Photophysics of Photodynamic Therapy

描述（由申请人提供）：光动力疗法（PDT）的癌症和各种其他条件继续获得临床认可。三种光敏药物Photofrin，Visudyne和Levulan在美国的批准以及世界各地对几种有前途的新药的持续临床评估为正在进行的旨在进一步了解和优化这种疗法的实验室研究提供了背景。在过去的几年中，该领域已经获得了更深层次的理解光敏药物，光，和氧气，共同定义PDT的剂量之间的复杂和动态的相互作用。本实验室的研究旨在定量定义治疗诱导的光化学耗氧量对治疗结果的影响。这项工作的一个至关重要的方面是更精确地定义，并在某种程度上，可以转化为临床相关的测量敏化药物的光降解，PDT诱导的氧消耗，光动力剂量和生物反应的详细沉积之间的关系。这反过来又需要改进的方法来执行和分析肿瘤中的荧光光谱法的结果，以及对肿瘤氧合的非侵入性评估。为了达到这些目的，本申请提出了以下三个具体目标：（1）扩大光动力疗法中氧问题的实验研究和理论分析;（2）建立敏化剂荧光光谱法报告体内肿瘤生物学反应的能力，并探讨同步光谱评估血氧的可行性，从荧光的空间分辨测量来确定NADH和敏化剂漂白/光产物动力学;和（3）确定用于诱导特定基因的PDT阈值剂量和诱导缺氧诱导因子-10c表达所需的PDT诱导缺氧的特定严重性和持续时间。将用于实现这些目标的实验方法包括使用O2敏感的微电极，激光扫描光学切片荧光显微镜和显微荧光光谱法，荧光光谱在体内和漫反射吸收光谱。

DESCRIPTION (provided by applicant): Photodynamic therapy (PDT) of cancer and of various other conditions continues to gain clinical acceptance. The approvals of three photosensitizing drugs, Photofrin, Visudyne and Levulan, in the United States and the ongoing clinical evaluation of several promising new agents throughout the world provide the context for ongoing laboratory studies that are designed to understand further and to optimize this therapy. During the past several years, the field has gained a deeper appreciation of the complex and dynamic interactions among the photosensitizing drug, light, and oxygen that together define the dosimetry of PDT. Research in this laboratory has been directed at defining quantitatively the consequences of therapy-induced, photochemical oxygen consumption for therapeutic outcome. A critically important aspect of this effort is to define more precisely and in a manner that can be translated into clinically relevant measurements the relationship between the photodegradation of the sensitizing drug, the PDT-induced consumption of oxygen, the detailed deposition of photodynamic dose and the biological response. This in turn requires improved methods for performing and analyzing results from fluorescence spectroscopy in tumors and for the noninvasive assessment of tumor oxygenation. Toward these general ends, the application poses the following three specific aims: (1) to expand the experimental investigation and theoretical analysis of the oxygen problem in PDT; (2) to establish the ability of sensitizer fluorescence spectroscopy to report biological response of tumors in vivo and to investigate the feasibility of simultaneous spectroscopic assessment of blood oxygen, NADH and sensitizer bleaching/photoproduct kinetics from spatially resolved measurements of fluorescence; and (3) to determine the PDT threshold dose for induction of specific genes and the specific severity and duration of PDT-induced hypoxia required to induce the expression of hypoxia-inducible factor-10c. The experimental methods that will be used to accomplish these aims include the use of O2-sensitive microelectrodes, laser scanning optical sectioning fluorescence microscopy and microspectrofluorimetry, fluorescence spectroscopy in vivo and diffuse reflectance absorption spectroscopy.