Preclinical evaluation of 68Ga-radiolabeled trimeric affibody for PDGFRβ-targeting PET imaging of hepatocellular carcinoma

Abstract

PurposeHepatocellular carcinoma (HCC) is a highly vascularized solid carcinoma and tumor vessel–targeted molecular imaging might be effective for early diagnosis of HCC. Herein, we developed a novel trimeric affibody (ZTRI) with highly specific binding to the platelet-derived growth factor receptor beta (PDGFRβ). The aim of this study is to evaluate the feasibility of 68Ga-radiolabeled ZTRI ([68Ga]Ga-DOTA-ZTRI) as PET tracer for diagnosis of HCC.MethodsThe bioinformatics analysis of clinical database and immunoblotting of clinical specimens were performed to validate the potential of PDGFRβ as HCC biomarker. The trimeric affibody ZTRI was conjugated with DOTA-NHS-ester and radiolabeled with 68Ga to produce [68Ga]Ga-DOTA-ZTRI conjugate. Immunoreactivity and specific uptake of [68Ga]Ga-DOTA-ZTRI were assessed by dose-dependent cell binding, autoradiography, and biodistribution analysis. [68Ga]Ga-DOTA-ZTRI PET/CT scanning of diethylnitrosamine (DEN)-induced primary HCC rats and a rare case of idiopathical HCC rhesus monkey was performed to evaluate the imaging capability and radiation dosimetry of [68Ga]Ga-DOTA-ZTRI in vivo.ResultsExcessive PDGFRβ was validated as a representative biomarker of HCC neovascularization. The radiolabeling of [68Ga]Ga-DOTA-ZTRI was achieved at more than 95% radiochemical yield. In vitro assays showed specific uptake of [68Ga]Ga-DOTA-ZTRI in HCC tumor vessels by autoradiography. Animal PET/CT imaging with [68Ga]Ga-DOTA-ZTRI successfully visualized the tumor lesions in primary HCC rats and rhesus monkey, and indicated radiation absorbed dose of 2.03E-02 mSv/MBq for each scanning.ConclusionsOur results demonstrated that [68Ga]Ga-DOTA-ZTRI conjugate could be applied as a promising PET tracer for early diagnosis of hepatocellular carcinoma.