3070 - Efficacy and Safety of Toripalimab Combined with Radiotherapy and S-1 Followed by Adjuvant Toripalimab Maintenance Therapy for Older Patients with Esophageal Cancer

W. B. Shen¹, and W. Deng²; ¹Radiotherapy Department,the Fourth Hospital of Hebei Medical University, shijiazhuang, hebei, China, ²Department of Radiation Oncology, Fourth Hospital of Hebei Medical University,, Shijiazhuang, China

Purpose/Objective(s): This trial aims to assess efficacy and safety of toripalimab combined with radiotherapy and S-1 followed by adjuvant toripalimab maintenance therapy for older patients with stage II-III esophageal cancer. Materials/

Methods: This is a phase II clinical trial of 56 eligible elderly patients with esophageal cancer. Patients treated with toripalimab in combination with S-1 and radiotherapy. The prescription doses of SIB-IMRT (different doses in different target areas but with the same irradiation times) were 60Gy for 100%GTV and 100%GTVnd, with 30 times, and a single dose of 2 Gy,and 54Gy for 95%PTV and 95%PTVnd, with 30 times, and a single dose of 1.8 Gy. The primary study endpoints are objective remission rate (ORR), disease control rate (DCR), duration of remission (DOR) and safety. Secondary study endpoints are overall survival (OS) and progression-free survival (PFS).
Results: Overall, 25 patients were enrolled from January 1st, 2019, to August 1st, 2023, with the median follow-up duration of 20.9 months. The population included 13 men (52%) and 12 women (48%). The median age was 74.64 (interquartile range, 67-83 years. A total of 22 patients (84%) had stage III disease, 25(100%) had squamous cell carcinoma. The 1, 2, 3-year progression-free survival (PFS) were 78%, 59%, 50%, respectively, and median PFS was 29 months (95% con?dence interval: 1-60.25). The 1, 2, 3-year OS were 96%, 65%, 54%, respectively, and median OS was 45 months (95% con?dence interval: 0-92.56). The objective remission rate (ORR) is 88%, disease control rate (DCR) is 100%, 1 patient achieved CR, 21 patients achieved PR, 3 patients achieved SD. The grade 2 or higher major toxic effects were Leukopenia, Neutropenia, Thrombocytopenia, Esophagitis, Pneumonitis and Nausea,1 patient (4%) with grade 2 of Hypothyroidism,2 patients (8%) with grade 3 of Leukopenia,1 patient (4%) with grade 3 of Neutropenia, 2 patient (8%) with grade 3 of Esophagitis, no grade 4 or 5 toxic effects were observed.
Conclusion: In this phase 2 clinical trial, toripalimab combined with radiotherapy and S-1 followed by adjuvant toripalimab maintenance therapy can be a safe regimen for older adult patients with EC.