Real-Time Fluorescence Monitoring System for Optimal Light Dosage in Cancer Photoimmunotherapy

• Main Authors: Hideki Tanaka (Author), Yoshikatsu Koga (Author), Mayumi Sugahara (Author), Hirobumi Fuchigami (Author), Akihiro Ishikawa (Author), Toru Yamaguchi (Author), Akiko Banba (Author), Takeshi Shinozaki (Author), Kazuto Matsuura (Author), Ryuichi Hayashi (Author), Shingo Sakashita (Author), Masahiro Yasunaga (Author), Tomonori Yano (Author)
• Format: Book
• Published: MDPI AG, 2024-09-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 10.3390/ph17091246; 1424-8247
• Keywords: photoimmunotherapy; fluorescence imaging; real-time imaging; IR700; antibody-drug conjugate; anticancer therapy; Medicine; R; Pharmacy and materia medica; RS1-441
• Source: Pharmaceuticals, Vol 17, Iss 9, p 1246 (2024)

<b>Background/Objectives</b>: Near-infrared photoimmunotherapy (NIR-PIT) was recently approved for the treatment of unresectable locally advanced or recurrent head and neck cancers in Japan; however, only one clinical dose has been validated in clinical trials, potentially resulting in excessive or insufficient dosing. Moreover, IRDye700X (IR700) fluorescence intensity plateaus during treatment, indicating a particular threshold for the antitumor effects. Therefore, we investigated the NIR laser dose across varying tumor sizes and irradiation methods until the antitumor effects of the fluorescence decay rate plateaued. <b>Methods</b>: Mice were subcutaneously transplanted with A431 xenografts and categorized into control, clinical dose (cylindrical irradiation at 100 J/cm², frontal irradiation at 50 J/cm²), and evaluation groups. The rate of tumor IR700 fluorescence intensity decay to reach predefined rates (−0.05%/s or −0.2%/s) until the cessation of light irradiation was calculated using a real-time fluorescence imaging system. <b>Results</b>: The evaluation group exhibited antitumor effects comparable to those of the clinical dose group at a low irradiation dose. Similar results were observed across tumor sizes and irradiation methods. <b>Conclusions</b>: In conclusion, the optimal antitumor effect of NIR-PIT is achieved when the fluorescence decay rate reaches a plateau, indicating the potential to determine the appropriate dose for PIT using a real-time fluorescence monitoring system.