Antibody-dependent Cellular Cytotoxicity Research Articles

Nivolumab and rituximab in treatment naive follicular lymphoma: the phase II '1st FLOR' study.

Follicular lymphoma (FL) outcomes are heavily influenced by host immune activity with immune anti-tumor activity mitigated by PD-1/PD-L1 pathway engagement. Combination CD20-directed therapy plus PD-1 inhibition (PD-1i) increases T-cell tumor killing and NK-cell antibody-dependent cell cytotoxicity (ADCC). Mounting evidence supports immune-priming using PD-1i before cancer-directed agents. Our multicentre, open-label, phase II 1st FLOR study (NCT03245021) enrolled 39 previously-untreated advanced-stage FL patients to receive 4 cycles of nivolumab (240mg) then 4 cycles of 2-weekly nivolumab plus rituximab 375mg/m2 (induction) then 1 year of monthly nivolumab (480mg) plus 2 years of 2-monthly rituximab maintenance. Participants with complete response (CR) after nivolumab priming continued nivolumab monotherapy. The primary endpoint was toxicity during induction. Adverse events (AEs) ≥ grade 3 during induction occurred in 33% (n=13); most commonly elevated amylase/lipase (15%), liver enzyme derangement (11%) and infection (10%). Three patients discontinued nivolumab secondary to toxicity; two pancreatitis, one acute kidney injury. Overall response rate (ORR) was 92% (CR 59%). Median follow-up was 51 months. Median and 4-year progression-free survival (PFS) were 61 months (95%CI 2-72) and 58% (95%CI 34-97); 70% of responders remained in CR. 4-year overall survival was 95%. High baseline total metabolic tumor volume and total lesion glycolysis conferred inferior PFS (p=0.04 and p=0.02). Additionally, high baseline tumor CD8A gene expression was associated with improved PFS (p=0.03). Nivolumab priming followed by nivolumab-rituximab in treatment-naive FL is associated with favorable toxicity and high response rates potentially providing an alternative to chemotherapy. TMTV and high tumor CD8A expression are promising immunotherapy biomarkers for FL.

A Phase I, First-In-Human Study of CBA-1205, an Anti-DLK1 Monoclonal Antibody, in Patients With Advanced Solid Tumors.

CBA-1205 is a novel humanized antibody targeting delta-like 1 homolog (DLK1) that enhances antibody-dependent cellular cytotoxicity activity. DLK1 overexpression has been reported in various cancer types, such as hepatocellular carcinoma and neuroblastoma. CBA-1205 demonstrates potent antitumor activity in multiple tumor models, making it a potential treatment option for DLK1-expressing cancers. This first-in-human, open-label Phase I study includes three parts. Part 1, the dose-escalation phase, primarily evaluates the safety profile, tolerability, and maximum tolerated dose of CBA-1205. The drug is administered intravenously every 2 weeks in a 28-day cycle. A standard 3 + 3 dose-escalation design was used across seven cohorts. In a cohort of 22 Japanese patients, over 80% had undergone three or more prior treatments. CBA-1205 was well tolerated, with no dose-limiting toxicity observed at doses ranging from 0.1 to 30 mg/kg, the planned highest dose. There were no treatment-related serious adverse events or trial-related deaths. CBA-1205 exposure, as measured by Cmax, AUC0-14, and AUC0-∞, increased in a dose-dependent manner. No serum anti-CBA-1205 antibodies were detected. Serum DLK1 concentrations were found in 6 out of 22 patients. Stable disease for over 6 months was observed in six patients, with progression-free survival ranging from 29 to 144 weeks. CBA-1205 was well tolerated, showing no severe toxicity in patients with advanced or recurrent solid tumors. The favorable safety profile and indications of potential activity support further investigation in Parts 2 and 3 of this Phase I study to evaluate the safety, tolerability, and preliminary efficacy of CBA-1205.

Serum autoantibody-based biomarkers for prognosis in early-stage lung cancer patients with surgical resection

Background Lung cancer is the cancer with the highest morbidity and mortality in the world. With the increasing diagnosis rate of patients with early-stage lung cancer, surgery treatment becomes an option for more patients. However, there is a lack of effective indicators to assess the risk of recurrence after lung cancer surgery. Methods We collected levels of serum autoantibodies and evaluated their roles as biomarkers especially for postoperative recurrence of lung cancer. In vitro experiments including antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and complement-dependent cytotoxicity (CDC) were performed to explore the functions of serum autoantibodies. Results Our study demonstrated that serum autoantibody-positive patients with early-stage lung cancer had a longer postoperative progression period. The levels of serum autoantibodies in patients with lung cancer were higher than that in patients with benign lung diseases. But all the serum autoantibodies had no difference between patients with stage I and II. In addition, the results of in vitro experiments indicated that serum autoantibodies can mediate immune responses and enhance anti-tumor effects. Conclusion This study proposed effective biomarkers for prognosis in lung cancer patients after surgery which is critical to reduce the recurrence.

Novel oral adjuvant to enhance cytotoxic memory like NK cell responses in HIV vaccine platform

Natural killer (NK) cell-driven effector mechanisms, such as antibody-dependent cell-mediated cytotoxicity, emerged as a secondary correlate of protection in the RV144 HIV vaccine clinical trial, the only vaccine thus far demonstrating some efficacy in human trials. Therefore, leveraging NK cells with enhanced cytotoxic effector responses may bolster vaccine-induced protection against HIV. Here, we investigated the effect of orally administering indole-3-carbinol (I3C), an aryl hydrocarbon receptor (AHR) agonist, as an adjuvant to an RV144-like vaccine platform in a mouse model. We demonstrate the expansion of KLRG1-expressing NK cells induced by the vaccine together with I3C. This NK cell subset exhibited enhanced vaccine antigen-specific cytotoxic memory-like features. Our study underscores the potential of incorporating I3C as an oral adjuvant to HIV vaccine platforms to enhance antigen-specific cytotoxicity of NK cells against HIV-infected cells. This approach may contribute to enhancing the protective efficacy of HIV preventive vaccines against HIV acquisition.

Decoupling Individual Host Response and Immune Cell Engager Cytotoxic Potency.

Immune cell engagers are molecular agents, usually antibody-based constructs, engineered to recruit immune cells against cancer cells and kill them. They are versatile and powerful tools for cancer immunotherapy. Despite the multiplication of engagers tested and accepted in the clinic, how molecular and cellular parameters influence their actions is poorly understood. In particular, disentangling the respective roles of host immune cells and engager biophysical characteristics is needed to improve their design and efficiency. Focusing here on harnessing antibody-dependent Natural Killer cell cytotoxicity, we measure the efficiency of 6 original bispecific antibodies (bsAb), associating an anti-HER2 nanobody and an anti-CD16 nanobody. In vitro cytotoxicity data using primary human NK cells on different target cell lines exposing different antigen densities were collected, exhibiting a wide range of bsAb dose response. In order to rationalize our observations, we introduce a simple multiscale model, postulating that the density of bsAb bridging the two cells is the main parameter triggering the cytotoxic response. We introduce two microscopic parameters: the surface cooperativity describing bsAb affinity at the bridging step and the threshold of bridge density determining the donor-dependent response. Both parameters permit ranking Abs and donors and predicting bsAb potency as a function of antibodies bulk affinities and receptor surface densities on cells. Our approach thus provides a general way to decouple donor response from immune engager characteristics, rationalizing the landscape of molecule design.

FT538, iPSC-derived NK cells, enhance AML cell killing when combined with chemotherapy.

Induced pluripotent stem cell (iPSC)-derived natural killer (NK) cells offer an opportunity for a standardized, off-the-shelf treatment with the potential to treat a wider population of acute myeloid leukaemia (AML) patients than the current standard of care. FT538 iPSC-NKs express a high-affinity, noncleavable CD16 to maximize antibody dependent cellular cytotoxicity, a CD38 knockout to improve metabolic fitness, and an IL-15/IL-15 receptor fusion preventing the need for cytokine administration, the main source of adverse effects in NK cell-based therapies. Here, we sought to evaluate the potential of FT538 iPSC-NKs as a therapy for AML through their effect on AML cell lines and primary AML cells. We observed that FT538 iPSC-NKs induce effector-to-target cell ratio dependent apoptosis in cell lines and primary AML cells, including cells from high-risk patients. Flow cytometric analysis revealed that FT538 iPSC-NKs induce AML cell death when combined with the AML therapies: cytarabine, venetoclax and gilteritinib. Moreover, cytarabine did not affect FT538 iPSC-NK viability, suggesting that iPSC-derived NK therapies and chemotherapy may be a promising treatment combination. This study provides the basis for further study of iPSC-derived NK cell therapies as a treatment option for high-risk AML patients, particularly those with disease resistant to standard therapies.

Flow Cytometric Assessment of FcγRIIIa-V158F Polymorphisms and NK Cell Mediated ADCC Revealed Reduced NK Cell Functionality in Colorectal Cancer Patients.

Antibody-dependent cell-mediated cytotoxicity (ADCC) by NK cells is a key mechanism in anti-cancer therapies with monoclonal antibodies, including cetuximab (EGFR-targeting) and avelumab (PDL1-targeting). Fc gamma receptor IIIa (FcγRIIIa) polymorphisms impact ADCC, yet their clinical relevance in NK cell functionality remains debated. We developed two complementary flow cytometry assays: one to predict the FcγRIIIa-V158F polymorphism using a machine learning model, and a 15-color flow cytometry panel to assess antibody-induced NK cell functionality and cancer-immune cell interactions. Samples were collected from healthy donors and metastatic colorectal cancer (mCRC) patients from the FIRE-6-Avelumab phase II study. The machine learning model accurately predicted the FcγRIIIa-V158F polymorphism in 94% of samples. FF homozygous patients showed diminished cetuximab-mediated ADCC compared to VF or VV carriers. In mCRC patients, NK cell dysfunctions were evident as impaired ADCC, decreased CD16 downregulation, and reduced CD137/CD107a induction. Elevated PD1+ NK cell levels, reduced lysis of PDL1-expressing CRC cells and improved NK cell activation in combination with the PDL1-targeting avelumab indicate that the PD1-PDL1 axis contributes to impaired cetuximab-induced NK cell function. Together, these optimized assays effectively identify NK cell dysfunctions in mCRC patients and offer potential for broader application in evaluating NK cell functionality across cancers and therapeutic settings.

Vectorized Human Antibody-Mediated Anti-Eosinophil Gene Therapy.

Chronic hypereosinophilia, defined as persistent elevated blood levels of eosinophils ≥1,500/μL, is associated with tissue infiltration of eosinophils and consequent organ damage by eosinophil release of toxic mediators. The current therapies for chronic hypereosinophilia have limited success, require repetitive administration, and are associated with a variety of adverse effects. As a novel approach to treat chronic hypereosinophilia, we hypothesized that adeno-associated virus (AAV)-mediated delivery of an anti-human eosinophil antibody would provide one-time therapy that would mediate persistent suppression of blood eosinophil levels. To assess this hypothesis, we first generated a human monoclonal antibody (mAb) directed against Siglec8, a sialic-acid binding immunoglobulin-like lectin, expressed at high levels on the cell surface of human eosinophils. Transgenic mice with a human immunoglobulin repertoire were immunized with human Siglec8 protein or DNA encoding human Siglec8. Based on target binding assessments, the 08C07 mAb was chosen for further study. The human variable regions of 08C07 were joined to the human Ig constant region, creating H08C07 (hAntiEos), a fully human anti-human eosinophil mAb. Using the gene sequence of hAntiEos, we created AAVrh.10hAntiEos, an AAVrh.10-based vector expressing the heavy and light chains of H08C07. Intravenous administration of AAVrh.10hAntiEos (1011 genome copies or gc) to C57Bl/6 mice resulted in persistent elevated serum levels of hAntiEos. In vivo gene therapy generated hAntiEos bound to recombinant human Siglec8 protein in a dose-dependent manner and to human eosinophils, mediated apoptosis of human eosinophils, and antibody-dependent cellular cytotoxicity activity against human eosinophils. Consistent with these data, administration of AAVrh.10hAntiEos to human CD34+ transplanted NSG-SGM3 immunodeficient mice suppressed levels of human eosinophils invivo. AAVrh.10hAntiEos holds the potential to offer therapeutic benefit to patients with chronic hypereosinophilia.

Fc mutagenesis enhances the functionality of anti-RhD monoclonal antibodies.

Haemolytic disease of the foetus and newborn (HDFN) due to Rhesus D (RhD) antigen mismatch between the mother and foetus has been a significant cause of neonatal jaundice, recurrent miscarriage and stillbirth throughout history. Anti-RhD prophylaxis using polyclonal immunoglobulin G (RhD-pIgG) derived from the plasma of RhD-negative donors immunised with RhD-positive red blood cells (RBCs), has reduced the incidence of HDFN, but this approach is currently restricted to developed countries. Monoclonal antibodies (mAbs) offer a promising alternative to address this pressing need, but prior attempts to develop effective anti-RhD mAbs have failed, in some cases due to differences in fucosylation patterns between mAbs produced in cell lines and RhD-pIgG. CHO cell lines, commonly used for pharmaceutical protein production, induce high levels of fucosylation, reducing the antibody-dependent cellular cytotoxicity (ADCC) activity crucial for clearing RhD-positive RBCs. In contrast,RhD-pIgG has lower fucosylation levels, which enhances ADCC activity. Regulating the glycan levels of mAbs during production requires specialized cell lines and culture conditions. In this study, we took an alternative approach through antibody engineering. The Fc regions of two existing anti-RhD mAbs (Brad3 and Fog1) were subjected to mutagenesis to introduce ADCC enhancing mutations and then expressed in CHO cells under standard conditions. We demonstrate that targeted Fc mutagenesis significantly enhanced ADCC compared to the wild-type mAbs, while preserving RhD binding and efficient production in CHO cells. Furthermore, these Fc variants achieved comparable efficacy to RhD-pIgG, suggesting a new strategy for producing anti-RhD mAbs with improved functionality, without the need for glycoengineering.

A Novel Glycoengineered Humanized Antibody Targeting DLK1 Exhibits Potent Anti-Tumor Activity in DLK1-Expressing Liver Cancer Cell Xenograft Models.

Delta-like 1 homolog (DLK1), a non-canonical Notch ligand, is highly expressed in various malignant tumors, especially in hepatocellular carcinoma (HCC). CBA-1205 is an afucosylated humanized antibody against DLK1 with enhanced antibody-dependent cellular cytotoxicity (ADCC). The binding characteristics of CBA-1205 were analyzed by enzyme-linked immunosorbent assay and fluorescence-activated cell sorting assay. The ADCC activity of CBA-1205 was assessed. The anti-tumor efficacy of CBA-1205 was evaluated in xenograft mouse models, and toxicity and toxicokinetic profiles of CBA-1205 were evaluated in cynomolgus monkeys. CBA-1205 selectively bound to DLK1 among the Notch ligands and only to monkey and human DLK1. The binding epitope was between epidermal growth factor-like domains 1 and 2 of DLK1, which are not involved in any known physiological functions. The ADCC activity of CBA-1205 was confirmed using human peripheral blood mononuclear cells as effector cells. CBA-1205 as a single agent and in combination with lenvatinib demonstrated long-lasting anti-tumor efficacy, including tumor regression, in two liver cancer xenograft models. The toxicity and toxicokinetic profiles of CBA-1205 in cynomolgus monkeys were favorable. These findings suggest that CBA-1205 has the potential to be a useful therapeutic option for drug treatment in HCC. A phase 1 study is ongoing in patients with advanced cancers (jRCT2080225288, NCT06636435).

EBV-induced upregulation of CD55 reduces the efficacy of cetuximab treatment in nasopharyngeal carcinoma

Cetuximab, an anti-epidermal growth factor receptor (EGFR) antibody, has been shown to improve survival in nasopharyngeal carcinoma (NPC) patients. However, a correlation between the expression of EGFR and the response to cetuximab has not been observed, indicating that the mechanism underlying the effects of cetuximab needs to be further elucidated. The antitumour response involves immunotherapeutic mechanisms that target tumour-associated antigens, including complement-dependent cytotoxicity (CDC) and antibody-dependent cellular cytotoxicity (ADCC), act either alone or, more often, in combination. However, EBV infected NPC cells often develop resistance mechanisms that allow them to evade immune surveillance. Here, we found that overexpression of the complement-regulated protein CD55 in EBV-associated NPC cells mainly suppresses ADCC activity thus reduces the efficacy of cetuximab. Mechanistically, EBV latent membrane protein 1 (LMP1) mediated upregulation of CD55 through the NF-κB signalling pathway. The present study provides a rationale for the development of CD55 inhibitors to improve the clinical efficacy of cetuximab in NPC.

The FcγRIIIA (CD16) L48-H/R polymorphism enhances NK cell-mediated antibody-dependent cellular cytotoxicity by promoting serial killing.

Many tumor-specific monoclonal antibody therapies stimulate antibody-dependent cellular cytotoxicity (ADCC) by natural killer (NK) cells through FcγRIIIa (CD16). The efficacy of these ADCC-based immunotherapies is potentiated in patients with the common CD16 polymorphic variant F158-V that increases the binding affinity between the receptor and the IgG Fc domain. However, other CD16 variants are less well characterized. Here, we report that CD16 L48-H and L48-R variants both significantly enhance in vitro ADCC responses in primary NK cells and NK-92 cells. During ADCC responses, NK cells expressing CD16 48-H killed and disengaged from target cells faster than those expressing CD16 48-L, resulting in improved serial killing of tumor cells. We found that CD16 48-H also formed an immunological synapse with a more compact interface, as well as more robust intracellular calcium signaling and quicker polarization of cytolytic vesicles. The ADCC response observed occurs due to increased cytolytic signaling and target cell disengagement, which drives NK cell-mediated serial killing of tumor cells. The L48-H/R polymorphism has potential to benefit patient responses to cancer antibody therapies and may also potentiate anti-tumor ADCC responses if incorporated into adoptive NK cell therapeutic platforms.

Discovery of a pan anti-SARS-CoV-2 monoclonal antibody with highly efficient infected cell killing capacity for novel immunotherapeutic approaches

ABSTRACT Unlocking the potential of broadly reactive coronavirus monoclonal antibodies (mAbs) and their derivatives offers a transformative therapeutic avenue against severe COVID-19, especially crucial for safeguarding high-risk populations. Novel mAb-based immunotherapies may help address the reduced efficacy of current vaccines and neutralizing mAbs caused by the emergence of variants of concern (VOCs). Using phage display technology, we discovered a pan-SARS-CoV-2 mAb (C10) that targets a conserved region within the receptor-binding domain (RBD) of the virus. Noteworthy, C10 demonstrates exceptional efficacy in recognizing all assessed VOCs, including recent Omicron variants. While C10 lacks direct neutralization capacity, it efficiently binds to infected lung epithelial cells and induces their lysis via natural killer (NK) cell-mediated antibody-dependent cellular cytotoxicity (ADCC). Building upon this pan-SARS-CoV-2 mAb, we engineered C10-based, Chimeric Antigen Receptor (CAR)-T cells endowed with efficient killing capacity against SARS-CoV-2-infected lung epithelial cells. Notably, NK and CAR-T-cell mediated killing of lung infected cells effectively reduces viral titers. These findings highlight the potential of non-neutralizing mAbs in providing immune protection against emerging infectious diseases. Our work reveals a pan-SARS-CoV-2 mAb effective in targeting infected cells and demonstrates the proof-of-concept for the potential application of CAR-T cell therapy in combating SARS-CoV-2 infections. Furthermore, it holds promise for the development of innovative antibody-based and cell-based therapeutic strategies against severe COVID-19 by expanding the array of therapeutic options available for high-risk populations.

Natural killer cells as promising candidates in Cancer therapeutics and related immune resistance in tumor microenvironment

Natural killer (NK) cells, as critical components of the innate immune system, have emerged as promising candidates in cancer therapy due to their ability to recognize and destroy tumor cells without prior sensitization. Their mechanisms of action, including perforin-granzyme release and antibody-dependent cellular cytotoxicity (ADCC), position them as versatile agents in cancer immunotherapy. Recent advancements, such as chimeric antigen receptor (CAR)-NK cells and cytokine-based stimulation, have demonstrated enhanced efficacy and reduced side effects compared to conventional immunotherapies. However, the immunosuppressive tumor microenvironment (TME) remains a significant obstacle, imposing challenges like immune checkpoint activation, cytokine suppression, and metabolic constraints that impair NK cell activity. This paper explores the therapeutic potential of NK cells, the challenges of immune resistance in the TME, and emerging strategies to enhance NK cell efficacy. Addressing these challenges is crucial for optimizing NK cell-based treatments and achieving durable responses in cancer patients.

Zolbetuximab for Unresectable and Metastatic Gastric and Gastroesophageal Junction Adenocarcinoma: A Review of Literature.

This article comprehensively reviews the working, efficacy, and safety profile of zolbetuximab. Zolbetuximab is a pioneering chimeric monoclonal antibody designed to target Claudin 18.2 (CLDN18.2), a tight junction protein frequently overexpressed in various gastrointestinal cancers, including gastric (G) and gastroesophageal junction (GEJ) adenocarcinomas. This drug has captured attention in the treatment of unresectable and metastatic G/GEJ cancer, especially in HER2-negative patients whose tumours express CLDN18.2.Zolbetuximab is a drug that binds to CLDN18.2, and its binding initiates an immune response that attacks and kills the cancer cells. It is typically co-prescribed with fluoropyrimidine and platinum-containing chemotherapy. The drug (formerly IMAB362), brand name Vyloy, was developed by Astellas Pharma, Tokyo, Japan. After multiple rounds of clinical trials, it was approved by the U.S. Food and Drug Administration (FDA) as a first-line treatment for locally advanced, unresectable cancer, establishing itself as a promising option for advanced G/GEJ cancers. Studies reveal that it targets CLDN18.2 for the selective killing of cancer cells while sparing most healthy tissues. Zolbetuximab has demonstrated a significant improvement in progression-free survival (PFS) when combined with chemotherapy (like mFOLFOX6 or CAPOX). Also, it showed prolonged PFS compared to chemotherapy alone in previously untreated, CLDN18.2-positive, HER2-negative patients. Zolbetuximab has also shown improvements in overall survival (OS), regardless of whether the cancer progresses. This is a crucial benefit for patients with advanced G/GEJ adenocarcinomas. Additionally, zolbetuximab's dual action triggers antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC).This enhances the immune system's ability to destroy cancerous cells and results in highly potent tumour destruction compared with chemotherapy alone. Zolbetuximab is a relatively safe drug with a few adverse effects. The most frequently reported side effects were gastrointestinal, namely nausea, fatigue, vomiting, decreased appetite, diarrhea, neutropenia, anemia, and thrombocytopenia, potentially due to specific CLDN18.2 expression in the gastric mucosa. Its side effects are generally manageable, with no unexpected toxicity beyond those typically seen in patients receiving chemotherapy.

A Vaccine Against Fibroblast Activation Protein Improves Murine Cardiac Fibrosis by Preventing the Accumulation of Myofibroblasts.

Myofibroblasts are primary cells involved in chronic response-induced cardiac fibrosis. Fibroblast activation protein (FAP) is a relatively specific marker of activated myofibroblasts and a potential target molecule. This study aimed to clarify whether a vaccine targeting FAP could eliminate myofibroblasts in chronic cardiac stress model mice and reduce cardiac fibrosis. We coadministered a FAP peptide vaccine with a cytosine-phosphate-guanine (CpG) K3 oligonucleotide adjuvant to male C57/BL6J mice and confirmed an elevation in the anti-FAP antibody titer. After continuous angiotensin II and phenylephrine administration for 28 days, we evaluated the degree of cardiac fibrosis and the number of myofibroblasts in cardiac tissues. We found that cardiac fibrosis was significantly decreased in the FAP-vaccinated mice compared with the angiotensin II and phenylephrine control mice (3.45±1.11% versus 8.62±4.79%; P=4.59×10-3) and that the accumulation of FAP-positive cells was also significantly decreased, as indicated by FAP immunohistochemical staining (4077±1746 versus 7327±1741 cells/mm2; FAP vaccine versus angiotensin II and phenylephrine control; P=6.67×10-3). No systemic or organ-specific inflammation due to antibody-dependent cell cytotoxicity induced by the FAP vaccine was observed. Although the transient activation of myofibroblasts has an important role in maintaining the structural robustness in the process of tissue repair, the FAP vaccine showed no adverse effects in myocardial infarction and skin injury models. Our study demonstrates the FAP vaccine can be a therapeutic tool for cardiac fibrosis.

Efficacy and Safety of Zolbetuximab in Gastric Cancer.

Gastric cancer remains a major global health concern with high incidence and mortality rates, particularly in East Asia. Patients often have poor outcomes due to limited treatment efficacy. Zolbetuximab, a monoclonal antibody targeting claudin 18.2 (CLDN18.2)-overexpressed in 50% to 80% of gastric cancers-demonstrates promise by initiating antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity in CLDN18.2-positive cells. In clinical trials, zolbetuximab with chemotherapy improved progression-free survival (PFS) and overall survival (OS). The FAST trial showed a median OS increase from 8.4 months to 13.2 months (HR, 0.72; P < .01). The SPOTLIGHT trial found PFS extended to 11.0 months vs. 8.9 months (HR, 0.73; P = .0024) with OS reaching 18.2 months in the zolbetuximab arm. The GLOW trial also confirmed efficacy, with median OS improving from 12.16 months to 14.39 months (HR, 0.771; P = .0118). Zolbetuximab's targeted action, combined with manageable adverse effects, positions it as a promising therapy for advanced gastric cancer.

Discovery of anti-SARS-CoV-2 S2 protein antibody CV804 with broad-spectrum reactivity with various beta coronaviruses and analysis of its pharmacological properties in vitro and in vivo.

The SARS-CoV-2 pandemic alerted the potential for significant harm due to future cross-species transmission of various animal coronaviruses to human. There is a significant need of antibody-based drugs to treat patients infected with previously unseen coronaviruses. In this study, we generated CV804, an antibody that binds to the S2 domain of SARS-CoV-2 spike protein, which is highly conserved across the coronavirus family and less susceptible to mutations. CV804 demonstrated broad cross-reactivities not only disease-associated human beta coronaviruses including SARS-CoV, MERS-CoV, HCoV-OC43, HCoV-HKU1 and with existing mutant strains of SARS-CoV-2 and but also with 20 representative animal-origin coronaviruses. CV804 exhibits strong antibody-dependent cellular cytotoxicity (ADCC) to SARS-CoV-2 spike protein expressed on cells in vitro, while completely lacks virus-neutralization activity. In animal models, CV804 suppressed disease progression caused by SARS-CoV-2 infection. Structural studies using HDX-MS combined with reactivity analysis with point mutants of recombinant spike proteins revealed that CV804 binds to a unique conformational epitope within the S2 domain of the spike proteins that is highly conserved among various coronaviruses. Overall, obtained data suggest that the non-neutralizing CV804 antibody recognizes the conformational structure of the spike protein displayed on the surface of infected cells and weakens the viral virulence by supporting the host immune cells' attack through ADCC activity in vivo. The CV804 epitope information revealed in this study is useful for designing pan-corona antibody therapeutics and universal coronavirus vaccines for preparing potential future pandemics.

Cytomegalovirus-Specific T-Cell-Receptor-like Antibodies Target In Vivo-Infected Human Leukocytes Inducing Natural Killer Cell-Mediated Antibody-Dependent Cellular Cytotoxicity.

Cytomegalovirus (CMV) reactivation after stem cell or solid organ transplantation remains a major cause of morbidity and mortality in this setting. T-cell receptor (TCR)-like antibodies bind to intracellular peptides presented in major histocompatibility complex (MHC) molecules on the cell surface and may have the potential to replace T-cell function in immunocompromised patients. Three previously selected CMV-specific, human leukocyte antigen (HLA)-restricted (HLA-A*0101, HLA-A*0201 and HLA-B*0702) Fab-antibodies (A6, C1 and C7) were produced as IgG antibodies with Fc optimization. All antibodies showed specific binding to CMV peptide-loaded tumor cell lines and primary fibroblasts expressing the corresponding MHC-I molecules, leading to specific target cell lysis after the addition of natural killer (NK) cells. When deployed in combination as an antibody pool against target cells expressing more than one matching HLA allele, cytotoxic effects were amplified accordingly. CMV-specific TCR-like antibodies were also able to mediate their cytotoxic effects through neutrophils, which is important considering the delayed recovery of NK cells after stem cell transplantation. When tested on patient blood obtained during CMV reactivation, CMV-specific antibodies were able to bind to and induce cytotoxic effects in lymphocytes. CMV-specific TCR-like antibodies may find application in patients with CMV reactivation or at risk of CMV reactivation. In contrast to previous HLA/peptide-directed therapeutic approaches, the concept of a TCR-like antibody repertoire covering more than one HLA allele would make this therapeutic format available to a much larger group of patients.

Sustained Endocytosis Inhibition via Locally-Injected Drug-Eluting Hydrogel Improves ADCC-Mediated Antibody Therapy in Colorectal Cancer.

The epidermal growth factor receptor (EGFR) is a validated therapeutic target for RAS/RAF wild-type colorectal cancer (CRC). However, monoclonal antibody-based anti-EGFR therapies such as cetuximab have limited effectiveness. Herein, it is identified that EGFR internalization is associated with poor treatment response and prognosis in patients with CRC, based on a retrospective analysis of patients treated with cetuximab. It is further demonstrated that the endocytosis inhibitor prochlorperazine (PCZ) can move EGFR, which is hidden inside the cell, to the cell surface to improve therapeutic antibody binding. Thus, a thermosensitive hydrogel co-loaded with cetuximab and PCZ (Gel@Cmab/PCZ) is constructed for sustained inhibition of endocytosis and effective cetuximab delivery. Peritumoral injection of Gel@Cmab/PCZ shows strong antitumor efficacy in subcutaneous and orthotopic CRC tumor models and completely abrogated liver metastasis when combined with chemotherapy. In a humanized patient-derived xenograft model, a single injection of Gel@Cmab/PCZ with one-third of theconventional cetuximab dose achieved 91% tumor growth inhibition, which promoted NK cell infiltration into tumor tissues and their antibody-dependent cell-mediated cytotoxicity effect. This study represents a novel strategy to boost the monoclonal antibody-mediated anti-tumor response in CRC.