Chimeric Bispecific OC/TR Monoclonal Antibody Mediates Lysis of Tumor Cells Expressing the Folate-Binding Protein (MOv18) and Displays Decreased Immunogenicity in Patients

• DOI: 10.1097/00002371-199711000-00010
• Publication Date: 2006-10-09T11:14:29Z
• Authors: Rosalie M. Luiten; Sven O. Warnaar; David Sanborn; Cornelis H. J. La...; Reinder L. H. Bol...; Sergey V. Litvinov; Vincent R. Zurawski; Leslie R. Coney
• Keywords: Cytotoxicity, Immunologic; Ovarian Neoplasms; 0301 basic medicine; Hybridomas; CD3 Complex; Recombinant Fusion Proteins; T-Lymphocytes; Folate Receptors, GPI-Anchored; Antibodies, Monoclonal; Gene Expression; Receptors, Cell Surface; Antibodies, Anti-Idiotypic; Cell Line; 3. Good health; Immunoglobulin Fab Fragments; Mice; 03 medical and health sciences; Antibodies, Bispecific; Animals; Humans; Female; Immunotherapy; Carrier Proteins; EMC 04-01-DD-12-01

The bispecific OC/TR monoclonal antibody (mAb) cross-links the CD3 molecule on T cells with the human folate-binding protein (FBP), which is highly expressed on nonmucinous ovarian carcinomas. Clinical trials of patients with ovarian carcinoma with the OC/TR mAb have shown some complete and partial responses. Most patients developed human anti-murine immunoglobulin antibodies (HAMA), which can inhibit OC/TR mAb-mediated lysis. We generated a chimeric version of the OC/TR mAb to decrease the immunogenicity of the OC/TR mAb and to allow more extended treatment schedules. Sp2/0 myeloma cells were transfected with chimeric heavy- and light-chain genes encoding the anti-CD3 mAb and the MOv18 mAb, respectively, which are reactive with FBP. The resulting cell line produced 80 micrograms/ml of total immunoglobulin G (IgG), of which 11.5% was the functionally active chimeric OC/TR mAb. Chimeric OC/TR F(ab')2 fragments mediated lysis of IGROV-1 ovarian carcinoma cells by human T cells at antibody concentrations of > or = 1 pg/ml. Specific lysis was still detectable at an effector-to-target cell ratio as low as 0.4. Two patients with ovarian carcinoma treated with F(ab')2 fragments of the murine OC/TR developed distinct HAMA titers, which were mainly anti-idiotypic and only partly directed against the murine antibody constant regions. However, of the two patients that were treated with the F(ab')2 fragments of the chimeric OC/TR mAb, only one developed a low transient HAMA response just above background level. In conclusion, the generation of chimeric OC/TR may allow more extended clinical studies of bispecific mAb-mediated immunotherapy of ovarian carcinoma.