Molecules that contain two distinct antigen binding domains, bispecific antibodies, have shown promise as novel anti-cancer therapeutic agents. To date, such bispecific antibodies have been prepared by two methods. The fusion of two hybridoma cell lines, one of which produces an anti-tumor antibody and one which produces an anti-effector antibody and chemical conjugation of the antibody proteins. Both methods present significant problems for purification and production scale up of the bispecific antibody. We propose to circumvent these difficulties by the construction of a recombinant bispecific antibody like molecule as two genetically fused single chain variable regions (scFv). Individual variable region cDNA's will be used to construct the individual scFv genes which will be used to express the proteins. These genes will be used to construct a sequence encoding tow antibody variable regions joined by a peptide linker. We have chosen to construct an scFv with specificity for both erbB-2 and for CD-3, a T-cell surface antigen. A second bispecific scFv with specificity for two different epitopes on erbB-2 will also be constructed. Other bispecific scFvs are contemplated.
