Glypican-3-targeted immunoPET imaging of hepatocellular carcinoma: a translational study.

Abstract

Accurate diagnosis of hepatocellular carcinoma (HCC) remains a clinical challenge. Glypican-3 (GPC3) is highly expressed in HCC but not in normal liver tissue, making it a promising target for PET-based molecular imaging, which may complement existing approaches for HCC diagnosis. In this study, we developed a new GPC3-targeted immunoPET radiotracer for noninvasive visualization of GPC3 expression and conducted a first-in-human, proof-of-concept evaluation in patients with HCC to assess its clinical feasibility. An anti-GPC3 antigen-binding fragment (Fab) was generated under Good Manufacturing Practice conditions and labeled with Gallium-68 (⁶⁸Ga) to obtain [⁶⁸Ga]Ga-aGPC3-Fab. In vitro assays, small-animal PET/CT scans, and ex vivo biodistribution experiments were conducted to examine its GPC3 targeting ability. Five patients with radiologically suspected or diagnosed HCC were enrolled in a pilot clinical study and underwent [⁶⁸Ga]Ga-aGPC3-Fab PET imaging. Radiotracer uptake in tumor and non-tumor tissues was quantitatively analyzed. [⁶⁸Ga]Ga-aGPC3-Fab was synthesized with high radiochemical purity and demonstrated strong affinity and efficient internalization in GPC3-positive cells. It enabled clear tumor visualization in both subcutaneous and orthotopic GPC3-positive HCC mouse models. All five patients tolerated the PET procedure well, with no adverse effects. [⁶⁸Ga]Ga-aGPC3-Fab successfully detected intrahepatic metastases approximately 1 cm in diameter with high imaging contrast, including lesions that missed on magnetic resonance imaging. [⁶⁸Ga]Ga-aGPC3-Fab demonstrated a favorable safety profile and enabled effective visualization of GPC3-positive lesions. It may serve as a complementary approach to conventional imaging to improve the diagnostic accuracy of HCC. ClinicalTrials.gov, NCT06383520. Registered on April 25, 2024 ( https://clinicaltrials.gov/study/NCT06383520 ).