Nanoparticle Enabled L-asparaginase Therapy for CLL

描述(申请人提供)：L-天冬酰胺酶用于治疗急性淋巴细胞白血病(ALL)已有40多年的历史。然而，尽管有证据表明成人白血病对天冬酰胺和其他氨基酸的耗竭也很敏感，但天冬酰胺酶疗法并未扩展到儿童白血病以外的领域，原因有几个。首先是L-天冬酰胺酶的免疫原性，它可以限制治疗持续时间，并可能导致过敏反应和过敏反应等潜在副作用。其他副作用，包括胰腺炎和凝血障碍，也可能限制这种治疗形式在慢性淋巴细胞白血病(CLL)患者中的吸引力。该项目的长期目标是为L开发一个新的平台-天冬酰胺酶疗法，克服这两个限制。该平台包括两个组件：由我们的合作者Donald Durden博士开发的新型重组L-天冬酰胺酶，以及保护该酶免受体内免疫反应和免疫中和的纳米颗粒载体。这种从产琥珀酸狼菌中提取的酶缺乏谷氨酰胺酶活性，而谷氨酰胺酶活性会导致与临床批准的酶相关的毒副作用。然而，由于免疫抑制是被我们的酶消除的副作用之一，如果这种酶在没有某种形式的屏蔽的情况下使用，免疫原性问题可能特别严重。我们已经开发了一种纳米颗粒递送系统，我们称之为二氧化硅中空酶载球(SHELS)。这些壳最初被合成为带有大孔的“纳米维夫球”，允许它们装载未经修饰的酶，然后用允许小酶底物扩散但不能被大分子和蛋白质渗透的多孔层密封，从而同时包裹酶并保护其免受抗体识别。我们有初步数据表明，原代人类CLL细胞对天冬酰胺的耗尽非常敏感。根据我们的具体目标，我们的方法分为三个一般阶段。首先，我们将优化重组产琥珀酸狼疮L-天冬酰胺酶(rWSasp-Shels)的用量。在第二项研究中，我们将评估rWSasp-Shels在植入单独的CLL细胞或联合应用CLL细胞和激活的T细胞以促进分裂的小鼠中的效果。前者将允许在代表静止的CLL群体的模型中对颗粒进行测试，而后者将对颗粒对增殖室的影响进行建模。在最终目的中，我们将比较rWSasp-Shels和目前临床使用的聚乙二醇天冬酰胺酶的毒性分布。

DESCRIPTION (provided by applicant): L-asparaginase has been used to treat acute lymphoblastic leukemia (ALL) for over 40 years. However, despite evidence that adult leukemias are also sensitive to asparagine and other amino acid depletion, asparaginase therapy has not expanded beyond pediatric leukemia for several reasons. Foremost is the immunogenicity of L-asparaginase which can limit the duration of therapy and contribute to potential side effects such as hypersensitivity reactions and anaphylaxis. Other side effects, including pancreatitis and coagulopathy, may also limit the appeal of this form of therapy in Chronic Lymphocytic Leukemia (CLL) patients. The long term goal of this project is to develop a new platform for L-asparaginase therapy that overcomes both of these limitations. This platform has two components: a new recombinant L-asparaginase, developed by our collaborator Dr. Donald Durden, and a nanoparticle delivery vehicle that protects the enzyme from immune response and immune neutralization in vivo. This enzyme, derived from Wolinella succinogenes lacks glutaminase activity that contributes to the toxic side effects associated with the clinicall approved enzymes. However, since immune suppression is one of those side effects abrogated by our enzyme, the immunogenicity problem may be particularly acute if this enzyme is used without some form of shielding. We have developed a nanoparticle delivery system that we term silica hollow enzyme loaded spheres (SHELS). These SHELS are initially synthesized as "nano-wiffle balls" with large holes that allow them to be loaded with unmodified enzymes and subsequently sealed with a porous layer that allows diffusion of small enzyme substrates but is impermeable to large molecules and proteins, thus simultaneously encapsulating the enzyme and protecting it from antibody recognition. We have preliminary data that shows that primary human CLL cells are extremely sensitive to asparagine depletion. Our approach is divided into three general phases aligned with our specific aims. In the first, we will optimize the dosing of recombinant Wolinella succinogenes L-asparaginase loaded in SHELS (rWSasp-SHELS). In the second, we will evaluate the efficacy of rWSasp- SHELS in mice engrafted with either CLL cells alone or CLL cells co-administered with activated T cells to promote division. The former will allow for the testing of the particles in a model representative of the resting CLL population whereas the latter will model the impact of the particles on the proliferative compartment. In the final aim we will compare the toxicity profile of the rWSasp-SHELS with the current clinically used PEG- asparaginase.