Bispecific antibodies: design, therapy, perspectives

Sedykh, Sergey E; Prinz, Victor V; Buneva, Valentina N; Nevinsky, Georgy A

Sedykh et al increases significantly after attachment to HL fragments. CVX241 BsAbs were produced by the addition of two short peptides that inhibited VEGF or angiopoietin 2 with a branched linker and then with the Abs. 82 However, the clinical trials of CVX241 were terminated ahead of schedule, due to a lack of pharmacological effect. 2 Chemical conjugation of Abs against CD3 and CD20 (rituximab) was used to obtain T cells with BsAb-coated surfaces. 83 Autologous polyclonal activated T lymphocytes were generated by the surface localization of antigen-binding sites against a CD20 receptor. Such cells in the first phase of clinical trials were administered after high-dose chemotherapy and transplantation of peripheral blood stem cells. Injections increased natural and specific cellular response in refractory non-Hodgkin's lymphoma. 84 IMCgp100, developed by ImmTAC technology, contains a single-chain anti-CD3 mAb with an attached mature T-cell receptor that recognizes peptides of human leukocyte antigen. The drug is now undergoing clinical trials against metastatic melanoma. 85 IMCgp100 directs and activates CD8 and CD4 + effector cells and memory cells, 86 and then after the death of melanoma cells, its antigens are presented by dendritic cells. 87 The dock-and-lock method allows the production of polyvalent, multispecific, and multifunctional constructs. 88, 89 The linker covalently bonds the first Fab to the dimerization and docking domain of cAMP-dependent protein kinase (contains a sulfhydryl group), and the second Fab bonds to the anchoring domain of A-kinase (contains two sulfhydryl groups). The interaction of the two cAMP-dependent proteinkinase domains results in the dimerization of the structures carrying Fab, and then the resulting fragment binds to the protein A-kinase domain bearing the third Fab. Further, the formation of disulfide bonds covalently stabilizes the triple construction. 88, 90 The trifunctional constructs containing four cytokine IFNα 2b molecules linked to the anti-CD20 Ab (veltuzumab) are effective in non-Hodgkin's lymphoma and multiple myeloma. 91, 92 The hexavalent construct containing BsAbs against CD20 and CD22 (veltuzumab and epratuzumab) penetrates lipid rafts, stimulates apoptosis, and inhibits tumor growth. 90 A hexavalent construct composed of anti-CD22 and anti-CD19 BsAbs (epratuzumab, hA19) enhances the formation of the immunological synapse and trogocytosis (transmission of antigens) of CD19, CD20, CD21, and CD22 between B lymphocytes and antigen-presenting cells and represents a candidate molecule for the treatment of autoimmune diseases. 93 Another construct containing a single-chain anti-CD3 Ab covalently bounds the antitumor Fab dimer; bispecific binding of the BsAb to tumor cells and further to T cells results in antitumor T-cell cytotoxicity. 94 Therapeutic Ab fragments (scFv, diabody) may be fused with albumin 95 or proteins that bind albumin, 96 which increases the half-life of the drug in the blood up to five to six times. The construction of such molecules gives unpredictable results, thereby BsAbs generated as the result of different Ab-fragment fusion or binding of Abs to other proteins have limited application in research and development of new therapeutic molecules. Formats of BsAb generation based on Ab or Ab-fragment conjugation today are not used, because of the possibility of stable fusion recombinant protein generation. 2 Protein, cellular, and genetic engineering Coexpression o