Abstract ND12: M0324, a novel MUC-1 conditional CD40 agonist for selective immune activation in MUC-1 overexpressing tumors

Abstract Background: Anti-CD40 agonistic antibodies have been explored in clinical trials over the last few decades; however, to date none have been approved. Systemic activation of CD40 by anti-CD40 antibodies can lead to adverse effects such as liver toxicity, infusion-related reactions, thrombocytopenia, and cytokine release syndrome, limiting the therapeutic window of these agents. Targeting CD40 activation specifically to the tumor microenvironment could enhance antitumor activity while minimizing systemic toxicity. MUC-1 is a glycoprotein commonly overexpressed in various cancers, playing a pivotal role in tumor progression and immune evasion. M0324 is a novel MUC-1-conditional CD40 agonist composed of an anti-MUC-1 IgG and two identical camelid heavy-chain variable domains (VHH) binding CD40, designed to conditionally activate immune cells in the presence of MUC-1-overexpressing tumor cells. Methods: The effect of M0324 on the activation of CD40 expressed on human dendritic cells (DCs) was assessed in vitro, using MUC-1 expressing HCC827 tumor cell line co-cultured with primary human monocyte-derived DCs. In vivo efficacy was evaluated using MUC-1 overexpressing tumor models and M0324m, a mouse surrogate for M0324. Results: Preclinical in vitro studies demonstrated that M0324 significantly enhanced the activation of DCs when interacting with MUC-1-positive tumor cells, with no activity observed in the absence of MUC-1 expressing cells. Compared with anti-CD40 agnostic antibodies currently under clinical evaluation, M0324 showed superior ability to activate IL-12p40 expression in DC tumor cell co-cultures. The ability of M0324 to activate CD40 on immune cells was reliant on MUC-1 expression of tumor cells. Single dose, single agent M0324m treatment demonstrated robust tumor eradication in two different immune competent mouse tumor models (93% tumor-free mice in orthotopic Panc02-MUC-1 model and 100% tumor-free mice in MC38-MUC-1 model). The conditional activation of CD40 occurred solely in the presence of MUC-1, minimizing off-tumor effects and enhancing the therapeutic index. In contrast to M0324m, anti-mouse CD40 benchmark antibody induced body weight loss of mice and a marginally tolerable dose of anti-mouse CD40 failed to control tumor growth. Conclusions: M0324 is the first MUC-1 conditional CD40 agonist, engineered to selectively activate immune cells in the presence of MUC-1 overexpressing tumor cells. The conditional mode of action of M0324 leverages the high expression of MUC-1 in carcinomas to induce targeted antitumor immunity, potentially overcoming the safety limitations of traditional CD40 agonists. Our encouraging preclinical data support the clinical investigation of M0324 in patients with MUC-1 overexpressing tumors. Citation Format: Weixiao Sha, Yilang Tang, Jing Ni, Anika Bergmann, Nathalie Duncan, Bo Marelli, Feng Jiang, Julia Marie Mueller, Sina Junkers, Edith Doering, Christina Hubl, Ivana Durutovic, Sonia Jaramillo, Laura Helming, Paul Lyne. M0324, a novel MUC-1 conditional CD40 agonist for selective immune activation in MUC-1 overexpressing tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr ND12.