Enabling multi-modal imaging and photoimmunotherapy of oral cancer spheroids through an EGFR-targeted antibody conjugate

Delineating tumor margins during surgery and eliminating residual disease is a major challenge in the treatment of oral cancers. The dual function antibody conjugate (DFAC) developed in this study can enable 3D-imaging and destroy residual microscopic disease by photoimmunotherapy in a single intra-operative setting. DFAC was synthesized by routine carbodiimide crosslinker chemistry. Multi-modal imaging (Photoacoustic and fluorescence imaging) and photoimmunotherapy was performed on oral cancer spheroids. Photoacoustic imaging could detect tumor spheroids, even of the smallest size (0.01 mm3), while fluorescence imaging could detect only larger spheroids with volumes greater than 0.049 mm3 and treated with a higher DFAC concentration. Photoimmunotherapy showed a spheroid size dependent response, with smaller spheroids of volumes 0.018 mm3 and lower showing no recurrence. The complementary imaging and treatment capabilities of DFAC could help in minimizing healthy tissue resection and enhance recurrence free survival in oral cancer patients.