Piccoli R, Olson K A, Vallee B L, Fett J W
Center for Biochemical and Biophysical Sciences and Medicine, Harvard Medical School, 250 Longwood Avenue, Boston, MA 02115, USA.
Proc Natl Acad Sci U S A. 1998 Apr 14;95(8):4579-83. doi: 10.1073/pnas.95.8.4579.
Angiogenin (Ang), an inducer of neovascularization, is secreted by several types of human tumor cells and appears critical for their growth. The murine anti-Ang monoclonal antibody (mAb) 26-2F neutralizes the activities of Ang and dramatically prevents the establishment and metastatic dissemination of human tumor cell xenografts in athymic mice. However, for use clinically, the well-documented problem of the human anti-globulin antibody response known to occur with murine antibodies requires resolution. As a result, chimeric as well as totally humanized antibodies are currently being evaluated as therapeutic agents for the treatment of several pathological conditions, including malignancy. Therefore, we have constructed a chimeric mouse/human antibody based on the structure of mAb 26-2F. Complementary DNAs from the light and heavy chain variable regions of mAb 26-2F were cloned, sequenced, and genetically engineered by PCR for subcloning into expression vectors that contain human constant region sequences. Transfection of these vectors into nonproducing mouse myeloma cells resulted in the secretion of fully assembled tetrameric molecules. The chimeric antibody (cAb 26-2F) binds to Ang and inhibits its ribonucleolytic and angiogenic activities as potently as mAb 26-2F. Furthermore, the capacities of cAb 26-2F and its murine counterpart to suppress the formation of human breast cancer tumors in athymic mice are indistinguishable. Thus cAb 26-2F, with its retained neutralization capability and likely decreased immunogenicity, may be of use clinically for the treatment of human cancer and related disorders where pathological angiogenesis is a component.
血管生成素（Ang）是一种新血管形成诱导剂，由多种人类肿瘤细胞分泌，对肿瘤生长至关重要。鼠抗Ang单克隆抗体（mAb）26 - 2F可中和Ang的活性，并显著抑制人类肿瘤细胞异种移植瘤在无胸腺小鼠体内的形成和转移扩散。然而，在临床应用中，鼠源抗体已知会引发人抗球蛋白抗体反应这一有充分记录的问题需要解决。因此，嵌合抗体以及完全人源化抗体目前正在作为治疗包括恶性肿瘤在内的多种病理状况的治疗剂进行评估。为此，我们基于mAb 26 - 2F的结构构建了一种嵌合小鼠/人抗体。克隆了mAb 26 - 2F轻链和重链可变区的互补DNA，进行测序，并通过PCR进行基因工程改造，以便亚克隆到包含人类恒定区序列的表达载体中。将这些载体转染到不产生抗体的小鼠骨髓瘤细胞中，导致分泌出完全组装的四聚体分子。嵌合抗体（cAb 26 - 2F）与Ang结合，并像mAb 26 - 2F一样有效地抑制其核糖核酸酶活性和血管生成活性。此外，cAb 26 - 2F及其鼠源对应物在抑制无胸腺小鼠体内人乳腺癌肿瘤形成方面的能力没有差异。因此，cAb 26 - 2F保留了中和能力且可能免疫原性降低，在临床上可能用于治疗人类癌症及相关疾病，其中病理性血管生成是一个组成部分。
