KAT-101 in Subjects With Hepatocellular Carcinoma (HCC)

Inclusion Criteria: * Confirmed HCC not amenable to surgical resection or curative-intent locoregional ablative treatments and who are not eligible for liver transplantation. * Systemic treatment-naive for unresectable locally advanced or metastatic HCC. In addition, have progressed on, refused or were intolerant to sorafenib, lenvatinib, or atezolizumab in combination with bevacizumab. A maximum of 2 prior lines of systemic therapy (including chemotherapy or targeted therapy, not including locoregional therapy) will be allowed. * At least one measurable lesion based on RECIST 1.1 * Eastern Cooperative Oncology Group (ECOG) performance status 0-2 * Adequate organ function Exclusion Criteria: * Prior to the first administration of the study treatment: 1. Major surgery within 28 days 2. Radiotherapy within 14 days including palliative radiation 3. Use of steroids (except for topical agents) within 14 days 4. Chemotherapy within 3 weeks (6 weeks for nitrosourea compounds) 5. Prior treatment with biologic agents, including hormone therapy, within the last 3 weeks, or at least 5 half-lives, whichever is shorter 6. Tumor infiltration in the portal vein, hepatic veins or inferior vena cava that completely blocks circulation in liver 7. Treatment with another investigational product within 4 weeks prior to screening or for which 5 half-lives have not elapsed, whichever is longer 8. Uncontrolled central nervous system (CNS) metastasis * Any clinically significant abnormal intestinal findings that may interfere with the investigational product * Severe cardiac disorders or subjects with comorbidities of other serious internal disorders on investigator's judgment * QTcF \> 450 msec or congenital long QT syndrome * Suspected serious infectious diseases, intestinal paralysis, bowel obstruction, interstitial pneumonia, or pulmonary fibrosis * Serious underlying medical or psychiatric condition, dementia or altered mental status that would impair the ability to understand informed consent, contraindicate participation in the study or confound the results of the study * Known human immunodeficiency virus (HIV) infection or chronic or active hepatitis B virus (HBV) hepatitis C virus (HCV). Subjects with HCV who have a documented cure (undetectable HCV ribonucleic acid (RNA) 24 weeks after the end of treatment) may be enrolled. * Severe physical or mental trauma that results from injury or a wound(s). * Any condition or non-removable device contraindicated for MRI examination * Pregnant women or nursing mothers. * Women of childbearing potential (WOCBP) who are unwilling to use a medically acceptable method of birth control during the study until 185 days after the last dose of study treatment * Men with partners of childbearing potential who are unwilling to use condoms in combination with a second medically acceptable method of contraception during the study until 95 days after the last dose of study treatment.