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

Purpose Hepatocellular 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 (Z TRI ) with highly specific binding to the platelet-derived growth factor receptor beta (PDGFRβ). The aim of this study is to evaluate the feasibility of 68 Ga-radiolabeled Z TRI ([ 68 Ga]Ga-DOTA-Z TRI ) as PET tracer for diagnosis of HCC. Methods The bioinformatics analysis of clinical database and immunoblotting of clinical specimens were performed to validate the potential of PDGFRβ as HCC biomarker. The trimeric affibody Z TRI was conjugated with DOTA-NHS-ester and radiolabeled with 68 Ga to produce [ 68 Ga]Ga-DOTA-Z TRI conjugate. Immunoreactivity and specific uptake of [ 68 Ga]Ga-DOTA-Z TRI were assessed by dose-dependent cell binding, autoradiography, and biodistribution analysis. [ 68 Ga]Ga-DOTA-Z TRI 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 [ 68 Ga]Ga-DOTA-Z TRI in vivo. Results Excessive PDGFRβ was validated as a representative biomarker of HCC neovascularization. The radiolabeling of [ 68 Ga]Ga-DOTA-Z TRI was achieved at more than 95% radiochemical yield. In vitro assays showed specific uptake of [ 68 Ga]Ga-DOTA-Z TRI in HCC tumor vessels by autoradiography. Animal PET/CT imaging with [ 68 Ga]Ga-DOTA-Z TRI 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. Conclusions Our results demonstrated that [ 68 Ga]Ga-DOTA-Z TRI conjugate could be applied as a promising PET tracer for early diagnosis of hepatocellular carcinoma.