Therapeutic Immunodepletion of a Transthyretin Aggregation Intermediate

摘要 甲状腺素运载蛋白淀粉样变性（ATTR）是一种罕见的、进行性的、最终致命的疾病，其特征在于： 外周神经内甲状腺素运载蛋白（TTR）蛋白的异常细胞外沉积（ATTR-PN）和/或 在心脏内（ATTR-CM）。有两种类型的ATTR：（1）遗传性ATTR（hATTR），其中不稳定的 TTR基因中的突变是遗传的，或（2）ATTRwt，其中具有野生型TTR基因序列的人 偶尔发病。最近的估计将全球受ATTR影响的人数定为 大约500，000;然而，这些患者人群被认为是严重诊断不足。 近年来，第一种治疗剂已被批准通过用抗肿瘤药物稳定TTR来治疗ATTR。 小分子（tafamidase和diflunisal）或通过反义寡核苷酸降低TTR表达水平 寡核苷酸（patisiran和inotersen）。然而，并非所有患者都对治疗有反应， 反应持续下降;疾病进展减缓但不逆转。 从正常TTR到淀粉样蛋白沉积的途径通过单体中间体进行， 假设患者持续下降的原因是由于其持续存在。以实体为目标 与聚集有关的游离单体中间体，可能会导致更好的治疗方法 其中天然TTR的总库保持不变，并且仅除去易于聚集的中间体。 因此，ADRx方法是使用专有抗体来结合这种中间聚集物质， 把它从病人的血液中清除掉抗体是这种治疗的理想方法，因为它的半衰期长， 亲和性、精确的特异性和血流中中间体的可用性。 通过专有的抗体发现程序，高效和特异性的单体结合抗体已经被发现。 被发现其中一种抗体将用于在小鼠中进行概念验证实验， 评估其从小鼠血液中消除这些异常的易聚集单体的能力。 由于缺乏现成的动物模型，新的ATTR治疗开发工作受到阻碍 来测试功效虽然已经开发了转基因动物模型来模拟小鼠中的TTR沉积，但是这些转基因动物模型在小鼠中的分布不稳定。 模型很难复制在人类ATTR患者中发现的TTR沉积模式，并且还显示出很大的差异。 沉积物的数量、类型和位置的差异。此外，这些模型可能需要几个月的沉积 在某些情况下，超过24个月。在下面的应用中，我们提出研究来表明，我们的 专有抗体可以在短时间内有效地发现并清除动物体内的TTR中间体。 如果成功的话，这些实验将显示，对于所用的剂量，来自动物的TTR的聚集形式的消耗。 首次这将建立这些抗体临床前开发的第一步， 它可以作为独立治疗或与其他批准的药物联合用于ATTR患者。

ABSTRACT Transthyretin amyloidosis (ATTR) is a rare, progressive, and ultimately fatal condition characterized by the abnormal extracellular deposition of transthyretin (TTR) protein within the peripheral nerves (ATTR-PN) and/or within the heart (ATTR-CM). There are two types of ATTR: (1) hereditary ATTR (hATTR), where the destabilizing mutation in the TTR-gene is inherited, or (2) ATTRwt, in which people with the wild-type TTR-gene sequence develop the disease sporadically. Recent estimates put the worldwide number of people affected by ATTR at approximately 500,000; however, these patient populations are thought to be significantly underdiagnosed. In recent years, the first therapeutics have been approved to treat ATTR either through stabilization of TTR with a small molecule (tafamidis and diflunisal) or reduction of TTR expression levels through antisense oligonucleotides (patisiran and inotersen). However, not all patients respond to treatment and those that do respond continue to decline; disease progression is slowed but not reversed. The path from normal TTR to amyloid deposition proceeds through a monomeric intermediate and it is hypothesized that the reason patients continue to decline is due to its continued presence. Targeting the entity implicated in aggregation, the dissociated monomeric intermediate, could lead to a better therapeutic approach where the total pool of native TTR remains unaltered and only the aggregation prone intermediate is removed. Hence, the ADRx approach is to use a proprietary antibody to bind this intermediate aggregating species and clear it from the patient’s blood. An antibody is an ideal approach for this therapeutic due to its long half-life, high affinity, exquisite specificity, and availability of the intermediate within the bloodstream. Through a proprietary antibody discovery program, highly potent and specific monomer binding antibodies have been discovered. One of these antibodies will be used to perform proof-of-concept experiments in mice to evaluate its ability to deplete these aberrant aggregation-prone monomers from the blood of mice. Novel ATTR therapeutic development efforts have been hindered by the lack of readily available animal models to test efficacy. While transgenic animal models have been developed to mimic TTR deposition in mice, these models poorly replicate the TTR deposition patterns found in human ATTR patients and furthermore show great variance in amount, type, and location of deposition. Additionally, these models can take months for deposition to occur, in some cases upwards of 24 months. In the following application we propose studies to show that our proprietary antibody can efficiently find and clear the TTR intermediate within an animal on a short timescale. If successful, these experiments will show the depletion of the aggregating form of TTR from an animal for the first time. This will establish the first step in preclinical development of these antibodies towards a therapeutic that can be used in ATTR patients as a stand-alone therapy or in combination with other approved drugs.