Implantable Light Irradiation Device For Photodynamic Therapy

Background

Photodynamic therapy (PDT) is a light therapy that has proven to be an effective cancer treatment. PDT utilizes the properties of photosensitizers that accumulate in lesions in human bodies to administer a photosensitizer of its precursor to the living body, irradiate the photosensitizer with light, and selectively destroy abnormal tissue in the lesion, using reactive oxygen species generated in the tissue. In recent years, PDT has been widely used in the treatment of tumorous lesions in the field of dermatology, and there have been many studies attempting clinical applications in lung cancer, esophageal cancer, gastric cancer, colorectal cancer, malignant brain tumors, and more. Tumor-selective treatment is possible when light can be directed only to the tumor, and PDT therefore spares patients from many of the adverse eff­ects associated with chemotherapy, radiation, and surgery. Since optical devices such as fiber optics, which directly irradiate the cancer tissues, are used in PDT, the clinical applications of PDT have been limited to specified cancers, including skin cancers, cancers in the upper aerodigestive tract, and brain tumors. Although PDT for tumors in deeply located organs is possible in principle, it has not been clinically applicable. This can be because the procedure involves surgical invasion, such as laparotomy, and because of concerns about complications such as organ damage and postoperative adhesion due to the high irradiation intensity (> 100 mW/cm2) used in conventional PDT. A new modality of PDT for treating tumors in deeply located organs is therefore needed.

Description

Researchers at the University of California, Santa Barbara have created a novel light irradiation device to provide PDT. This device is implanted in the human body to enable multiple and semi-permanent PDT using a wireless power supply device, which is characterized by having a light source unit with one or more LED elements each having a peak wavelength in the wavelength range of 400 nm to 420 nm, 500 nm to 520 nm, and 625 nm to 645 nm, arranged on a flexible substrate, and containing a power receiving coil for wireless power supply. The device was designed to provide PDT with 5-aminolevulinic acid (ALA-PDT) in patients with malignant tumors. 5-aminoevulinic acid, which is used in the worldwide popular photodynamic diagnosis, has no serious side effects. Currently, pancreatic cancer and glioblastoma, a malignant brain tumor, have the poorest prognoses among malignant tumors, with an average survival of less than 2 years. These tumors are lethal even with standard therapies such as surgery, chemotherapy, and radiotherapy, and new treatment methods are needed. Research suggests that ALA-PDT is useful not only for these tumors but also for tumors of other organs, and ALA-PDT has already been clinically applied to treat skin cancer. Therefore, this device can be a treatment for pancreatic cancer, glioblastoma, and tumors that occur in deeply located organs. 

Advantages

• Offers expanded opportunity for treatment of malignant tumors
• Allows for the treatment of deeply located tumors
• Offers uniform illuminance even to a tumor surface having irregular shape
• Enables multiple and semi-permanent PDT

Applications

• Cancer treatment

Patent Status

Patent Pending