PET Imaging of Vaso-Occlussive Crisis in Sickle Cell Disease

项目摘要/摘要 镰状细胞病(SCD)是一种遗传性疾病，影响全球数百万人。转基因SCD小鼠的研究进展 已经表明SCD的特征是黏附分子在细胞表面的过度表达(高黏附) 内皮细胞和血细胞。过度粘连导致血管闭塞，进而导致急性 SCD的疼痛发作称为血管闭塞危象(VOC)。高粘连和VOC的主要参与者是 黏附分子P-选择素，将网织红细胞和中性粒细胞与内皮细胞捆绑在一起，而且很晚 抗原-4(VLA-4)，负责P-选择素下游的牢固黏附。面临的核心挑战是 SCD的临床处理是既不存在生物标志物，也不存在直接可见的高粘连 人类。随着针对黏附分子的新药问世，有关黏附过度的知识缺失是必然的。 预防VOC的方法正在开发中，但目前还没有生物标记物来指导其使用。具体而言，SCD护理 供应商不能采用精确医学方法来选择哪些患者将对P-选择素有反应 阻滞剂Crizanlizumab仅对约50%的患者有效，成本较高，并可能导致严重的 不良反应。这项提议旨在通过开发第一个生物标志物来促进该领域的发展。 活化的vla-4在人类SCD患者中的高粘附性。我们假设正电子发射 VLA-4的断层扫描(PET)成像将在治疗前测量粘连过度及其反应性的降低 到抗粘附性药物。我们的多学科团队开发了PET示踪剂64Cu-CB-TE1Al1P-PEG4- 与活化的VLA-4结合的LLP2A(64Cu-LLP2A)。我们发现LLP2A可以检测到VLA-4介导的 SCD小鼠对内毒素(LPS)的高黏附反应，这种高黏附作用可通过以下方法减少 使用抗P-选择素单抗(类似于crizanlizumab)治疗。我们现在建议：1)阐明 小鼠高粘连的其他触发因素(即氯化高铁血红素和缺氧)，以更彻底地模拟人类病理 (目标1)；ii)比较P-选择素阻滞剂与FDA批准的新的Voxelotor在小鼠体内对64Cu-LLP2A的摄取 针对溶血并可能间接影响过度粘连的SCD药物(目标2)；以及iii)对患者进行成像 在治疗前后使用64Cu-LLP2A的SCD，我们在2020年获得了监管部门的批准 与Crizanlizumab(目标3)。如果我们的研究成功，将为生物标记物驱动的精准医学铺平道路 以及对这一未得到充分服务的患者群体的未来研究。未来抗VOC治疗的临床试验可能 结合64Cu-LLP2A来预测、量化和监测响应。

Project Summary/Abstract Sickle cell disease (SCD) is a genetic disorder that affects millions worldwide. Research in transgenic SCD mice has shown that SCD is characterized by the overexpression of adhesion molecules (hyperadhesion) on the endothelium and blood cells. Hyperadhesion causes vascular occlusion, which in turn leads to the hallmark acute pain episodes of SCD named vaso-occlusive crises (VOC). Key players in hyperadhesion and VOC are the adhesion molecules P-selectin, that tethers reticulocytes and neutrophils to the endothelium, and Very Late Antigen-4 (VLA-4), that is responsible for firm adhesion downstream of P-selectin. The central challenge in the clinical management of SCD is that there exist no biomarkers nor direct visualization of hyperadhesion in humans. The knowledge deficit on hyperadhesion is consequential, as new drugs targeting adhesion molecules to prevent VOC are being developed, yet there are no biomarkers to guide their use. Specifically, SCD care providers cannot adopt a precision medicine approach to select which patients will respond to the P-selectin blocker crizanlizumab, which is only efficacious in ~50% of patients, carries a high cost, and may cause severe adverse reactions. This proposal aims to advance the field by developing the first-ever biomarker to image hyperadhesion in humans with SCD by imaging activated VLA-4. We hypothesize that positron emission tomography (PET) imaging of VLA-4 will measure hyperadhesion before treatment, and its decrease in response to anti-hyperadhesive drugs. Our multidisciplinary team has developed the PET tracer 64Cu-CB-TE1A1P-PEG4- LLP2A (64Cu-LLP2A) that binds to activated VLA-4. We found that LLP2A can detect VLA-4-mediated hyperadhesion in response to lipopolysaccharide (LPS) in SCD mice, and that hyperadhesion is reduced by treatment with anti-P-selectin mAb (analogous to crizanlizumab). We now propose to i) elucidate the role of additional triggers of hyperadhesion (i.e. hemin and hypoxia) in mice, to more thoroughly model human pathology (Aim 1); ii) to compare 64Cu-LLP2A uptake in mice after P-selectin blockade vs. voxelotor, a new FDA-approved drug for SCD that targets hemolysis and may impact hyperadhesion indirectly (Aim 2); and iii) to image patients with SCD using 64Cu-LLP2A, for which we were granted regulatory approval in 2020, before and after treatment with crizanlizumab (Aim 3). Our studies, if successful, will pave the way for biomarker-driven precision medicine and future research for this underserved group of patients. Future clinical trials of anti-VOC treatments may incorporate 64Cu-LLP2A to predict, quantify, and monitor response.