3116 - "Pacific" Modality in Locally Advanced Esophageal Squamous Cell Carcinoma: A Propensity Score-Matched Analysis of a Real-World Multicenter Study

N. Yu¹, X. Yang², J. Li¹, G. Feng¹, Z. Zheng³, L. Deng⁴, T. Zhang¹, W. Wang⁴, W. Liu Jr¹, J. Wang⁵, Q. Feng¹, J. Lv¹, Z. Zhou¹, Z. Xiao¹, N. Bi⁴, Y. Jiang⁶, C. Chen⁷, X. Wang⁸, Q. Xiao⁹, X. Ge¹⁰, and X. Wang⁴; ¹Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, ²Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China, Beijing, 100021, China, ³National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, ⁴Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), Beijing, China, ⁵Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China, ⁶Department of Oncology, Province Geriatric Hospital, Nanjing, Jiangsu 210029, China, Nanjing, China, ⁷Department of Radiation and Medical Oncology, Zhongnan Hospital of Wuhan University, Wuhan, China, ⁸Department of Radiation Oncology, Anyang Cancer Hospital, Anyang, China, ⁹Hunan Cancer Hospital, the Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China, Changsha, China, ¹⁰Jiangsu Province Hospital and Nanjing Medical University First Affiliated Hospital, Nanjing, China

Purpose/Objective(s): To compare the efficacy of definitive concurrent chemoradiotherapy (dCRT) and dCRT followed by immune checkpoint inhibitors (dCRT+ICIs) in locally advanced esophageal squamous cell carcinoma (ESCC) and to evaluate the safety of the dCRT+cICIs modality. Materials/

Methods: A total of 353 patients with esophageal cancer from five provincial hospitals in China were included in the study. The inclusion criteria were as follows: 1) aged 18–75 years; 2) with pathologically or cytologically proven ESCC; 3) with clinical stages T3N+M0-1 and T4N0/+M0-1 (according to the American Joint Committee on Cancer, version 8) with M1 limited to the supraclavicular lymph nodes metastases; 4) who have received dCRT or dCRT+cICIs. Clinical factors including gender, age, smoking history, alcohol consumption, tumor location, clinical T, N, M and total stage were matched in a ratio of 2:1 between the dCRT and dCRT+ICIs groups using propensity score matching (PSM). Overall survival (OS) and progression-free survival (PFS) were analyzed between the two groups, and objective response rate (ORR) and irAEs were calculated in the dCRT+ICIs group.
Results: A total of 176 ESCC patients from 2019 to 2021 were enrolled, including 123 patients in the dCRT group and 53 patients in the dCRT+cICIs group. The median age of the entire patient group was 65, with 83% being male. Additionally, 60.2% of the patients were classified as stage ?A and ?B. Median follow-up of the entire patients was 37.8 months. After PSM, there were 90 patients in dCRT group and 45 patients in dCRT+cICIs group. After PSM, median OS was 15.4 months in the dCRT group and 37.0 months in the dCRT+cICIs group (HR, 0.46; 95%CI, 0.28-0.75; P=0.0016). OS at 1 and 2 years was significantly higher in dCRT+cICIs group than in the dCRT group (88.7% and 61.3% vs 60.9% and 31.6%). After PSM, median PFS was 9.3 months in the dCRT group and 27.4 months in the dCRT+cICIs group (HR, 0.47; 95%CI, 0.30-0.74; P=0.00094). Patients in dCRT+cICIs group had better 1- and 2-year PFS than patients in the dCRT group (77.8% and 55.8% vs 43.1% and 20.1%). Approximately 43.4% of patients experienced irAEs, and grade 3-4 irAEs occurred in 13.2% of patients. The most common was hypothyroidism in 11.3% of patients.
Conclusion: Our preliminary findings suggest that consolidation immunotherapy after dCRT could prolong the OS and PFS in patients with locally advanced ESCC and that irAEs were tolerated.