Abstract 5311: KK2269, an epithelial cell adhesion molecule-targeted CD40 agonist, stimulates anti-tumor immunity resulting in sustained anti-tumor effect against mouse intrahepatic tumor without hepatotoxicity

Abstract Several anti-CD40 agonist antibodies have been evaluated in clinical trials based on their preclinical antitumor activity via generation of antitumor innate and adaptive immunity through activation of antigen-presenting cells. However, conventional monospecific anti-CD40 agonist antibodies have faced limitations in terms of safety margins and clinical efficacy. To address this problem, we developed KK2269, a novel bispecific antibody (REGULGENT™ format) that binds to both CD40 and epithelial cell adhesion molecule (EpCAM), which is highly expressed in several types of tumors. KK2269 demonstrated EpCAM-dependent activation of CD40 signals both in vitro and in vivo, confirming that it is a tumor-targeting CD40 agonist. Liver metastasis is common in EpCAM-positive cancers, including colon, stomach, and lung cancers. Intrahepatic tumors can attenuate the efficacy of immune checkpoint inhibitors due to the liver tumor-specific suppressive immune milieu. Although CD40 agonists are expected to overcome the immunosuppressive environment, non-tumor-targeting CD40 agonists cause hepatotoxicity. In the present study, we used a syngeneic intrahepatic tumor model to examine whether KK2269 exhibits antitumor efficacy without causing hepatotoxicity. Firstly, we confirmed that KK2269 administration did not increase aspartate aminotransferase (AST) or cause pathological abnormalities in the liver despite Il12b induction in the EpCAM-positive tumor. Additionally, gene expression analysis of peritumoral normal liver revealed that KK2269 did not induce inflammatory cytokines. In contrast, a conventional anti-CD40 agonist antibody increased AST, caused pathological abnormalities, and upregulated inflammatory cytokines in peritumoral normal liver, as reported in the clinical setting. Secondly, the antitumor effect of KK2269 in combination with docetaxel was evaluated. The combination therapy synergistically reduced intrahepatic tumor volume, and the effect persisted even 21 days after the administration. Gene expression analysis revealed a lower immune infiltration in the intrahepatic tumor versus subcutaneous tumor and that KK2269 in combination with docetaxel increased T-cell infiltration and activation even in the immunosuppressive intrahepatic tumor. In summary, our study demonstrated that KK2269 activated dendritic cells in an EpCAM-positive tumor in the liver but did not affect peritumoral normal liver tissues. In addition, KK2269 in combination with docetaxel showed potent antitumor effect accompanied by T-cell infiltration and activation against the intrahepatic tumor, which has a lower immune infiltration. These results suggest that the combination therapy of KK2269 and docetaxel is promising for metastatic EpCAM-positive tumors. Citation Format: Yoshiki Sumitomo, Kyoko Kawasaki, Yuta Tezuka, Masato Saito, Akari Yao, Munetoshi Ando. KK2269, an epithelial cell adhesion molecule-targeted CD40 agonist, stimulates anti-tumor immunity resulting in sustained anti-tumor effect against mouse intrahepatic tumor without hepatotoxicity abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 5311.