Abstract 1601: Neoadjuvant programmed death-1 blockade plus chemotherapy in locally advanced esophageal squamous cell carcinoma

Abstract Background: Immunotherapy is effective in treating unresectable esophageal squamous cell carcinoma (ESCC), but little is known about its activities in the preoperative setting. We aimed to evaluate the safety, feasibility and efficacy of neoadjuvant treatment with camrelizumab plus chemotherapy in locally advanced ESCC. Methods: Patients diagnosed with locally advanced ESCC were retrospectively included if they had received three courses of neoadjuvant camrelizumab plus nab-paclitaxel and S1 capsule followed by radical esophagectomy between November, 2019 and June, 2020 at Sun Yat-sen University Cancer Center. Primary endpoints were safety and feasibility. Pathological response and association between tumor immune microenvironment (TIME)/tumor mutational burden (TMB) and treatment response were also explored. Results: Twelve patients were included. Neoadjuvant treatment with camrelizumab plus nab-paclitaxel/S1 was well tolerated without any grade 3 or higher toxicities. No surgical delay or perioperative death was reported. Nine patients (75%) responded to the treatment, four with a complete pathological response and five with a major pathological response. Treatment response by radiography was discordant with surgical pathology for five cases while endoscopic ultrasonography was accurate for the entire cohort. Neither programmed death-ligand 1 expression nor TMB was correlated with treatment response. In the TIME, higher abundance of CD56dim natural killer cells was associated with better pathological response in the primary tumor while lower density of M2-tumor-associated macrophages was associated with better pathological response in the lymph nodes. Conclusions: Neoadjuvant camrelizumab plus nab-paclitaxel and S1 is safe, feasible and effective in locally advanced ESCC and is worth further investigation. Citation Format: Guozhen Yang, Xiaodong Su, Hong Yang, Guangyu Luo, Chan Gao, Yating Zheng, Wenzhuan Xie, Mengli Huang, Yuezong Bai, Zhiqiang Wang, Peiqiang Cai, Haoqiang He, Jin Xiang, Muyuan Cai, Yijun Zhang, Chunhua Qu, Jianhua Fu, Qianwen Liu, Yi Hu, Jiudi Zhong, Yuanheng Huang, Qiyu Guo, Xu Zhang. Neoadjuvant programmed death-1 blockade plus chemotherapy in locally advanced esophageal squamous cell carcinoma [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 1601.