Background: Sintilimab, a programmed death-1 checkpoint inhibitor, has demonstrated efficacy in relapsed/refractory cHL after the primary analysis of the ORIENT-1 study. Here, we report the updated safety and efficacy profile after long-term follow-up. Methods: ORIENT-1 is a multicenter, single-arm, phase II study in China. Classical Hodgkin’s lymphoma patients who had failed ≥2 lines of systemic therapy, including autologous hematopoietic stem cell transplantation (HSCT) were enrolled. Sintilimab, 200 mg IV was given every 3 weeks, until disease progression, death, unacceptable toxicity, or withdrawal from study. The primary endpoint objective response rate (ORR) by an independent radiological review committee (IRRC) per IWG 2007 has been reported before. The progression free survival (PFS) by IRRC follow-up data are reported herein. Results: 96 patients were treated. As of the data cutoff on 30 Sep, 2019, 57.3 % patients complete two-year treatment, with a median follow-up of 26.7 months. The median duration of treatment was 24.1 months (range: 0.7 to 24.8). Of 49 patients with progressive disease (PD) by investigator, 39/49 (79.6%) patients received treatment beyond PD, with a median treatment duration after PD of 8.0 months (range: 1.4 to 20.8). The median PFS was 18.6 months (95%CI: 14.4 to 22.3). Median overall survival has not been reached. Two-year OS rate was 96.3% (95%CI: 88.9% to 98.8%). The treatment-related adverse event (TRAE) was reported in 92/96 (95.8%) patients, most (71/96, 74.0%) of which were grade 1-2. The most common grade 3 or 4 TRAEs were pyrexia (3/96, 3.1%), lipase increased (3/96, 3.1%) and lymphocyte decreased (3/96, 3.1%). Conclusions: The results from long-term follow-up showed that, in addition to a high rate of response, sintilimab also demonstrated durable efficacy and favorable long-term safety profile. Considering the high rate (nearly 80%) of treatment beyond PD, IWG 2007 which was used to evaluate PFS may not be a suitable criteria for evaluating the efficacy of anti-PD-1 antibody in cHL. Further investigation and analysis are required. Clinical trial information: NCT03114683.