Beta-2 Microglobulin Depletion Columns for Amyloidosis Prevention and Treatment

 描述(由申请人提供)：大约400,000名美国人因完全肾功能衰竭(或称为终末期肾病(ESRD))而接受常规透析治疗。1980年至2009年间，患有这种疾病的患者数量增加了6倍。在终末期肾病患者中，血清2-微球蛋白浓度很容易累积到正常水平的10-50倍，导致2M纤维沉积在骨骼和关节间隙，在一种称为透析相关淀粉样变性(DRA)的疼痛、衰弱的情况下。目前的数据表明，从ESRD患者的循环中消耗2M可以降低DRA症状的严重程度。此外，清除2m的量与症状改善的程度成正比。这表明，从循环中去除2m是治疗DRA的有效策略，尽可能多地去除2m将使治疗效果最大化。为此，我们将开发血浆分离柱，使用小肽选择性地从人体血浆中耗尽？2M。在我们设想的分离产品中，将使用自动和连续的在线电路来去除ESRD患者的血液，然后将其分离为细胞和血浆部分。血浆部分将流经我们的ü2M-耗尽柱，与患者的血细胞重新结合，然后安全地重新注入体内。目前用于治疗DRA的分离柱(例如，Lixelle；在日本获得批准，但在美国不可用)从血液中耗尽2M。即使使用最大、安全允许的柱子大小(~350毫升)，该设备也只从ESRD患者中排出75%的？2M。此外，该专栏是非特定的。Lixelle耗尽其他蛋白质，如细胞因子，还通过与柱基的非特异性相互作用结合血细胞。这种缺乏特异性(再加上柱的体积很大)导致了严重的不良事件，如低血压和贫血，需要许多患者停止治疗。为了消除特异性问题，研究人员开发了基于抗体的色谱柱，可以从血浆中耗尽？2M，但由于抗体质量较大，这些色谱柱的耗尽量甚至更少(比Lixelle低约60%-90%)。我们预计，用小肽制成的耗尽柱将专门针对2m，并结合多达7倍于所有现有技术的2m。从灌流血浆中进行多肽介导的2M耗竭的特异性将大大减少副作用，最大限度地使这种治疗方法为最大数量的患者带来好处。此外，大规模生产多肽的成本将比抗体低得多，从而增强了我们设备的商业潜力。在这个第一阶段的应用中，我们将使用噬菌体展示生物扫描技术来鉴定小肽(~2.5kD)，它们与？2M具有高亲和力和特异性。这些多肽将被嫁接到琼脂糖底物上，并用于从人体血浆中捕获？2M。最终，这项技术将改善接受长期透析的终末期肾病患者的生活质量。

 DESCRIPTION (provided by applicant): Approximately 400,000 Americans undergo regular dialysis treatment because of complete kidney failure, otherwise known as end-stage renal disease (ESRD). The number of patients afflicted with this condition increased six-fold between 1980 and 2009. In ESRD patients, serum concentrations of ß2- microglobulin (ß2m) readily accumulate 10-50 times higher than normal levels, leading to the formation of ß2m fibrils that deposit in the bone and joint space in a painful, debilitating condition termed dialysis-related amyloidosis (DRA). Current data indicates that depleting ß2m from the circulation of ESRD patients reduces the severity of DRA symptoms. Furthermore, the amount of ß2m removed is proportional to the extent of symptom improvement. This suggests that removal of ß2m from circulation is an effective strategy for treating DRA, and that treatment efficacy would be maximized by removing as much ß2m as possible. To this end, we will develop plasmapheresis columns that use small peptides to selectively deplete ß2m from human plasma. In the apheresis product we envision, an automated and continuous in-line circuit will be used to remove an ESRD patients' blood, which will then be separated into cell and plasma fractions. The plasma fraction will flow through our ß2m-depletion column, recombine with the patient's blood cells, and then be safely reintroduced into the body. Current apheresis columns for treating DRA (e.g. Lixelle; approved in Japan but not available in the U.S.) deplete ß2m from blood. This device depletes only 75% of ß2m from ESRD patients even when using the maximum, safely allowable column size (~350 mL). Moreover, the column is non-specific. Lixelle depletes other proteins such as cytokines, and also binds blood cells through non-specific interactions with the column substrate. This lack of specificity (coupled with the column's large volume) leads to significant adverse events such as hypotension and anemia that require many patients to halt treatment. To remedy specificity concerns, researchers have developed antibody-based columns that can deplete ß2m from plasma, but these columns deplete even less ß2m (~60-90% lower than Lixelle) due to the large mass of antibodies. We expect that depletion columns made with small peptides will be specific for ß2m and bind up to 7-fold more ß2m than all existing techniques. The specificity of peptide-mediated ß2m depletion from perfused plasma will drastically reduce side effects, maximizing the benefits of this treatment for the largest number of patients. Moreover, mass-scale production of peptides will be significantly less expensive than antibodies, enhancing the commercialization potential of our device. In this Phase 1 application, we will use phage display biopanning to identify small (~2.5 kD) peptides that bind with high affinity and specificity to ß2m. These peptides will be grafted onto agarose substrates and used to capture ß2m from human plasma. Ultimately, this technology will improve the quality of life for ESRD patients on long-term dialysis.