Recombinant Human TSH Superagonists for Imaging of Thyroid Cancer

描述（申请人提供）：甲状腺癌是最常见的内分泌组织恶性肿瘤，大多数患者需要终身监测诊断促甲状腺激素（TSH）刺激放射碘成像以及残余或转移性消融放射碘治疗。其他成像技术，包括超声和正电子发射断层扫描也越来越重要的后续监测方法。然而，这些其他方法对甲状腺组织并没有本质上的特异性，仍然需要新的、特异性的甲状腺成像方法，特别是对于甲状腺球蛋白产生越来越多的肿瘤，但由于缺乏或失去相对不稳定的碘化钠同调物而导致放射性碘吸收不良。该PI与Genzyme共同发明和共同开发了野生型重组人TSH，目前已被批准用于甲状腺癌的诊断成像，现在提议开发新的123I或125i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。我们之前的结构-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，其受体结合亲和力和生物活性显著增加（“超活性类似物”）。在目前的提案中，我们计划生产，纯化和表征大量这种新型TSH类似物，用于商业开发作为显像剂。我们在目标1中建议开发稳定的细胞系，产生高水平的候选超活性类似物，并产生足够数量的初始成像研究。该目标将包括构建具有可扩增标记物和突变亚基cdna的双双性载体，随后是扩增，生产，纯化和未纯化类似物的表征。选定的TSH类似物将通过乳酸过氧化物酶方法标记为123I或125I，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将包括伽玛相机成像的原发性和转移性甲状腺肿瘤与123I-TSH在一个新的转基因甲状腺癌小鼠模型。这些小鼠仅在甲状腺中表达人类RET/PTC3，并发展为甲状腺增生、乳头状癌和转移性癌的实体瘤变体。此外，125I-TSH类似物的定量摄取研究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。这种新的标记TSH成像方法可能会扩展到甲状腺癌的新治疗方法，包括TSH受体介导的治疗剂递送，如放射性核素或毒素，以及TSH受体定位基因治疗方法。甲状腺癌是最常见的内分泌组织恶性肿瘤，大多数患者需要终身监测诊断性促甲状腺激素（TSH）刺激放射碘成像，以发现复发肿瘤。PI已经开发了一种改进的TSH形式，并提出了一种全新的甲状腺癌成像方法，这将大大提高早期发现，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.