Novel Recombinant Immunoglobulin Forms for Cancer Therap

用于癌症治疗的新型重组免疫球蛋白形式

• 批准号: 7291795
• 负责人: JEFFREY SCHLOM
• 金额: --
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7291795
• 关键词: Novel; Recombinant; Immunoglobulin; Forms; Cancer

SDR GRAFTING OF A MURINE ANTIBODY USING MULTIPLE HUMAN GERMLINE TEMPLATES TO MINIMIZE ITS IMMUNOGENICITY. The humanization of mAbs by complementarity-determining region (CDR)-grafting has become a standard procedure to improve the clinical utility of xenogeneic Abs by reducing human anti-murine Ab (HAMA) responses elicited in patients. However, CDR-grafted humanized Abs may still evoke anti-V region responses when administered in patients. To minimize anti-V region responses, the Ab may be humanized by grafting onto the human templates only the specificity-determining residues (SDRs), the residues that are essential for the surface complementarity of the Ab and its ligand. Typically, humanization of an Ab, whether by CDR or SDR grafting, involves the use of a single human template for the entire VL or VH domain of an Ab. We hypothesized, however, that the homology between the human template sequences and mAb to be humanized may be maximized by using templates from multiple human germline sequences corresponding to the different segments of the variable domain. This could be more advantageous in reducing the potential immunogenicity of the humanized Ab. This study describes the SDR grafting of the murine anti-carcinoembryonic antigen (CEA) mAb COL-1 using three different human germline V-kappa sequences as templates for the VL CDRs and another human template for the VL frameworks. In competition RIAs, the SDR-grafted COL-1 (HuCOL-1SDR) completely inhibited the binding of radiolabeled murine COL-1 (mCOL-1) to CEA, and showed that its binding affinity is comparable to that of the CDR-grafted Ab (HuCOL-1). The HuCOL-1SDR showed similar binding reactivity to the CEA expressed on the surface of a tumor cell line as the HuCOL-1. More importantly, compared to HuCOL-1 and the "abbreviated" CDR-grafted Ab, HuCOL-1SDR showed lower reactivity to patients' sera carrying anti-V region Abs to mCOL-1. HuCOL-1SDR, which shows a lower sera reactivity than that of the parental Abs while retaining its Ag-binding property, is a potentially useful clinical reagent. To the best of our knowledge, this is the first time a VL or VH domain of an Ab has been humanized by grafting the SDRs onto a human template comprised of several Ab sequences. We have shown that humanization of an Ab can be optimized using multiple human templates for a single variable domain of an Ab. This approach maximizes the homology between the target Ab and the human templates in both the frameworks and the CDRs by choosing as the template the human sequence that displays the highest local sequence identity to the frameworks and to each of the CDRs of the target Ab.RADIOIMMUNOTHERAPY OF HUMAN COLON CARCINOMA XENOGRAFTS USING A 213BI-LABELED DOMAIN-DELETED HUMANIZED MONOCLONAL ANTIBODY. We have carried out the first study of a humanized domain-deleted monoclonal antibody (HuCC49DeltaCH2) to be utilized in a radioimmunotherapeutic (RIT) application with 213Bi. An initial study indicated that 111In-HuCC49DeltaCH2 targets the subcutaneously implanted human colon carcinoma xenograft, LS-174T, when injected via a peritoneal route. The HuCC49DeltaCH2 was then radiolabeled with 213Bi, an alpha-emitting radionuclide with a half-life of 45.6 minutes, and evaluated for therapeutic efficacy. Dose titration studies indicated that a single dose of 500-1000 microCi, when injected by an intraperitoneal route, resulted in the growth inhibition or regression of the tumor xenograft. The radioimmunotherapeutic effect was found to be dose-dependent. Specificity of the therapeutic efficacy was confirmed in a subsequent experiment with athymic mice bearing TAG-72 negative MIP (human colorectal) xenografts. A preliminary study was also performed to assess a multiple-dose administration of 213Bi-HuCC49DeltaCH2. Doses (500 microCi) were administered at 14-day intervals after tumor implantation.

使用多个人类种系模板对鼠抗体进行 SDR 嫁接，以最大限度地降低其免疫原性。通过互补决定区 (CDR) 移植进行的单克隆抗体人源化已成为通过减少在患者中引起的人抗鼠抗体 (HAMA) 反应来提高异种抗体临床效用的标准程序。然而，CDR 移植的人源化抗体在给予患者时仍可能引起抗 V 区反应。为了最大限度地减少抗 V 区反应，可以通过仅将特异性决定残基 (SDR) 移植到人模板上来对抗体进行人源化，这些残基对于抗体及其配体的表面互补性至关重要。通常，Ab 的人源化，无论是通过 CDR 还是 SDR 移植，都涉及对 Ab 的整个 VL 或 VH 结构域使用单一人模板。然而，我们假设，通过使用来自对应于可变结构域的不同片段的多个人种系序列的模板，可以最大化人模板序列和待人源化的mAb之间的同源性。这可能更有利于降低人源化抗体的潜在免疫原性。本研究描述了使用三种不同的人种系 V-kappa 序列作为 VL CDR 的模板和另一个人类模板作为 VL 框架的鼠抗癌胚抗原 (CEA) mAb COL-1 的 SDR 移植。在竞争RIAs中，SDR移植的COL-1（HuCOL-1SDR）完全抑制放射性标记的鼠COL-1（mCOL-1）与CEA的结合，并表明其结合亲和力与CDR移植的抗体相当。 （HuCOL-1）。 HuCOL-1SDR 对肿瘤细胞系表面表达的 CEA 显示出与 HuCOL-1 相似的结合反应性。更重要的是，与HuCOL-1和“缩写的”CDR移植抗体相比，HuCOL-1SDR对携带mCOL-1抗V区抗体的患者血清表现出较低的反应性。 HuCOL-1SDR 的血清反应性低于亲本抗体，同时保留其 Ag 结合特性，是一种潜在有用的临床试剂。据我们所知，这是首次通过将 SDR 移植到由多个 Ab 序列组成的人类模板上来人源化 Ab 的 VL 或 VH 结构域。我们已经证明，可以使用针对抗体的单个可变域的多个人类模板来优化抗体的人源化。这种方法通过选择与框架和目标抗体的每个 CDR 表现出最高局部序列同一性的人类序列作为模板，最大化了框架和 CDR 中目标抗体和人类模板之间的同源性。使用 213 双标记结构域删除的人源化单克隆抗体进行人类结肠癌异种移植抗体。我们对人源化结构域缺失单克隆抗体 (HuCC49DeltaCH2) 进行了首次研究，该抗体将与 213Bi 一起用于放射免疫治疗 (RIT) 应用。一项初步研究表明，当通过腹膜途径注射时，111In-HuCC49DeltaCH2 靶向皮下植入的人类结肠癌异种移植物 LS-174T。然后用 213Bi（一种半衰期为 45.6 分钟的 α 发射放射性核素）对 HuCC49DeltaCH2 进行放射性标记，并评估治疗效果。剂量滴定研究表明，单剂量500-1000 microCi，当通过腹膜内途径注射时，导致肿瘤异种移植物的生长抑制或消退。发现放射免疫治疗效果具有剂量依赖性。随后对携带 TAG-72 阴性 MIP（人结直肠）异种移植物的无胸腺小鼠进行的实验证实了治疗功效的特异性。还进行了一项初步研究来评估 213Bi-HuCC49DeltaCH2 的多剂量给药。肿瘤植入后每隔 14 天施用一次剂量（500 微居里）。