Clinical and biomarker analyses of sintilimab versus chemotherapy as second-line therapy for advanced or metastatic esophageal squamous cell carcinoma: a randomized, open-label phase 2 study (ORIENT-2).

This randomized, open-label, multi-center phase 2 study (NCT03116152) assessed sintilimab, a PD-1 inhibitor, versus chemotherapy in patients with esophageal squamous cell carcinoma after first-line chemotherapy. The primary endpoint was overall survival (OS), while exploratory endpoint was the association of biomarkers with efficacy. The median OS in the sintilimab group was significantly improved compared with the chemotherapy group (median OS 7.2 vs.6.2 months; P = 0.032; HR = 0.70; 95% CI, 0.50-0.97). Incidence of treatment-related adverse events of grade 3-5 was lower with sintilimab than with chemotherapy (20.2 vs. 39.1%). Patients with high T-cell receptor (TCR) clonality and low molecular tumor burden index (mTBI) showed the longest median OS (15.0 months). Patients with NLR < 3 at 6 weeks post-treatment had a significantly prolonged median OS (16.6 months) compared with NLR ≥ 3. The results demonstrate a significant improvement in OS of sintilimab compared to chemotherapy as second-line treatment for advanced or metastatic ESCC.