Preclinical imaging of epidermal growth factor receptor with ABY‐029 in soft‐tissue sarcoma for fluorescence‐guided surgery and tumor detection

Background and Objectives Fluorescence‐guided surgery using epidermal growth factor receptor (EGFR) targeting has been performed successfully in clinical trials using a variety of fluorescent agents. We investigate ABY‐029 (anti‐EGFR Affibody® molecule labeled with IRDye 800CW) compared with a small‐molecule perfusion agent, IRDye 700DX carboxylate, in a panel of soft‐tissue sarcomas with varying levels of EGFR expression and vascularization. Methods Five xenograft soft‐tissue sarcoma cell lines were implanted into immunosuppressed mice. ABY‐029 and IRDye 700DX were each administered at 4.98 μM. Fluorescence from in vivo and ex vivo (fresh and formalin‐fixed) fixed tissues were compared. The performance of three fluorescence imaging systems was assessed for ex vivo tissues. Results ABY‐029 is retained longer within tumor tissue and achieves higher tumor‐to‐background ratios both in vivo and ex vivo than IRDye 700DX. ABY‐029 fluorescence is less susceptible to formalin fixation than IRDye 700DX, but both agents have disproportional signal loss in a variety of tissues. The Pearl Impulse provides the highest contrast‐to‐noise ratio, but all systems have individual advantages. Conclusions ABY‐029 demonstrates promise to assist in wide local excision of soft‐tissue sarcomas. Further clinical evaluation of in situ or freshly excised ex vivo tissues using fluorescence imaging systems is warranted.