SPECT/NIR Fluorescence Bimodal Use of Aza-BODIPY Probe Coupled with Cetuximab for Detection of Cancer: Proof of Concept on a Preclinical Head and Neck Squamous Cell Carcinoma Model

The study reports the synthesis and biological evaluation of [111In]In-WAZABY, a novel bimodal imaging probe based on a water-soluble NIR-II aza-BODIPY fluorophore. The platform enables the design of a bimodal imaging probe through conjugation to the anti-epithelial growth factor receptor (EGFR) antibody cetuximab and incorporation of a [111In]In-DOTA complex for single-photon emission computed tomography (SPECT) imaging. The resulting probe efficiently targets EGFR-expressing tumors in a murine model of head and neck squamous cell carcinoma (HSNCC). Multimodal imaging combining NIR-I/NIR-II fluorescence and SPECT revealed specific tumor accumulation and a strong spatial correlation between optical and SPECT signals, demonstrating that DOTA grafting does not compromise fluorophore behavior or in vivo stability. These results establish [111In]In-WAZABY as a promising dual-modality contrast agent for peroperative tumor localization and future fluorescence-guided surgery (FGS), enabling complementary deep-tissue and high-resolution imaging.