Novel RNase-based Immunotoxin for CD74-positive B-cell Malignancies

描述（由申请人提供）：这是1 R43 CA 121468 -01的修订申请，最初于2005年7月29日提交。Immunomedics，Inc.已经开发了一系列重组免疫毒素，其由两个分子的豹蛙酶（Rap）（一种两栖动物核糖核酸酶（RNase））组成，每个分子融合到内化人源化IgG的轻（L）链的N-末端。构建了第一种这样的免疫毒素2L-Rap-hLL 1-γ 4 P，以靶向表达CD 74的肿瘤，用于通过融合Rap经由快速内化的抗CD 74人源化抗体hLL 1杀伤，并且已经在人伯基特淋巴瘤异种移植模型中证明了有效的抗肿瘤活性（Chang CH，et al.，新型重组核糖核酸酶/抗CD 74人源化IgG 4抗体免疫毒素对人淋巴瘤异种移植物的有效治疗Blood，2005，106：4308-431）。由于2L-Rap-hLL 1-γ 4P中的野生型Rap是糖基化的，2L-Rap-hLL 1-γ 4P的成功促使我们产生2L-Rap（N69 Q）-hLL 1-γ 4P，其含有Rap的非糖基化变体，但在许多属性上与2L-Rap-hLL 1-γ 4P等同，包括所有体外评价的性质，体内肝毒性，和抗肿瘤活性。在本申请中，我们提出进一步临床前开发2L-Rap（N69 Q）-hLL 1-γ 4P作为治疗CD 74阳性癌症，特别是多发性骨髓瘤（MM）和非霍奇金淋巴瘤（NHL）的潜在治疗剂。具体而言，我们将评估2L-Rap（N69 Q）-hLL 1-γ 4P在携带MM或NHL人肿瘤异种移植物的SCID小鼠中以单剂量或多剂量方案的抗肿瘤功效。我们还将通过研究肝毒性是否与免疫毒素的高pI相关以及检查抗炎药是否可有效减少此类肝损伤来解决观察到的非特异性肝毒性。另一个目标是扩增生产克隆以提高产量，并使完全扩增的克隆适应在无血清条件下生长。完成这些研究后，我们应该能够确定2L-Rap-hLL 1（N69 Q）-γ 4 P在携带人NHL或MM异种移植物的SCID小鼠模型中的治疗窗口，并大规模生产2L-Rap-hLL 1（N69 Q）-γ 4P用于GLP药理学/食蟹猴毒理学研究，以获得支持提交用于治疗复发性或难治性MM患者的I期临床IND的数据，或NHL。

DESCRIPTION (provided by applicant): This is an amended application of 1 R43 CA121468-01, which was originally submitted on July 29, 2005. Immunomedics, Inc. has developed a series of recombinant immunotoxins that are composed of two molecules of ranpirnase (Rap), an amphibian ribonuclease (RNase), each fused to the N- terminus of the light (L) chain of an internalizing humanized IgG. The first of such immunotoxins, 2L-Rap-hLL1-gamma4P, was constructed to target CD74-expressing tumors for killing by fused Rap via the rapidly internalizing anti-CD74 humanized antibody hLL1, and has demonstrated potent anti-tumor activity in human Burkitt lymphoma xenograft models (Chang CH, et al., Effective therapy of human lymphoma xenografts with a novel recombinant ribonuclease/anti-CD74 humanized IgG4 antibody immunotoxin. Blood, 2005, 106: 4308-431). Because the wild-type Rap in 2L- Rap- hLL1-gamma4P is glycosylated, the success of 2L- Rap-hLL1-gamma4P prompted us to generate 2L- Rap(N69Q)-hLL1-gamma4P, which contains the non-glycosylated variant of Rap, but is otherwise equivalent to 2L-Rap-hLL1-gamma4P in many attributes, including all in vitro properties evaluated, in vivo liver toxicity, and anti-tumor activity in SCID mice bearing Daudi lymphoma xenografts. In this application, we propose to pursue further preclinical development of 2L-Rap(N69Q)-hLL1-gamma4P as a potential therapeutic for treating CD74-positive cancers, in particular, multiple myeloma (MM) and non-Hodgkin lymphoma (NHL). Specifically, we will evaluate 2L-Rap(N69Q)-hLL1-gamma4P for anti-tumor efficacy in SCID mice bearing MM or NHL human tumor xenografts with a single-dose or multiple-dose regimen. We will also address the observed nonspecific liver toxicity by investigating whether the hepatotoxicity could be related to the high pI of the immunotoxin and examining whether anti- inflammatory agents could be effective in reducing such liver injury. A further goal is to amplify the production clone to increase yields and adapt the fully amplified clone to grow in serum-free conditions. Upon completing these studies, we should be able to define the therapeutic window of 2L-Rap-hLL1 (N69Q)-gamma4P in SCID mice models bearing human NHL or MM xenografts, and produce 2L-Rap-hLL1 (N69Q)-gamma4P in large scale for GLP Pharmacology/Toxicology studies in cynomolgus monkeys to obtain data for supporting the submission of a phase I clinical IND for treating patients with recurrent or refractory MM or NHL.