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CLDN18.2 (Claudin18.2)-targeting therapeutic antibodies have shown promising clinical efficacy in approximately 30% of gastric cancers expressing high levels of CLDN18.2 and less pronounced activity in low expressing malignancies. Here, we report that ZL-1211 is a mAb targeting CLDN18.2 engineered to promote enhanced antibody-dependent cellular cytotoxicity (ADCC) with the goal of achieving more potent activity in a wider spectrum of high- and low-CLDN18.2 expressing tumors. ZL-1211 demonstrated more robust in vitro ADCC activity than clinical benchmark not only in CLDN18.2-high but also CLDN18.2-low expressing gastric tumor cell lines. Greater antitumor efficacy was also observed in mouse xenograft models. Natural killer (NK) cell played critical roles in ZL-1211 efficacy and NK-cell depletion abrogated ZL-1211–mediated ADCC activity in vitro. ZL-1211 efficacy in vivo was also dependent on the presence of an NK compartment. Strikingly, NK cells strongly induced an inflammatory response in response to ZL-1211 treatment, including increased IFNγ, TNFα, and IL6 production, and were recruited into tumor microenvironment in patient-derived gastric tumors expressing CLDN18.2 upon ZL-1211 treatment to lyse the tumor cells. Taken together, our data suggest that ZL-1211 more effectively targets CLDN18.2-high gastric cancers as well as -low expressing malignancies that may not be eligible for treatment with the leading clinical benchmark by inducing enhanced ADCC response and activating NK cells with robust inflammation to enhance antitumor efficacy. Clinical activity of ZL-1211 is currently under evaluation in a phase I clinical trial (NCT05065710). Significance: ZL-1211, anti-CLDN18.2 therapeutic antibody can target CLDN18.2-high as well as -low gastric cancers that may not be eligible for treatment with clinical benchmark. ZL-1211 treatment induces NK-cell activation with robust inflammation to further activate antitumor immunity in tumor microenvironment.

Supplementary Figure 3 shows CLDN18.2 expression in gastric tumor cell lines and ZL-1211-induced CDC for the gastric tumor cell lines.

CLDN18.2 (Claudin18.2)-targeting therapeutic antibodies have shown promising clinical efficacy in approximately 30% of gastric cancers expressing high levels of CLDN18.2 and less pronounced activity in low expressing malignancies. Here, we report that ZL-1211 is a mAb targeting CLDN18.2 engineered to promote enhanced antibody-dependent cellular cytotoxicity (ADCC) with the goal of achieving more potent activity in a wider spectrum of high- and low-CLDN18.2 expressing tumors. ZL-1211 demonstrated more robust in vitro ADCC activity than clinical benchmark not only in CLDN18.2-high but also CLDN18.2-low expressing gastric tumor cell lines. Greater antitumor efficacy was also observed in mouse xenograft models. Natural killer (NK) cell played critical roles in ZL-1211 efficacy and NK-cell depletion abrogated ZL-1211–mediated ADCC activity in vitro. ZL-1211 efficacy in vivo was also dependent on the presence of an NK compartment. Strikingly, NK cells strongly induced an inflammatory response in response to ZL-1211 treatment, including increased IFNγ, TNFα, and IL6 production, and were recruited into tumor microenvironment in patient-derived gastric tumors expressing CLDN18.2 upon ZL-1211 treatment to lyse the tumor cells. Taken together, our data suggest that ZL-1211 more effectively targets CLDN18.2-high gastric cancers as well as -low expressing malignancies that may not be eligible for treatment with the leading clinical benchmark by inducing enhanced ADCC response and activating NK cells with robust inflammation to enhance antitumor efficacy. Clinical activity of ZL-1211 is currently under evaluation in a phase I clinical trial (NCT05065710).Significance:ZL-1211, anti-CLDN18.2 therapeutic antibody can target CLDN18.2-high as well as -low gastric cancers that may not be eligible for treatment with clinical benchmark. ZL-1211 treatment induces NK-cell activation with robust inflammation to further activate antitumor immunity in tumor microenvironment.

Despite the promise of immunotherapy for cancer treatment, nearly 80% of patients fail to respond to checkpoint inhibitor (CPI) therapy. Regulatory T cells (Tregs), which inhibit immune responses in the tumor microenvironment via multiple suppressive mechanisms, have been proposed to play a key role in those patients who are not responding to CPI therapy. Therefore, targeted depletion of Tregs should promote more effective antitumor immunity. CCR8 is a chemokine receptor that is selectively expressed on highly activated human tumor-resident Tregs, and these intratumoral CCR8+ Tregs have been shown to drive immunosuppression that leads to poor prognosis for cancer patients. Here, we demonstrate that CCR8 is highly expressed on intratumoral FoxP3+ Treg cells in multiple cancers and is absent on other major immune cell populations in tumor microenvironment including effector T cells, conventional CD4 T cells, B cells, NK cells, some FoxP3+ cells, and myeloid cells. Importantly, no CCR8 protein expression was observed on any peripheral human leukocyte subset examined. These results provide strong rationale for targeting CCR8 as a cancer immunotherapy by selectively depleting the most suppressive intratumoral Treg cells. We have developed a humanized therapeutic antibody, ZL-1218, that binds to human CCR8 with high affinity and specificity and can induce potent ADCC activity enabling strong NK cell-mediated killing of CCR8-expressing Tregs. We show that in human CCR8 knock-in mouse models bearing syngeneic tumors, ZL-1218 reduces intratumoral Treg cells and thus elicits significant tumor growth inhibition in a dose-dependent manner. We have recently explored the potential for ZL-1218 in combination immunotherapy, examining the enhanced antitumor activity when ZL-1218 is combined with anti-PD-1. Using human dissociated tumor samples, we further observed that different tumor types may induce different CCR8 expression levels on intratumoral Tregs leading to multiple, distinct CCR8+ subsets in various indications. We are currently exploring the significance of these distinct populations and the impact of ZL-1218-mediated depletion of both CCR8 high- and CCR8 low-expressing subsets in multiple indications. Together, these data support the advancement of ZL-1218 into clinical evaluation as a novel therapeutic candidate to treat human solid tumors. Citation Format: Jing Zhang, Wenhua Shi, Min Chen, Xinchuan Dai, Hongshui Liu, Shou Li, Lina Wang, Bee-Chun Sun, Monica You, Vivian Morton, Qiuping Ye, Lishan Kang, Bing Wan, Peter Brams, David I. Bellovin. ZL-1218, a novel anti-CCR8 antibody, exerts potent antitumor effect by depleting intratumoral regulatory T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3590.

Targeting the lineage marker CLDN18.2 with ADCC-eliciting monoclonal antibody therapeutics has shown promising clinical activity in the gastric, esophageal, and pancreatic cancer indications. However, clinical efficacy was mainly observed in tumors that expressed very high levels of CLDN18.2, which represented only ~30% of cases, and was much less pronounced in tumors with low levels of CLDN18.2. Here we present ZL-1211, a novel CLDN18.2-targeting monoclonal antibody that was engineered to promote enhanced ADCC and to drive efficacy in tumors that exhibit a broad range of CLDN18.2 expression levels. We demonstrate that ZL-1211 can robustly inhibit the growth of tumor cells that express not only high but also low levels of CLDN18.2 in vitro as well as a variety of in vivo models. ZL-1211 strongly induced ADCC, ADCP, and CDC and inhibited the growth of a series of in vitro models more potently than the leading clinical benchmark, including cell lines engineered to exogenously express varying levels of CLDN18.2 as well as gastric and pancreatic cancer cell lines that endogenously express low, medium, and high target levels. Consistent with our in vitro findings, ZL-1211 also exhibited greater anti-tumor efficacy than the leading clinical benchmark in CLDN18.2-positive patient-derived xenograft and syngeneic models in vivo. Together, our data suggest that ZL-1211 might provide therapeutic benefit for a wider spectrum of low- and high-CLDN18.2 expressing tumors than the leading clinical benchmark. A Ph1 dose escalation study to assess the safety and preliminary efficacy of ZL-1211 is planned. Citation Format: Hiroyasu Konno, Yong Li, Xinchuan Dai, Bee Sun, Wenhua Shi, Min Chen, Wenying Li, Shou Li, Lishan Kang, Holly Li, Frank Tao, Sophia Yin, Bingbing Wang, Lishen Shan, Bing Wan, Petter Veiby, James Yan, Karl Hsu, David Bellovin, Omar Kabbarah. ZL-1211 exhibits broad anti-tumor activity in CLDN18.2 high- and low-expressing models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1203.

// Kuikui Ge 1, * , Jinjiang Huang 1, * , Wei Wang 1 , Meigang Gu 2 , Xinchuan Dai 1 , Yuqiang Xu 1 , Hongyu Wu 1, 3 , Guodong Li 3 , Hairong Lu 3 , Jiang Zhong 1 , Qingshan Huang 1 1 State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200433, China 2 Laboratory of Virology and Infectious Disease Center for the Study of Hepatitis C, Rockefeller University, New York, NY 10065, USA 3 Shanghai High-Tech United Bio-Technological R&D Co., Ltd, Shanghai 201206, China * These authors contributed equally to this work Correspondence to: Qingshan Huang, email: qshuang@fudan.edu.cn Keywords: SPINK6, HCC, tumor suppressor, invasion, proliferation Received: April 11, 2016 Accepted: December 12, 2016 Published: December 16, 2016 ABSTRACT Hepatocellular carcinoma (HCC) causes significant medical burdens worldwide. Diagnosis, especially in the early stages, is still challenging. Therapeutic options are limited and often ineffective. Although several risk factors have been known important for development of HCC, the molecular basis of the process is rather complex and has not been fully understood. We have found that a subpopulation of HCC cells which are resistant to oncolytic parvovirus H1 superinfection highly express serine protease inhibitor Kazal-type 6 (SPINK6). This protein is specifically reduced in all HCC cell lines and tissues we analyzed. When upregulated, SPINK6 could suppress the malignant phenotypes of the HCC cells in several in vitro models. The putative tumor suppression role of SPINK6 is, however, independent of its protease inhibitory activity. To suppress the malignancy of HCC cells, SPINK6 has to be secreted to trigger signals which regulate an intracellular signaling molecule, ERK1/2, as well as a series of downstream factors involved in cell cycle progression, apoptosis and migration. Our study supports that SPINK6 is an important tumor suppressor in liver, and further investigations may help develop more effective diagnostic and therapeutic approaches.