Metronomic Photodynamic Therapy Using an Implantable Green Color LED Device and Orally Administered 5-Aminolevulinic Acid

Metronomic photodynamic therapy (mPDT) initiates cancer cell death by intermittent continuous irradiation with low power light for extended durations (several days). We developed a wireless powered, fully implantable LED device capable of transmitting significant anti-tumor effects of mPDT. Considering application to clinical practice, repeated intravenous administration of photosensitizers for mPDT may increase the patient’s burden. Therefore, in this study, 5-aminolevulinic acid (ALA) was selected to be administered orally as a photosensitizer, and studied the anti-tumor effects of mPDT. In the mice intradermal tumor model, with orally administered ALA (200 mg/kg daily for five days), the tumor in each mouse was irradiated (8 h/day for five days) using a wirelessly powered implantable green LED device (532 nm, 0.05 mW). Tumor growth in mPDT-treated mice was suppressed by about half compared to untreated mice. Results proved mPDT using the wirelessly powered implantable LED device with orally administered ALA displayed significant anti-tumor effects. This treatment regimen could reduce the burden of photosensitizer administration for a patient.