Abstract

Periostin, an extracellular matrix protein, plays key role in cell adhesion and motility within the tumor microenvironment, and is correlated with tumor invasion. We developed and characterized a PET tracer that specifically targets periostin, and evaluated the probe in preclinical models of esophageal squamous cell carcinoma (ESCC).
METHODS: The Institutional Animal Care and Use Committee approved all animal studies. Anti-periostin-F(ab')2 was generated from a monoclonal antibody by enzymatic digestion, conjugated to DOTA and labeled with 64Cu. Human ESCC cell lines, TE-11 with high and TT with minimal periostin expression, were implanted in nu/nu mice to generate the positive and control tumor models, respectively. PET/CT imaging was performed at 6, 12, and 24 hours and organ specific biodistribution at 24 hours after probe injection. Additionally the probe was tested in a genetically engineered mouse model (GEMM) of periostin-expressing distal esophageal/forestomach ESCC. Tissue microarrays of esophageal neoplasms and ESCC as well as extracted tumor samples were stained for periostin.
RESULTS: We generated a 64Cu-DOTA-anti- periostin-F(ab')2 with dissociation constant of 29.2 ± 3.0 nM. PET/CT images and biodistribution studies showed significantly higher tracer uptake in TE-11 compared to TT tumors (SUVmax-24h: 0.67±0.09 vs. 0.36±0.03, p CONCLUSION: We demonstrated that specific imaging of ECM periostin in ESCC is feasible using a targeted PET tracer. Detection of periostin in the tumor microenvironment may help with early detection, post-surgical follow up, and with in situ characterization of primary and metastatic lesions.