title: Humanization and molecular modeling of the anti-CD4 monoclonal antibody, OKT4A.
abstract: OKT4A, a murine mAb that recognizes an epitope on the CD4 receptor, is a potent immunosuppressive agent in vitro and in a variety of nonhuman primate models of graft rejection and autoimmune disease. Initial human cardiac transplant trials suggest that OKT4A does not cause either cytokine release syndrome or CD4+ cell depletion, but does induce a human anti-mouse Ab (HAMA) response despite strong concurrent immunosuppression. To further investigate the potential of OKT4A as an immunomodulator, it was necessary to decrease its immunogenicity. Therefore, we developed a humanized version of this Ab (gOKT4A-4), which has the same binding affinity and in vitro immunosuppressive properties of OKT4A, but retains only three murine sequence-derived amino acid residues outside of the complementarity-determining regions (CDRs). Detailed computer modeling of both OKT4A and gOKT4A-4 provided a computational rationale for the changes necessary to regain activity after humanization. This has also provided a plausible representation of the Ag binding site. Preliminary clinical results with gOKT4A-4 suggest that we have eliminated the immunogenicity observed in the parent murine Ab.
authors.affiliation: Drug Discovery, R.W. Johnson Pharmaceutical Research Institute, Raritan, NJ 08869, USA.
authors.forename: V L
authors.initials: VL
authors.lastname: Pulito
authors.forename: V A
authors.initials: VA
authors.lastname: Roberts
authors.forename: J R
authors.initials: JR
authors.lastname: Adair
authors.forename: A L
authors.initials: AL
authors.lastname: Rothermel
authors.forename: A M
authors.initials: AM
authors.lastname: Collins
authors.forename: S S
authors.initials: SS
authors.lastname: Varga
authors.forename: C
authors.initials: C
authors.lastname: Martocello
authors.forename: M
authors.initials: M
authors.lastname: Bodmer
authors.forename: L K
authors.initials: LK
authors.lastname: Jolliffe
authors.forename: R A
authors.initials: RA
authors.lastname: Zivin
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification; D000915:Antibody Affinity / Q000235:genetics; D015704:CD4 Antigens / Q000276:immunology*; D003001:Cloning, Molecular; D003198:Computer Simulation; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics / Q000302:isolation & purification; D007147:Immunoglobulin Light Chains / Q000235:genetics / Q000302:isolation & purification; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000737:chemistry* / Q000302:isolation & purification; D013045:Species Specificity
chemical_list: D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; C079851:OKT4A monoclonal antibody; D011993:Recombinant Fusion Proteins