Abstract 4433: Preclinical evaluation of LM-364TME: A next-generation anti-Nectin4 ADC with promising efficacy and reduced toxicity

Abstract Background: Antibody-drug conjugates (ADCs) has shown significant efficacy across multiple tumor types. Nectin-4, an adhesion molecule with limited expression in normal tissues (restricted to skin and secretory glands), is overexpressed in bladder, triple-negative breast, and other epithelial cancers. The clinical success of enfortumab vedotin valudated Nectin-4 as a therapeutic target; however, dose-limiting skin rash and neuropathy arise from on target, off-tumor toxicity due to low Nectin-4 epxression in nomal tissues. Extracelluar adenine nucleotides (ANP:ATP/ADP/AMP) accumulate to micromolar concentrations within the tumor microenvironment (TME), while remaining at nanomolar levels in heathy tissues. LM-364TME is a novel anti-Nectin-4 ADC designed to exploit this metabolic difference. It comprises a humanized antibody endineered for ANP-dependent binding to Nectin-4, conjugated via a cleavable linker to topoisomerase I inhibitor payload, with a drug-to-antibody ration of 8. Methods: Binding activity, specificity, and cross-species reactivity of LM-364TME were evaluated by flow cytometry. Internalization was evaluated using a pH-sensitive fluorescent probe. Cytotoxicity was measured via CellTiter-Glo luminescent cell viability assay. In vivo anti-tumor activity of LM-364TME was evaluated in Nectin 4-positive cell line-derived xenografts (CDX) and patient-derived xenografts (PDX) models. Repeated-dose toxicity studies were performed in Sprague-Dawley rats and rhesus monkeys. Results: LM-364TME exhibited strong ANP-dependent binding to Nectin 4, with an EC50 of 0.02 nM to huNectin4 protein and 0.187 -1.837 nM in Nectin-4 positive tumor cells under high ANP conditions, butnegligible binding in the absence of ANP, resulting a large selectivity window. LM-364TME also exhibited cross-reactivity with Nectin-4 in rodent and non-human primate models. LM-364TME showed robust ANP-dependent internalization and cytotoxicity in in MDA-MB-468 and huNectin 4 CHOK1 cells. In vivo, LM-364TME treatment (3-6 mg/kg) significantly induced tumor growth and regression in multiple models, including MDA-MB-468 (TGI 119.1%), urothelial carcinoma PDX (TGI 107.46%) , esophageal cancer PDX (TGI 86.73%), and cervical cancer PDX (TGI 168.79%). In repeat-dose studies, LM-364TME was well tolerated in both rats and rhesus monkeys. Conclusion: LM-364TME is an ANP-dependent, conditionally active anti-Nectin-4-ADC that demonstrates potent and selective antitumor activity with favorable safety profile in preclinical models. These data support LM-364TME as a promising next-generation Nectin-4-targeted therapy with the potential to improve the therapeutic index of this class. Disclosure: The study was funded by LaNova Medicines Limited, China. Citation Format: Lei Shi, Yun Zhang, Rongrong Huang, Xia Qin, Da Fei, Yuan Li, Wei Cao. Preclinical evaluation of LM-364TME: A next-generation anti-Nectin4 ADC with promising efficacy and reduced toxicity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 4433.