Background: The mortality of hepatocellular carcinoma (HCC) is increasing worldwide, but outcome of systemic treatments in advanced HCC is suboptimal. Adoptive T-cell transfer therapy represents a promising field that exploits the ability of T-cells to recognize and eliminate their target. Targeting the tumor-associated antigen glypican- 3 (GPC3) through chimeric antigen receptors (CAR) engineered T cells is a mechanistically rational novel treatment for advanced HCC. This study aims to determine the dose and early signals of GPC3 targeted (CAR)-T cells in advanced GPC3 expressing HCC (NCT05003895). Methods: This phase I first in human dose escalation trial will study the safety and feasibility of CAR (hYP7)- T cells in advanced HCC patients expressing GPC3. Eligibility criteria includes advanced HCC, not candidates for curative interventions, progressed on first line systemic treatment, tumor GPC3 positivity of ³ 25% by IHC, Child-Pugh Class A, ³1 measurable lesion, ECOG 0 or 1, adequate organ and marrow function. ParticipantsÕ T cells collected through leukapheresis will be transduced with a lentivirus encoding the CAR construct to generate CAR expressing T cells. Patients receive a conditioning chemotherapy regimen of cyclophosphamide and fludarabine prior to the infusion of the GPC3 directed CAR-T cells (Table). The trial has a 4-level modified Fibonacci dose escalation with a minimum of 3 patients at each level and a 28-day interval between the first three patients. Response will be assessed by imaging every two months during the first year. Patients undergo close monitoring with safety assessments during the first year and are followed for life. The primary objective is to determine the MTD, DLT, safety and feasibility of anti-GPC3 CAR expressing T- cells in patients with GPC3-expressing advanced HCC. Secondary objectives include best overall response and overall survival. Exploratory objectives are multiple and include studies to evaluate the persistence and peak levels of anti-GPC3 CAR-T cells after infusion. Recruitment began in December 2021 and the two patients at dose level -1 has been treated; the planned sample size is 38 patients. Table 1 Dose Level Anti-GPC3 CAR-T Cyclophosphamide (mg/m2) Fludarabine (mg/m2) Level -1 0.3x106 CAR-T per kg bw 200 30 Level 1 0.3x106 CAR-T per kg bw 300 30 Level 2 1x106 CAR-T per kg bw 300 30 Level 3 3x106 CAR-T per kg bw 300 30. Clinical trial information: NCT05003895.