This study (ORIENT-4) aimed to assess the efficacy and safety of sintilimab, a humanized anti-PD-1 antibody, in patients with relapsed/refractory extranodal NK/T cell lymphoma (r/r ENKTL). ORIENT-4 is a multicenter, single-arm, phase 2 clinical trial (NCT03228836). Patients with r/r ENKTL who failed to at least one asparaginase-based regimen were enrolled to receive sintilimab 200 mg intravenously every 3 weeks for up to 24 months. The primary endpoint was the objective response rate (ORR) based on Lugano 2014 criteria. Twenty-eight patients with r/r ENKTL were enrolled from August 31, 2017 to February 7, 2018. Twenty-one patients (75.0%, 95% CI: 55.1-89.3%) achieved an objective response. With a median follow-up of 30.4 months, the median overall survival (OS) was not reached. The 24-month OS rate was 78.6% (95% CI, 58.4-89.8%). Most treatment-related adverse events (TRAEs) were grade 1-2 (71.4%), and the most common TRAE was decreased lymphocyte count (42.9%). Serious adverse events (SAEs) occurred in 7 (25.0%) patients, and no patient died of adverse events. Sintilimab is effective and well tolerated in patients with r/r ENKTL and could be a novel therapeutic approach for the control of ENKTL in patients.
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