Consolidative camrelizumab following definitive concurrent chemoradiotherapy with involved-field irradiation in locally advanced esophageal squamous cell carcinoma: A single-arm phase 2 trial.

2597 Background: Definitive concurrent chemoradiotherapy (dCCRT) is considered the standard treatment for esophageal squamous cell carcinoma (ESCC). The PACIFIC study demonstrated that consolidation durvalumab significantly improves overall survival (OS) in patients with stage III non-small cell lung cancer (NSCLC) after dCCRT. However, the efficacy of consolidation immunotherapy in ESCC still remains unclear. We conducted a clinical trial to evaluate the efficacy of camrelizumab in patients with unresectable, locally advanced ESCC following dCCRT. Methods: This single-arm, phase 2 study enrolled patients with locally advanced ESCC. All participants received dCCRT with involved-field irradiation (IFI). Patients were treated with camrelizumab within 1 to 42 days after completing dCCRT. Camrelizumab was administered intravenously over 30 minutes every 2 weeks for up to 12 months. The primary endpoint was progression-free survival (PFS). Secondary endpoints included disease control rate (DCR), objective response rate (ORR), duration of response (DoR), overall survival (OS), and safety. Results: Thirty-five patients were enrolled between April 2020 and November 2023. Data from 32 patients were analyzed. As of December 22, 2024, the median follow-up was 25.1 months (IQR 5.5–56.8). Twelve patients experienced disease progression, and seven patients died. The DCR was 59.4%. The median PFS and OS were not reached. The 1- and 2-year PFS rates were 81.3% and 60.6%, respectively. The 1- and 2-year OS rates were 96.9% and 81.0%, respectively. The most common adverse events were grade 1-2. No grade 4 or 5 adverse events were reported. Pneumonia occurred in 31.3% of patients, all of whom experienced grade 1-2. Conclusions: Consolidative camrelizumab following definitive concurrent chemoradiotherapy with IFI shows promising efficacy and manageable toxicity in patients with unresectable locally advanced ESCC. Clinical trial information: NCT04286958 .