This is a Phase 2 study to evaluate the efficacy and safety of BB102, a highly selective and potent FGFR4 inhibitor, as monotherapy in subjects with advanced or unresectable FGF19-overexpressing hepatocellular carcinoma. This study has two phase: dose escalation phase and expansion phase.

Inclusion Criteria:

• (1) Age ≥ 18 years old, with no gender restrictions.
• (2) Disease progressed after receiving at least one anti-angiogenic and/or immune checkpoint inhibitor (including PD-1, PD-L1, CTLA-4) therapy, or the treatment is not tolerable.
• (3) Histologically confirmed primary HCC with FGF19 overexpression, which meets the Barcelona Clinic Liver Cancer (BCLC) staging criteria for patients with stage B suitable for systemic therapy or stage C.
• (4) At least one measurable lesion as defined by RECIST v1.1.
• (5) Eastern Cooperative Oncology Group (ECOG) score ≤1.
• (6) Expected survival ≥ 3 months.
• (7) Adequate organ function.
• (8) Female subjects of childbearing potential must have a negative pregnancy test prior to the first dose and are required to use effective contraception from signing the ICF until 6 months after the last dose of study treatment.
• (9) Fully informed of the study and voluntarily signed the informed consent form (ICF), and willing to follow and have the ability to complete all trial procedures.

Exclusion Criteria:

• (1) Use of systemic immunosuppressive or systemic cortisol (≥10 mg prednisone or other equivalent hormones) within 2 weeks.
• (2) Prior use of selective FGFR4 inhibitor therapy.
• (3) Use of Tyrosine kinase inhibitor within 2 weeks.
• (4) Use of systemic chemotherapy, radiotherapy (>30% bone marrow exposure), interventional embolization, ablation therapy and immunotherapycytotoxic chemotherapeutics within 4 weeks.
• (5) Use of other clinical investigational drug or therapy that was not marketed within 4 weeks.
• (6) The patient is receiving drugs or therapies prohibited in the protocol and cannot discontinue such use at least 7 days.
• (7) Pregnant or lactating females.
• (8) Presence of clinically significant gastrointestinal disorder that may affect the intake, transport, or absorption of the study drug at screening.
• (9) Patient with history of a second primary malignancy other than hepatocellular carcinoma within 5 years.
• (10) Presence of clinically symptomatic metastases to the central nervous system or meninges at screening, which, at the investigator's discretion, is not suitable for enrollment.
• (11) History of severe neurological or psychiatric disorders, including epilepsy, dementia, moderate to severe depression, etc.
• (12) Clinically significant and uncontrolled cardiovascular diseases.
• (13) Pulmonary embolism within 6 months.
• (14) Presence of uncontrollable infectious disease, congenital immunodeficiency disease,acquired immunodeficiency syndrome, syphilis, active hepatitis B, hepatitis C virus (HCV) infection.