P1.084. Exploring the Role of Adjuvant Nivolumab After Neoadjuvant FLOT Followed by Surgery in Resectable ESCC: Implications for Cisplatin-Unfit Patients

Abstract

Abstract Topic Esophageal Cancer: Adjuvant and Neo-Adjuvant Therapies Background In Western countries, neoadjuvant chemoradiotherapy (CRT) is standard, and CheckMate 577 showed adjuvant nivolumab prolonged disease free survival (DFS) with non-pathological complete response (non-pCR). In Japan, DCF is standard based on JCOG1109. For cisplatin-unfit patients, FLOT may be an alternative option but adjuvant nivolumab remains unclear in this population. Methods We retrospectively analyzed patients with resectable locally advanced esophageal squamous cell carcinoma who received neoadjuvant FLOT between November 2022 and September 2025 at our institution and achieved R0 resection with non-pCR. DFS and overall survival (OS) were evaluated to assess the efficacy and the safety of adjuvant nivolumab compared to observation group. Results A total of 50 patients were analyzed: 37 (74%) underwent observation and 13 (26%) received adjuvant nivolumab. Median follow-up was 16.4 vs 11.5 months. Median age was 79 vs 78 years, and males comprised 75.7% vs 76.9%. Postoperative performance status (0/1/2) was 56.8/40.5/2.7% vs 61.5/30.8/7.7%. Pathological ypStage (I/II/III/IVB) was 35.1/35.1/27.0/2.7% vs 15.4/30.8/30.8/53.8%. pT0/1/2/3 was 5.4/48.6/10.8/32.4% vs 0/23.0/23.0/53.8%, and pN0/1/2/3 was 48.6/27.0/16.2/8.1% vs 30.8/46.2/15.4/7.7%. Lymph node positivity was significantly higher in the nivolumab group (p=0.01), with a trend toward more ypT3 disease (p=0.07). Median DFS and OS were not reached. One-year DFS was 80.7% vs 80.8% (HR 1.61, 95%CI 0.41–6.36), and one-year OS was 89.9% vs 80.0% (HR 0.80, 95%CI 0.09–7.03). Immune-related adverse events included Grade 3 pneumonitis (n=1), Grade 2 adrenal insufficiency (n=2), and Grade 1 dermatitis (n=1), all manageable without treatment-related deaths. Conclusion In patients with resectable locally advanced ESCC who underwent neoadjuvant FLOT followed by R0 resection with non-pCR, adjuvant nivolumab was well-tolerated. However, this retrospective study was a small population, the further investigation is needed to evaluate long-term efficacy.