This is a Phase 1, open-label, first-in-human (FIH) study designed to evaluate the safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and preliminary antineoplastic activity of BLU- 554 administered orally in patients with hepatocellular carcinoma (HCC). The study consists of 2 parts, a dose-escalation part (Part 1) and an expansion part (Part 2) exploring both a once daily (qd) and twice daily (bid) dosing schedule.