Phase I Clinical Study of the Safety of Photodynamic Therapy (PDT) Using LS11 in Children With Plexiform Neurofibromas

Plexiform neurofibromas (PN) represent one of the most significant complications of NF1. They are a significant cause of morbidity in neurofibromatosis type 1 (NF1) by causing pain, impaired function, and disfigurement. They may become life-threatening through mechanical compression of vital organs such as the trachea, great vessels, or spinal cord, and may significantly interfere with normal function when located in the extremities or orbit. The only effective therapy for PN is total surgical excision. However, due to local infiltration of normal tissue, gross total resection is usually not feasible, and often PN are completely unresectable due to their location, size, and multiplicity. To date, other therapeutic modalities, including radiotherapy and chemotherapy, have not shown efficacy in PN. In the present study, local photodynamic therapy will be investigated. Photodynamic therapy (PDT) utilizes a drug, called a photosensitizer or photosensitizing agent, and a particular type of light. When photosensitizers are exposed to a specific wavelength of light, they produce a form of oxygen that kills nearby cells. PDT is expected to result in treatment response with shrinkage of tumor. The main purpose of the study is to determine the maximum amount of light that can be safely used with LS11 for PDT in children with plexiform neurofibromas.