Primary Objective:~To determine if consolidation therapy with Tislelizumab following local therapy improves one year progression-free survival in patients with locally advanced, unresectable Hepatocellular carcinoma ( HCC). Progression-free survival (PFS) is defined as the time from first administration of Tislelizumab until the criteria for disease progression is met by response evaluation criteria in solid tumors (RECIST)1.1 or death as a result of any cause, whichever occurs first.~Secondary Objectives:~To determine if consolidation therapy with Tislelizumab after definitive therapy improves time to metastatic disease and overall survival (OS) in subjects with localized, inoperable Hepatocellular carcinoma (HCC).~To assess objective response rate, disease control rate, duration of response with consolidation therapy with Tislelizumab after local therapy in subjects with localized, inoperable Hepatocellular carcinoma (HCC).~To assess the safety profile of Tislelizumab after definitive therapy.~To assess biomarker response as measured by Alpha fetoprotein (AFP), should the patient's tumor produce AFP.~Exploratory objectives:~To determine the association of the tumor molecular profile from next-generation sequencing (NGS), of the tissue prior to the initiation of therapy with the treatment response.~To analyze Circulating tumor DNA (ct DNA) as a biomarker of response to therapy and early detection of disease progression.
The investigators hypothesize that the addition of Tislelizumab after definitive local therapy for locally advanced inoperable Hepatocellular carcinoma (HCC) will synergize with local therapy as well as treat micro metastatic disease and improve one year progression-free survival rates for participants and optimize local control.