Short-term Outcomes of Adjuvant Nivolumab After Neoadjuvant Chemotherapy in Patients With Resected Esophageal Squamous Cell Carcinoma

Background/Aim: CheckMate 577 evaluated adjuvant nivolumab therapy after neoadjuvant chemoradiotherapy and surgery for esophageal cancers. However, the efficacy of this treatment in patients who received neoadjuvant chemotherapy remains unknown. This study investigated the short-term outcomes of adjuvant nivolumab therapy in patients with advanced esophageal squamous cell carcinoma post-neoadjuvant chemotherapy. Patients and Methods: Out of 956 patients with thoracic esophageal cancer who underwent radical esophagectomy, 227 who exhibited ypN1-3 after neoadjuvant chemotherapy and surgery were included in this study. Results: Among 227 patients, 30 received adjuvant nivolumab and 197 received non-nivolumab adjuvant therapy. The nivolumab group displayed a higher number of lymph node metastases compared to the control group. Patients with ypN1-2 tended to have longer recurrence-free survival (RFS) in the nivolumab group than in the non-nivolumab group (p=0.095). In the propensity score-matched cohort, no differences in patient characteristics were observed. Adjuvant nivolumab therapy significantly prolonged RFS in patients who received neoadjuvant chemotherapy (p=0.013). Patients with ypN1-2 in the nivolumab group had significantly longer RFS than their counterparts in the non-nivolumab group (p=0.001), but not in ypN3 (p=0.784). The 1-year postoperative recurrence rates were 59% for the non-nivolumab group and 24% for the nivolumab group (p=0.007). Nivolumab-related adverse events in patients receiving neoadjuvant chemotherapy were mostly consistent across all grades, while the frequency of increased aspartate aminotransferase (AST) levels was relatively higher compared to CheckMate577. Conclusion: Adjuvant nivolumab was more likely to prolong 1-year RFS in patients receiving neoadjuvant chemotherapy, especially in those with ypN1-2, and had acceptable adverse events.