PET Imaging of Cancer with pH (Low) Insertion Peptide (pHLIP)

描述(由申请人提供)： 生理过程(如缺氧、酸度和温度变化)存在于90%的肿瘤微环境中，被认为是肿瘤靶向的有前途的环境标志物。我们建议使用固有的肿瘤酸度通过非侵入性核成像来检测肿瘤。我们的方法是基于PHLIP(pH(低)插入肽)与细胞膜的pH选择性相互作用。PHLIP多肽含有37个残基，在中性pH时与膜表面的相互作用很弱，但在酸性pH(？lt；7.0)时，它插入膜并形成一个稳定的跨膜1-螺旋。PHLIP结合到PET或SPECT放射性核素上，提供了开发一种非侵入性成像方法的可能性，该方法将可移植到临床上用于实体肿瘤和转移的诊断。该项目的主要目标是开发一种基于PHLIP的放射性药物的实体肿瘤成像的新方法，最终目标是将试剂转化为临床。在拟议的研究中，我们计划实现四个具体目标：(1)开发确定基于64Cu-PHLIP的最佳放射性药物的接合和标记方案，并在LNCaP和PC-3肿瘤模型中进行体内外比较测试；(2)确定PHLIP的最佳体内给药的放射金属结果；(3)建立PHLIP-S-S-金属络合物的偶联方法，并通过全身荧光成像评价PHLIP在脂质体、细胞培养和体内的荧光递送作用。(4)通过核磁共振波谱研究确定与肿瘤Phe直接相关的SA1、SA2和SA3三种最有前景的结构。通过结合两个中心(URI和MSKCC)的知识和经验，我们的目标是开发一种优化的、新型的放射性金属PHLIP多肽结构，作为一种PET显像剂，它将可翻译到临床上，用于诊断和监测原发癌和转移癌早期发展阶段的治疗。

DESCRIPTION (provided by applicant): Physiological processes (e.g., hypoxia, acidity and changes in temperature), which are present in 90% of tumor microenvironments, are considered promising environmental markers for tumor targeting. We propose to employ intrinsic tumor acidity for the detection of tumors by non-invasive nuclear imaging. Our method is based on the pH- selective interaction of pHLIP (pH (Low) Insertion Peptide) with cell membranes. The pHLIP peptide contains 37 residues and at neutral pH it interacts weakly with the surface of membranes, but at acidic pH (<7.0) it inserts across the membrane and forms a stable transmembrane 1-helix. pHLIP conjugated to a PET or SPECT radionuclide, offers the possibility of developing a non-invasive imaging method that will be translatable to the clinical for the diagnosis of solid tumors and metastasis. The major objective of this project is to develop a new approach for the imaging of solid tumors based on pHLIP- based radiopharmaceuticals, with the final goal of translating an agent to the clinic. There are four Specific Aims we plan to undertake in the proposed study (1) To develop conjugation and labeling protocols for determining the optimal 64Cu-pHLIP-based radiopharmaceutical and to perform comparative testing in vitro and in vivo in the LnCAP and PC-3 tumor models; (2) To determine which radiometal results in the optimal in vivo tumor delivery of pHLIP; (3) To develop a conjugation protocol for the preparation of pHLIP-S-S-metal-chelate, and, secondly, to evaluate the intracellular delivery of fluorescent Eu-DOTA by pHLIP on liposomes, cell culture and in vivo by whole-body fluorescent imaging, and, (4) The most promising constructs from SA1, SA2 & SA3 will be studied with PET imaging and pharmacokinetics studies with direct correlation to tumor pHe determined by MRS studies. By combining the knowledge and experience of the two centers (URI and MSKCC), we aim to develop an optimized, novel radiometal- pHLIP peptide construct as a PET imaging agent which will be translatable to the clinic for the diagnosis and monitoring of therapy of primary cancers and metastasis in their earliest stages of development.