Abstract 2116: 2MW7061, a novel LILRB4xCD3 bispecific T-cell engager targeting monocytic acute myeloid leukemia

Abstract

Abstract Background: Acute myeloid leukemia (AML) is a highly aggressive hematologic malignancy with a high recurrence rate, highlighting the urgent need for therapies that induce durable responses and improve survival outcomes. LILRB4 is highly expressed in FAB M4 and M5 subtypes of AML, while absent in normal hematopoietic stem and progenitor cells, making it an appealing target for selective immunotherapy. We developed 2MW7061, a bispecific LILRB4xCD3 T-cell engager, designed to target and eliminate LILRB4-expressing tumor cells by selectively activating T cells. Methods: 2MW7061 was generated through the screening and optimization of bispecific antibodies with varying geometries, formats, and CD3-binding affinities. The final construct utilizes a 1+2 format, with two Fab arms targeting LILRB4 and one single-chain variable fragment (scFv) arm targeting CD3. The affinity of 2MW7061 was measured using Octet, and its binding to T cells and AML cell lines was assessed. Functional activity was evaluated using Jurkat NF-AT reporter assays, T-cell activation assays, and tumor-directed cytotoxicity assays (TDCC). In vivo anti-tumor efficacy was tested in B-NDG/hu-PBMC and B-NCG/hu-PBMC mouse models implanted with THP-1-luc and MOLM-13 tumors, respectively. Safety and tolerability were evaluated in cynomolgus monkeys. Results: 2MW7061 demonstrated reduced binding to T cells in the absence of tumor cells, effectively minimizing off-target T-cell activation and mitigating the risk of cytokine release syndrome (CRS). In vitro, 2MW7061 exhibited tumor-associated antigen (TAA)-dependent binding and induced potent cytotoxicity. In vivo, 2MW7061 significantly inhibited tumor growth in both THP-1 (high LILRB4 expression) and MOLM-13 (low LILRB4 expression) xenograft models, indicating that its anti-tumor activity is LILRB4-dependent. In non-human primates, 2MW7061 administration resulted in minimal and transient increases in serum cytokines and C-reactive protein, with no significant signs of toxicity observed. Conclusion: 2MW7061 is a bispecific T-cell engager with potent LILRB4-dependent anti-tumor activity in preclinical models of monocytic AML. Its low nonspecific T-cell binding and favorable safety profile in non-human primates support its continued development as a promising therapeutic candidate for clinical evaluation in AML. Citation Format: Yu Pang, Cuicui Guo, Zhen Han, Fenglin Yun, Ao Li, Hai Wu, Xun Gui. 2MW7061, a novel LILRB4xCD3 bispecific T-cell engager targeting monocytic acute myeloid leukemia [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 2116.