Excitation-light blocking filter for photoimmunotherapy tailored to the ORBEYE 4K 3D exoscope

BACKGROUND: Photoimmunotherapy, which involves combining targeted antibodies with light-activatable dyes such as IRDye700DX (IR700), is an emerging cancer treatment modality. Cetuximab-based photoimmunotherapy is approved for the treatment of unresectable head and neck cancer and has been covered by the national health insurance in Japan since 2021. Use of conventional ceiling surgical lighting during photoimmunotherapy is problematic due to concerns about potential cytotoxic effects. METHODS: To ensure safe surgical application, we developed a custom short-pass filter for the ORBEYE surgical exoscope to block IR700 excitation light. The filter's impact on the color tone was evaluated using human skin and a color checker, while that on the cytotoxicity was assessed in vitro using cetuximab-IR700 and an HSC-3 cell line. The clinical feasibility of using this filter was tested in six patients who underwent short surgical procedures (e.g., tracheostomy, arterial ligation) during photoimmunotherapy. RESULTS: Recalibrating the white balance after filter placement preserved the natural color tones. In vitro, the filter neutralized the significant cytotoxicity observed under the ORBEYE light. Clinically, the filter could be used safely in all cases with no evidence of postoperative skin damage. CONCLUSION: This filter system enhances the safety and feasibility of surgical procedures during photoimmunotherapy.