Humanization and molecular modeling of the anti-CD4 monoclonal antibody, OKT4A.
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.
Pulito
V L
VL
Drug Discovery, R.W. Johnson Pharmaceutical Research Institute, Raritan, NJ 08869, USA.
Roberts
V A
VA
Adair
J R
JR
Rothermel
A L
AL
Collins
A M
AM
Varga
S S
SS
Martocello
C
C
Bodmer
M
M
Jolliffe
L K
LK
Zivin
R A
RA
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
D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; C079851:OKT4A monoclonal antibody; D011993:Recombinant Fusion Proteins