50 Background: A+B is commonly used as first line systemic therapy in HCC patients with CP-B liver function, although in the IMbrave150 clinical trial, its efficacy was only assessed in patients with CP-A liver function. We evaluated outcomes in patients with CP-B liver function and compared to those with CP-A. Methods: We completed a multi-institution, retrospective review of patients with HCC from Mayo Clinic and University Hospitals Seidman Cancer Center, who had received A+B in the first line setting between March 2018 and November 2023. CP score was calculated at time of treatment, response was assessed, and progression free (PFS) and overall (OS) survival were determined using the Kaplan Meier method. Results: Among 322 patients with HCC, median age was 66.5 years, 78.6% were male, and 82.6% were white. Eighty-six patients (27%) had CP-B liver function, while 226 (70%) had CP-A and 10 (3%) had CP-C. Etiology of liver disease in patients with CP-B included hepatitis B in 7.0%, hepatitis C in 38.4%, alcohol use in 30.2%, and metabolic associated steatohepatitis in 20.9%. Median OS in patients with CP-B liver function was 6.4 months, while mOS was 21.6 months for those with CP-A ( p<0.0001). Further stratifying, mOS in those with CP-B7 was 9.1 months, CP-B8 was 5.5 months, and CP-B9 was 4.0 months. 12-month OS in patients with CP-B was 32.4%, compared to 69.3% in CP-A. Median PFS was 4.8 months in those with CP-B and 8.9 months in those with CP-A. Median PFS in those with CP-B7, -B8, and -B9 was 6.4 months, 2.7 months, and 2.7 months, respectively. Among those with CP-B, 1 patient had a complete response, 17 (19.8%) had a partial response, 29 (33.7%) had stable disease, and 37 (43.0%) had progressive disease. Adverse events in CP-B patients included hypertension in 14.0% (grade 3 in 1 patient), bleeding in 16.3% (grade 3 or greater in 11.6%), fatigue in 38.4%, and an immune-related adverse event in 17.4% (grade 3 in 5.8%). Conclusions: Patients with advanced HCC and CP-B7 liver function may still benefit from A+B. Importantly, no additional safety risks were identified in this subgroup. Those with CP-B8 and CP-B9 have significantly worse survival than those with CP-B7 and the likelihood of benefit from systemic therapy is minimal. It is important for providers to address the impact of baseline liver function on expected outcomes in patient with HCC.