Russoniello C, Somasundaram C, Schlom J, Deo Y M, Keler T
Medarex, Inc., Annandale, New Jersey 08801, USA.
Clin Cancer Res. 1998 Sep;4(9):2237-43.
A bispecific antibody was made by chemical conjugation of Fab' fragments from humanized antibodies specific for tumor-associated glycoprotein-72 (TAG-72) and high-affinity immunoglobulin receptor, FcgammaA receptor type I (FcgammaRI). The purified anti-TAG-72 x anti-FcgammaRI (HCC49xH22) bispecific antibody had an approximate Mr of 111,000, consistent with a F(ab')2, and bound specifically to KLEB and LS174T tumor cell lines, which express the TAG-72 tumor antigen. Furthermore, HCC49x H22 was shown to simultaneously bind to KLEB cells and a soluble FcgammaRI fusion protein, demonstrating the bifunctional nature of the molecule. Using IFN-gamma-treated monocytes as effector cells, concentrations of the bispecific antibody in the range of 1-10,000 ng/ml mediated specific lysis of TAG-72-positive tumor cells. In contrast, the bispecific antibody did not promote antibody-dependent cellular cytotoxicity of a cell line that was negative for TAG-72 antigen. Importantly, the antibody-dependent cellular cytotoxicity activity of the bispecific antibody was significantly greater than that of the monoclonal antibody HCC49. These in vitro data indicate that the humanized bispecific antibody HCC49xH22 has the appropriate specificity and functional activity for further evaluation as potential immunotherapy for TAG-72-positive malignancies.
通过将针对肿瘤相关糖蛋白72（TAG - 72）的人源化抗体的Fab'片段与高亲和力免疫球蛋白受体I型FcγA受体（FcγRI）进行化学偶联，制备了一种双特异性抗体。纯化后的抗TAG - 72×抗FcγRI（HCC49×H22）双特异性抗体的相对分子质量约为111,000，与F(ab')2一致，并且能特异性结合表达TAG - 72肿瘤抗原的KLEB和LS174T肿瘤细胞系。此外，HCC49×H22被证明能同时结合KLEB细胞和可溶性FcγRI融合蛋白，证明了该分子的双功能性质。以经IFN - γ处理的单核细胞作为效应细胞，浓度在1 - 10,000 ng/ml范围内的双特异性抗体介导了TAG - 72阳性肿瘤细胞的特异性裂解。相比之下，双特异性抗体并未促进TAG - 72抗原阴性细胞系的抗体依赖性细胞毒性。重要的是，双特异性抗体的抗体依赖性细胞毒性活性显著高于单克隆抗体HCC49。这些体外数据表明，人源化双特异性抗体HCC49×H22具有适当的特异性和功能活性，可作为TAG - 72阳性恶性肿瘤潜在免疫疗法进行进一步评估。
