Preclinical Diagnostic Imaging of Amyloid

描述（由申请方提供）：淀粉样蛋白与一组不同的通常致命的遗传性和散发性蛋白质错误折叠疾病相关，其特征为重要器官和组织中的原纤维和硫酸乙酰肝素蛋白聚糖沉积。虽然最常见的表现是阿尔茨海默病患者，但在美国，外周（非脑）淀粉样蛋白疾病的发病率估计为每年约5300例，超过急性淋巴细胞白血病（每年约4，000例）。外周淀粉样变性的治疗选择是有限的，并且集中于减少淀粉样蛋白的合成，目前有31项治疗AL、AA和ATTR淀粉样变性的新试验正在进行中（clinicaltrials.gov）。不幸的是，在美国没有方法可以直接可视化对这些抗淀粉样蛋白治疗的反应，也没有方法可以确定患者中淀粉样蛋白沉积或靶器官的程度和严重程度。这种信息可以通过使用淀粉样蛋白特异性放射性示踪剂进行成像来获得。因此，迫切需要鉴定靶向淀粉样蛋白的示踪剂用于全身成像，其可用于在临床内和作为临床试验的一部分监测疾病进展和对治疗的反应。该提案的目的是靶向淀粉样蛋白生物标志物硫酸乙酰肝素蛋白聚糖，并测试特异性结合所有已知淀粉样蛋白沉积物的该成分的抗体衍生和肽示踪分子。我们的方法是基于这样一个事实，即所有淀粉样蛋白沉积物含有硫酸乙酰肝素蛋白多糖的水平高达250 5克每克病变组织。我们已经开始测试一组已知结合硫酸乙酰肝素的抗体衍生蛋白（scFv）结合淀粉样蛋白沉积物中硫酸乙酰肝素的能力。我们已经表明，即使硫酸乙酰肝素在一些正常组织中表达，高硫酸化硫酸乙酰肝素的scFv也成功地在体内成像淀粉样蛋白。新的硫酸乙酰肝素结合肽也将产生和测试。淀粉样蛋白反应性scFv和肽的体外表征将通过表面等离子体共振和ELISA进行，以鉴定具有<1.5M的平衡结合亲和力的那些scFv-适合于在患者中成像。将使用小动物SPECT、PET和CT成像来比较可用和新型硫酸乙酰肝素结合示踪剂的共定位，并鉴定具有可接受（3：1）靶与背景比的示踪剂。我们将使用已建立的系统性外周（AA）淀粉样变性的小鼠模型，该模型概括了人类淀粉样疾病的许多方面，包括蛋白聚糖的沉积，这提高了我们将识别用于成像淀粉样变性的示踪剂的可能性，这些示踪剂有利地转化为临床。鉴定和验证特异性结合组织淀粉样蛋白中发现的硫酸乙酰肝素蛋白聚糖的分子将为这种毁灭性疾病患者的临床评估提供新的试剂。公共卫生相关性：外周淀粉样变性是一种与2型糖尿病、慢性炎症性疾病（如结核病和类风湿性关节炎）以及某些B细胞恶性肿瘤相关的蛋白质错误折叠疾病。目前，在美国还没有方法可以检测外周淀粉样变性患者的淀粉样蛋白沉积程度，也没有监测其进展或记录其对治疗的反应。这种信息可以通过使用淀粉样蛋白特异性放射性示踪剂进行成像来获得。为此，我们的目标是针对淀粉样蛋白生物标志物硫酸乙酰肝素蛋白聚糖和测试抗体衍生的和肽示踪分子，这些分子特异性结合所有已知淀粉样蛋白沉积物的这种成分，用于全身成像，可用于监测疾病进展和对治疗的反应。

DESCRIPTION (provided by applicant): Amyloid is associated with a diverse group of often fatal hereditary and sporadic protein misfolding disorders, characterized by the deposition of fibrils and heparan sulfate proteoglycan in vital organs and tissues. Although the most common manifestation is in patients with Alzheimer's disease, the incidence of peripheral (non-cerebral) amyloid diseases in the USA, is estimated to be ~ 5300 per yr which exceeds that for acute lymphocytic leukemia (~ 4,000 per yr). Treatment options for peripheral amyloidosis are limited and focus on reducing synthesis of the amyloidogenic protein e.g., with high dose chemotherapy and there are currently 31 new trials for treating AL, AA, and ATTR amyloidosis underway (clinicaltrials.gov). Unfortunately, there are no methods available in the USA to visualize response to these anti-amyloid therapies directly, nor to determine the extent and severity of amyloid deposits or the target organ in patients. This kind of information can be obtained by imaging, using an amyloid-specific radiotracer. There exists therefore an urgent need to identify tracers that target amyloid for whole body imaging that can be used for monitoring disease progression and response to therapy both within the clinic and as part of clinical trials. The aim of this proposal is to target the amyloid biomarker heparan sulfate proteoglycan and test antibody-derived and peptide tracer molecules that bind specifically to this constituent of all known amyloid deposits. Our approach is based on the fact that all amyloid deposits contain heparan sulfate proteoglycan at levels as high as 250 5g per gram of diseased tissue. We have begun testing a panel of antibody-derived proteins (scFv) known to bind heparan sulfate, for their ability to bind heparan sulfate in amyloid deposits. We have shown that scFvs to hypersulfated heparin sulfate successfully imaged amyloid in vivo even though heparan sulfate was expressed in some normal tissues. Novel heparan sulfate-binding peptides will also be generated and tested. In vitro characterization of the amyloid-reactive scFv and peptides will be performed by surface plasmon resonance and ELISA to identify those scFv with equilibrium binding affinity of < 1 5M - suitable for imaging in patients. Small animal SPECT, PET, and CT imaging will be used to compare the co-localization of the available and novel heparan sulfate- binding tracers and identify those with acceptable (3:1) target to background ratios. We will use an established murine model of systemic peripheral (AA) amyloidosis that recapitulates many aspects of human amyloid disease including the deposition of proteoglycans which enhances the probability that we will identify tracers for imaging amyloidosis that translate favorably into the clinic. Identifying and validating molecules that specifically bind heparan sulfate proteoglycan found in tissue amyloid will provide new reagents for the clinical evaluation of patients with this devastating disease. PUBLIC HEALTH RELEVANCE: Peripheral amyloidosis is a protein-misfolding condition associated with type 2 diabetes, chronic inflammatory disorders such as tuberculosis and rheumatoid arthritis, as well as certain B-cell malignancies. Currently here are no methods available in the USA that can detect the extent of amyloid deposits in patients with peripheral amyloidosis, nor to monitor their progression, or document their removal in response to therapy. This kind of information can be obtained by imaging, using an amyloid-specific radiotracer. To this end, we aim to target the amyloid biomarker heparan sulfate proteoglycan and test antibody-derived and peptide tracer molecules that bind specifically to this constituent of all known amyloid deposits for the purpose of whole body imaging that can be used to monitor disease progression and response to therapy.