Non-invasive diffuse optical methods were incorporated for monitoring and potentially correlating changes in measured parameters with the PDT response. We have initiated a Phase I clinical trial of HPPH-mediated PDT in head and neck cancer patients to determine the maximally tolerated dose. HPPH has been used at RPCI in treating dysplasia in Barrett’s esophagus and in lung cancer. HPPH is a second-generation PS developed at Roswell Park Cancer Institute (RPCI) with an absorption peak wavelength of 665 nm, which allows enhanced tissue penetration depth, and with less prolonged skin photosensitivity compared to Photofrin. In this report, we present changes in hemodynamic parameters and drug photobleaching as a response to 2-1-2-devinylpyropheophorbide-a (HPPH)-mediated PDT in a patient with a squamous cell carcinoma of the oral cavity. Diffuse optical methods allow assessing these markers fast, repetitively and non-invasively, and therefore have significant advantages for monitoring PDT. Therefore, it is important to monitor functional vascular related biomarkers that may affect PDT efficacy. Functional contrast of vascular parameters may change during PDT and these changes may be useful early biomarkers for therapy outcome and planning. Tissue oxygenation is greatly affected by functional vascular parameters such as blood flow and blood oxygenation. Tissue oxygenation is a central component for PDT since in the presence of oxygen, the PS initiates chemical reactions, which results in cellular and vascular damage in targeted tissue. The efficacy of PDT is largely dependent on the hemodynamics of tumor blood flow, oxygenation, and photosensitizer (PS) uptake and photobleaching. It can also be applied repeatedly should a single treatment fail. Since PDT is a local therapy, it is expected to induce fewer adverse side effects compared to conventional systemic therapies. PDT has been successfully utilized for early stage head and neck squamous cell carcinomas of the oral cavity and larynx, with a high degree of preservation of vital organ functions such as speech and swallowing (reviewed in ref ). Photodynamic therapy (PDT) is an emerging treatment option for head and neck cancer. Further, normal tissue injuries may lead to changes in applied dose quantity, and/or treatment re-schedule, which may affect treatment efficacy. Chemo and radiation therapies may induce permanent vasculature dysfunction and necrosis, severe toxicities and irreversible injuries to non-tumor tissue such as the oral mucosa and the salivary glands, often resulting in morbidity and severe impairment of patients’ quality of life. For example, surgery may require resection of vital functional tissue such as part of the tongue. In spite of improvements in treatment schemes, they have their limitations. Several treatment options that afford excellent tumor control are available including surgery, chemotherapy, radiation therapy or combinations thereof. Head and neck cancer arises in the regions of the oral cavity, oropharynx, larynx and salivary glands.
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