Metronomic Photodynamic Therapy Using an Implantable Electronic Device, a Preclinical Experiment for Introducing Phototherapy into Cancer Treatments in Internal Organs

Abstract

Introduction: In a modern aging society, people expect high-quality cancer treatment but don't want to impair their quality of life. These trends made us imagine the needs of a novel cancer treatment system. We intend to develop a less invasive, low-cost cancer treatment system by using an implantable electronic device and introducing photodynamic therapy (PDT) into the treatment of malignancies in internal organs, including HBP area. Methods: We combined wirelessly powered fingernail-size LED chip, and tissue adhesive biomaterials to develop suture-free, tissue-adhesive, wirelessly powered LED devices. As a preclinical experiment, we investigated the anti-tumor effect of low-power and long-term photodynamic therapy, termed metronomic PDT, by using this device for the mouse cancer model. The device was implanted subcutaneously beneath intradermal tumors on the back of mice, and the mice could move freely in the cage placed on the antenna board that enables continuous illumination on the tumor. During the ten days of treatment, a photosensitizer (photofrin) was administered intravenously for two times. Results: The mice receiving mPDT showed significant growth suppression of the tumor when compared to the control mice. There was no adverse reaction in the surrounding normal tissues of the treatment group. Also, this experiment showed the effectiveness of green light, which has yet to be used clinically in PDT for the treatment of solid tumors. Conclusions: Metronomic PDT using implantable optoelectronic devices can be applied safely into the treatment of HBP malignancies as a low cost and less invasive local treatment method.