Binding Of Monoclonal Antibodies Research Articles

Siltuximab for chimeric antigen receptor T-cell therapy–related CRS and ICANS: a multicenter retrospective analysis

AbstractChimeric antigen receptor T-cell (CAR-T) therapies are effective in many hematologic malignancies; however, adverse events including cytokine release syndrome (CRS) and immune effector cell–associated neurotoxicity syndrome (ICANS) can affect a significant number of patients. Those who develop refractory CRS or ICANS have few treatment options. Siltuximab, a monoclonal antibody binding circulating interleukin-6, has been proposed to have clinical activity in both CRS and ICANS. We conducted a multicenter retrospective analysis of siltuximab treatment for CRS and ICANS after CAR-T therapy in a real-world cohort from 6 academic centers. Fifty-four patients were evaluated. Sixteen patients had CRS previously treated with tocilizumab and 17 patients had ICANS previously treated with steroids. Of the patients with CRS at the time of siltuximab, 75% had improvement in CRS grade. Of the patients with ICANS at the time of siltuximab, 60% had improvement in ICANS grade. To our knowledge, this is the largest cohort of patients treated with siltuximab for CRS and/or ICANS after CAR-T therapies. Siltuximab appeared to be effective for both CRS and ICANS, including previously treated toxicities. These data support the use of siltuximab in CRS and ICANS as well as provide rationale for future prospective studies.

Salivary Cortisol Detection with a Fully Inkjet-Printed Paper-Based Electrochemical Sensor

Electrochemical paper-based analytical devices (ePADs) offer an innovative, low-cost, and environmentally friendly approach for real-time diagnostics. In this study, we developed a functional all-inkjet paper-based electrochemical immunosensor using gold (Au) printed ink to detect salivary cortisol. Covalent binding of the cortisol monoclonal antibody onto the printed Au surface was achieved through electrodeposition of 4-carboxymethylaniline (CMA), with ethanolamine passivation to prevent non-specific binding. The ePAD exhibited a linear response within the physiological cortisol range (5–20 ng/mL), with sensitivities of 25, 23, and 19 Ω·ng/mL and R2 values of 0.995, 0.979, and 0.99, respectively. Additionally, interference studies against tumor necrosis factor-α (TNF-α) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) yielded excellent results. This novel ePAD, fabricated using inkjet printing technology on paper, simplifies the process, reduces environmental impact, and lowers fabrication costs.

Structural basis for antibody-mediated NMDA receptor clustering and endocytosis in autoimmune encephalitis.

Antibodies against N-methyl-D-aspartate receptors (NMDARs) are most frequently detected in persons with autoimmune encephalitis (AE) and used as diagnostic biomarkers. Elucidating the structural basis of monoclonal antibody (mAb) binding to NMDARs would facilitate the development of targeted therapy for AE. Here, we reconstructed nanodiscs containing green fluorescent protein-fused NMDARs to label and sort individual immune B cells from persons with AE and further cloned and identified mAbs against NMDARs. This allowed cryo-electron microscopy analysis of NMDAR-Fab complexes, revealing that autoantibodies bind to the R1 lobe of the N-terminal domain of the GluN1 subunit. Small-angle X-ray scattering studies demonstrated NMDAR-mAb stoichiometry of 2:1 or 1:2, structurally suitable for mAb-induced clustering and endocytosis of NMDARs. Importantly, these mAbs reduced the surface NMDARs and NMDAR-mediated currents, without tonically affecting NMDAR channel gating. These structural and functional findings imply that the design of neutralizing antibody binding to the R1 lobe of NMDARs represents a potential therapy for AE treatment.

Predicting monoclonal antibody binding sequences from a sparse sampling of all possible sequences

Previous work has shown that binding of target proteins to a sparse, unbiased sample of all possible peptide sequences is sufficient to train a machine learning model that can then predict, with statistically high accuracy, target binding to any possible peptide sequence of similar length. Here, highly sequence-specific molecular recognition is explored by measuring binding of 8 monoclonal antibodies (mAbs) with specific linear cognate epitopes to an array containing 121,715 near-random sequences about 10 residues in length. Network models trained on resulting sequence-binding values are used to predict the binding of each mAb to its cognate sequence and to an in silico generated one million random sequences. The model always ranks the binding of the cognate sequence in the top 100 sequences, and for 6 of the 8 mAbs, the cognate sequence ranks in the top ten. Practically, this approach has potential utility in selecting highly specific mAbs for therapeutics or diagnostics. More fundamentally, this demonstrates that very sparse random sampling of a large amino acid sequence spaces is sufficient to generate comprehensive models predictive of highly specific molecular recognition.

Comparison of batch and continuous multi-column capture of monoclonal antibodies with convective diffusive membrane adsorbers

Protein A affinity membrane adsorbers are a promising alternative to resins to intensify the manufacturing of monoclonal antibodies. This study examined the process performance of convective diffusive membrane adsorbers operated in batch and continuous multi-column mode. Therefore, three different processes were compared regarding membrane utilization, productivity, and buffer consumption: the batch process, the rapid cycling parallel multi-column chromatography process, and the rapid cycling simulated moving bed process. The influence of the monoclonal antibody loading concentration (between 0.5 g L-1 and 5.2 g L-1) and the loading flow rate (between 1.25 MV min-1 and 10 MV min-1) on the monoclonal antibody binding behavior of the membrane adsorber were studied with breakthrough curve experiments. The determined breakthrough curves were used to calculate the monoclonal antibody dynamic binding capacity, the duration of the loading steps for each process, and the number of required membrane adsorbers for the continuous processes rapid cycling parallel multi-column chromatography and rapid cycling simulated moving bed. The highest productivity for the batch (176 g L-1 h-1) and rapid cycling parallel multi-column chromatography process (176 g L-1 h-1) was calculated for high monoclonal antibody loading concentrations and low loading flow rates. In contrast, the rapid cycling simulated moving bed process achieved the highest productivity (217 g L-1 h-1) for high monoclonal antibody loading concentrations and loading flow rates. Furthermore, due to the higher membrane utilization, the buffer consumption of the rapid cycling simulated moving bed process (1.1 L g-1) was up to 1.9 times lower than that of the batch or rapid cycling parallel multi-column chromatography operation (2.1 L g-1).

Structural and genetic basis for the binding of a mouse monoclonal antibody to Flavobacterium psychrophilum lipopolysaccharide.

A mouse monoclonal antibody (mAb FL100A) previously prepared against Flavobacterium psychrophilum (Fp) CSF259-93 has now been examined for binding to lipopolysaccharides (LPS) of this strain and Fp 950106-1/1. The corresponding O-polysaccharides (O-PS) of these strains are formed by identical trisaccharide repeats composed of l-Rhamnose (l-Rha), 2-acetamido-2-deoxy-l-fucose (l-FucNAc) and 2-acetamido-4-R1-2,4-dideoxy-d-quinovose (d-Qui2NAc4NR1) where R1 represents a dihydroxyhexanamido moiety. The O-PS loci of these strains are also identical except for the gene (wzy1 or wzy2) that encodes the polysaccharide polymerase. Accordingly, adjacent O-PS repeats are joined through d-Qui2NAc4NR1 and l-Rha by wzy2-dependent α(1-2) linkages in Fp CSF259-93 versus wzy1-dependent β(1-3) linkages in Fp 950106-1/1. mAb FL100A reacted strongly with Fp CSF259-93 O-PS and LPS but weakly or not at all with Fp 950106-1/1 LPS and O-PS. Importantly, it also labelled cell surface blebs on the former but not the latter strain. Additionally, mAb binding was approximately 5-times stronger to homologous Fp CSF259-93 LPS than to LPS from a strain with a different R-group gene. A conformational epitope for mAb FL100A binding was suggested from molecular dynamic simulations of each O-PS. Thus, Fp CSF259-93 O-PS formed a stable well-defined compact helix in which the R1 groups were displayed in a regular pattern on the helix exterior while unreactive Fp 950106-1/1 O-PS adopted a flexible extended linear conformation. Taken together, the findings establish the specificity of mAb FL100A for Wzy2-linked F. psychrophilum O-PS and LPS.

Emerging variants develop total escape from potent monoclonal antibodies induced by BA.4/5 infection

The rapid evolution of SARS-CoV-2 is driven in part by a need to evade the antibody response in the face of high levels of immunity. Here, we isolate spike (S) binding monoclonal antibodies (mAbs) from vaccinees who suffered vaccine break-through infections with Omicron sub lineages BA.4 or BA.5. Twenty eight potent antibodies are isolated and characterised functionally, and in some cases structurally. Since the emergence of BA.4/5, SARS-CoV-2 has continued to accrue mutations in the S protein, to understand this we characterize neutralization of a large panel of variants and demonstrate a steady attrition of neutralization by the panel of BA.4/5 mAbs culminating in total loss of function with recent XBB.1.5.70 variants containing the so-called ‘FLip’ mutations at positions 455 and 456. Interestingly, activity of some mAbs is regained on the recently reported variant BA.2.86.

Real-world clinical remission of severe asthma with benralizumab in Spanish adults with severe asthma

Objective Patients with severe eosinophilic asthma experience high risk of exacerbations and reduced quality of life. Benralizumab, a monoclonal antibody binding to IL-5 receptor α subunit, is an approved drug for its treatment. The objective was to describe clinical remission after benralizumab prescription in routine clinical practice. Methods Retrospective multicenter study with data from four hospitals in Valencian Community (Spain) with asthma units between 2019 and 2020. Data was gathered at baseline and after 12 months. We considered clinical remission after 1 year if the patient remained without exacerbations and use of systemic corticosteroids and with good clinical control and normal lung function. Results Data from 139 patients was gathered. At the 12-month follow-up, 44.1% were in clinical remission, since 84.0%, 77.5%, 51.0% and 95.5% of patients did not experience exacerbations, had total asthma control test score of ≥20, prebronchodilator FEV1 of ≥80% and did not use systemic corticosteroids. A significant reduction of long-acting muscarinic antagonists (p = 0.0001), leukotriene receptor antagonists (p = 0.0326), oral corticosteroids (p < 0.0001) and short-acting beta agonists (p = 0.0499) was observed. Baseline factors with greatest individual influence on clinical remission were employment situation, tobacco use, comorbidity number, eosinophil value, number of exacerbations, FEV1, emergency visit number, and ACT, MiniAQLQ and TAI scores. Final analysis of multiple logistic regression indicated that having baseline FEV1 value below 80% increases remission chance 9.7 times a year compared to FEV1 >80%. Conclusion Clinical remission after treatment with benralizumab is achievable in a high percentage of patients with severe asthma eosinophilia not controlled in real life.

Potent Apoptosis Induction by a Novel Trispecific B7-H3xCD16xTIGIT 2+1 Common Light Chain Natural Killer Cell Engager.

Valued for their ability to rapidly kill multiple tumor cells in succession as well as their favorable safety profile, NK cells are of increasing interest in the field of immunotherapy. As their cytotoxic activity is controlled by a complex network of activating and inhibiting receptors, they offer a wide range of possible antigens to modulate their function by antibodies. In this work, we utilized our established common light chain (cLC)-based yeast surface display (YSD) screening procedure to isolate novel B7-H3 and TIGIT binding monoclonal antibodies. The chicken-derived antibodies showed single- to low-double-digit nanomolar affinities and were combined with a previously published CD16-binding Fab in a 2+1 format to generate a potent NK engaging molecule. In a straightforward, easily adjustable apoptosis assay, the construct B7-H3xCD16xTIGIT showed potent apoptosis induction in cancer cells. These results showcase the potential of the TIGIT NK checkpoint in combination with activating receptors to achieve increased cytotoxic activity.

Evidence to Date on the Therapeutic Potential of Zolbetuximab in Advanced Gastroesophageal Adenocarcinoma.

Gastric adenocarcinoma (GAC) continues to be a prevalent worldwide malignancy and a leading cause of cancer death, and it is frequently cited as incurable. Targeted therapy in GAC has lagged behind other solid tumors. The human epidermal growth factor receptor-2 (HER-2) represented the single target in GACs for many years, seen in approximately 20% of patients with advanced GAC. Recent advances in management now include the addition of immunotherapy checkpoint inhibition to select front-line advanced GACs. Unfortunately, outcomes remain poor for most patients. We anticipate finding a key to future discoveries in GACs in next-generation sequencing and more targeted approaches. Claudin 18.2 (CLDN18.2) has emerged as a therapeutic target in GACs. CLDN18.2 is reportedly expressed in 14-87% of GACs, and CLDN18.2 is available for monoclonal antibody (mAb) binding as it is expressed on the outer cell membrane. Here, we review the exploration of CLDN18.2 as a target in GACs via the use of zolbetuximab (IMAB362). Zolbetuximab is now under priority FDA review for GACs, and we eagerly await the review outcome.

Recent clinical evidence on nutrition, novel pharmacotherapy, and vaccination in inflammatory bowel diseases.

Inflammatory bowel diseases (IBD), which enclose Crohn's disease (CD) and ulcerative colitis (UC), are chronic, relapsing inflammatory ailments. Their specific pathogenesis is not completely clarified, the worldwide incidence and prevalence of IBD has been steadily growing, and there is still not a definitive cure. The management of IBD has become more and more targeted, with specific immune mediators identified to be involved in its pathogenesis. Vedolizumab, a humanised monoclonal antibody binding specifically to the α4β7 integrin, is a gut-selective immunosuppressive biologic drug administered for both CD and UC. With the same indications as vedolizumab, ustekinumab is a fully human IgG1κ monoclonal antibody binding with specificity to the shared p40 protein subunit of human cytokines interleukin (IL)-12 and IL-23. Several selective IL-23p19 monoclonal antibodies (risankizumab, mirikizumab, and guselkumab) have also revealed admirable efficacy and safety in IBD patients. Nutrition is a very important environmental factor associated with the onset and progression of IBD, and the Western diet is considered to contribute to the development of IBD. In this narrative review, our aim is to present an overview of the main results from recent clinical studies on IBD regarding diet, new drug treatments, and also vaccination.

Design of an Ara h 2 hypoallergen from conformational epitopes.

Adverse reactions are relatively common during peanut oral immunotherapy. To reduce the risk to the patient, some researchers have proposed modifying the allergen to reduce IgE reactivity, creating a putative hypoallergen. Analysis of recently cloned human IgG from patients treated with peanut immunotherapysuggested that there are three common conformational epitopes for the major peanut allergen Ara h 2. We sought to test if structural information on these epitopes could indicate mutagenesis targets for designing a hypoallergen and evaluated the reduction in IgE binding via immunochemistry and a mouse model of passive cutaneous anaphylaxis (PCA). X-ray crystallography characterized the conformational epitopes in detail, followed by mutational analysis of key residues to modify monoclonal antibody (mAb) and serum IgE binding, assessed by ELISA and biolayer interferometry. A designed Ara h 2 hypoallergen was tested for reduced vascularization in mouse PCA experiments using pooled peanut allergic patient serum. A ternary crystal structure of Ara h 2 in complex with patient antibodies 13T1 and 13T5 was determined. Site-specific mutants were designed that reduced 13T1, 13T5, and 22S1 mAbs binding by orders of magnitude. By combining designed mutations from the three major conformational bins, a hexamutant (Ara h 2 E46R, E89R, E97R, E114R, Q146A, R147E) was created that reduced IgE binding in serum from allergic patients. Further, in the PCA model where mice were primed with peanut allergic patient serum, reactivity upon allergen challenge was significantly decreased using the hexamutant. These studies demonstrate that prior knowledge of common conformational epitopes can be used to engineer reduced IgE reactivity, an important first step in hypoallergen design.

Zolbetuximab for Claudin18.2-positive gastric or gastroesophageal junction cancer.

Claudins (CLDNs) are a family of major membrane proteins that form components of tight junctions. In normal tissues, CLDNs seal the intercellular space in the epithelial sheets to regulate tissue permeability, paracellular transport, and signal transduction. Claudin18.2 (CLDN18.2), a member of the CLDN family, is expressed specifically in gastric mucosal cells in normal tissue, and its expression is often retained in gastric cancer cells. CLDN18.2 is ectopically expressed in many cancers other than gastric cancer such as esophageal cancer, pancreatic cancer, biliary tract cancer, non-small-cell lung cancer, and ovarian cancer. Structurally, CLDN18.2 is localized on the apical side of the cell membrane and has extracellular loops capable of binding monoclonal antibodies. Upon malignant transformation, CLDN18.2 is exposed to the cell surface of the whole membrane, which enables the binding of monoclonal antibodies. Based on these characteristics, CLDN18.2 was considered to be optimal for target therapy, and zolbetuximab was developed which is a first-in-class chimeric immunoglobulin G1 monoclonal antibody highly specific for CLDN18.2. It binds to CLDN18.2 on the tumor cell surface and stimulates cellular and soluble immune effectors that activate antibody-dependent cytotoxicity and complement-dependent cytotoxicity. Recently, zolbetuximab combined with chemotherapy demonstrated a survival benefit in patients with CLDN18.2-positive and HER-2-negative gastric or gastroesophageal junction cancers in the global phase III SPOTLIGHT and GLOW trials. From these clinically meaningful results, CLDN18.2-targeting therapy including zolbetuximab has attracted a lot of attention. In this review, we summarize the clinical implications of CLDN18.2-positive gastric or GEJ cancer, and CLDN18.2-targeting therapy, mainly for zolbetuximab.

Engagement of CD300c by a novel monoclonal antibody induces the differentiation of monocytes to M1 macrophages

Human CD300c is expressed on various immune or cancer cells and is a novel B7 family member, functioning as an activity modulator on immune cells. To elucidate the function of CD300c, we developed CL7, a human CD300c-specific monoclonal antibody, and assessed its biological activity. The specific binding of CL7 monoclonal antibody against recombinant CD300c antigen was confirmed using enzyme-linked immunosorbent assay and surface plasmon resonance analysis. The binding affinity of CL7 was strong at the sub-nanomolar level. Furthermore, CL7 effectively bound to exogenously expressed CD300c on 293T cells. CL7 antibody differentiated monocytes to M1 macrophages, as evidenced by the upregulated expression of M1-specific cell surface markers and increased secretion of M1-specific cytokines in vitro in THP-1 cells and primary macrophages, as well as the increased population size of M1 macrophages in tumors grafted into mice. Additionally, CL7 treatment upregulated PD-L1 expression on THP-1 cells. We confirmed that the mechanism of M1 macrophage differentiation was through the mitogen-activated protein kinase and NF-κB signaling pathways. CD300c expression on various immune and cancer cells was similar to that of the well-known immune checkpoint PD-L1, suggesting the possibility of CD300c as a novel tumor biomarker. We also confirmed that the tumor size was substantially reduced by CL7 antibody treatment in the CT26 mouse model. Our study supports that CD300c is a potential therapeutic target in immuno-oncology. Overall, the CD300c-specific monoclonal antibody, CL7, is a promising immunotherapeutic agent, and it induces enhanced differentiation of M1 macrophages and/or their infiltration into the tumor microenvironment.

Quantitative Rapid Magnetic Immunoassay for Sensitive Toxin Detection in Food: Non-Covalent Functionalization of Nanolabels vs. Covalent Immobilization.

In this study, we present a novel and ultrasensitive magnetic lateral flow immunoassay (LFIA) tailored for the precise detection of zearalenone, a mycotoxin with significant implications for human and animal health. A versatile and straightforward method for creating non-covalent magnetic labels is proposed and comprehensively compared with a covalent immobilization strategy. We employ the magnetic particle quantification (MPQ) technique for precise detection of the labels and characterization of their functionality, including measuring the antibody sorption density on the particle surface. Through kinetic studies using the label-free spectral phase interferometry, the rate and equilibrium constants for the binding of monoclonal antibodies with free (not bound with carrier protein) zearalenone were determined to be kon = 3.42 × 105 M-1s-1, koff = 7.05 × 10-4 s-1, and KD = 2.06 × 10-9 M. The proposed MPQ-LFIA method exhibits detection limits of 2.3 pg/mL and 7.6 pg/mL when employing magnetic labels based on covalent immobilization and non-covalent sorption, with dynamic ranges of 5.5 and 5 orders, correspondingly. We have successfully demonstrated the effective determination of zearalenone in barley flour samples contaminated with Fusarium graminearum. The ease of use and effectiveness of developed test systems further enhances their value as practical tools for addressing mycotoxin contamination challenges.

High-Throughput Screening of Surface Engineered Cyanine Nanodots for Active Transport of Therapeutic Antibodies into Solid Tumor.

The successful delivery of therapeutic biomacromolecules into solid tumorholds great challenge due to their high resistance to penetrate through the complex tumor microenvironments. Here, active-transporting nanoparticles are harnessed to efficiently deliver biomacromolecular drugs into solid tumors through cell transcytosis. A series of molecularly precise cyanine 5-cored polylysine G5 dendrimers (Cy5 nanodots) with different peripheral amino acids (G5-AA) is prepared. The capability of these positively charged nanodots to induce cell endocytosis, exocytosis, and transcytosis is evaluated via fluorescence-based high-throughput screen. The optimized nanodots (G5-R) are conjugated with αPD-L1 (a therapeutic monoclonal antibody binding to programmed-death ligand 1) (αPD-L1-G5-R) to demonstrate the nanoparticle-mediated tumor active transport. The αPD-L1-G5-R can greatly enhance the tumor-penetration capability through adsorption-mediated transcytosis (AMT). The effectiveness of αPD-L1-G5-R is tested in treating mice bearing partially resected CT26 tumors, mimicking the local immunotherapy of residual tumors post-surgery in clinic. The αPD-L1-G5-R embedded in fibrin gel can efficiently mediate tumor cell transcytosis, and deliver αPD-L1 throughout the tumor, thereby enhancing immune checkpoint blockade, reducing tumor recurrence, and significantly prolonging the survival time. The active-transporting nanodots are promising platforms for efficient tumor delivery of therapeutic biomacromolecules.

Lecanemab Clarity AD: Quality-of-Life Results from a Randomized, Double-Blind Phase 3 Trial in Early Alzheimer’s Disease

BackgroundLecanemab is a humanized IgG1 monoclonal antibody binding with high affinity to amyloid-beta protein protofibrils. In phase 3 development, lecanemab has been shown to reduce markers of amyloid in early Alzheimer’s disease and reduce decline on clinical endpoints of cognition and function at 18 months.ObjectivesTo describe the health-related quality-of-life (HRQoL) results from Clarity AD which were exploratory outcomes in this trial.DesignClarity AD was an 18-month, multi-center, doubleblind, phase 3 trial.SettingEarly Alzheimer’s disease.ParticipantsIndividuals 50–90 years of age with a diagnosis of mild cognitive impairment or mild dementia due to Alzheimer’s disease and positron emission tomography or cerebrospinal fluid evidence of cerebral amyloid accumulation.InterventionPlacebo or lecanemab 10-mg/kg IV biweekly.MeasurementsHRQoL was measured at baseline and every 6 months using the European Quality of Life–5 Dimensions (EQ-5D-5L; by subject) and Quality of Life in AD (QOL-AD; by subject and proxy). Study partner burden was measured using the Zarit Burden Interview (ZBI).ResultsA total of 1795 participants were enrolled (lecanemab:898; placebo:897). At month 18, adjusted mean change from baseline in EQ-5D-5L and QOL-AD by subject showed 49% and 56% less decline, respectively. QOL-AD rated by study partner as proxy resulted in 23% less decline. ZBI adjusted mean change from baseline at 18 months resulted in 38% less increase of care partner burden. Individual HRQoL test items and dimensions also showed lecanemab benefit.ConclusionsLecanemab was associated with a relative preservation of HRQoL and less increase in caregiver burden, with consistent benefits seen across different quality of life scales and within scale subdomains. These benefits provide valuable patient reported outcomes which, together with previously reported benefits of lecanemab across multiple measures of cognition, function, disease progression, and biomarkers, demonstrate that lecanemab treatment may offer meaningful benefits to patients, care partners, and society.

Riding the Wave: Unveiling the Conformational Waves from RBD of SARS-CoV-2 Spike Protein to ACE2.

The binding affinity between angiotensin-converting enzyme 2 (ACE2) and the receptor-binding domain (RBD) plays a crucial role in the transmission and reinfection of SARS-CoV2. Here, microsecond molecular dynamics simulations revealed that point mutations in the RBD domain induced conformational transitions that determined the binding affinity between ACE2 and RBD. These structural changes propagated through the RBD domain, altering the orientation of both ACE2 and RBD residues at the binding site. ACE2 receptor shows significant structural heterogeneity, whereas its binding to the RBD domain indicates a much greater degree of structural homogeneity. The receptor was more flexible in its unbound state with the binding of RBD domains inducing structural transitions. The structural heterogeneity observed in the ACE2 unbound form plays a role in the promiscuity of viral entry, as it may allow the receptor to interact with various related and unrelated ligands. Furthermore, rigidity may be important for stabilizing the complex and ensuring the proper orientation of the RBD-binding interface with ACE2. The greater structural homogeneity observed in the ACE2-RBD complex revealed the effectiveness of neutralizing antibodies and vaccines that are primarily directed toward the RBD-binding interface. The binding of the B38 monoclonal antibody revealed restricted conformational transitions in the RBD and ACE2 receptors, attributed to its potent binding interaction.

Epitope editing enables targeted immunotherapy of acute myeloid leukaemia.

Despite the considerable efficacy observed when targeting a dispensable lineage antigen, such as CD19 in B cell acute lymphoblastic leukaemia1,2, the broader applicability of adoptive immunotherapies is hampered by the absence of tumour-restricted antigens3-5. Acute myeloid leukaemia immunotherapies target genes expressed by haematopoietic stem/progenitor cells (HSPCs) or differentiated myeloid cells, resulting in intolerable on-target/off-tumour toxicity. Here we show that epitope engineering of donor HSPCs used for bone marrow transplantation endows haematopoietic lineages with selective resistance to chimeric antigen receptor (CAR) T cells or monoclonal antibodies, without affecting protein function or regulation. This strategy enables the targeting of genes that are essential for leukaemia survival regardless of shared expression on HSPCs, reducing the risk of tumour immune escape. By performing epitope mapping and library screenings, we identified amino acid changes that abrogate the binding of therapeutic monoclonal antibodies targeting FLT3, CD123 and KIT, and optimized a base-editing approach to introduce them into CD34+ HSPCs, which retain long-term engraftment and multilineage differentiation ability. After CAR T cell treatment, we confirmed resistance of epitope-edited haematopoiesis and concomitant eradication of patient-derived acute myeloid leukaemia xenografts. Furthermore, we show that multiplex epitope engineering of HSPCs is feasible and enables more effective immunotherapies against multiple targets without incurring overlapping off-tumour toxicities. We envision that this approach will provide opportunities to treat relapsed/refractory acute myeloid leukaemia and enable safer non-genotoxic conditioning.

P-107 MICROFLUIDIC SPERM SEXING: An XLD (X-linked Disorder) model for preventing genetic disorders in newborns

Abstract Study question Can sperm sexing based on unique surface membrane markers – enable genotypic sperm sorting by allosomal content to prevent certain X-linked disorders in newborns? Summary answer In an X-Linked-Disorder prevention model, we utilized a microfluidic device functionalized with H-Y monoclonal antibodies attached to magnetic beads to enrich Y-chromosome bearing sperm sorts. What is known already About 4% of newborns are at risk of being born with an X-linked disease such as Fragile X Syndrome. The current clinically approved mitigation plan for preventing such genetic disorders is to consider Preimplantation Genetic Testing for Monogenetic diseases (PGT-M) which involves an invasive microsurgical procedure on fragile embryos. To minimize this invasiveness, we proposed a less invasive microsurgical exclusion approach to prevent such genetic disorders by genotypically sorting sperm cells that can be used for IUI/IVF/ICSI – with microfluidics – using their allosomal characteristics. Study design, size, duration Semen samples purchased from FairFax Cryobank from anonymous donors were used in immuno-magnetic microfluidic sorting protocols with the use of phycoerythrin (PE) binding Tetrameric Antibody Complexes (TAC) coupled with magnetic beads to tag H-Y monoclonal antibody (mab) binding activities on the sperm surface membrane. Participants/materials, setting, methods Immuno-magnetic sorting was conducted with specially fabricated microfluidic-sperm-sorting (MSS) chips. Sort yield and purities of positively selected sperm populations were assessed by flow-cytometry, immunofluorescence, fluorescent-in-situ-hybridization (FISH) and by quantitative-PCR (qPCR – Cq &amp; Tm). Quantitative experiments were run in triplicates and the results were expressed as absolute means for comparison between paired variables. Statistical analyses were performed using Student’s t-test and a p-value of less than 0.05 was considered to be statistically significant. Main results and the role of chance For the assessment of H-Y sperm sorts, our preliminary data showed that flow cytometry was able to confirm the positive sperm selection (which were mostly Y-chromosome bearing sperm cells) in a sperm genotyping protocol – initially utilizing immuno-magnetic sort tubes prior to flowing through microfluidic chips. Both immuno-magnetic sort tubes and the microfluidic chips were able to optimally confirm from qPCR-Cq means – the negative selection – being the X-chromosome bearing sperm that may have been largely unselected by the H-Y-mab. Values for Cq means compared under H-Y-qPCR data sets were statistically significant with a p value of 0.000023 (p values is significant at &amp;lt; 0.05). Our study was able to elucidate a potential less invasive clinical application of genotypically sorting sperm cells with mab-functionalized microfluidic chips for an XLD-model. Molecular down stream applications like flow cytometry may therefore be utilized to experimentally confirm sort purities of positively selected sperm populations (with H-Y markers) – based on the utility of the SMCX and SMCY gene in the X and Y sperm chromosome bearing sperm cells respectively. Limitations, reasons for caution Physiological effect of magnetic fields of varying tesla or gauss strengths on sperm selected with immuno-magnetic beads may warrant further safety studies prior to actual clinical applications. Optimal selection results may be achieved with the use of freshly collected normospermic rather than frozen-thawed samples. Wider implications of the findings Although we had de-emphasized the clinical application of the microfluidic sperm sexing protocol for legitimate use in sex selection and gender balancing, this study design was solely focused on adapting a less invasive method of preventing X-linked genetic disorders with the potential exclusion of microsurgical procedures leading to PGT-M. Trial registration number NA