Labeling nanobodies with 18F residualizing labels for HER2 specific PET imaging

 描述（由申请人提供）：HER 2在25-30%的乳腺癌中过表达，是肿瘤侵袭性和复发的主要因素。这导致了HER 2靶向治疗的发展，如曲妥珠单抗，它可以在过度表达HER 2的患者中有效。真实的准确评估肿瘤HER 2水平有助于个性化HER 2靶向治疗和监测治疗反应。与目前用于评估HER 2水平的方法如免疫组织化学和荧光原位杂交（FISH）不同，定量正电子发射断层扫描（PET）成像是非侵入性的，可以重复进行，并且可以真实的时间提供准确的HER 2水平。此外，PET成像的高灵敏度可以允许检测隐匿性微转移和可能的HER 2表达乳腺癌干细胞。纳米抗体（Nbs）是具有IgG分子量的十分之一的单结构域抗体，使其成为与最广泛使用的PET放射性核素18F组合使用的理想靶向载体。传统的蛋白质标记方法可能会导致蛋白质在经历内化和细胞内催化后从肿瘤细胞中丢失18F。我们计划扩展残基标记（RL）的方法，成功地使用放射性碘，合成新的试剂，旨在产生18F-标记的catalogues，将被困在肿瘤细胞后，铌内化。将产生N-琥珀酰亚胺基4-胍基甲基-3-碘苯甲酸酯（SGMIB）的氟-18-标记的类似物，SGMIB是我们开发的用于放射性碘标记内化生物分子的最佳残留剂。我们试图将联合收割机结合我们在布鲁塞尔的同事开发的新的HER 2靶向2 Rs 15 d Nb与新型18 F标记化学物质，目的是生成用于评估乳腺癌中HER 2水平的PET成像工具，从而用于HER 2靶向治疗的个性化。如果成功，我们将开发的18F标记试剂和方法可以应用于靶向HER 2和其他在乳腺癌中过度表达的内化受体的其他蛋白质和肽。我们提出以下具体目标：1。基于最佳Nb放射性碘标记残基化剂N-琥珀酰亚胺基4-胍基甲基-3-[*I]碘苯甲酸酯（[*I]SGMIB），开发用于18F标记Nbs的辅基。2.用这些试剂标记Nb，并确定标记的Nb缀合物的特性。3.使用表达HER 2的乳腺癌细胞在体外评价标记的Nbs。4.在携带乳腺癌异种移植物的小鼠中体内评价标记的Nbs。

 DESCRIPTION (provided by applicant): HER2 is overexpressed in 25-30% of breast cancers and is a major contributor to tumor aggressiveness and recurrence. This has led to the development of HER2-targeted therapies such as trastuzumab, which can be effective in patients overexpressing HER2. Accurate assessment of tumor HER2 levels in real time could help personalize HER2-targeted therapy and monitor therapy response. Unlike current methods for assessing HER2 levels such as immunohistochemistry and fluorescence in situ hybridization (FISH), quantitative positron emission tomography (PET) imaging is noninvasive, can be performed repeatedly, and could provide accurate levels of HER2 in real time. Moreover, the high sensitivity of PET imaging could permit the detection of occult micrometastases and possibly HER2-expressing breast cancer stem cells. Nanobodies (Nbs) are single domain antibodies with a tenth of the molecular weight of an IgG, making them an ideal targeting vector for use in combination with the most widely utilized PET radionuclide, 18F. Conventional methods for protein labeling may result in the loss of 18F from tumor cells after a protein undergoes internalization and intracellular catabolism. We plan to extend the residualizing label (RL) approach, used successfully with radioiodine, to synthesize novel reagents designed to generate 18F-labeled catabolites that will be trapped in tumor cells after Nb internalization. Fluorine-18- labeled analogues of N-succinimidyl 4-guanidinomethyl-3-iodobenzoate (SGMIB), the best residualizing agent that we developed for radioiodination of internalizing biomolecules, will be generated. We seek to combine a new HER2 targeted 2Rs15d Nb developed by our colleague in Brussels, with a novel 18F- labeling chemistry with the goal of generating a PET imaging tool for assessing HER2 levels in breast cancer and thereby for the personalization of HER2 targeted therapy. If successful, the 18F-labeling reagents and methods that we shall develop could be applied to other proteins and peptides targeting HER2 and other internalizing receptors that are over expressed on breast cancers. We propose the following specific aims: 1. Develop prosthetic groups for 18F-labeling of Nbs based on the best Nb radioiodination residualizing agent, N-succinimidyl 4-guanidinomethyl-3-[*I] iodobenzoate ([*I]SGMIB). 2. Label Nbs with these agents and determine the characteristics of the labeled Nb conjugates. 3. Evaluate labeled Nbs in vitro using HER2-expressing breast cancer cells. 4. Evaluate labeled Nbs in vivo in mice bearing breast carcinoma xenografts.