Humanized antibody against human tissue factor (TF) and process of production of the humanized antibody
A humanized antibody against tissue factor (TF), comprising: A: a humanized H chain comprising (1) a H chain V region comprising the H chain CDRs of a mouse monoclonal antibody against TF and the H chain FRs of a human antibody, and (2) the H chain C region of a human antibody; and B: a humanized L chain comprising (1) an L chain V region comprising the L chain CDRs of a mouse monoclonal antibody against TF and the L chain FRs of a human antibody, and (2) the L chain C region of a human antibody. After generating a humanized V region by grafting the CDRs of a mouse monoclonal antibody onto a human antibody, a humanized antibody having a higher activity is searched by replacing the FR of the above region with the corresponding FR of the human antibody having a high homology.
1. A process of preparing a natural humanized antibody that has complementarity determining regions (CDRs) derived from non-humans and a framework region (FR) derived from a natural human antibody and that has a reduced immunogenicity, said method comprising the steps of:
(1) preparing a non-human monoclonal antibody responsive to an antigen of interest;
(2) preparing a plurality of human antibodies having a high homology with the amino acid sequences of FRs of heavy chain (H chain) or light chain (L chain) in the monoclonal antibodies of the step (1);
(3) preparing a first humanized antibody by steps comprising:
a) replacing all FRs of H chain of the non-human antibody prepared in step (1) with corresponding FRs H chain of one human antibody prepared in step (2);
b) replacing all FRs of L chain of the non-human antibody prepared in step (1) with corresponding FRs of L chain of one human antibody prepared in step (2); and
c) changing constant region of the non-human antibody prepared in step (1) to constant region of a human antibody;
(4) generating second antibodies by:
a) in an H chain V region of the first humanized antibody prepared on said (3)a), replacing 1 to 3 FRs having at least one of FR2 and FR3, with corresponding FRs of a human antibody different from the antibody used in (3)a) selected from the human antibodies prepared in the step (2);
b) in an L chain V region of the first humanized antibody prepared on said (3)b), replacing 1 to 3 FRs having at least one of FR2 and FR3, with corresponding FRs of a human antibody different from the antibody used in (3)b) selected from the human antibodies prepared in the step (2); and
c) obtaining a second humanized antibody comprising an H chain obtained in a), an L chain obtained in b, and a constant region of a human antibody in (3)c);
(5) determining ability of the first and the second humanized antibodies to bind to the antigen or ability of the first and the second humanized antibodies to neutralize a biological activity of the antigen;
(6) comparing the ability of the first and the second antibodies determined in step (5), and selecting antibodies which have a higher antigen binding ability or higher ability to neutralize a biological activity of an antigen; and
(7) repeating the steps of (4) to (6) while using the antibody selected in step (6) as a first humanized antibody in step (4) until a humanized antibody is selected having the same level or more of ability as the non-human monoclonal antibody in step (1), wherein said ability is to bind to the antigen or to neutralize a biological activity of the antigen.
2. The process according to claim 1 , in which said antigen of interest is human tissue factor (TF).
3. The process according to claim 1 , wherein said FRs to be replaced contain FR2 and FR3.
4. A process for production of a natural humanized antibody, comprising the steps of isolating nucleic acid encoding a natural humanized antibody obtainable by a process according to claim 1 , and introducing the nucleic acid into a host cell, and culturing the host cell so as to obtain the natural humanized antibody.
5. A process according to 4 , further comprising the steps of introducing the nucleic acid into an expression vector, and introducing the expression vector into a host cell.