Background: NIVO monotherapy is approved in the United States and other countries for pts with HCC treated with sorafenib (SOR) based on CheckMate 040 (NCT01658878) results, which reported 14% objective response rate (ORR) and 16-month median overall survival (mOS; El-Khoueiry et al. Lancet 2017). Primary efficacy and safety of NIVO + IPI in pts with aHCC previously treated with SOR were presented recently (Yau et al. J Clin Oncol 2019). Here, we will present subgroup analyses from this study. Methods: Pts were randomized to 3 arms: [A] NIVO 1 mg/kg + IPI 3 mg/kg Q3W (4 doses) or [B] NIVO 3 mg/kg + IPI 1 mg/kg Q3W (4 doses), each followed by NIVO 240 mg Q2W, or [C] NIVO 3 mg/kg Q2W + IPI 1 mg/kg Q6W. Treatment continued until intolerable toxicity or disease progression. Primary endpoints included safety/tolerability, ORR, and duration of response (DOR; investigator assessment per RECIST v1.1). Key secondary endpoints included disease control rate (DCR), OS, and progression-free survival (blinded independent central review [BICR] per RECIST v1.1); key exploratory endpoints included ORR (BICR per RECIST v1.1). Data cutoff was January 2019. Results: A total of 148 pts were randomized. Minimum OS follow-up from last pt randomization date to data cutoff was 28 months. At baseline, 34% of all pts had vascular invasion; 82% had extrahepatic spread; and 91% had Barcelona Clinic Liver Cancer stage C; 84% discontinued SOR because of disease progression and 14% because of toxicity. For all treated pts, ORR was 31% (7 had complete response), with median DOR of 17 months; DCR was 49%; the 30-month OS rate was 37%. NIVO + IPI was well tolerated; 38% of pts had grade 3–4 treatment-related adverse events (TRAEs; most common any grade: pruritus and rash; most common grade 3–4: aspartate aminotransferase increase and lipase increase); 5% had grade 3–4 TRAEs leading to discontinuation. Subgroup analyses based on duration of prior SOR therapy and other pt characteristics will be presented. Conclusions: NIVO + IPI led to clinically meaningful benefits, with a manageable safety profile in pts previously treated with SOR. NIVO + IPI may provide a new treatment option for these pts. Clinical trial information: NCT01658878