Abstract 2245: TFF-2-mediated CXCR4 partial agonism outperforms CXCR4 antagonism in reducing murine gastric cancer by suppressing PMN-MDSC generation
Authors: Jin Qian, Chenkai Ma, Quin T. Waterbury, Xiaofei Zhi, Christine S. Moon, Ruhong Tu, Hiroki Kobayashi, Feijing Wu, Biyun Zheng, Yi Zeng, Hualong Zheng, Yosuke Ochiai, Ruth A. White, David W. Harle, Jonathan S. LaBella, Leah B. Zamechek, Lucas ZhongMing Hu, Ryan H. Moy, Arnold S. Han, Bruce L. Daugherty, Seth Lederman, Timothy C. Wang
Journal: Cancer Research (2025)

Abstract Introduction: Polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) are pathologically activated neutrophils that impair immunotherapy responses. The chemokine receptor CXCR4, a central regulator of hematopoiesis, represents an attractive PMN-MDSC target. Methods: We generated a novel peptide, TFF2-MSA, as a CXCR4 partial agonist by fusing Trefoil Factor 2 (TFF2) with murine serum albumin (MSA), and compared its treatment efficacy in combination with anti-PD-1 antibody to that of the clinically available CXCR4 antagonist plerixafor (AMD3100). Murine syngeneic gastric cancer cells were subcutaneously implanted into the Hdc-GFP transgenic mice, which enabled tracking of PMN-MDSCs via histidine decarboxylase (Hdc) expression across multiple tissues. Treatments were then initiated every three days. To elucidate mechanisms, myeloid progenitors were cultured with or without TFF2-MSA in vitro. Bone marrow Lin-c-Kit+ hematopoietic progenitors from tumor-bearing Hdc-GFP (CD45.2) mice following vehicle or TFF2-MSA treatments were transferred into CD45.1 mice to validate TFF2-MSA’s effects on PMN-MDSC generation. In tumor-free mice, we compared the short-term bone marrow cell mobilization effects of TFF2-MSA and AMD3100. Additionally, we analyzed human blood and single-cell RNA sequencing (scRNA-seq) data from gastric cancer tissues for immune profiles. Results: The combination of TFF2-MSA plus anti-PD-1 antibody showed significant efficacy in reducing/eradicating primary and metastatic tumors and extending mouse survival, in contrast to the CXCR4 antagonist AMD3100, which did not enhance anti-PD-1 response. Mechanistically, TFF2-MSA inhibited the expansion of CXCR4-high granulocyte-monocyte progenitors (GMPs) and the generation of Hdc-GFP+ PMN-MDSCs in culture, which underlies its systemic reduction of Hdc-GFP+ PMN-MDSCs in tumor, blood, and spleen and GMPs in bone marrow in vivo. In contrast, AMD3100 induced peripheral accumulation of Hdc-GFP+ PMN-MDSCs and compensatory elevation of GMP levels in bone marrow. Congenic adoptive transfer experiments confirmed that TFF2-MSA suppressed Hdc-GFP+ PMN-MDSC generation in vivo. Consistently, in tumor-free mice, TFF2-MSA did not significantly mobilize granulocytes from bone marrow, unlike AMD3100, thus better preserving bone marrow homeostasis. In gastric cancer patients, a CXCR4+LOX-1+ PMN-MDSC population expanded in both blood and tumor, exhibiting immunosuppressive potential, and associated with reduced TFF2 plasma level compared with healthy donors. Conclusions: The novel CXCR4 partial agonist exhibited superiority in tumor control and effective PMN-MDSC reduction, and preservation of bone marrow homeostasis compared to the CXCR4 antagonist AMD3100. CXCR4 partial agonism may represent a promising strategy for targeting PMN-MDSCs in gastric cancer patients. Citation Format: Jin Qian, Chenkai Ma, Quin T. Waterbury, Xiaofei Zhi, Christine S. Moon, Ruhong Tu, Hiroki Kobayashi, Feijing Wu, Biyun Zheng, Yi Zeng, Hualong Zheng, Yosuke Ochiai, Ruth A. White, David W. Harle, Jonathan S. LaBella, Leah B. Zamechek, Lucas ZhongMing Hu, Ryan H. Moy, Arnold S. Han, Bruce L. Daugherty, Seth Lederman, Timothy C. Wang. TFF-2-mediated CXCR4 partial agonism outperforms CXCR4 antagonism in reducing murine gastric cancer by suppressing PMN-MDSC generation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 2245.