Detection and Specific Elimination of EGFR⁺ Ovarian Cancer Cells Using a Near Infrared Photoimmunotheranostic Approach

Purpose: Targeted theranostics is an alternative strategy in cancer management that aims to improve cancer detection and treatment simultaneously. This approach combines potent therapeutic and diagnostic agents with the specificity of different cell receptor ligands in one product. The success of antibody drug conjugates (ADCs) in clinical practice has encouraged the development of antibody theranostics conjugates (ATCs). However, the generation of homogeneous and pharmaceutically-acceptable ATCs remains a major challenge. The aim of this study is to detect and eliminate ovarian cancer cells on-demand using an ATC directed to EGFR. Methods: An ATC with a defined drug-to-antibody ratio was generated by the site-directed conjugation of IRDye®700 to a self-labeling protein (SNAP-tag) fused to an EGFR-specific antibody fragment (scFv-425). Results: In vitro and ex vivo imaging showed that the ATC based on scFv-425 is suitable for the highly specific detection of EGFR⁺ ovarian cancer cell, human tissues and ascites samples. The construct was also able to eliminate EGFR⁺ cells and human ascites cells with IC₅₀ values of 45–66 nM and 40–90 nM, respectively. Conclusion: Our experiments provide a framework to create a versatile technology platform for the development of ATCs for precise detection and treatment of ovarian cancer cells.