Next-generation cell-penetrating antibodies for tumor targeting and RAD51 inhibition.

Monoclonal antibody therapies for cancer have demonstrated extraordinary clinical success in recent years. However, these strategies are thus far mostly limited to specific cell surface antigens, even though many disease targets are found intracellularly. Here we report studies on the humanization of a full-length, nucleic acid binding, monoclonal lupus-derived autoantibody, 3E10, which exhibits a novel mechanism of cell penetration and tumor specific targeting. Comparing humanized variants of 3E10, we demonstrate that cell uptake depends on the nucleoside transporter ENT2, and that faster cell uptake and superior in vivo tumor targeting are associated with higher affinity nucleic acid binding. We show that one human variant retains the ability of the parental 3E10 to bind RAD51, serving as a synthetically lethal inhibitor of homology-directed repair in vitro. These results provide the basis for the rational design of a novel antibody platform for therapeutic tumor targeting with high specificity following systemic administration.

Broadly potent spike-specific human monoclonal antibodies inhibit SARS-CoV-2 Omicron sub-lineages.

The continuous emergence of SARS-CoV-2 variants of concern has rendered many therapeutic monoclonal antibodies (mAbs) ineffective. To date, there are no clinically authorized therapeutic antibodies effective against the recently circulating Omicron sub-lineages BA.2.86 and JN.1. Here, we report the isolation of broad and potent neutralizing human mAbs (HuMabs) from a healthcare worker infected with SARS-CoV-2 early in the pandemic. These include a genetically unique HuMab, named K501SP6, which can neutralize different Omicron sub-lineages, including BQ.1, XBB.1, BA.2.86 and JN.1, by targeting a highly conserved epitope on the N terminal domain, as well as an RBD-specific HuMab (K501SP3) with high potency towards earlier circulating variants that was escaped by the more recent Omicron sub-lineages through spike F486 and E484 substitutions. Characterizing SARS-CoV-2 spike-specific HuMabs, including broadly reactive non-RBD-specific HuMabs, can give insight into the immune mechanisms involved in neutralization and immune evasion, which can be a valuable addition to already existing SARS-CoV-2 therapies.

Tuning Responses to Polatuzumab Vedotin in B-cell Lymphoma.

Polatuzumab vedotin, an antibody-drug conjugate targeting CD79B, is the first new drug approved for first-line therapy of diffuse large B-cell lymphoma in more than two decades, although factors determining treatment responses to polatuzumab vedotin remain unknown. Two new studies identified central mechanisms of lower sensitivity, namely reduced accessibility of the CD79B epitope through N-linked glycosylation of CD79B and lower CD79B surface expression levels due to the activity of the KLHL6 E3 ligase. See related article by Corcoran et al., p. 1653 (6) See related article by Meriranta et al. (7).

A monoclonal antibody recognizing CD98 on human embryonic stem cells shows anti-tumor activity in hepatocellular carcinoma xenografts.

CD98, also known as SLC3A2, is a multifunctional cell surface molecule consisting of amino acid transporters. CD98 is ubiquitously expressed in many types of tissues, but expressed at higher levels in cancerous tissues than in normal tissues. CD98 is also upregulated in most hepatocellular carcinoma (HCC) patients; however, the function of CD98 in HCC cells has been little studied. In this study, we generated a panel of monoclonal antibodies (MAbs) against surface proteins on human embryonic stem cells (hESCs). NPB15, one of the MAbs, bound to hESCs and various cancer cells, including HCC cells and non-small cell lung carcinoma (NSCLC) cells, but not to peripheral blood mononuclear cells (PBMCs) and primary hepatocytes. Immunoprecipitation and mass spectrometry identified the target antigen of NPB15 as CD98. CD98 depletion decreased cell proliferation, clonogenic survival, and migration and induced apoptosis in HCC cells. In addition, CD98 depletion decreased the expression of cancer stem cell (CSC) markers in HCC cells. In tumorsphere cultures, the expression of CD98 interacting with NPB15 was significantly increased, as were known CSC markers. After cell sorting by NPB15, cells with high expression of CD98 (CD98-high) showed higher clonogenic survival than cells with low expression of CD98 (CD98-low) in HCC cells, suggesting CD98 as a potential CSC marker on HCC cells. The chimeric version of NPB15 was able to induce antibody-dependent cellular cytotoxicity (ADCC) against HCC cells in vitro. NPB15 injection showed antitumor activity in an HCC xenograft mouse model. The results suggest that NPB15 may be developed as a therapeutic antibody for HCC patients.

Exploiting human immune repertoire transgenic mice for protective monoclonal antibodies against antimicrobial resistant Acinetobacter baumannii.

The use of monoclonal antibodies for the control of drug resistant nosocomial bacteria may alleviate a reliance on broad spectrum antimicrobials for treatment of infection. We identify monoclonal antibodies that may prevent infection caused by carbapenem resistant Acinetobacter baumannii. We use human immune repertoire mice (Kymouse platform mice) as a surrogate for human B cell interrogation to establish an unbiased strategy to probe the antibody-accessible target landscape of clinically relevant A. baumannii. After immunisation of the Kymouse platform mice with A. baumannii derived outer membrane vesicles (OMV) we identify 297 antibodies and analyse 26 of these for functional potential. These antibodies target lipooligosaccharide (OCL1), the Oxa-23 protein, and the KL49 capsular polysaccharide. We identify a single monoclonal antibody (mAb1416) recognising KL49 capsular polysaccharide to demonstrate prophylactic in vivo protection against a carbapenem resistant A. baumannii lineage associated with neonatal sepsis mortality in Asia. Our end-to-end approach identifies functional monoclonal antibodies with prophylactic potential against major lineages of drug resistant bacteria accounting for phylogenetic diversity and clinical relevance without existing knowledge of a specific target antigen. Such an approach might be scaled for a additional clinically important bacterial pathogens in the post-antimicrobial era.

Antitumor activities of anti­CD44 monoclonal antibodies in mouse xenograft models of esophageal cancer.

CD44 is a type I transmembrane glycoprotein associated with poor prognosis in various solid tumors. Since CD44 plays a critical role in tumor development by regulating cell adhesion, survival, proliferation and stemness, it has been considered a target for tumor therapy. Anti­CD44 monoclonal antibodies (mAbs) have been developed and applied to antibody­drug conjugates and chimeric antigen receptor­T cell therapy. Anti-pan­CD44 mAbs, C44Mab­5 and C44Mab­46, which recognize both CD44 standard (CD44s) and variant isoforms were previously developed. The present study generated a mouse IgG2a version of the anti­pan­CD44 mAbs (5­mG2a and C44Mab­46­mG2a) to evaluate the antitumor activities against CD44­positive cells. Both 5­mG2a and C44Mab­46­mG2a recognized CD44s­overexpressed CHO­K1 (CHO/CD44s) cells and esophageal tumor cell line (KYSE770) in flow cytometry. Furthermore, both 5­mG2a and C44Mab­46­mG2a could activate effector cells in the presence of CHO/CD44s cells and exhibited complement-dependent cytotoxicity against both CHO/CD44s and KYSE770 cells. Furthermore, the administration of 5­mG2a and C44Mab­46­mG2a significantly suppressed CHO/CD44s and KYSE770 xenograft tumor development compared with the control mouse IgG2a. These results indicate that 5­mG2a and C44Mab­46­mG2a could exert antitumor activities against CD44­positive cancers and be a promising therapeutic regimen for tumors.

Discovery of potent allosteric antibodies inhibiting EGFR.

In this work, we report the discovery of potent anti-epidermal growth factor receptor (EGFR) allosteric heavy-chain antibodies by combining camelid immunization and fluorescence-activated cell sorting (FACS). After immunization and yeast surface display library construction, allosteric clones were obtained by introducing the labeled EGF Fc fusion protein as an additional criterion for FACS. This sorting method enabled the identification of 11 heavy-chain antibodies that did not compete with the orthosteric ligand EGF for the binding to EGFR. These antibodies bind to a triple-negative breast cancer cell line expressing EGFR with affinities in the picomolar to nanomolar range. Those camelid-derived antibodies also exhibit interesting properties by modulating EGFR affinity for EGF. Moreover, they are also able to inhibit EGF-induced downstream signaling pathways. In particular, we identified one clone that is more potent than the approved blocking antibody cetuximab in inhibiting both PI3K/AKT and MAPK/ERK pathways. Our results suggest that allosteric antibodies may be potential new modalities for therapeutics.

Effect of antiemetics on zolbetuximab-induced gastric injury and emesis in ferrets.

Claudin-18 splice variant 2 (CLDN18.2), a tight junction protein, is a highly cell type-specific antigen that is expressed by differentiated gastric mucosa cells. The expression of CLDN18.2 in gastric mucosa cells may be retained upon malignant transformation and is displayed on the surface of several tumors, including gastric/gastroesophageal junction adenocarcinoma. Zolbetuximab is a genetically engineered, highly purified chimeric (mouse/human IgG1) antibody directed against CLDN18.2. Nausea and vomiting were observed as adverse events of zolbetuximab. To investigate the mechanism of nausea and vomiting in humans, we evaluated emesis (retching and vomiting) and conducted histopathologic assessment in ferrets after the administration of zolbetuximab. Emesis was frequently observed in all ferrets treated with zolbetuximab in the first hour after administration. Histopathologic assessment revealed the surface of the gastric mucosa was the primary site of emesis-associated tissue damage. The effect of antiemetics (dexamethasone, ondansetron, fosaprepitant, and olanzapine) on emesis induced by zolbetuximab was investigated. Fosaprepitant showed suppressive effects on emesis, and use of dexamethasone or concomitant use of fosaprepitant with other antiemetics tended to alleviate gastric tissue damage. The onset of emesis in humans receiving zolbetuximab may be associated with damage in the gastric mucosa, and antiemetics may mitigate gastrointestinal adverse events.

Therapeutic efficacy of JEW-M449, an anti-TCTP monoclonal antibody, administered via the nasal route in a BALB/c mouse model of ovalbumin-induced acute asthma.

Numerous studies have highlighted the role of translationally controlled tumor protein (TCTP) as a key inflammatory mediator of asthma and allergies. Our previous study revealed that blocking the cytokine-like activity of TCTP using JEW-M449, an anti-TCTP monoclonal antibody (mAb), alleviated allergic inflammation in asthmatic mice. This study aimed to determine whether directly delivering JEW-M449 into the respiratory tract is a more effective way of mitigating airway inflammation in a mouse model of ovalbumin (OVA)-induced allergic airway inflammation than delivering this antibody via the intraperitoneal (IP) route. OVA-sensitized mice were intranasally administered JEW-M449 to enable its direct delivery to the respiratory tract before OVA challenge. We evaluated the changes in the levels of bronchoalveolar lavage fluid (BALF) cells, T helper type 2 (Th2) cytokines, OVA-specific immunoglobulin E (IgE), and histopathological alterations in the lung tissues. Intranasal (IN) administration of JEW-M449 significantly ameliorated the pathological changes associated with OVA-induced lung injury, including reduced inflammatory cell infiltration and mucus hypersecretion. Mice IN administered JEW-M449 also showed decreased OVA-mediated induction of Th2 cytokines in BALF and lung homogenates. Importantly, JEW-M449 delivered via the IN route reached the lung tissue more effectively and exerted superior anti-inflammatory effects in OVA-challenged mice than the IP-delivered JEW-M449. This study is the first to demonstrate the efficacy of directly delivering JEW-M449 anti-TCTP mAb into the respiratory tract to alleviate the asthma phenotype in a mouse model, thereby highlighting a potential delivery strategy for novel inhaled mAb therapeutics for human asthma.

What's in It for Me? Contextualizing the Potential Clinical Impacts of Lecanemab, Donanemab, and Other Anti-ß-amyloid Monoclonal Antibodies in Early Alzheimer's Disease.

A new era of disease-modifying therapy for Alzheimer's disease (AD) arrived in 2021 following the Food and Drug Administration's (FDA) decision to grant accelerated approval for aducanumab, an anti-ß-amyloid (Aß) monoclonal antibody designed to target Aß aggregates, a biological component of AD. More recently, trial outcomes for lecanemab and donanemab, two additional antibodies of this drug class, have shown favorable and significant slowing of metrics for cognitive and functional decline. Lecanemab and donanemab have since received similar FDA approval to aducanumab in January 2023 and July 2024, respectively. Given that these therapies are a clearly emerging tool in the repertoire of clinicians treating AD and related dementias, a critical dialogue has been ongoing regarding the potential impacts and place for these therapies. Here, we seek to contextualize this debate by first considering factors involved in theoretically extrapolating current randomized control trial outcomes to estimate meaningful clinical impacts. In the process of this exercise, we outline a generally useful concept termed Summative Treatment-Associated Benefit measuring Long-term Efficacy/Effectiveness Area as a metric of summative benefits of treatment over the life course of an individual. Second, we consider current real-world factors, such as conditions of FDA approval and other points involved in clinical decision-making that will influence and/or temper the actual impacts of this drug class.

A novel anti-CD47 antibody with therapeutic potential for NK/T-cell lymphoma.

NK/T-cell lymphoma (NKTCL) is a rare type of non-Hodgkin lymphoma (NHL). Although L-asparaginase-based chemotherapy has significantly improved survival in early-stage patients, the prognosis is poor in advanced and relapsed or refractory patients. CD47 is a promising target for cancer immunotherapy. However, the expression of CD47 in NKTCL and the antitumor effect and mechanism of the anti-CD47 monoclonal antibody (mAb) AK117 in NKTCL remain unclear. Firstly, the expression level of CD47 protein in NKTCL cells was detected by immunoblot and flow cytometry. Secondly, in order to validate the role of CD47 downregulation in the proliferation, apoptosis, and cell cycle of NKTCL cells, we used shRNA transfection to knock down CD47 expression. We determined the effect of knocking down CD47 and the novel anti-CD47 antibody AK117 on the phagocytosis of NKYS and YTS cells by M2 macrophages in vitro. Finally, we assessed the ability of AK117 to inhibit tumor growth in an NKTCL xenograft model in which YTS cells were engrafted in SCID mice. The results showed that CD47 is relatively highly expressed in NKTCL cells. CD47 knockdown in NKTCL promoted phagocytosis by M2 macrophages in an in vitro coculture assay. The study also demonstrated that anti-CD47 mAb AK117 promoted phagocytosis of NKTCL cells by M2 macrophages. In addition, in vivo experiments showed that the anti-CD47 mAb AK117 significantly inhibited the growth of subcutaneous xenograft tumors in SCID mice compared to the control antibody IgG. Our results indicate that targeting CD47 monoclonal antibodies is a potential therapeutic strategy for NKTCL.

Efficacy and Safety of Durvalumab/Tremelimumab in Unresectable Hepatocellular Carcinoma as Immune Checkpoint Inhibitor Rechallenge Following Atezolizumab/Bevacizumab Treatment.

BACKGROUND: While guidelines recommend immune checkpoint inhibitor (ICI) rechallenge as second-line therapy for unresectable hepatocellular carcinoma (HCC), data supporting this remain limited, particularly regarding a standard regimen for first- and second-line treatments. Tremelimumab/durvalumab was recently approved but data on ICI rechallenge are lacking. OBJECTIVES: The purpose of this study was to evaluate the early efficacy and safety of tremelimumab/durvalumab for HCC as an ICI rechallenge following initial ICI therapy with atezolizumab/bevacizumab. PATIENTS AND METHODS: This multicenter retrospective study included patients with HCC who underwent treatment with tremelimumab/durvalumab, with relevant available clinical information. We evaluated the safety and efficacy of tremelimumab/durvalumab as ICI rechallenge following initial treatment with atezolizumab/bevacizumab. We analyzed the outcomes in patients who underwent tremelimumab/durvalumab as an ICI rechallenge and those who received tremelimumab/durvalumab as their initial ICI therapy RESULT: A total of 45 patients treated with tremelimumab/durvalumab were included, with 55.6% (25/45) undergoing ICI rechallenge. The objective-response and disease-control rates in patients who underwent ICI rechallenge were 14.3% (3/21) and 47.6% (10/21), respectively, similar to those in patients initially treated with tremelimumab/durvalumab. All patients (n = 3) who experienced the best response to progressive disease (PD) with initial atezolizumab/bevacizumab experienced PD during ICI rechallenge. The incidence rates of adverse events were similar between patient groups treated with tremelimumab/durvalumab as ICI rechallenge and initial ICI. Among patients experiencing immune-related adverse events (irAEs) with atezolizumab/bevacizumab, 75% (3/4) encountered similar irAEs during ICI rechallenge. CONCLUSION: Early safety and efficacy profiles of durvalumab/tremelimumab as ICI rechallenge are satisfactory.

The Nuclear Speckles Protein SRRM2 Is Exposed on the Surface of Cancer Cells.

The membrane composition of extracellular vesicles (EVs) largely reflects that of the plasma membrane of the cell of origin. We therefore hypothesized that EVs could be used for immunizations to generate monoclonal antibodies against well-known tumor antigens but possibly also against hitherto unknown tumor-associated target molecules. From an immunization experiment, we obtained a monoclonal antibody specific for SRRM2, an RNA-binding protein involved in splicing and a major component of nuclear speckles. Here, we used this antibody to demonstrate that SRRM2 is exposed on the surface of most cancer cell lines from various entities and, even more important, on cancer cells in vivo. Moreover, we demonstrated that SRRM2-specific CAR-T cells are functional in vitro and in vivo. Collectively, we identified SRRM2 as a promising new target molecule exposed on the cancer cell surface and showed that our SRRM2-specific antibody can be used as a basis for the development of new targeted cancer therapies.

Anti-CD44 Variant 10 Monoclonal Antibody Exerts Antitumor Activity in Mouse Xenograft Models of Oral Squamous Cell Carcinomas.

CD44 regulates cell adhesion, proliferation, survival, and stemness and has been considered a tumor therapy target. CD44 possesses the shortest CD44 standard (CD44s) and a variety of CD44 variant (CD44v) isoforms. Since the expression of CD44v is restricted in epithelial cells and carcinomas compared to CD44s, CD44v has been considered a promising target for monoclonal antibody (mAb) therapy. We previously developed an anti-CD44v10 mAb, C44Mab-18 (IgM, kappa), to recognize the variant exon 10-encoded region. In the present study, a mouse IgG2a version of C44Mab-18 (C44Mab-18-mG2a) was generated to evaluate the antitumor activities against CD44-positive cells compared with the previously established anti-pan CD44 mAb, C44Mab-46-mG2a. C44Mab-18-mG2a exhibited higher reactivity compared with C44Mab-46-mG2a to CD44v3-10-overexpressed CHO-K1 (CHO/CD44v3-10) and oral squamous cell carcinoma cell lines (HSC-2 and SAS) in flow cytometry. C44Mab-18-mG2a exerted a superior antibody-dependent cellular cytotoxicity (ADCC) against CHO/CD44v3-10. In contrast, C44Mab-46-mG2a showed a superior complement-dependent cytotoxicity (CDC) against CHO/CD44v3-10. A similar tendency was observed in ADCC and CDC against HSC-2 and SAS. Furthermore, administering C44Mab-18-mG2a or C44Mab-46-mG2a significantly suppressed CHO/CD44v3-10, HSC-2, and SAS xenograft tumor growth compared with the control mouse IgG2a. These results indicate that C44Mab-18-mG2a could be a promising therapeutic regimen for CD44v10-positive tumors.

Agonist antibody to guanylate cyclase receptor NPR1 regulates vascular tone.

Heart failure is a leading cause of morbidity and mortality1,2. Elevated intracardiac pressures and myocyte stretch in heart failure trigger the release of counter-regulatory natriuretic peptides, which act through their receptor (NPR1) to affect vasodilation, diuresis and natriuresis, lowering venous pressures and relieving venous congestion3-8. Recombinant natriuretic peptide infusions were developed to treat heart failure but have been limited by a short duration of effect9,10. Here we report that in a human genetic analysis of over 700,000 individuals, lifelong exposure to coding variants of the NPR1 gene is associated with changes in blood pressure and risk of heart failure. We describe the development of REGN5381, an investigational monoclonal agonist antibody that targets the membrane-bound guanylate cyclase receptor NPR1. REGN5381, an allosteric agonist of NPR1, induces an active-like receptor conformation that results in haemodynamic effects preferentially on venous vasculature, including reductions in systolic blood pressure and venous pressure in animal models. In healthy human volunteers, REGN5381 produced the expected haemodynamic effects, reflecting reductions in venous pressures, without obvious changes in diuresis and natriuresis. These data support the development of REGN5381 for long-lasting and selective lowering of venous pressures that drive symptomatology in patients with heart failure.

A novel dual-epigenetic inhibitor enhances recombinant monoclonal antibody expression in CHO cells.

Epigenetic regulation plays a central role in the regulation of a number of cellular processes such as proliferation, differentiation, cell cycle, and apoptosis. In particular, small molecule epigenetic modulators are key elements that can effectively influence gene expression by precisely regulating the epigenetic state of cells. To identify useful small-molecule regulators that enhance the expression of recombinant proteins in Chinese hamster ovary (CHO) cells, we examined a novel dual-HDAC/LSD1 inhibitor I-4 as a supplement for recombinant CHO cells. Treatment with 2 µM I-4 was most effective in increasing monoclonal antibody production. Despite cell cycle arrest at the G1/G0 phase, which inhibits cell growth, the addition of the inhibitor at 2 µM to monoclonal antibody-expressing CHO cell cultures resulted in a 1.94-fold increase in the maximal monoclonal antibody titer and a 2.43-fold increase in specific monoclonal antibody production. In addition, I-4 significantly increased the messenger RNA levels of the monoclonal antibody and histone H3 acetylation and methylation levels. We also investigated the effect on HDAC-related isoforms and found that interference with the HDAC5 gene increased the monoclonal antibody titer by 1.64-fold. The results of this work provide an effective method of using epigenetic regulatory strategies to enhance the expression of recombinant proteins in CHO cells. KEY POINTS: • HDAC/LSD1 dual-target small molecule inhibitor can increase the expression level of recombinant monoclonal antibodies in CHO cells. • By affecting the acetylation and methylation levels of histones in CHO cells and downregulating HDAC5, the production of recombinant monoclonal antibodies increased. • It provides an effective pathway for applying epigenetic regulation strategies to enhance the expression of recombinant proteins.

The role of respiratory syncytial virus G protein in immune cell infection and pathogenesis.

Severe respiratory syncytial virus (RSV) disease is a significant contributor to the global burden of disease in infants and children. The RSV attachment protein (G) has been shown to be critical in invading airway epithelial cells through its CX3C motif interacting with the host receptor CX3CR1. The ubiquitous expression of this receptor on immune cells may explain their susceptibility to RSV infection. The RSV G protein may enhance disease severity through reprogramming of normal cellular functionality leading to inhibition of antiviral responses. While existing preventives targeting the RSV fusion (F) protein are highly effective, there are no RSV therapeutics based on the G protein to limit RSV pathogenesis. Monoclonal antibodies targeting the RSV G protein administered as post-infection therapeutics in mice have been shown to improve the antiviral response, reduce viral load and limit disease severity. Further research is required to better understand how RSV infection of immune cells contributes to pathogenesis for the development of more targeted and efficacious therapeutics.

Multiple sclerosis: a narrative overview of current pharmacotherapies and emerging treatment prospects.

Multiple sclerosis (MS) is a chronic autoimmune disease characterized by pathological processes of demyelination, subsequent axonal loss, and neurodegeneration within the central nervous system. Despite the availability of numerous disease-modifying therapies that effectively manage this condition, there is an emerging need to identify novel therapeutic targets, particularly for progressive forms of MS. Based on contemporary insights into disease pathophysiology, ongoing efforts are directed toward developing innovative treatment modalities. Primarily, monoclonal antibodies have been extensively investigated for their efficacy in influencing specific pathological pathways not yet targeted. Emerging approaches emphasizing cellular mechanisms, such as chimeric antigen receptor T cell therapy targeting immunological cells, are attracting increasing interest. The evolving understanding of microglia and the involvement of ferroptotic mechanisms in MS pathogenesis presents further avenues for targeted therapies. Moreover, innovative treatment strategies extend beyond conventional approaches to encompass interventions that target alterations in microbiota composition and dietary modifications. These adjunctive therapies hold promise as complementary methods for the holistic management of MS. This narrative review aims to summarize current therapies and outline potential treatment methods for individuals with MS.

Enhancing the therapeutic potential of P29 protein-targeted monoclonal antibodies in the management of alveolar echinococcosis through CDC-mediated mechanisms.

Alveolar echinococcosis (AE) is a highly lethal helminth infection. Current chemotherapeutic strategies for AE primarily involve the use of benzimidazoles (BZs) such as mebendazole (MDZ) and albendazole (ABZ), which exhibit limited efficacy. In a previous study, the vaccine of recombinant Echinococcus granulosus P29 (rEgP29) showed significant immunoprotection against E. granulosus in both mice and sheep. In the current study, we utilized hybridoma technology to generate five monoclonal antibodies (mAbs) against P29, among which 4G10F4 mAb exhibited the highest antigen-specific binding capacity. This mAb was selected for further investigation of anti-AE therapy, both in vivo and in vitro. In vitro, 4G10F4 inhibited a noteworthy inhibition of E. multilocularis protoscoleces and primary cells viability through complement-dependent cytotoxicity (CDC) mechanism. In vivo, two experiments were conducted. In the first experiment, mice were intraperitoneally injected with Em protoscoleces, and subsequently treated with 4G10F4 mAb (2.5/5/10 mg/kg) at 12 weeks postinfection once per week for 8 times via tail vein injection. Mice that were treated with 4G10F4 mAb only in dosage of 5mg/kg exhibited a significant lower mean parasite burden (0.89±0.97 g) compared to isotype mAb treated control mice (2.21±1.30 g). In the second experiment, mice were infected through hepatic portal vein and treated with 4G10F4 mAb (5mg/kg) at one week after surgery once per week for 8 times. The numbers of hepatic metacestode lesions of the 4G10F4 treatment group were significantly lower in comparison to the isotype control group. Pathological analysis revealed severe disruption of the inner structure of the metacestode in both experiments, particularly affecting the germinal and laminated layers, resulting in the transformation into infertile vesicles after treatment with 4G10F4. In addition, the safety of 4G10F4 for AE treatment was confirmed through assessment of mouse weight and evaluation of liver and kidney function. This study presents antigen-specific monoclonal antibody immunotherapy as a promising therapeutic approach against E. multilocularis induced AE.