Translation of a novel EphA2-targeted PET tracer from preclinical models to first-in-human studies in pancreatic cancer.

Abstract

Ephrin type-A receptor 2 (EphA2) is a promising target in pancreatic ductal adenocarcinoma (PDAC). However, the clinical potential of targeting EphA2 requires further imaging evaluation. This study developed and preliminarily evaluated a novel ⁶⁸Ga-labeled radiotracer for PET imaging of EphA2 expression in PDAC patients. ⁶⁸Ga-FZEAR-1, ⁶⁸Ga-FZEAR-2, and ⁶⁸Ga-FZEAR-3 were synthesized, and their stability, affinity, pharmacokinetics were evaluated in vitro and in vivo. Further biological evaluation was performed in EphA2-positive and EphA2-negative tumor xenografts. A pilot first-in-human PET/CT study of the lead candidate, ⁶⁸Ga-FZEAR-2, was subsequently conducted in two PDAC patients. The three ⁶⁸Ga-radiotracers were synthesized with high radiochemical purity (> 99%) and demonstrated high stability and nanomolar affinity for EphA2. Cellular uptake was consistent with EphA2 expression and blocking assays confirmed specificity. In vivo, all tracers exhibited high tumor accumulation with low off-target uptake. ⁶⁸Ga-FZEAR-2 showed favorable tumor-targeting ability, pharmacokinetics, and safety profile. In the pilot clinical study (n = 2), ⁶⁸Ga-FZEAR-2 PET/CT visualized primary and metastatic lesions clearly without adverse effects. Immunohistochemical analysis confirmed EphA2 expression in lesions exhibiting high tracer uptake. A series of ⁶⁸Ga-labeled tracers for EphA2 imaging was successfully developed and evaluated. The lead candidate, ⁶⁸Ga-FZEAR-2, showed promising targeting specificity and favorable pharmacokinetics. A pilot study indicated that ⁶⁸Ga-FZEAR-2 provided preliminary evidence of noninvasive visualization of EphA2 expression in PDAC patients, thereby suggesting its potential as a tool for precision diagnosis in PDAC.