Camrelizumab plus chemotherapy combined with consolidative radiotherapy as first-line treatment for oligometastatic esophageal squamous cell carcinoma (ESCORT-1st-RT): A single-arm, open-label, phase 2 trial.

e16043 Background: Compared to chemotherapy alone, immunotherapy combined with chemotherapy as the first-line standard treatment for esophageal squamous cell carcinoma (ESCC) can increase progression-free survival (PFS) to 5.8-7.2 months. This study aimed to explore the feasibility and safety of combining camrelizumab and chemotherapy with consolidative radiotherapy in the treatment of advanced oligometastatic ESCC. Methods: This study included newly diagnosed patients with stage IV ESCC confirmed by histopathology and imaging examination who had ≤ 5 metastatic lesions in ≤ 3 organs. All patients were treated with camrelizumab combined with albumin paclitaxel and carboplatin for 4 cycles, followed by consolidative radiotherapy. The primary esophageal lesion and metastatic lymph nodes were treated with involved-field irradiation therapy, receiving 2.0 Gy per fraction over 25 daily sessions. For distant metastases in organs like the liver, lungs, brain, or bones, radiotherapy was tailored to individual clinical needs, often employing hypofractionated radiation therapy with doses starting at 3 Gy per fraction or above. The maintenance duration of camrelizumab treatment was limited to a maximum of 12 months. The primary endpoint was PFS. The secondary endpoints were objective response rate (ORR), disease control rate (DCR), overall survival (OS), and safety. Results: From October 26, 2021, to September 28, 2022, 29 patients with ESCC, median age 63 (range 51-74), were enrolled; 93.1% were male. All had an ECOG score of 0 or 1 and stage IV disease. 27 (93.1%) patients completed planned radiotherapy. Of 29 evaluated patients, 23 achieved an objective response and 6 maintained stable disease. Thus, the ORR and DCR were 79.3% (95% CI 78.2-80.4) and 100% (95% CI 100-100), respectively. With 23.3 months (95%CI 21.5-25.1) of follow-up, the median PFS was13.7 months (95% CI 9.9-17.5) , the median OS has not reached and the 1-year and 2-year OS rates were established at 72.4% (95% CI 52.3-85.1) and 61.4% (95% CI 41.1-76.5), respectively. The most common treatment-emergent adverse events (TEAEs) of grade 3-4 were lymphocyte count decreased (65.5%), neutrophil count decreased (27.6%), and white blood cell count decreased (20.7%). 1 patients discontinued camrelizumab treatment due to radiation esophagitis. No grade 5 TEAEs occurred. Conclusions: Consolidative radiotherapy following camrelizumab combined with chemotherapy showed potential efficacy and manageable tolerability in patients with advanced oligometastatic ESCC.