Antibody-dependent Cell-mediated Cytotoxicity Activity Research Articles

Druggability properties of a L309K mutation in the antibody CH2 domain.

In the early stages of antibody drug development, it is imperative to conduct a comprehensive assessment and enhancement of the druggability attributes of potential molecules by considering their fundamental physicochemical properties. This study specifically concentrates on the surface-exposed hydrophobic region of the candidate antibody aPDL1-WT and explores the effectiveness of the L309K mutation strategy. The resulting aPDL1-LK variant demonstrates a notable enhancement over the original antibody in addressing the issue of aggregation and formation of large molecular impurities under accelerated high-temperature conditions. The mutated molecule, aPDL1-LK, exhibits excellent physicochemical properties such as hydrophilicity, conformational stability, charge variant stability, post-translational modifications, and serum stability. In terms of biological function, aPDL1-LK maintains the same glycosylation pattern as the original antibody and shows no significant difference in affinity for antigen hPDL1 protein, CD16a-F158, CD64, CD32a-H131, and complement C1q, compared to aPDL1-WT. The L309K mutation results in an approximately twofold reduction in its affinity for CD16a-V158 and CD32a-R131. In vitro biological assays, including antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and complement-dependent cytotoxicity (CDC), reveal that the L309K mutation may decrease CD16a-V158-mediated ADCC activity due to the mutation-induced decrease in ligand affinity, while not affect CD32a-R131-mediated ADCP activity. In conclusion, the L309K mutation offers a promising strategy to enhance the druggability properties of candidate antibodies.

A bispecific antibody targeting HER2 and CLDN18.2 eliminates gastric cancer cells expressing dual antigens by enhancing the immune effector function.

Gastric cancer (GC) is widely regarded as one of the toughest cancers to treat. Trastuzumab, which targets the human epidermal growth factor receptor 2 (HER2) for GC treatment, has demonstrated clinical success. However, these patients have a high likelihood of developing resistance. Additionally, Claudin18.2 (CLDN18.2) is a promising emerging target for GC treatment. Therefore, therapies that simultaneously target both HER2 and CLDN18.2 targets are of great significance. Here, we constructed a bispecific antibody targeting both HER2 and CLDN18.2 (HC-2G4S; BsAb), which displayed satisfactory purity, thermostability and enhancing antibody-dependent cell-mediated cytotoxicity (ADCC) activity. In a tumor spheroids model of GC, BsAb demonstrated greater therapeutic efficacy than monoclonal antibodies (mAb) or combination treatment strategies. We propose that the enhanced anti-tumor potency of BsAbs in vivo is due to the monovalent binding of single-chain antibodies to more targets due to weaker affinity, resulting in a more potent immune effect function. Therefore, HC-2G4S could be a productive agent for treating GC that is HER2-positive, CLDN18.2-positive, or both, with the potential to overcome trastuzumab resistance and provide significant clinical benefits and expanded indications.

ZGGS15, a Novel IgG4 Bispecific Monoclonal Antibody Targeting Both LAG-3 and Tigit, Demonstrates Outstanding Anti-Tumor Activity and Can be Used As Monotherapy or in Combination with Anti-PD-1 Antibodies for Cancer Immunotherapy

Background This study aims to evaluate the anti-tumor efficacy of ZGGS15, a novel IgG4 bispecific monoclonal antibody (BsAb) targeting TIGIT and LAG-3, for cancer immunotherapy. Methods: ZGGS15 was generated in-house with the standard recombinant BsAb technology. ZGGS15 proteins were purified with protein A affinity column chromatography and evaluated for purity by size-exclusion high-performance liquid chromatography. The ZGGS15 affinity was assessed using a biolayer interferometry (BLI) assay. The EC50s of ZGGS15 binding to TIGIT and LAG-3 were determined using the ELISA technique. The EC50s of ZGGS15 binding to REH, Hela, MCF-7, and HCC1954 cells were measured by flow cytometry. Antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) activities were also evaluated by flow cytometry. BALB/c-hPD-1/hLAG-3 and BALB/c-hPD-1/hTIGIT subcutaneously transplanted with CT26.WT tumor mouse models, and peripheral blood mononuclear cells (PBMC) -humanized NOG bearing A375 tumor mouse model were used for in vivo anti-tumor efficacy evaluation. Results ZGGS15 binds specifically to activated CD4 + and CD8 + T cells and human LAG-3 and TIGIT proteins expressed by CHO-K1 cells identically with a dose-dependent nanomolar affinity of 0.69 nM and 1.87 nM for human LAG-3 and TIGIT, respectively. In vitro kinetic analysis BLI results revealed ZGGS15 has high affinity for human LAG-3 and human TIGIT proteins, with KDs of 3.05 nM and 2.65 nM, respectively. ZGGS15 binds to human LAG-3 and human TIGIT simultaneously with similar affinity. Furthermore, ZGGS15 competitively inhibited the binding of LAG-3 to MHC-II (IC50 = 0.77 nM) and the binding of TIGIT to CD155 (IC50=0.24 nM). ZGGS15 induced better T cell activation than single anti-LAG3 or anti-TIGIT mAb agent or combined with different stimuli with or without cancer cells. When combined with nivolumab, ZGGS15 can further enhance the T cell activation in a dose-dependent manner. ADCC/CDC assay results showed that ZGGS15 binding to target cells does not induce ADCC or CDC. ZGGS15 interacts with the human neonatal Fc receptor in a pH-dependent manner, which can promote recirculation of ZGGS15 with a prolonged half-life in plasma. Besides, ZGGS15 interacts with human Fc-γ receptors and the human complement component, C1q, with low binding affinities. However, ZGGS15 does not induce obvious cytokine production from PBMCs, including IFN-γ, IL-2, IL-6, IL-10, and TNF-α. In vivo anti-tumor efficacy for ZGG15 in PBMC humanized NOG mice bearing A375 tumors showed that ZGGS15 had significant anti-tumor effects in the subcutaneous A375 xenograft model. ZGGS15 showed a better anti-tumor inhibition than single anti-LAG-3 or anti-TIGIT agent and a synergetic effect when combined with nivolumab. On day 18 post-treatment, the ZSAB015 plus nivolumab treatment demonstrated a significantly tumor growth inhibition (TGI) of 95.80% ( p =0.001), compared with the vehicle group. In vivo efficacy tests in BALB/c-hPD-1/hLAG-3 mice subcutaneously transplanted with CT26.WT tumor model showed that both high and low doses of ZGGS15 could inhibit the growth of CT26.WT colon cancer. The combination of high-dose ZGGS15 plus nivolumab has better efficacy than high-dose ZGGS15 and is slightly better than nivolumab alone. The tumor volume inhibition rate (TGITV) for ZGGS15 at 2 mg/kg was 69.70%, and for ZGGS15 at 5 mg/kg plus nivolumab at 1 mg/kg, it was 94.03% ( p < 0.001). During the experiment, the tumor-bearing mice tolerated it well, and no adverse reactions were observed. In vivo efficacy tests of ZGG15 in BALB/c-hPD-1/hTIGIT mice subcutaneously transplanted with CT26.WT tumor model showed that ZGGS15 at a low dose (1.5 mg/kg) demonstrated a significant tumor inhibitory effect, with the TGITV of 51.42% ( p < 0.01). The combination of ZGGS15 high-dose with nivolumab (5 mg/kg + 1 mg/kg) showed a better tumor inhibitory effect compared with ZGGS15 high-dose (5 mg/kg), with the TGITV of 81.15% and 41.54%, respectively ( p < 0.05). Conclusions ZGGS15 has excellent anti-tumor activity by inhibiting LAG-3 and TIGIT as a new IgG4 BsAb. ZGGS15 also exhibits potent anti-tumor efficacy in transgenic mouse models combined with nivolumab. Additionally, ZGGS15 does not elicit ADCC or CDC, therefore avoiding the cross-reaction of non-target binding. Finally, ZGGS15 does not induce cytokine production, mitigating any potential adverse effects of CRS.

A novel Fc-enhanced humanized monoclonal antibody targeting B7-H3 suppresses the growth of ESCC

ABSTRACT Esophageal squamous cell carcinoma (ESCC) is a prevalent malignant tumor of the digestive tract with a low 5-year survival rate due to the lack of effective treatment methods. Although therapeutic monoclonal antibodies (mAbs) now play an important role in cancer therapy, effective targeted mAbs are still lacking for ESCC. B7-H3 is highly expressed in a variety of tumors and has emerged as a promising therapeutic target. Several mAbs against B7-H3 have advanced to clinical trials, but their development has not yet been pursued for ESCC. Here, we developed a humanized and Fc-engineered anti-B7H3 mAb 24F-Hu-mut2 and systematically evaluated its anti-tumor activity in vitro and in vivo. The 24F-Hu-mut2 was humanized and modified in Fc fragment to obtain stronger antibody-dependent cell-mediated cytotoxicity(ADCC) activity and nanomolar affinity. Furthermore, both of ESCC cell-derived xenograft (CDX) and patient-derived xenograft (PDX) mice models indicated that 24F-Hu-mut2 displayed potent in vivo anti-tumor activity. In addition, a computational docking model showed that the mAb bound to IgC1 and IgC2 domain of B7-H3, which is closer to the cell membrane. Consistently, our ELISA results verified the binding of 24F-Hu-WT and IgC1 and IgC2. Our results indicate that 24F-Hu-mut2 has significant anti-ESCC activity both in vitro and in vivo, and this monoclonal antibody may be a promising antibody against ESCC and other B7-H3 overexpressing tumors.

Potentiation of natural killer cells to overcome cancer resistance to NK cell-based therapy and to enhance antibody-based immunotherapy.

Natural killer (NK) cells are cellular components of the innate immune system that can recognize and suppress the proliferation of cancer cells. NK cells can eliminate cancer cells through direct lysis, by secreting perforin and granzymes, or through antibody-dependent cell-mediated cytotoxicity (ADCC). ADCC involves the binding of the Fc gamma receptor IIIa (CD16), present on NK cells, to the constant region of an antibody already bound to cancer cells. Cancer cells use several mechanisms to evade antitumor activity of NK cells, including the accumulation of inhibitory cytokines, recruitment and expansion of immune suppressor cells such as myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs), modulation of ligands for NK cells receptors. Several strategies have been developed to enhance the antitumor activity of NK cells with the goal of overcoming cancer cells resistance to NK cells. The three main strategies to engineer and boost NK cells cytotoxicity include boosting NK cells with modulatory cytokines, adoptive NK cell therapy, and the employment of engineered NK cells to enhance antibody-based immunotherapy. Although the first two strategies improved the efficacy of NK cell-based therapy, there are still some limitations, including immune-related adverse events, induction of immune-suppressive cells and further cancer resistance to NK cell killing. One strategy to overcome these issues is the combination of monoclonal antibodies (mAbs) that mediate ADCC and engineered NK cells with potentiated anti-cancer activity. The advantage of using mAbs with ADCC activity is that they can activate NK cells, but also favor the accumulation of immune effector cells to the tumor microenvironment (TME). Several clinical trials reported that combining engineered NK cells with mAbs with ADCC activity can result in a superior clinical response compared to mAbs alone. Next generation of clinical trials, employing engineered NK cells with mAbs with higher affinity for CD16 expressed on NK cells, will provide more effective and higher-quality treatments to cancer patients.

Development of a concise and reliable method for quantifying the antibody loaded onto lipid nanoparticles modified with Herceptin

Antibodies are essential components of the immune system with a wide range of molecular targets. They have been recognized as modalities for treating several diseases and more than 130 approved antibody-based therapeutics are available for clinical use. However, limitations remain associated with its efficacy, tissue permeability, and safety, especially in cancer treatment. Nanoparticles, particularly those responsive to external stimuli, have shown promise in improving the efficacy of antibody-based therapeutics and tissue-selective delivery. In this study, we developed a reliable and accurate method for quantifying the amount of antibody loaded onto lipid nanoparticles modified with Herceptin® (Trastuzumab), an antibody-based therapeutic used to treat HER2-positive cancers, using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by silver staining. This method proved to be a suitable alternative to commonly used protein quantification techniques, which are limited by lipid interference present in the samples. Furthermore, the amount of Herceptin modified on the liposomes, measured by this method, was confirmed by Herceptin's antibody-dependent cell-mediated cytotoxicity activity. Our results demonstrate the potential of this method as a critical tool for developing tissue-selective antibody delivery systems, leading to improved efficacy and reduced side effects of antibody-based therapeutics.

Development, methodological evaluation and application of a cell-based TRF assay for analysis of ADCC activity

Interaction of an antibody with its FcγR plays an important role in effector functions such as antibody-dependent cell-mediated cytotoxicity (ADCC). Nowadays altered ADCC activity of an antibody can be achieved by utilizing an effective glyco-engineering strategy, which often involves changes of sugar moieties in Fc part of the antibody, thereby affecting its receptor binding with effector cells. We aimed to construct a cell-based time-resolved fluorescence (TRF) assay for the evaluation of ADCC activity triggered by the antibody drug Trastuzumab (anti-HER2) and T-DM1. The assay was initiated by incubating 2,2′:6′,2 "-Terpyridine-6,6"-dicarboxylic acid (TDA)-labeled target SK-BR3 cells with the testing antibodies and engineered NK-92 effector cells. After incubation, the target cells were lysed to detect TDA released into the supernatant. Together with added Eu, the TDA in the supernatant formed a stable chelate of EuTDA with high-intensity fluorescence. The ADCC activity was then determined by measuring the fluorescence of EuTDA. Consequently, the method demonstrated good accuracy, precision, linearity, and specificity over methodological assessment and compared well with the Luciferase release assay in terms of the agreement of the achieved results. Using the developed assay, we evaluated the ADCC activity of two glyco-engineered anti-HER-2 antibody-drug conjugates (ADCs) and the results showed that antibody Fc glycosylation modifications influenced antibody ADCC activity to varying degrees. In conclusion, the present assay is able to accurately assess the ADCC activity induced by Trastuzumab (anti-HER2) and T-DM1, and a similar methodology can be applied to other therapeutic antibodies during drug development to help screen for antibodies with desirable ADCC activity.

Alterations in immune cell phenotype and cytotoxic capacity in HER2+ breast cancer patients receiving HER2-targeted neo-adjuvant therapy.

The phase II neo-adjuvant clinical trial ICORG10-05 (NCT01485926) compared chemotherapy in combination with trastuzumab, lapatinib or both in patients with HER2+ breast cancer. We studied circulating immune cells looking for alterations in phenotype, genotype and cytotoxic capacity (direct and antibody-dependent cell-mediated cytotoxicity (ADCC)) in the context of treatment response. Peripheral blood mononuclear cells (PBMCs) were isolated from pre- (n = 41) and post- (n = 25) neo-adjuvant treatment blood samples. Direct/trastuzumab-ADCC cytotoxicity of patient-derived PBMCs against K562/SKBR3 cell lines was determined ex vivo. Pembrolizumab was interrogated in 21 pre-treatment PBMC ADCC assays. Thirty-nine pre-treatment and 21 post-treatment PBMC samples were immunophenotyped. Fc receptor genotype, tumour infiltrating lymphocyte (TIL) levels and oestrogen receptor (ER) status were quantified. Treatment attenuated the cytotoxicity/ADCC of PBMCs. CD3+/CD4+/CD8+ T cells increased following therapy, while CD56+ NK cells/CD14+ monocytes/CD19+ B cells decreased with significant post-treatment immune cell changes confined to patients with residual disease. Pembrolizumab-augmented ex vivo PBMC ADCC activity was associated with residual disease, but not pathological complete response. Pembrolizumab-responsive PBMCs were associated with lower baseline TIL levels and ER+ tumours. PBMCs display altered phenotype and function following completion of neo-adjuvant treatment. Anti-PD-1-responsive PBMCs in ex vivo ADCC assays may be a biomarker of treatment response.

S-531011, a Novel Anti-Human CCR8 Antibody, Induces Potent Antitumor Responses through Depletion of Tumor-Infiltrating CCR8-Expressing Regulatory T Cells.

Although regulatory T cells (Treg) are inhibitory immune cells that are essential for maintaining immune homeostasis, Tregs that infiltrate tumor tissue promote tumor growth by suppressing antitumor immunity. Selective reduction of tumor-infiltrating Tregs is, therefore, expected to activate antitumor immunity without affecting immune homeostasis. We previously reported that selective Treg depletion targeted by a C-C motif chemokine receptor 8 (CCR8) resulted in induction of strong antitumor immunity without any obvious autoimmunity in mouse models. Thus, herein, we developed a novel humanized anti-CCR8 monoclonal antibody, S-531011, aimed as a cancer immunotherapy strategy for patients with cancer. S-531011 exclusively recognized human CCR8 among all chemokine receptors and showed potent antibody-dependent cell-mediated cytotoxicity activity toward CCR8+ cells and neutralization activity against CCR8-mediated signaling. We observed that S-531011 reduced tumor-infiltrating CCR8+ Tregs and induced potent antitumor activity in a tumor-bearing human-CCR8 knock-in mouse model. Moreover, combination therapy with S-531011 and anti-mouse programmed cell death 1 (PD-1) antibody strongly suppressed tumor growth compared with anti-PD-1 antibody alone with no observable adverse effects. S-531011 also depleted human tumor-infiltrating Tregs, but not Tregs derived from human peripheral blood mononuclear cells. These results suggest that S-531011 is a promising drug for inducing antitumor immunity without severe side effects in the clinical setting.

Inhibiting N-glycan processing increases the antibody binding affinity and effector function of human natural killer cells.

Novel approaches are required to improve the efficacy of immunotherapies and increase the proportion of patients who experience a benefit. Antibody-dependent cell-mediated cytotoxicity (ADCC) contributes to the efficacy of many monoclonal antibodies therapies. Natural killer (NK) cells mediate ADCC, though responses are highly variable and depend on prior treatment as well as other factors. Thus, strategies to increase NK cell activity are expected to improve multiple therapies. Both cytokine treatment and NK cell receptor engineering are being explored to increase ADCC. Post-translational modifications, including glycosylation, are widely recognized as mediators of cellular processes but minimally explored as an alternative strategy to increase ADCC. We evaluated the impact of treatment with kifunensine, an inhibitor of asparagine-linked (N-)glycan processing, on ADCC using primary and cultured human NK cells. We also probed affinity using binding assays and CD16a structure with nuclear magnetic resonance spectroscopy. Treating primary human NK cells and cultured YTS-CD16a cells with kifunensine doubled ADCC in a CD16a-dependent manner. Kifunensine treatment also increased the antibody-binding affinity of CD16a on the NK cell surface. Structural interrogation identified a single CD16a region, proximal to the N162 glycan and the antibody-binding interface, perturbed by the N-glycan composition. The observed increase in NK cell activity following kifunensine treatment synergized with afucosylated antibodies, further increasing ADCC by an additional 33%. These results demonstrate native N-glycan processing is an important factor that limits NK cell ADCC. Furthermore, optimal antibody and CD16a glycoforms are defined that provide the greatest ADCC activity.

Abstract 2938: Preclinical development of a novel bispecific mAb-Trap fusion protein, IMM2902, targeting both HER2 and CD47 as cancer immunotherapy

Abstract The overexpression of human epidermal growth factor receptor 2 (HER2) has been identified in a variety of solid tumors including breast cancer (BC), gastric cancer and is associated with tumor recurrence, brain metastasis, and an overall poor prognosis. As such, HER2 has become a major target in the research and development of anticancer drugs. CD47, an integrin-associated protein, is expressed in many human cancer cells, especially upregulated preferentially in HER2-expressing cells. Co-expression of HER2 and CD47 is more frequently detected in recurrent BC patients with poor prognosis when comparing with the counterpart primary tumors. IMM2902 is a first-in-class, clinical-stage, novel recombinant bispecific mAb-Trap fusion protein targeting both CD47 and HER2 simultaneously. The binding activities of IMM2902, measured as EC50, to total CD47+ and HER2+ in BT474, NCI-N87 and SKOV-3 cancer cell lines are 16, 11 and 5 nM respectively. The affinity of IMM2902 to HER2 is about 15 times higher than that of CD47. IMM2902 not only prevents the engagement of CD47 with SIRPα and hence blocks “don’t eat me” signal of CD47/SIRPα, but also induces strong antibody-dependent cell-mediated cytotoxicity (ADCC, EC50 = 0.0045 - 0.0544 nM) and antibody-dependent cellular phagocytosis (ADCP, EC50 = 0.05 - 0.13 nM) activity with specifically engineered IgG1 Fc fragment. Most importantly, IMM2902 induces accelerated HER2 degradation in tumor tissues. Despite its high affinity to CD47, IMM2902 does not binds to CD47 on erythrocyte membrane, therefore, unlike conventional CD47 mAb, IMM2902 demonstrated a minimal impact on red blood cells (RBC). In preclinical research, IMM2902 has demonstrated a much stronger antitumor activity with excellent tolerability in a mouse model of human breast cancer (dose range 3.5 - 10 mg/kg) and a mouse model of human gastric cancer (dose range 1 -18 mg/kg) than that of trastuzumab (targeting HER2 only) alone, IMM01 (a SIRPα-Fc fusion protein) alone, and the combination of trastuzumab and IMM01. In HER2-low SUN-1 xenograft models, IMM2902 has showed a strong tumor growth inhibition at doses between 2 to 18 mg/kg. Intriguingly, IMM2902 also has exhibited potent tumor killing activity against breast cancer resistant to trastuzumab (HCC-1954 and patient-derived xenografts herceptin-resistant model) at doses between 3.5 to 10 mg/kg. Given the strong preclinical antitumor activity as well as the favorable safety profile, IMM2902 may serve as a potent immunotherapy for HER2-expressing cancers via dual blockade of CD47 and HER2. A Phase 1 clinical trial exploring safety, tolerability, and preliminary efficacy of IMM2902 in patients with HER2-expressing advanced solid tumors is currently ongoing in both China (CXSL2101035) and USA (NCT05076591). Citation Format: Binglei Zhang, Song Li, Dianze Chen, Dandan Liu, Huiqin Guo, Chunmei Yang, Li Zhang, Wei Zhang, Xiaoping Tu, Liang Peng, Gui Zhao, Ruliang Zhang, Frank X. Gan, Wenzhi Tian, Fan Zhang, Yongping Song. Preclinical development of a novel bispecific mAb-Trap fusion protein, IMM2902, targeting both HER2 and CD47 as cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2938.

Abstract 890: ADAM17 knockout NK or CAR NK cells augment antibody dependent cellular cytotoxicity (ADCC) and anti-tumor activity

Abstract Natural killer (NK) cells are a critical component of the innate immune system and do not elicit graft-versus-host disease, making them an attractive source of ‘off-the-shelf’ allogeneic cell therapy. NK cells are also amenable to CRISPR and chimeric antigen receptor (CAR) genomic engineering for enhanced functions. Another important anti-tumor role of NK cells is via antibody-dependent cell mediated cytotoxicity (ADCC). The process is mediated by CD16a of NK cells, which binds the Fc portion of antibodies. After NK cell activation, the CD16a ectodomain is rapidly cleaved from the NK cell surface by a disintegrin, Metalloprotease-17 (ADAM17), that is produced by both tumor cells and activated NK cells. This dampens NK cell activity by preventing NK cell attachment to antibody-coated target cells and diminishes CD16a signaling. Inhibiting ADAM17-mediated CD16a cleavage leads to augmented ADCC activity and increased cytokine production by human NK cells. Other NK cell activating receptors are known to be regulated by a similar mechanism1. In this study, we have utilized CRISPR-Cas9 ribonucleoproteins (RNPs) to disrupt the ADAM17 gene in isolated peripheral blood NK cells from healthy donors. FACS and Amplicon NGS Sequencing data confirmed successful disruption of the gene. Edited NK cells were expanded using IL-2 and stimulation with NKSTIM, a modified K562 stimulatory cell line expressing a membrane-bound form of IL-15 (mbIL-15) and 4-1BBL. IL-12 and IL-18 were added during expansion to drive memory-like NK cell differentiation. Furthermore, we transduced ADAM17 edited NK cells to express a CD70 CAR2 or CD19 CAR3 construct and mbIL-15. CAR expression was assessed by FACS. In vitro cytotoxicity was measured by IncuCyte. Using an artificial activation system (phorbol 12-myristate 13-acetate [PMA]), we showed that ADAM17 KO NK cells maintain dramatically higher surface expression of CD16a and CD62L than control NK cells. In IncuCyte cytotoxicity assays against Raji tumor cells in the presence of rituximab (anti-CD20), ADAM17 KO NK cells and ADAM17 KO CD19 CAR NK cells demonstrated higher cytotoxicity compared to control NK cells. Similarly, ADAM17 KO NK cells and ADAM17 KO CD70 CAR NK cells also showed enhanced cytotoxicity against 786-O tumor cells in the presence of anti-EGFR antibody, cetuximab. Furthermore, ADAM17/CISH/CBLB triple KO CD70 CAR NK cells exhibited enhanced antitumor efficacy in vivo in a 786-O RCC tumor and a HL60 AML xenograft model. Taken together, we show ADAM17 KO NK or ADAM17 KO CAR NK cells demonstrate improved ADCC and ADAM17 KO can enhance in vivo anti-tumor activity of CISH/CBLB KO CD70 CAR NK cells against relevant tumor models. These data support the further exploration of ADAM17 gene knockout NK cells for clinical application and to improve efficacy of therapeutic antibodies in combination with adoptive transfer of engineered NK cells. Citation Format: Chao Guo, Yanying Fan, Alexander Aronov, Nikki Kimura, Damie Juat, Jessica Sood, Ivan H. Chan, James B. Trager. ADAM17 knockout NK or CAR NK cells augment antibody dependent cellular cytotoxicity (ADCC) and anti-tumor activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 890.

Abstract 4423: XMT-2056, a HER2-targeted STING agonist antibody-drug conjugate, exhibits ADCC function that synergizes with STING pathway activation and contributes to anti-tumor responses

Abstract XMT-2056 is a systemically administered Immunosynthen STING agonist antibody-drug conjugate (ADC) that targets a novel HER2 epitope and induces complete tumor regressions with a single dose in multiple tumor models. We have previously shown that XMT-2056 delivers its STING agonist payload into tumor cells and FcγRI (CD64)-expressing myeloid cells, activating STING signaling in both cell types, leading to type I interferon (IFN) and anti-tumor innate immune responses. Here, we demonstrate that XMT-2056 exhibits ADCC (antibody-dependent cell-mediated cytotoxicity) function, which synergizes with STING pathway activation and induces potent cancer cell-killing activity in co-cultures of HER2-expressing cancer cells and FcγRIII+ (CD16+) immune cells. We show that both XMT-2056 and HT-19 (the unconjugated parental antibody) retain significant cancer cell-killing activity in an Fc-dependent manner in PBMC co-cultures depleted of FcγRI-expressing myeloid cells. This activity is abrogated by co-depletion of FcγRIII+ immune cells, illustrating the ADCC function of XMT-2056. In this setting, XMT-2056 cancer cell-killing activity was significantly increased compared to HT-19, suggesting that the STING payload contributes to the differential activity observed with XMT-2056 treatment. Indeed, co-treatment of cancer cell and immune cell co-cultures with HT-19 and free STING agonist payload enhanced the anti-tumor responses, although to a lesser extent than XMT-2056, suggesting a synergy between the ADCC function and STING pathway activation. Consistently, XMT-2056 treatment of HER2-expressing cancer cells co-cultured with unstimulated CD56+/FcγRIII+ NK cells induced granzyme b and IFN-γ cytokine production, expression of NK cell activation markers, and cancer cell-killing activity. The ADCC activity of HT-19 was comparable to that of trastuzumab in NK cell co-cultures. Finally, we found that depletion of FcγRI+ cells inhibited the cancer cell-killing activity of XMT-2056 in cancer cell and PBMC co-cultures more substantially compared to depletion of FcγRIII+ cells or CD56+ NK cells, indicating a greater contribution of myeloid cells to the XMT-2056 mechanism of action in this setting. Notably, XMT-2056 was capable of engaging both FcγRI+ myeloid cells and FcγRIII+ NK cells, activating both STING-mediated innate immune responses and ADCC function in triple cultures with HER2-expressing cancer cells. Collectively, our data reveal a synergy between ADCC function and STING pathway induction both mediated by XMT-2056, which enhances the cancer cell-killing activity of FcγRIII+ cells. This additional mechanism of action of XMT-2056 can potentially impact the overall anti-tumor immune responses in tumors infiltrated by FcγRIII+ cells. Citation Format: Jahna Soomer-James, Marc Damelin, Naniye Malli. XMT-2056, a HER2-targeted STING agonist antibody-drug conjugate, exhibits ADCC function that synergizes with STING pathway activation and contributes to anti-tumor responses. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4423.

Immunological effects and activity of multiple doses of zolbetuximab in combination with zoledronic acid and interleukin-2 in a phase 1 study in patients with advanced gastric and gastroesophageal junction cancer

PurposeZolbetuximab (IMAB362) is engineered to induce antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity. We evaluated ADCC activity and the impact of the immune-modulating drugs zoledronic acid (ZA) and interleukin-2 (IL-2) as co-treatment with zolbetuximab on relevant immune cell populations and ADCC lysis activity.MethodsThis phase 1, multicenter, open-label study investigated the immunological effects and activity, safety, tolerability, and antitumor activity of multiple doses of zolbetuximab alone (n = 5) or in combination with ZA (n = 7) or with ZA plus two different dose levels of IL-2 (low dose: 1 million international units [mIU] [n = 9]; intermediate dose: 3 mIU [n = 7]) in pretreated patients with advanced gastric and gastroesophageal junction (G/GEJ) adenocarcinoma.ResultsTwenty-eight patients with previously treated advanced G/GEJ adenocarcinoma that was CLDN18.2-expressing were enrolled into four treatment arms. Treatment with zolbetuximab + ZA + IL-2 induced short-lived expansion and activation of ADCC-mediating cell populations, namely γ9δ2 T cells and natural killer cells, within 2 days after administration; this effect was more pronounced with intermediate-dose IL-2. Expansion and activation of regulatory T cells treated with either IL2 dose was moderate and short-lived. Strong ADCC activity was observed with zolbetuximab alone. Short-lived ADCC activity was observed in several patients treated with ZA + intermediate-dose IL-2, but not lower-dose IL-2. In the clinical efficacy population, the best confirmed response was stable disease (n = 11/19; 58%).ConclusionsZolbetuximab mediates proficient ADCC in patients with pretreated advanced G/GEJ cancers. Co-treatment with ZA + IL-2 did not further improve this effect.Trial registration: NCT01671774

Application of Pseudotyped Viruses.

Highly pathogenic emerging and reemerging viruses have serious public health and socioeconomic implications. Although conventional live virus research methods can more reliably investigate disease pathogenicity and evaluate antiviral products, they usually depend on high-level biosafety laboratories and skilled researchers; these requirements hinder in vitro assessments of efficacy, as well as efforts to test vaccines and antibody drugs. In contrast, pseudotyped viruses (i.e., single-round infectious viruses that mimic the membrane structures of various live viruses) are widely used in studies of highly pathogenic viruses because they can be handled in biosafety level 2 facilities. This chapter provides a concise overview of various aspects of pseudotyped virus technologies, including (1) exploration of the mechanisms of viral infection; (2) evaluation of the efficacies of vaccines and monoclonal antibodies based on pseudovirion-based neutralization assay; (3) assessment of antiviral agents (i.e., antibody-based drugs and inhibitors); (4) establishment of animal models of pseudotyped virus infection in vivo; (5) investigation of the evolution, infectivity, and antigenicity of viral variants and viral glycosylation; and (6) prediction of antibody-dependent cell-mediated cytotoxic activity.

An Fc variant with two mutations confers prolonged serum half-life and enhanced effector functions on IgG antibodies

The pH-selective interaction between the immunoglobulin G (IgG) fragment crystallizable region (Fc region) and the neonatal Fc receptor (FcRn) is critical for prolonging the circulating half-lives of IgG molecules through intracellular trafficking and recycling. By using directed evolution, we successfully identified Fc mutations that improve the pH-dependent binding of human FcRn and prolong the serum persistence of a model IgG antibody and an Fc-fusion protein. Strikingly, trastuzumab-PFc29 and aflibercept-PFc29, a model therapeutic IgG antibody and an Fc-fusion protein, respectively, when combined with our engineered Fc (Q311R/M428L), both exhibited significantly higher serum half-lives in human FcRn transgenic mice than their counterparts with wild-type Fc. Moreover, in a cynomolgus monkey model, trastuzumab-PFc29 displayed a superior pharmacokinetic profile to that of both trastuzumab-YTE and trastuzumab-LS, which contain the well-validated serum half-life extension Fcs YTE (M252Y/S254T/T256E) and LS (M428L/N434S), respectively. Furthermore, the introduction of two identified mutations of PFc29 (Q311R/M428L) into the model antibodies enhanced both complement-dependent cytotoxicity and antibody-dependent cell-mediated cytotoxicity activity, which are triggered by the association between IgG Fc and Fc binding ligands and are critical for clearing cancer cells. In addition, the effector functions could be turned off by combining the two mutations of PFc29 with effector function-silencing mutations, but the antibodies maintained their excellent pH-dependent human FcRn binding profile. We expect our Fc variants to be an excellent tool for enhancing the pharmacokinetic profiles and potencies of various therapeutic antibodies and Fc-fusion proteins.

Specific location of galactosylation in an afucosylated antiviral monoclonal antibody affects its FcγRIIIA binding affinity.

Monoclonal antibodies (mAbs) comprise an essential type of biologic therapeutics and are used to treat diseases because of their anti-cancer and anti-inflammatory properties, and their ability to protect against respiratory infections. Its production involves post-translational glycosylation, a biosynthetic process that conjugates glycans to proteins, which plays crucial roles in mAb bioactivities including effector functions and pharmacokinetics. These glycans are heterogeneous and have diverse chemical structures whose composition is sensitive to manufacturing conditions, rendering the understanding of how specific glycan structures affect mAb bioactivity challenging. There is a need to delineate the effects of specific glycans on mAb bioactivity to determine whether changes in certain glycosylation profiles (that can occur during manufacturing) will significantly affect product quality. Using enzymatic transglycosylation with chemically-defined N-glycans, we show that galactosylation at a specific location of N-glycans in an afucosylated anti-viral mAb is responsible for FcγRIIIA binding and antibody-dependent cell-mediated cytotoxicity (ADCC) activity. We report a facile method to obtain purified asymmetric mono-galactosylated biantennary complex N-glycans, and their influence on bioactivity upon incorporation into an afucosylated mAb. Using ELISA, surface plasmon resonance and flow cytometry, we show that galactosylation of the α6 antenna, but not the α3 antenna, consistently increases FcγRIIIA binding affinity. We confirm its relevance in an anti-viral model of respiratory syncytial virus (RSV) using an adapted ADCC reporter assay. We further correlate this structure-function relationship to the interaction of the galactose residue of the α6 antenna with the protein backbone using 2D-1H-15N-NMR, which showed that galactosylation of at this location exhibited chemical shift perturbations compared to glycoforms lacking this galactose residue. Our results highlight the importance of identifying and quantifying specific glycan isomers to ensure adequate quality control in batch-to-batch and biosimilar comparisons.

116 (PB106) - Preclinical activity for TPX-4589 (LM-302), an antibody-drug conjugate targeting tight junction protein CLDN18.2 in solid tumors

Background: Claudin 18 isoform 2 (CLDN18.2) is a tight junction protein involved in the regulation of epithelial cell permeability, barrier function, and polarity. In healthy tissue, CLDN18.2 is selectively expressed in tight junctions of gastric epithelial tissue and hence largely inaccessible to intravenous antibodies. On malignant transformation, CLDN18.2 is exposed on the cancer cell surface and expressed in many solid tumors, including gastric cancer (GC) and pancreatic cancer (PC). CLDN18.2 expression is associated with tumor pathogenesis, proliferation, and metastasis, making it a promising target for cancer therapies. TPX-4589, a novel antibody-drug conjugate (ADC) coupled with cytotoxic payload monomethyl auristatin E (MMAE), was developed to target CLDN18.2. Materials and methods: Preclinical studies were conducted to characterize TPX-4589 in CLDN18.2-positive cells, including binding affinity, antibody-dependent cell-mediated cytotoxicity (ADCC), cell proliferation inhibition, and in vivo efficacy in gastric and pancreatic tumor models. Results: TPX-4589 bound to endogenous CLDN18.2 GC GAXC031 cells in a dose-dependent manner, with an EC50 of 47.25 nM. Internalization was shown in both high- and low-expressing CLDN18.2-positive cells, with superior internalization when compared to zolbetuximab, a monoclonal antibody (mAb) that specifically binds to CLDN18.2 (table). TPX-4589 showed strong concentration-dependent ADCC activity, with EC50 of 0.11 nM, and inhibited tumor cell proliferation in vitro with nanomolar potency in GAXC031 and PC MIA PaCa2-high CLDN18.2 cell lines. In a cell-line xenograft GC tumor model with high CLDN18.2 expression, TPX-4589 significantly reduced tumor volume in a dose-dependent manner and demonstrated superior efficacy to zolbetuximab. In a CLDN18.2-high patient-.derived xenograft (PDX) PC tumor model, increasing doses of TPX-4589 demonstrated superior tumor growth inhibition compared to gemcitabine and LM-102, a compound with identical anti-CLDN18.2 mAb component as LM-302, and similar efficacy to LM-102 + gemcitabine in combination. In a PDX PC tumor model with low CLDN18.2 expression, TPX-4589 showed potent inhibition of tumor growth.Table(abstract: 116 (PB106)). TPX-4589 internalization in CLDN18.2-positive cellsCell lineTPX-4589 (LM-102 conjugated with MMAE)LM-102 (CLDN18.2 mAb)ZolbetuximabControl hIgG1EC50 (nM)CLDN18.2/MKN45.#1(low CLDN18.2 expression)22.44.8NANAEC50 (nM)CLDN18.2/MKN45.#14(high CLDN18.2 expression)3.53.583.93NA Open table in a new tab Conclusions: TPX-4589, a novel CLDN18.2-targeting ADC, showed potent inhibitory effects on tumor cell proliferation in vitro and reduced tumor volume in both high- and low-expressing CDLN18.2 tumor models, with superior internalization and efficacy to zolbetuximab in a GC tumor model. These data suggest that TPX-4589 is a promising therapeutic candidate that warrants further investigation in clinical studies. Conflict of interest: Ownership: Stephanie Correia, Laura Rodon Turning Point Therapeutics Employee and Stock or Stock Options Other Substantive Relationships: Laura Rodon Turning Point Therapeutics Patents planned, issued or pending Yifan Li: Nothing to disclose Zhifang Liu: Nothing to disclose Runsheng Li: Nothing to disclose Yuan Li: Nothing to disclose Wentao Huang: Nothing to disclose

Strategies to evaluate potential effector function of glycan variants: A case study of ordesekimab (AMG 714 or PRV-015)

The potential for effector functions of therapeutic antibodies, including antibody-dependent cell-mediated cytotoxicity (ADCC), is a biological activity of interest for characterization, regardless of if ADCC is an intended primary pharmacological effect. The composition of the conserved antibody Fc glycan can vary as a function of post-translational processing which may affect the binding affinity to Fc receptors, leading to a change of effector activity. Ordesekimab (AMG 714 or PRV-015), a fully human immunoglobulin G1-kappa anti-interleukin (IL)-15 monoclonal antibody, is in clinical development for celiac disease. The binding of ordesekimab to IL-15 inhibits the interaction of IL-15 with the IL-2Rβ and common γ chain of the IL-15 receptor complex, but not with the IL-15Rα chain. Therefore, the simultaneous binding of ordesekimab to the Fcγ receptor (R) IIIα expressed on natural killer (NK) cells and to the IL-15/IL-15Rα complex on cells such as monocytes may theoretically enable ADCC toward the IL-15Rα-expressing cells. The high mannose (HM) levels on the Fc glycan were found to vary in different lots of ordesekimab resulting from refinements to the manufacturing process, and the impact on ordesekimab-mediated ADCC activity was evaluated in in vivo and in vitro studies. A review of nonclinical and clinical data found no evidence of ordesekimab-induced depletion of monocytes, or cytotoxicity in organs with wide IL-15Rα expression, suggesting a lack of in vivo ADCC activity. In addition, in vitro peripheral blood mononuclear cells-based ADCC assay did not reveal any cytolytic effect of ordesekimab with various levels of HM content when cocultured with recombinant human IL-15. Taken together, these data demonstrate that ADCC is not a potential liability for ordesekimab and does not contribute to the reduction of IL-15-mediated inflammation, the intended pharmacological effect.

Penpulimab, an Fc-Engineered IgG1 Anti-PD-1 Antibody, With Improved Efficacy and Low Incidence of Immune-Related Adverse Events.

BackgroundIgG4 anbibodies are deficient in stability and may contribute to tumor-associated escape from immune surveillance. We developed an IgG1 backbone anti-programmed cell death protein-1 (PD-1) antibody, penpulimab, which is designed to remove crystallizable fragment (Fc) gamma receptor (FcγR) binding that mediates antibody-dependent cell-mediated cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP) and proinflammatory cytokine release.MethodsAggregation of different anti-PD-1 antibodies was tested by size exclusion chromatography, and melting temperature midpoint (Tm) and aggregation temperature onset (Tagg) were also determined. The affinity constants of penpulimab for PD-1 and human FcγRs were measured by surface plasmon resonance and biolayer interferometry. ADCC and ADCP were determined in cellular assays and antibody-dependent cytokine release (ADCR) from human macrophages was detected by ELISA. Binding kinetics of penpulimab to human PD-1 was determined by Biacore, and epitope/paratope mapping of PD-1/penpulimab was investigated using x-ray crystallography. Additionally, patients from six ongoing trials were included for analysis of immune-related adverse events (irAEs).ResultsPenpulimab demonstrated better stability and a lower level of host-cell protein residue compared with IgG4 backbone anti-PD-1 antibodies. As expected, penpulimab exhibited no apparent binding to FcγRIa, FcγRIIa_H131, FcγRIIIa_V158 and FcγRIIIa_F158, elicited no apparent ADCC and ADCP activities, and induced no remarkable IL-6 and IL-8 release by activated macrophages in vitro. Penpulimab was shown in the co-crystal study to bind to human PD-1 N-glycosylation site at N58 and had a slower off-rate from PD-1 versus nivolumab or pembrolizumab. Four hundred sixty-five patients were analyzed for irAEs. Fifteen (3.2%) patients had grade 3 or above irAEs. No death from irAEs was reported.ConclusionsIgG1 backbone anti-PD1 antibody penpulimab has a good stability and reduced host cell protein residue, as well as potent binding to the antigen. Fc engineering has eliminated Fc-mediated effector functions of penpulimab including ADCC, ADCP and reduced ADCR, which may contribute to its more favorable safety profile.Clinical Trial Registration www.ClinicalTrials.gov, identifier: AK105-101: NCT03352531, AK105-201: NCT03722147, AK105-301: NCT03866980, AK105-202:NCT03866967, AK105-203: NCT04172571, AK105-204: NCT04172506.