Abstract Cancer therapy faces numerous challenges that can limit the effectiveness of treatment. In order to address these key hurdles, such as immunosuppression, tumor heterogeneity, and the likelihood of resistance, and offer longer-lasting control of the tumor, we’ve developed a novel dual drug ADC (BiADC), BR113, by conjugating an anti-hTrop2 antibody with a drug linker of a Topoisomerase I inhibitor payload, and another drug linker of an immunostimulator payload. The approach combining the direct cytotoxic effects of ADCs with the immune-enhancing properties of an immunostimulator not only eradicates tumor cells but also reprograms the tumor microenvironment, leading to durable and systemic anti-cancer immunity. Our in vitro studies proves that each BiADC molecule exerts biological functions from two distinct payloads. It not only directly kills tumor cells by inducing apoptosis or other forms of cell death from the payload toxin, but also releases cytokines, and chemokines from an activated innate immune system to activate tumor killing cells, such as T cells and natural killer (NK) cells. In vivo models proves that the combination of two payloads increases the tumor infiltrated immune cells population and turns immunologically "cold" tumors into "hot" tumors, making them more susceptible to immune-mediated attack. In a syngeneic mouse model, BR113 exhibits great treatment efficacy and survival benefit with a prolonged anti-tumor protection against the tumor re-challenge. In a more aggressive B16F10 tumor model, this synergistic anti-tumor activity is further confirmed with the combination of BiADC and check point inhibitors, which further improved anti-tumor activity significantly and completely controled tumor growth. Overall, this new ADC/IO combination therapy maximizes the activity of each drug and reduces the toxicity of each individual payload. The dual anti-tumor MOAs exert a synergistic effect by enhancing systemic immunity, which ensures comprehensive and sustained tumor control, making it a powerful strategy for improving patient outcomes. Citation Format: Jie Zhu, Xiaobei Zhao, Zhenwu Luo, Eileen Li, Hong Xu, Cindy Wu, Gang Chen, Lei Nie, Haibin Wang. A novel dual drug antibody-drug conjugate targeting hTrop2 has synergetic anti-tumor activity by enhancing systemic immunity [abstract]. In: Proceedings of the AACR IO Conference: Discovery and Innovation in Cancer Immunology: Revolutionizing Treatment through Immunotherapy; 2025 Feb 23-26; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Immunol Res 2025;13(2 Suppl):Abstract nr A056.