TUMOR RADIOSENSITIZATION USING A NITRIC-OXIDE-NEUTRAL, TUNABLE OXYGEN-BINDING PRO

描述（由申请人提供）：在实体肿瘤中常见的低氧条件（缺氧）被认为是通过放射治疗（放疗，RT）临床治疗癌症的主要障碍。此外，肿瘤明显缺氧的癌症患者生存预后往往较差。鉴于缺氧的临床相关性，实验性RT研究的长期目标是通过减弱或利用这种病理生理状态来有效地使实体肿瘤放射增敏。分子氧（oxygen）是一种天然而有效的放射增敏剂；因此，通过RT有效治疗缺氧肿瘤的一种策略是人为地增加其氧合。该项目旨在使用加州大学伯克利分校（UC Berkeley）开发的一种新的氧气输送技术——血红素-一氧化氮/氧结合（H-NOX）蛋白——来彻底改变癌症患者的RT。H-NOX技术在氧传递治疗领域有4个主要的改进：(1)氧结合H-NOX对一氧化氮（NO）是中性的，与无细胞血红蛋白的高NO反应性和高血压特性相比是有利的；(2)已经设计了50多种H-NOX候选物，每种候选物都具有特定的氧亲和力；整个车辆面板在1000万倍的范围内显示出氧气亲和力；(3) H-NOX车辆在75℃以上结构稳定，在室温下化学稳定数周；(4) H-NOX车辆是模块化的，并且可以通过表面修饰来改变尺寸、肿瘤特性或组织靶向性。简而言之，H-NOX技术提供了一个氧气输送工具工具箱，用于在缺氧组织和肿瘤中测试其提高氧气水平和增强放射治疗和化疗的能力。为了确定治疗开发的主要候选物，选择H-NOX候选物将被纯化并应用于表现缺氧层的多层细胞培养（mcs）。使用灵敏的定量显微镜，随着时间的推移，H-NOX进入组织团块的渗透将被评估。一旦组织渗透动力学被建立，实验将确定当H-NOX载体渗透并促进氧气从培养基扩散到缺氧细胞层时组织缺氧的变化。领先的H-NOX候选物显示出有效的组织渗透和减少缺氧，将被用于动物研究。携带人类肿瘤异种移植物的小鼠表现出明显的缺氧和对RT的抵抗，将用H-NOX载体治疗，与对照组相比，将评估肿瘤缺氧程度的降低。药代动力学和毒理学研究将同时进行，以监测H-NOX管理的全身影响。如果这些实验证明了肿瘤缺氧的减少，未来的实验将评估增强的RT肿瘤杀伤作用，并将推动主要候选药物的开发，用于携带缺氧肿瘤的癌症患者的测试。

DESCRIPTION (provided by applicant): Low oxygen conditions (hypoxia) commonly found in solid tumors are considered a major obstacle for the clinical management of cancer by radiation therapy (radiotherapy, RT). Moreover, cancer patients with significantly hypoxic tumors tend to have a poor prognosis for survival. Given the clinical relevance of hypoxia, a long-time objective of experimental RT research has been to effectively radiosensitize solid tumors by attenuating or exploiting this pathophysiological state. Molecular oxygen (oxygen) is a natural and potent radiosensitizer; thus, one strategy for effectively treating hypoxic tumors by RT is to artificially increase their oxygenation. This project aims to use a novel oxygen-delivery technology developed at the University of California, Berkeley (UC Berkeley)-heme-nitric oxide/oxygen-binding (H-NOX) proteins-to revolutionize RT for cancer patients. The H-NOX technology embodies 4 major improvements over prior efforts in the field of oxygen delivery therapeutics: (1) oxygen-binding H-NOXs are neutral towards nitric oxide (NO), comparing favorably with the high NO reactivity and hypertensive properties of cell-free hemoglobin; (2) over 50 H-NOX candidates have been engineered, each with a specific oxygen affinity; the entire panel of vehicles demonstrate oxygen affinities across a 10-million fold range; (3) H-NOX vehicles are structurally stable above 75 oC, and chemically stable for weeks at room temperature; (4) H-NOX vehicles are modular, and can be surface-modified to alter size, oncotic properties, or tissue targeting. In short, the H-NOX technology provides a toolbox of oxygen delivery vehicles to test in hypoxic tissues and tumors for their capacity to raise oxygen levels and enhance RT and chemotherapy. To identify leading candidates for therapeutic development, select H-NOX candidates will be purified and applied to multilayered cell cultures (MCCs) exhibiting layers of hypoxia. Using sensitive quantitative microscopy, penetration of H-NOX into the tissue mass will be evaluated over time. Once the kinetics of tissue penetration are established, experiments will determine the alteration in tissue hypoxia as H-NOX vehicles penetrate and facilitate oxygen diffusion from the culture media to the hypoxic cell layers. Leading H-NOX candidates that demonstrate effective tissue penetration and reduction of hypoxia will be taken forward into animal studies. Mice carrying human tumor xenografts that exhibit significant hypoxia and resistance to RT will be treated with H-NOX vehicles and tumors will be evaluated for reduction in hypoxia compared to controls. Pharmacokinetic and toxicology studies will be performed in parallel to monitor the systemic effects of H-NOX administration. Should these experiments demonstrate reduction in tumor hypoxia, future experiments will evaluate enhanced RT tumor killing, and lead candidates will be promoted into development for testing in cancer patients carrying hypoxic tumors. PUBLIC HEALTH RELEVANCE: Low oxygen conditions (hypoxia) commonly found in solid tumors are considered a major obstacle for the clinical management of cancer by radiation therapy (radiotherapy, RT). For the 500,000 cancer patients treated with RT each year, more than 50% present with hypoxic tumors and respond poorly. This project aims to use a breakthrough, oxygen-delivery technology that is tunable, stable, and modular, to revolutionize RT for cancer patients.