Recombinant Human TSH Superagonists for Imaging of Thyroid Cancer

描述（由申请方提供）：甲状腺癌是内分泌组织最常见的恶性肿瘤，大多数患者需要通过诊断性促甲状腺激素（TSH）刺激放射性碘成像进行终身监测，以及通过放射性碘治疗进行残留或转移消融。其他成像技术，包括超声波和正电子发射断层扫描也获得了越来越重要的后续监督方法。然而，这些其他方法本质上对甲状腺组织没有特异性，并且仍然需要新的特异性甲状腺成像方法，特别是对于通过甲状腺球蛋白产生而日益识别的肿瘤，但是由于相对不稳定的钠-碘同向转运体的缺乏或丧失而具有差的放射性碘摄取。PI是Genzyme野生型重组人TSH的共同发明者和共同开发者，目前已被批准用于甲状腺癌的诊断成像，现在提议开发新型123 I或125 I标记的高亲和力TSH类似物，通过特异性和相对稳定的TSH受体用于甲状腺癌的成像。我们先前的结构-功能研究导致发现了TSH和其他糖蛋白激素的第一个类似物，其在受体结合亲和力和生物活性方面具有显著增加（“超活性类似物”）。在目前的提案中，我们计划生产，纯化和表征大量的这种新型TSH类似物作为显像剂进行商业开发。我们在目标1中提出开发稳定的细胞系，产生高水平的候选超活性类似物，并产生足够用于初始成像研究的数量。该目标将包括构建具有可扩增标记和突变的亚基cDNA的双顺反子载体，然后扩增、产生、纯化和表征未纯化的类似物。然后通过乳过氧化物酶法用123 I或125 I标记选定的TSH类似物，并通过各种物理化学方法及其与TSH受体的结合亲和力进行表征。目的2将包括原发性和转移性甲状腺肿瘤与123 I-TSH在一个新的转基因小鼠模型的甲状腺癌的γ照相机成像。这些小鼠仅在甲状腺中表达人RET/PTC 3，并发生甲状腺增生、乳头状癌的实体瘤变体和转移性癌症。此外，将在各种器官和原发性和转移性甲状腺肿瘤的所有部位进行125 I-TSH类似物的定量摄取研究。这种新的标记TSH成像方法以后可能会扩展到甲状腺癌的新的治疗方法，包括TSH受体介导的治疗剂，如放射性核素或毒素的输送，以及TSH受体定位基因治疗方法。甲状腺癌是内分泌组织最常见的恶性肿瘤，大多数患者需要终身监测，诊断促甲状腺激素（TSH）刺激的放射性碘成像，以检测复发性肿瘤。PI开发了一种改进的TSH形式，并提出了一种全新的甲状腺癌成像方法，该方法应大大提高早期检测，并改善癌症治疗和生存率。

DESCRIPTION (provided by applicant): Thyroid cancer is the most common malignancy of endocrine tissues and most patients require lifelong surveillance with diagnostic thyroid-stimulating hormone (TSH)- stimulated radio-iodine imaging as well as remnant or metastatic ablation with radioiodine therapy. Other imaging techniques including ultrasound and positron- emission tomography have also gained increasing importance as follow-up surveillance methods. However these other methods are not intrinsically specific for thyroid tissue and there remains a need for novel, specific thyroid imaging methods, especially for tumors increasingly recognized by thyroglobulin production but with poor radio-iodide uptake due to absence or loss of the relatively labile sodium-iodide symporter. The PI, who was both co-inventor and co-developer with Genzyme of wild type recombinant human TSH, currently approved for diagnostic imaging of thyroid cancer, now proposes to develop novel 123I or 125I-labeled high affinity TSH analogs for imaging of thyroid cancer through the specific and relatively stable TSH receptor. Our previous structure- function studies resulted in the discovery of the first analogs of TSH and other glycoprotein hormones with major increases in receptor binding affinity and bioactivity ("superactive analogs"). In the current proposal we plan to produce, purify and characterize large amounts of such novel TSH analogs for commercial development as imaging agents. We propose in Aim 1 to develop stable cell lines producing high levels of candidate superactive analogs and produce quantities sufficient for initial imaging studies. This Aim will consist of construction of dicistronic vectors with amplifiable markers and mutated subunit cDNAs, followed by amplification, production, purification and characterization of unpurified analogs. Selected TSH analogs will then be labeled with 123I or 125I by the lactoperoxidase method and characterized by various physicochemical methods as well as their binding affinity to the TSH receptor. Aim 2 will consist of gamma camera imaging of both primary and metastatic thyroid tumors with 123I-TSH in a novel transgenic murine model of thyroid cancer. These mice express human RET/PTC3 solely in the thyroid and develop thyroid hyperplasia, solid tumor variants of papillary carcinoma and metastatic cancer. In addition, quantitative uptake studies of 125I-TSH analogs will be performed in various organs and in all sites of primary and metastatic thyroid tumors. This novel labeled TSH imaging method may later be extended to novel therapeutic approaches for thyroid cancer including TSH receptor-mediated delivery of therapeutic agents such as radionuclides or toxins as well as TSH-receptor localizing gene therapy approaches. Thyroid cancer is the most common malignancy of endocrine tissues and most patients require lifelong surveillance with diagnostic thyroid-stimulating hormone (TSH)- stimulated radio-iodine imaging to detect recurrent tumor. The PI has developed a much improved form of TSH and proposes a completely new method of thyroid cancer imaging that should greatly improve early detection and lead to improved cancer treatment and survival.