Abstract 1883: A MUC1 antibody-conjugated with a tubulysin B analog, DXC005, demonstrates excellent synergistic effect in combination with gemcitabine for treatment of pancreatic tumors
Authors: Cai Xiaobo , Cao Min , Guo Huihui , Yang Qingliang , Chen Yongxiang , Kong Xiangfei , Du Yong , Ye Zhicang , Guo Zhixiang , Zhang Lingli , Bai Lu , Jia Junxiang , Zheng Yunxia , Zheng Wei , Zheng Jun , Li Wenjun , Huang Yuanyuan , Fan Zhongliang , Chen Binbin , Yang Yanlei , Dai Meng , Zhao Robert Y. 
Published: March 2024

Abstract
Pancreatic cancer is a malignant tumor with high incidence and mortality. It is difficult to diagnose and detect in the early stage, with low surgical resection rate and high recurrence and metastasis rate after surgery. At present, the clinical therapeutic strategy is extremely limited. The first-line Standard of Care (SOC) for unresectable pancreatic cancer is chemotherapy. The preferred regimen includes gemcitabine combined with albumin paclitaxel or FOLFIRINOX (5-FU+Oxaliplatin+Irinotecan). Due to the limited long-term benefits and toxic side effects of chemotherapy, targeted therapy combined with chemotherapy has become a new therapeutic strategy. MUC1 is a highly glycosylated transmembrane mucin located on the lumen surface of epithelial cells. It can protect cells from extreme factors and plays an important role in tumor cell metabolism, apoptosis, epithelial-mesenchymal transition (EMT) and metastasis. Previous studies have confirmed that MUC1 is highly expressed in a variety of tumors, including pancreatic cancer, and is closely related to poor prognosis. DXC005 is a novel MUC1-targeting antibody-drug conjugate (ADC), generated by conjugating a Tubulysin B analogue to a recombinant humanized anti-Muc1 monoclonal antibody. DXC005 is the first MUC1-ADC IND in China, and is currently in phase I clinical trials. Preclinical studies have confirmed the efficacy of DXC005 monotherapy (2.5 mg/kg, 5 mg/kg, 10 mg/kg in one administration) in the HuPrime ® pancreatic cancer PDX model (PA1194). The tumor growth inhibition (TGI) was 42.53 %, 70.77 %, and 95.58 %, respectively. We want to further clarify whether DXC005 combined with chemotherapeutic drug Gemcitabine can ensure or even improve the efficacy while reducing the dosage of Gemcitabine. In PA1194 xenograft model, DXC005 (3 mg/kg or 6 mg/kg) in combination with Gemcitabine (10 mg/kg) showed significant anti-tumor efficacy with 58.77% and 93.17% TGIs, respectively. In contrast, the treatment with 10 mg/kg of Gemcitabine alone exhibited much less TGI. Furthermore, complete response (CR) was observed in some animals after treatment with DXC005 (6 mg/kg) plus Gemcitabine (10 mg/kg). All groups of treatment are tolerated well, no abnormal animal behavior and body weight loss were observed in the study. The above results concluded that DXC005 combined with Gemcitabine can achieve synergistic effect even with reduced dose of Gemcitabine, which will serve as a support for synergistic application in clinical studies.
Citation Format: Xiaobo Cai, Min Cao, Huihui Guo, Qingliang Yang, Yongxiang Chen, Xiangfei Kong, Yong Du, Zhicang Ye, Zhixiang Guo, Lingli Zhang, Lu Bai, Junxiang Jia, Yunxia Zheng, Wei Zheng, Jun Zheng, Wenjun Li, Yuanyuan Huang, Zhongliang Fan, Binbin Chen, Yanlei Yang, Meng Dai, Robert Y. Zhao. A MUC1 antibody-conjugated with a tubulysin B analog, DXC005, demonstrates excellent synergistic effect in combination with gemcitabine for treatment of pancreatic tumors [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(6_Suppl):Abstract nr 1883.