Abstract / Summary
Evidence for adjuvant immunotherapy remains limited in patients with resected esophageal squamous cell carcinoma (ESCC) who have residual pathological disease after neoadjuvant therapy or high-risk pathological features after upfront surgery. This phase II trial evaluated the efficacy and safety of adjuvant sintilimab monotherapy in this high-risk population. This was a single-center, prospective phase II trial (ChiCTR2100049784). Patients with R0-resected ESCC who had ypT1-4a and/or ypN+ disease after neoadjuvant therapy or pT3-4 and/or pN+ disease after upfront surgery received adjuvant sintilimab every 3 weeks for up to 12 months. The primary endpoint was the 1-year recurrence-free survival (RFS) rate. Secondary endpoints were overall survival (OS) and safety. Between August 2021 and July 2023, 32 patients received adjuvant sintilimab: 27 (84.4%) after neoadjuvant PD-1 inhibitor plus chemotherapy, 2 (6.3%) after neoadjuvant chemotherapy alone, and 3 (9.4%) after upfront surgery. At a median follow-up of 47.0 months, median RFS and OS were not reached. The 1-year and 2-year RFS rates were 87.5% and 65.6%, and the corresponding OS rates were 93.8 and 78.1%, respectively. Treatment-related adverse events (TRAEs) occurred in 13 patients (40.6%), including grade ≥3 TRAEs in 7 (21.9%); no treatment-related deaths occurred. Seventeen patients (53.1%) completed all 17 planned cycles. Adjuvant sintilimab monotherapy met the prespecified primary efficacy endpoint and showed manageable safety in high-risk resected ESCC enrolled in this phase II study. These findings support further evaluation in larger randomized controlled trials with longer follow-up.