CCR4-IL2 Bispecific Immunotoxin for Targeted Therapy of Cutaneous T-Cell Lymphoma

摘要 皮肤T细胞淋巴瘤是一种以皮肤为特征的结外非霍奇金淋巴瘤 恶性T淋巴细胞浸润性病变。真菌病和Sezary综合征是最常见的 两种最常见的CTCL类型。尽管存在治疗方法，但它们主要是姑息性的，反应低， 在没有任何治愈的情况下，反应的持久性。在目前的情况下，客观应答率保持在30%左右 难治性或复发性CTCL的治疗策略。尽管CTCL在大多数情况下是一种惰性、慢性病 在一些病例中，一些患者经历了严重的衰弱瘙痒，而另一些患者则有进行性疾病 广泛累及皮肤和器官。对于更有效的治疗，有一种未得到满足的医疗需求 改善难治性或复发性CTCL患者的反应。大多数临床诊断为CTCL的患者高度 表达表面标志物CC趋化因子受体4(CCR4)和/或CD25。我们已经产生了一个很有希望的 基于白喉毒素的CCR4-IL2双特异性免疫毒素靶向免疫治疗候选药物 CTCL的。我们的候选药物经过基因工程，同时含有抗人CCR4单链抗体和人IL-2 融合成一种截短的白喉毒素。我们的候选药物已经显示出良好的临床前疗效 与Ontak®相比，小鼠肿瘤模型的生存期(69天比33.5天)提高了106% -喜欢 人IL-2融合毒素。我们的候选药物是用一种新型的高级白喉毒素抗性来表达的 酵母(毕赤酵母)表达系统。我们的酵母表达系统克服了表达和纯化 在基于大肠杆菌的表达系统中遇到的问题，以提供高水平的生产和优秀的 我们的免疫毒素的纯化质量。重要的是，表面受体CCR4和CD25也表达 肿瘤浸润性效应T调节细胞(Tregs)在抗肿瘤免疫中的作用 回应。因此，我们的候选药物的一个潜在的后续适应症是消除肿瘤的浸润性。 CCR4+或/和CD25+Tregs，以促进对多种癌症的肿瘤免疫治疗。在这个项目的第一阶段 应用，我们将在两只大鼠身上进行非GLP毒理学、药代动力学和免疫原性试验 还有小猪。在第二阶段，我们将1)为大型商品开发可扩展的标准操作程序(SOP 生产实践(GMP)并生产足够的GMP级CCR4-IL2双特异性免疫毒素 用于I期和II期临床试验，以及2)进行GLP毒理学、药代动力学和免疫原性研究 在老鼠和小型猪身上都是如此。我们的目标是准备一个IND准备好的临床前数据包，然后将这个 产品进入临床试验。

Abstract Cutaneous T-cell lymphoma (CTCL) is a type of extra-nodal non-Hodgkin’s lymphoma characterized by skin lesions resulting from infiltration of malignant T lymphocytes. Mycosis fungoides and Sezary syndrome are the two most common types of CTCL. Although treatments exist, they are mainly palliative with low response and durability of response without any cure. The objective response rate remains approximately 30% with the current treatment strategies for refractory or recurrent CTCL. Despite CTCL being an indolent, chronic disease in most cases, some patients experience severe debilitating itchiness, while others have progressive disease with extensive skin and organ involvement. There is an unmet medical need for more effective treatments with improved response for refractory or recurrent CTCL patients. The majority of clinically diagnosed CTCL highly express the surface markers CC chemokine receptor 4 (CCR4) and/or CD25. We have generated a promising diphtheria toxin based CCR4-IL2 bispecific immunotoxin therapeutic candidate for targeted immunotherapy of CTCL. Our candidate drug is genetically engineered to contain both anti-human CCR4 scFv and human IL2 fused to a truncated diphtheria toxin. Our candidate drug has demonstrated promising preclinical efficacy in a mouse tumor model showing 106% improvement in survival (69 vs. 33.5 days) compared to an Ontak® -like human IL-2 fusion toxin. Our candidate drug is expressed using a novel, advanced diphtheria toxin-resistant yeast (Pichia pastoris) expression system. Our yeast expression system overcomes expression and purification problems encountered with E. coli-based expressions systems to deliver high production levels and excellent purification quality of our immunotoxin. Importantly, the surface receptors CCR4 and CD25 are also expressed on tumor-infiltrating effector T regulatory cells (Tregs) known to play a role in suppressing anti-tumor immune responses. Therefore, a potential follow-on indication for our candidate drug is depletion of tumor infiltrating CCR4+ or/and CD25+ Tregs to boost tumor immunotherapy for a broad spectrum of cancers. In phase I of this application, we will perform pilot non-GLP toxicology, pharmacokinetics, and immunogenicity studies in both rats and minipigs. In phase II, we will 1) develop a scalable standard operating procedure (SOP) for large-scale good manufacturing practice (GMP) production and produce enough GMP grade CCR4-IL2 bispecific immunotoxin for phase I and II clinical trials, and 2) perform GLP toxicology, pharmacokinetics, and immunogenicity studies in both rats and minipigs. Our goal is to prepare an IND-ready preclinical data package and then move this product into clinical trials.