detection and the number of cells exhibiting stem cell features among EpCAM- and EpCAM+ tumor cells, 2D and 3D cultures. All phenotypic variants of co-expression of stemness markers CD44, CD24, CD133, and ALDH were present both in the primary tumor and 2D/3D cultures. Stem cells in mammospheres had features of both epithelial and hybrid EMT phenotypes. In primary tumors and 2D/3D cultures, the smallest proportion consisted of stem cells with the CD44+CD24- phenotype and cells co-expressing CD44+CD24- with other stemness markers, while the largest proportion comprised stem cells with ALDH+ and ALDH+CD133+ phenotypes. Marked intra- and inter-tumor heterogeneity in the phenotypic composition of primary tumors, 2D, and 3D cultures was noted.Conclusion. The results indicate that EpCAM-negative and EpCAM-positive tumor cells of luminal molecular subtype of breast cancer are capable of exhibiting various phenotypic variants of stemness and EMT in the primary tumor and 2D and 3D cultures. In most cases, individual tumor cells show co-expression of several stemness markers. The phenotypic composition of primary tumors, 2D and 3D cultures is characterized by pronounced intra- and inter-tumor heterogeneity.

DNA Conformation-Regulated Hemin Switch for Lab-on-Chip Chemiluminescent Detection of an Antibody Secreted from Hybridoma Cells.

This work designed a DNA conformation-regulated hemin switch for rapid chemiluminescent (CL) detection of a monoclonal antibodies. This switch was performed with an affinity probe and an inhibition probe, which were conveniently prepared by hybridizing hemin-labeled DNA1 with KHL peptide-labeled DNA2 and binding biotin-labeled DNA3 to streptavidin, respectively. In the absence of the target antibody, streptavidin-DNA3 could hybridize with hemin-DNA1/KHL-DNA2 to release KHL-DNA2, which led to the loss of hemin activity due to the affinity hindrance of streptavidin-DNA3. After the KHL peptide was recognized by the target antibody, the strand replacement hybridization could be inhibited by the bound antibody, which retained the high catalytic activity of hemin overhung on the antibody-bound affinity probe for a CL reaction, leading to a "signal-on" process for CL antibody detection. Using a KHL-specific antibody, anti-proprotein convertase subtilisin/kexin type 9 antibody (PCSK9-Ab), as a target model and common L012-1,2,4-triazole-H2O2 CL system, the designed switch showed a detection range of 10 ng mL-1 to 1 μg mL-1 with a detection limit of 4.16 ng mL-1 (56.2 pM) and a short analytical time of 6.5 min. The proposed quick method could simply be used for lab-on-chip CL detection of PCSK9-Ab in situ-secreted from PCSK9-6E3 hybridoma cells, which showed an accuracy of 90.2% compared with the statistical results from general fluorescence imaging, providing a potential technique for screening specific hybridoma cells.

A Cancer-Specific Anti-Podoplanin Monoclonal Antibody, PMab-117-mG2a Exerts Antitumor Activities in Human Tumor Xenograft Models

Podoplanin (PDPN) overexpression is associated with poor clinical outcomes in various tumors. PDPN is involved in malignant tumor progression by promoting invasiveness and metastasis. Therefore, PDPN is considered a promising target of monoclonal antibody (mAb)-based therapy. Because PDPN also plays an essential role in normal cells such as kidney podocytes, cancer specificity is required to reduce adverse effects on normal cells. We developed a cancer-specific mAb (CasMab) against PDPN, PMab-117 (rat IgM, kappa), by immunizing rats with PDPN-overexpressed glioblastoma cells. The recombinant mouse IgG2a-type PMab-117 (PMab-117-mG2a) reacted with the PDPN-positive tumor PC-10 and LN319 cells but not with PDPN-knockout LN319 cells in flow cytometry. PMab-117-mG2a did not react with normal kidney podocytes and normal epithelial cells from the lung bronchus, mammary gland, and corneal. In contrast, one of the non-CasMabs against PDPN, NZ-1, showed high reactivity to PDPN in both tumor and normal cells. Moreover, PMab-117-mG2a exerted antibody-dependent cellular cytotoxicity in the presence of effector splenocytes. In the human tumor xenograft models, PMab-117-mG2a exhibited potent antitumor effects. These results indicated that PMab-117-mG2a could be applied to antibody-based therapy against PDPN-expressing human tumors while reducing the adverse effects.

Ranking Antibody Binding Epitopes and Proteins Across Samples from Whole Proteome Tiled Linear Peptides.

Ultradense peptide binding arrays that can probe millions of linear peptides comprising the entire proteomes of human or mouse, or hundreds of thousands of microbes, are powerful tools for studying the antibody repertoire in serum samples to understand adaptive immune responses. There are few tools for exploring high-dimensional, significant and reproducible antibody targets for ultradense peptide binding arrays at the linear peptide, epitope (grouping of adjacent peptides), and protein level across multiple samples/subjects (i.e. epitope spread or immunogenic regions of proteins) for understanding the heterogeneity of immune responses. We developed HERON (Hierarchical antibody binding Epitopes and pROteins from liNear peptides), an R package, which identifies immunogenic epitopes, using meta-analyses and spatial clustering techniques to explore antibody targets at various resolution and confidence levels, that can be found consistently across a specified number of samples through the entire proteome to study antibody responses for diagnostics or treatment. Our approach estimates significance values at the linear peptide (probe), epitope, and protein level to identify top candidates for validation. We test the performance of predictions on all three levels using correlation between technical replicates and comparison of epitope calls on two datasets, which shows HERON's competitiveness in estimating false discovery rates and finding general and sample-level regions of interest for antibody binding. The HERON R package is available at Bioconductor https://bioconductor.org/packages/release/bioc/html/HERON.html. Supplementary data are available at Bioinformatics online.

Diagnosing Autoimmune Bullous Diseases—An Indian Perspective

Abstract Introduction: Autoimmune bullous diseases (AIBDs) are a group of illnesses characterized by autoantibodies targeting adhesion molecules in the skin and mucosa. Accurate diagnosis of the specific subtype of AIBD is crucial for effective management and predicting prognosis, especially in cases with an increased risk of malignancy. However, differentiating between subtypes can be challenging due to overlapping symptoms. Overview of diagnostic tests: Direct immunofluorescence microscopy (DIF) detects in vivo bound antibodies in perilesional tissue biopsies and provides details about the probable site of autoantibody deposition within the skin/mucosae, immunoglobulin type, and pattern of antibody deposition. Indirect immunofluorescence (IIF) microscopy with organ substrate is a minimally invasive serological test that detects circulating autoantibodies. Enzyme-linked immunosorbent assay (ELISA) quantifies serum autoantibodies against specific autoantigens. Quantitative ELISA is useful for diagnosis, monitoring therapy, and assessing disease activity. Commercially available ELISA kits, including the multi-variant ones, can detect antibodies associated with AIBDs. BIOCHIP is a technique based on IIF that offers a sensitive and specific diagnostic alternative to ELISA. It uses microarrays with multiple antigenic substrates to simultaneously screen common AIBDs. The BIOCHIP slides contain different substrates, allowing the identification of multiple types of autoantibodies in a single test. Indian context: While these diagnostic tests offer valuable insights into target antigens, antibody patterns, and disease subtypes, it is important to note that the availability of these tests is limited in most centers across India. This limitation can be attributed to factors such as the relatively higher cost of these investigations, challenges related to the stability of immuno-reactants, and a shortage of trained personnel capable of performing such tests. Conclusion: This review discusses the diagnosis of AIBDs based on resources available in India, as of today. It also provides with practically applicable diagnostic algorithms for pragmatic diagnosis of AIBDs in Indian scenario.

Male fertility is preserved following ixekizumab treatment-a real life pilot study.

Preserving fertility is crucial when managing male patients with spondyloarthritis (SpA) and/or psoriasis (PsO), especially in young men. Chronic inflammation, hormonal dysregulation, and immunosuppressive therapies can negatively impact male fertility. Over the past decades, positive data have emerged regarding the reproductive safety of various therapies in men. Ixekizumab (IXE), a high-affinity monoclonal antibody targeting IL-17A, has shown a safe profile for male fertility in small studies. This pilot study assesses the impact of IXE treatment on sperm parameters in SpA and/or PsO patients in a real-world setting. Consecutive adult male SpA and/or PsO patients eligible for or undergoing IXE treatment were prospectively enrolled. Demographic data, disease characteristics, laboratory assessments, comorbidities, and previous treatments were recorded. Sperm analysis was conducted after a minimum of 6 months of IXE treatment, and also before treatment inititation in a subgroup of patients. Parallel sperm evaluations were performed in a control group of healthy donors. Ten patients were enrolled: 8 with SpA and 2 with PsO. After 6 months of IXE treatment, all patients had normal sperm parameters. One SpA and PsO patient with baseline oligozoospermia showed normal parameters at follow-up and achieved a successful pregnancy post-treatment. Compared with controls, IXE-treated patients had lower sperm concentrations but higher vitality. In our limited size pilot study on SpA and PsO patients, Ixekizumab exposure did not impair male fertility. Sperm parameters remained within normal ranges after a minimum of 6 months of treatment. Early Ixekizumab treatment may preserve or potentially reverse fertility impairment.

Daratumumab in the Management of Red Cell Aplasia Following Allogeneic Hematopoietic Stem Cell Transplantation.

Pure red cell aplasia (PRCA) is a rare but significant complication following major ABO-incompatible allogeneic hematopoietic stem cell transplantation (HSCT). The persistence of recipient B lymphocytes producing anti-donor isohemagglutinins leads to reticulocytopenia and anemia, often resulting in transfusion dependence. Current treatment options for post-HSCT PRCA are limited and frequently yield suboptimal responses, complicating patient management. Herein, we report three cases of post-HSCT PRCA successfully managed with daratumumab, a monoclonal antibody targeting CD38-expressing plasma cells. All patients demonstrated rapid reticulocyte recovery and transfusion independence after daratumumab treatment, despite prior treatment failures. These findings suggest that daratumumab may provide a more effective therapeutic approach, with a favorable safety profile compared to traditional therapies. Given its demonstrated efficacy and safety, daratumumab warrants consideration as a first-line treatment for post-HSCT PRCA, potentially improving patient quality of life and reducing transfusion-related complications. Further studies should explore optimal dosing and long-term outcomes.

Preclinical characterization of MTX-101: a novel bispecific CD8 Treg modulator that restores CD8 Treg functions to suppress pathogenic T cells in autoimmune diseases

IntroductionRegulatory CD8 T cells (CD8 Treg) are responsible for the selective killing of self-reactive and pathogenic CD4 T cells. In autoimmune disease, CD8 Treg may accumulate in the peripheral blood but fail to control the expansion of pathogenic CD4 T cells that subsequently cause tissue destruction. This CD8 Treg dysfunction is due in part to the expression of inhibitory killer immunoglobulin-like receptors (KIR; KIR2DL isoforms [KIR2DL1, KIR2DL2, and KIR2DL3]); these molecules serve as autoimmune checkpoints and limit CD8 Treg activation.MethodsHere we describe the pre-clinical characterization of MTX-101, a bispecific antibody targeting inhibitory KIR and CD8. Using human peripheral blood mononuculear cells (PBMC) derived from healthy donors and autoimmune patients, humanized mouse models, and human derived tissue organoids, we evaluated the molecular mechanisms and functional effects of MTX-101.ResultsBy binding to KIR, MTX-101 inhibited KIR signaling that can restore CD8 Treg ability to eliminate pathogenic CD4 T cells. MTX-101 bound and activated CD8 Treg in human peripheral blood mononuclear cells (PBMC), resulting in increased CD8 Treg cytolytic capacity, activation, and prevalence. Enhancing CD8 Treg function with MTX-101 reduced pathogenic CD4 T cell expansion and inflammation, without increasing pro-inflammatory cytokines or activating immune cells that express either target alone. MTX-101 reduced antigen induced epithelial cell death in disease affected tissues, including in tissue biopsies from individuals with autoimmune disease (i.e., celiac disease, Crohn’s disease). The effects of MTX-101 were specific to autoreactive CD4 T cells and did not suppress responses to viral and bacterial antigens. In a human PBMC engrafted Graft versus Host Disease (GvHD) mouse model of acute inflammation, MTX-101 bound CD8 Treg and delayed onset of disease. MTX-101 induced dose dependent binding, increased prevalence and cytolytic capacity of CD8 Treg, as well as increased CD4 T cell death. MTX-101 selectively bound CD8 Treg without unwanted immune cell activation or increase of pro-inflammatory serum cytokines and exhibited an antibody-like half-life in pharmacokinetic and exploratory tolerability studies performed using IL-15 transgenic humanized mice with engrafted human lymphocytes, including CD8 Treg at physiologic ratios.ConclusionCollectively, these data support the development of MTX-101 for the treatment of autoimmune diseases.

Antigen-specific modulation of chronic experimental autoimmune encephalomyelitis in humanized mice by TCR-like antibody targeting autoreactive T-cell epitope.

The development and application of human TCR-like (TCRL) antibodies recognizing disease-specific MHC-peptide complexes mayprove asan important tool for basic research and therapeutic applications. Multiple sclerosis is characterized by aberrant CD4 T-cell response to self-antigens presented by MHC class II molecules. This led us to select a panel of TCRL Abs targeting the immunodominant autoantigenic epitope MOG35-55 derived from myelin oligodendrocyte glycoprotein (MOG) presented on HLA-DR2, which is associated with multiple sclerosis (MS). We demonstrate that these TCRL Abs bind with high specificity to human HLA-DR2/MOG35-55-derived MHC class II molecules and can detect APCs that naturally present the MS-associated autoantigen in the humanized EAE transgenic mouse model. The TCRL Abs can block ex vivo and in vivo CD4 T-cell proliferation in response to MOG35-55 stimulation in an antigen-specific manner. Most significantly, administration of TCRL Abs to MOG35-55-induced EAE model in HLA-DR2 transgenic mice both prevents and regresses established EAE. TCRL function was associated with a reduction in autoreactive pathogenic T-cell infiltration into the CNS, along with modulation of activated CD11b+ macrophages/microglial APCs. Collectively, these findings demonstrate the combined action of TCRL Abs in blocking TCR-MHC interactions and modulating APC presentation and activation, leading to a profound antigen-specific inhibitory effect on the neuroinflammatory process, resulting in regression of EAE. Our study constitutes an in vivo proof of concept for the utility of TCR-like antibodies as antigen-specific immunomodulators for CD4-mediated autoimmune diseases such as MS, validating the importance of the TCR-MHC axis as a therapeutic target for various autoimmune and inflammatory diseases.

Fibroblast-like synoviocyte targeting antibodies are associated with failure to reach early and sustained remission or low disease activity after first-line therapy in rheumatoid arthritis

ObjectiveTo discover antibody biomarkers that can predict a lack of response to first-line therapy in rheumatoid arthritis (RA) patients.MethodsTwo RA cDNA phage display libraries were screened for novel antibodies in baseline RA sera from the Care in early RA (CareRA) trial, differentiating between patients who did or did not reach remission after first-line therapy (n=20 each). Antibody reactivity to identified University Hasselt (UH)-RA antigens was validated in baseline samples from 136 additional CareRA participants. The novel antibodies’ potential to predict failure to reach remission or low disease activity (LDA), according to the Disease Activity Score 28-joint C-reactive protein/erythrocyte sedimentation rate (DAS28CRP/ESR) and Clinical/Simplified Disease Activity Index (CDAI/SDAI), was studied by multivariate analyses. The presence of the antibody targets in RA synovial tissue and the fibroblast-like synoviocyte (FLS) cell line SW982 was determined by immunofluorescence.ResultsWe identified antibodies to 41 novel antigens. Antibodies against any of three antigens, UH-RA.305/318/329, discriminated between RA patients not reaching week (w)8 DAS28CRP remission and those that did (36% vs 13%,p=0.0031). In all patients, anti-UH-RA.305/318/329 antibody reactivity was associated with failure to reach week 8 DAS28CRP and DAS28ESR remission (OR 3.63,p=0.0031; OR 2.92,p=0.016; respectively), SDAI/CDAI sustained remission (OR 5.59,p=0.039 for both) and DAS28CRP and DAS28ESR sustained LDA (OR 3.7,p=0.009; OR 2.76,p=0.042; respectively). In rheumatoid factor/anti-citrullinated protein antibody (RF/ACPA) seronegative patients, these antibodies were strongly associated with failure to achieve week 8 DAS28CRP remission (OR 17.3,p=0.0029). Anti-UH-RA.305/329 antibodies were shown to target FLS in RA synovial tissue and SW982 cells.ConclusionWe identified three antibody biomarkers that are associated with failure to achieve remission/LDA after first-line RA therapy.

Phase 2b randomized clinical trial of amlitelimab, an anti-OX40 ligand antibody, in patients with moderate-to-severe atopic dermatitis

Amlitelimab, a fully human nondepleting monoclonal antibody targeting OX40 ligand on antigen-presenting cells, could prevent T-cell-driven inflammation seen in atopic dermatitis (AD). This trial evaluated the efficacy and safety of amlitelimab in adults with AD. In this 2-part, phase 2b, randomized, double-blinded placebo-controlled trial (NCT05131477), patients received subcutaneous amlitelimab every 4 weeks at doses of 250 mg with 500-mg loading dose, 250 mg, 125 mg, or 62.5 mg, or placebo for 24 weeks in Part 1 (1:1:1:1:1 randomization). In Part 2, clinical responders were reallocated 3:1 to withdraw amlitelimab or continue the previous dose regimen for 28 weeks. The primary end point was percent change in Eczema Area and Severity Index (EASI) from baseline to Week 16. 390 and 190 patients enrolled in Part 1 and Part 2, respectively. Significant percent change decreases in EASI were observed with amlitelimab vs. placebo (P<.001). Clinical responses at Week 24 (Investigator Global Assessment 0/1 and/or EASI-75) were maintained at Week 52 in patients continuing or withdrawn from amlitelimab. In patients maintaining clinical response at Week 52 while off-treatment, >80% had serum amlitelimab concentrations below a 4-μg/mL threshold for several weeks prior to Week 52. Reductions in AD-related biomarkers during Part 1 were maintained through Part 2. Amlitelimab was well tolerated over 52 weeks. Amlitelimab treatment significantly reduced clinical and biomarker responses, and was well tolerated in adults with AD through Week 52. Sustained responses were observed in the majority of patients after amlitelimab withdrawal for 28 weeks.

Structural insights into epitope-paratope interactions of a monoclonal antibody targeting CEACAM5-expressing tumors

Carcinoembryonic antigen-related cell adhesion molecules (CEACAMs) are overexpressed in some tumor types. The antibody-drug conjugate tusamitamab ravtansine specifically recognizes the A3-B3 domains of human CEACAM5 (hCEACAM5). To understand this specificity, here we map the epitope-paratope interface between the A3-B3 domains of hCEACAM5 (hCEACAM5A3-B3) and the antigen-binding fragment of tusamitamab (tusa Fab). We use hydrogen/deuterium exchange mass spectrometry to identify the tusa Fab paratope, which involves heavy chain (HC) residues 101–109 and light chain residues 48–54 and 88–104. Using surface plasmon resonance, we demonstrate that alanine variants of HC residues 96–108 abolish binding to hCEACAM5, suggesting that these residues are critical for tusa-Fab–antigen complex formation. The cryogenic electron microscopy structure of the hCEACAM5A3-B3- tusa Fab complex (3.11 Å overall resolution) reveals a discontinuous epitope involving residues in the A3-B3 domains and an N-linked mannose at residue Asn612. Conformational constraints on the epitope-paratope interface enable tusamitamab to target hCEACAM5A3-B3 and distinguish CEACAM5 from other CEACAMs.

Cardiac myosin-binding protein-C: assessing fragmentation patterns to differentiate between forms of myocardial injury

Abstract Background Cardiac myosin-binding protein-C (cMyC) is a novel biomarker of myocardial injury. We hypothesize that fragmentation of cMyC differs according to aetiology of myocardial injury. Assessing the fragmentation pattern of the protein may aid diagnosis of these conditions. Purpose This work represents an examination of cMyC fragmentation in human serum, and studies its utility in differentiating between forms of myocardial injury. Methods Patients who were admitted to a hospital during October-November 2023 with acute myocardial injury were recruited. Acute myocardial injury was defined as a dynamic troponin rise above the 99th centile (Abbott Alinity: cTnI&amp;gt;34ng/L male, cTnI &amp;gt;16ng/L female). Following collection, samples were left at room temperature for 30 minutes and then centrifuged. Serum was separated for cMyC measurement, frozen in liquid nitrogen and stored at -80 °C. Recruited patients were followed up during their inpatient journey. Their final diagnosis was defined using the 4th universal definition of MI by two cardiologists, with a third cardiologist acting as adjudicator, if required. The serum samples were analysed using two separate electrochemiluminescence sandwich ELISA assays detecting different portions of cMyC. One assay formulated for total concentration of cMyC using high affinity mouse N-terminal monoclonal antibodies (mAb) targeting epitopes in close proximity (Limit of Detection (LoD) = 9.0ng/L). The other assay uses a N-terminal and a C-terminal mouse mAb which straddle the major proteolytic cleavage site of cMyC. This assay detects the intact (fuller-length) cMyC (LoD= 14.2ng/L). Both assays perform with good sensitivity, low variability and are capable of detecting cMyC at concentrations well below the 99th centile. Results 11 patient samples were collected with final diagnoses of; type 1 MI (STEMI n=3, NSTEMI n=4), type 4 MI (alcohol septal ablation n=1), acute myocardial injury (myocarditis n=2) and type 2 MI (chest sepsis with known coronary disease n=2). Figure one details the percentage of intact cMyC relative to total cMyC measured in serum for each patient, and is split into their adjudicated diagnosis. The bars display the median and interquartile range (IQR). Our findings suggest that the fragmentation pattern of cMyC could help differentiate between forms of myocardial injury. The ratio of intact: total cMyC was higher in the type 2 MI than any other condition. The results did not reach statistical significance (p = 0.06) due to the small sample size. Conclusions The fragmentation pattern of cMyC is dependent on the type of myocardial injury and could aid in the differentiation between type 2 MI and other forms of myocardial injury.Figure One