Background: Classical Hodgkin’s lymphoma (cHL), characterized by chromosome 9p24.1 alteration and PD-1 ligands overexpression, is sensitive to PD-1/PD-L1 blockage in previous studies. This study will confirm the efficacy and safety of sintilimab (IBI308), a promising anti-PD-1 monoclonal antibody, in Chinese patients with relapsed/refractory (R/R) cHL. Methods: ORIENT-1 (NCT03114683) is a multicenter, single-arm, phase 2 study. Patients who failed 2 or more lines of systemic therapy, including autologous hematopoietic stem cell transplantation (HSCT) were enrolled. Sintilimab was given 200 mg intravenously every 3 weeks, until disease progression, death, unacceptable toxicity, or withdrawal from study. The primary endpoint was objective response rate (ORR) assessed by independent radiological review committee (IRRC) according to 2007 IWG criteria. The cut-off date for this analysis was Feb 8, 2018. Results: Among 96 treated patients enrolled between Mar 30^th 2017 and Nov 1^st 2017, the median number of previous chemotherapies was 3 (range: 1~13). 54.2% patients received prior radiotherapy and 18.8% failed HSCT. With median treatment cycles of 9 (range: 1~14), ORR was 74.0% (71/96, 97%CI: 64.2%, 83.7%) per IRRC review. 23 patients (24.0%) achieved complete response (CR). The median duration of response has not been reached. At the time of analysis, 64 of 71 complete and partial response patients had an on-going response. The most common treatment-related adverse event (TRAE) was pyrexia (43.8%, 42/96), and 92.9% were grade 1~2. Most of pyrexia happened in the day of first infusion and recovered within 1 day. Other common TRAEs were hypothyroidism (13.5%) and TSH increase (11.5%), and all were grade 1~2. The most common grade 3~4 TRAEs were pyrexia (3.1%) and thrombocytopenia (2.1%). No patient died. Conclusions: Till now, ORIENT-1 study is the largest cHL study in China. Patients in our study were sensitive to sintilimab, with 74.0% ORR and 24.0% CR rate. The safety profile was consistent with the findings of other anti-PD-1 monoclonal antibodies in cHL patients. Sintilimab could be a new treatment option for R/R cHL patients in China. Clinical trial information: NCT03114683