Panoply™ Human CLDN18 Over-expressing Stable Cell Line

Claudin18.2 (CLDN18.2) is a tight junction protein that has been clinically validated as a target for gastric cancer. Stimulating 4-1BB with agonist antibodies is also a promising immunotherapy strategy, as 4-1BB+ T cells have been reported to be present in the tumor microenvironment of gastric cancer patients. Here, researchers performed multiplex immunohistochemical staining on tumor tissues from 60 gastric cancer patients and observed the colocalization of 4-1BB+ T cells with CLDN18.2+ tumor cells. Givastomig/ABL111 binds with high affinity to cell lines expressing varying levels of CLDN18.2 and induces 4-1BB activation in vitro only under conditions of CLDN18.2 binding. The extent of T cell activation following givastomig/ABL111 treatment correlated closely with CLDN18.2 expression levels in tumor cells in a gastric cancer xenograft model. Mechanistically, givastomig/ABL111 treatment upregulated the expression of a range of pro-inflammatory and interferon-γ-responsive genes in human peripheral blood mononuclear cells co-cultured with CLDN18.2+ tumor cells. Furthermore, in humanized 4-1BB transgenic mice inoculated with human CLDN18.2-expressing tumor cells, givastomig/ABL111 induced localized immune activation in the tumor, characterized by an increase in the proportion of CD8+ regulatory T cells, resulting in excellent anti-tumor activity and a long-lasting memory response to tumor rechallenge. Givastomig/ABL111 was well tolerated, with no systemic immune reactions or hepatotoxicity observed in monkey studies.

First, the binding affinity of givastomig/ABL111 for the human 4-1BB protein was measured using surface plasmon resonance (SPR) technology (Figure 1A). Second, using the luciferase NF-κB/4-1BB reporter Jurkat cell line, when co-cultured with CHO-K1 cells overexpressing human CLDN18.2 (CLDN18.2+), givastomig/ABL111-induced 4-1BB activation was more robust than that induced by the 4-1BB monoclonal antibody urelumab. However, in the absence of CLDN18.2, givastomig/ABL111 failed to activate the 4-1BB pathway, while urelumab still induced robust 4-1BB signaling (Figure 1B). Consistent with the findings regarding 4-1BB signaling, givastomig/ABL111 produced significantly higher levels of IL-2 than urelumab in anti-CD3-primed PBMCs in the presence of CHO-K1 cells expressing CLDN18.2, whereas givastomig/ABL111 treatment did not induce IL-2 in the presence of control CHO-K1 cells (Figure 1C). Furthermore, the researchers evaluated the T cell activation effects of givastomig/ABL111 treatment when co-cultured with GC PDX tumor cells expressing varying levels of CLDN18.2. Figure 1D shows IHC staining and CLDN18.2 expression levels for each PDX sample. The data demonstrated that givastomig/ABL111 stimulated IL-2 production in a dose-dependent manner, and the increased levels of IL-2 correlated closely with the expression levels of CLDN18.2 in the tumors (Figure 1E). Together, these data demonstrate that givastomig/ABL111 can exert 4-1BB stimulation and subsequent T cell activation only in the context of CLDN18.2 engagement.

Figure 1. Givastomig/ABL111 activates the NF-κB pathway and T cells in a CLDN18.2 engagement-dependent manner. (Gao J, et al., 2023)