BIOENGINEERED ANTIBODIES

抗癌胚抗原抗体的分子工程 将致力于提高其在 腺癌的放射免疫治疗和放射免疫成像。三 蛋白质工程可以提高整体水平的关键领域 将对放射性标记抗体的质量和性能进行调查。 首先，尽管生产的疫苗降低了免疫原性 之前项目期间的嵌合体T84.66，用于临床治疗 相当大一部分患者的试验表明，人类抗人 嵌合抗体(HACA)。因此，抗体的进一步人源化 可变区域是高度优先的。T84.66将使用 重铺路面方法：将保留FY的内部并 选定的表面残基将被诱变为匹配的保守表面 人体抗体的残留物。因此，这种方法很有可能 保留亲本抗体的高亲和力和特异性， 虽然免疫原性降低将允许多次给药 在临床试验中。其次，位点特异性结合的研究进展 抗体将允许精确控制疾病的位置和程度 放射性标记，导致可重复生产 具有高免疫反应性和低免疫原性的放射免疫结合物。 独特的半胱氨酸残基(提供活性硫醇基团)或N-连接 糖基化位点(提供以下反应醛基团 高碘酸氧化)将被引入到VL-V H- CH3“微型体”先前被证明是优秀的异种移植 瞄准目标。这些微型体将使用新的双官能团进行连接 项目3中开发的螯合剂。第三，融合为生物活性 多肽或抗原结合域将作为一种手段进行研究 增加肿瘤放射性标记抗体的积聚。这些措施包括： 抗CEA-γ-干扰素融合局部增强人肝癌细胞CEA抗原表达 肿瘤；抗CEA-IL-2融合局部增加血管 肿瘤部位的渗透性；以及双特异性抗CEA-抗TAG72 抗体片段可增加异质性肿瘤的整体摄取 两种抗原的表达。抗体-细胞因子的预治疗 融合应增强随后给药的肿瘤摄取 放射性标记抗体。通过双特异性片段靶向肿瘤将 与相应的单特异性试剂进行比较。这两者结合在一起 多学科的方法应该产生大量的放射免疫结合物 提高了疗效。

Molecular engineering of anti-CEA (carcinoembryonic antigen) antibodies will be undertaken in a effort to increase their utility in radioimmunotherapy and radioimmunoimaging of adenocarcinomas. Three critical areas in which protein engineering can improve the overall quality and performance of radiolabeled antibodies will be investigated. First, despite the reduction in immunogenicity achieved by production of chimeric T84.66 during the previous project period, in clinical therapy trials a substantial fraction of patients have demonstrated human anti- chimeric antibodies (HACA). Thus, further humanization of the antibody variable regions is of high priority. T84.66 will be humanized using a resurfacing approach: the interior of the Fy will be retained and selected surface residues will be mutagenized to matched conserved surface residues in human antibodies. Thus approach has a high likelihood of retaining the high affinity and specificity of the parental antibody, while reduced immunogenicity will allow administration of multiple doses in clinical trials. Secondly, development of site-specific conjugation of antibodies will allow precise control over the location and extent of radiolabeling, resulting in reproducible production of radioimmunoconjugates with high immunoreactivity and low immunogenicity. Unique cysteine residues (providing reactive thiol groups) or N-linked glycosylation sites (to provide reactive aldehyde groups following periodate oxidation) will be introduced into the CH3 domain of a VL-V H - CH3 "minibody" previously shown to demonstrate excellent xenograft targeting. these minibodies will be conjugated using novel bifunctional chelating agents developed in project 3. Thirdly, fusion to bioactive peptides or antigen-binding domains will be investigated as a means to increase tumor accretion of radiolabeled antibodies. These will include: an anti-CEA-gamma-IFN fusion to locally increase CEA antigen expression in the tumor; an anti-CEA-IL-2 fusion to locally increase vascular permeability at the tumor site; and a bispecific anti-CEA-anti-TAG72 antibody fragment to increase overall uptake in tumors with heterogeneous expression of both antigens. Preadministration of the antibody-cytokine fusions should enhance tumor uptake of subsequently administered radiolabeled antibodies. Tumor targeting by the bispecific fragment will be compared with the corresponding monospecific agent. This combined multidisciplinary approach should yield radioimmunoconjugates with greatly improved efficacy.