Abstract 1056: Potent in vivo anti-tumor activity of D-1553 as a single agent and in combination with targeted therapeutics in a broad spectrum of patient-derived xenograft tumor models with KRas G12C mutation

Ras protein plays a critical role in cell growth and proliferation by transmitting signal from cell surface receptor tyrosine kinase to downstream cellular proteins such as RAF and MEK. KRas is one of the most frequently mutated oncogenes, with mutations at residues G12, G13, and Q61, found in lung, colon, pancreatic and other solid malignancies. We have developed an orally bioavailable, covalent inhibitor of KRas G12C, D-1553, with potent in vitro biochemical, cellular activity and in vivo efficacy. Here we report the efficacy of D-1553 in a large panel of patient-derived xenograft (PDX) tumor models with KRas G12C mutation. In the lung cancer PDX models, D-1553 exhibited tumor growth inhibition (TGI) from 43.6% to 124.3%, with 4 out of 8 models showing tumor regression. In the colorectal cancer PDX models, the range of TGI was from 60.9% to 105.7%, with 3 out of 9 models showing regression. Combination treatment of D-1553 with chemotherapy and targeted agents demonstrated enhanced anti-tumor activity resulting in more tumor regression compared to single agent treatment. These observations from PDX models support the combination treatment as a key to increased overall response rate to KRas G12C inhibitor in clinical trial. D-1553 is currently in a Phase 1/2 clinical trial for patients with advanced solid tumors harboring KRas G12C mutation (NCT04585035). Citation Format: Zhe Shi, Jifang Weng, Xiaochong Fan, Qingqing Zhu, Emily Robb, Alyssa Moriarty, Michael Wick, Yueheng Jiang, Ling Zhang, Xing Dai, Yaolin Wang. Potent in vivo anti-tumor activity of D-1553 as a single agent and in combination with targeted therapeutics in a broad spectrum of patient-derived xenograft tumor models with KRas G12C mutation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1056.