Her2 targeting agent

Abstract

An antibody that binds to HER2 expressed on a cancer cell or a fragment of the HER2, or an antigen binding fragment thereof are disclosed. Uses of the antibody or antigen binding fragment thereof are disclosed. The antibody or antigen binding fragment thereof is useful to target a HER2 expressing cancer cells. A-pharmaceutical composition containing the antibody or antigen binding fragment thereof is also disclosed.

1 . An isolated antibody or antigen-binding fragment thereof, said antibody or antigen binding fragment having a stronger binding affinity to HER2 expressed on a cancer cell than to HER2 expressed on a non-cancer cell. 
     
     
         2 . The antibody or antigen-binding fragment thereof according to  claim 1 , which specifically binds to a peptide that comprises any amino acid sequence selected from the group consisting of the amino acid sequences of SEQ ID NOs: 31 to 37. 
     
     
         3 . The antibody or antigen-binding fragment thereof according to  claim 1 , which has stronger binding affinity to a peptide consisting of an extracellular domain of HER2 than to a variant of the extracellular domain of HER2 having one or more amino acid mutations, and
 wherein the extracellular domain of HER2 consists of the amino acid sequence of from position 23 to position 652, both inclusive, of SEQ ID NO: 2, and   wherein the one or more amino acid mutations are selected from the group consisting of W614A, K615A, and F616A with respect to SEQ ID NO: 2.   
     
     
         4 . The antibody or antigen-binding fragment thereof according to  claim 1 , comprising:
 (i) a heavy chain variable region comprising   a heavy chain CDR1 comprising the amino acid sequence of SEQ ID NO: 18,   a heavy chain CDR2 comprising the amino acid sequence of SEQ ID NO: 19, and   a heavy chain CDR3 comprising the amino acid sequence of SEQ ID NO: 20, as well as   a light chain variable region comprising   a light chain CDR1 comprising the amino acid sequence of SEQ ID NO: 21,   a light chain CDR2 comprising the amino acid sequence of SEQ ID NO: 22, and   a light chain CDR3 comprising the amino acid sequence of SEQ ID NO: 23;   (ii) a heavy chain variable region comprising   a heavy chain CDR1 comprising the amino acid sequence of SEQ ID NO: 24,   a heavy chain CDR2 comprising the amino acid sequence of SEQ ID NO: 25, and   a heavy chain CDR3 comprising the amino acid sequence of SEQ ID NO: 26, as well as   a light chain variable region comprising   a light chain CDR1 comprising the amino acid sequence of SEQ ID NO: 27,   a light chain CDR2 comprising the amino acid sequence of SEQ ID NO: 28, and   a light chain CDR3 comprising the amino acid sequence of SEQ ID NO: 29; or   (iii) a variant of (i) or (ii), in which one or more of the CDRs have at least one substitution, addition, or deletion.   
     
     
         5 . The antibody or antigen-binding fragment thereof according to  claim 1 , comprising:
 (a) a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 14, and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 15;   (b) a heavy chain variable region comprising the amino acid sequence of SEQ ID NO: 16, and a light chain variable region comprising the amino acid sequence of SEQ ID NO: 17; or   (c) a variant of (a) or (b), in which each of the variable regions has at least one substitution, addition, or deletion.   
     
     
         6 . The antibody or antigen-binding fragment thereof according to  claim 1 , which is capable of specifically binding to a peptide that is produced by LN229 cells of a glioblastoma cell line and consists of the extracellular domain of HER2, said extracellular domain of HER2 consisting of the amino acid sequence of from position 23 to position 652, both inclusive, of SEQ ID NO: 2. 
     
     
         7 . The antibody or antigen-binding fragment thereof according to 1, wherein the cancer cell is an SK-BR-3 cell of a breast cancer cell line, and the non-cancer cell is an HaCaT cell of a normal human epidermal keratinocyte cell line. 
     
     
         8 . A pharmaceutical composition comprising, as an active ingredient, the antibody or antigen-binding fragment thereof according to  claim 1 . 
     
     
         9 . The antibody or antigen-binding fragment thereof according to  claim 1 , conjugated with a cytotoxic agent. 
     
     
         10 . A pharmaceutical composition comprising, as an active ingredient, the antibody or antigen-binding fragment thereof according to  claim 9 . 
     
     
         11 . (canceled) 
     
     
         12 . A method for treating cancer in a subject in need thereof; comprising administering an effective amount of a pharmaceutical compostions comprising the antibody or antigen-binding fragment thereof according to  claim 1 . 
     
     
         13 . A nucleic acid molecule encoding the antibody or antigen-binding fragment thereof according to  claim 2 . 
     
     
         14 . A method for producing, selecting or identifying the antibody or an antigen-binding fragment thereof according to  claim 1 , the method comprising:
 producing, selecting or identifying an antibody or an antigen-binding fragment of an antibody that does not significantly react to HER2 expressed on a non-cancer cell, but can specifically react to HER2 expressed on a cancer cell, from a population of antibodies or antigen-binding fragments thereof that bind to HER2 or a fragment of HER2.   
     
     
         15 . A method for producing, selecting or identifying an antibody or an antigen-binding fragment thereof according to  claim 1 , the method comprising:
 producing, selecting or identifying an antibody or an antigen-binding fragment thereof of an antibody that satisfies at least one selected from the group consisting of (i) to (iii) below, from a population of antibodies or antigen-binding fragments thereof that bind to HER2 or a fragment of HER2;   (i) binding to a peptide that comprises any amino acid sequence selected from the group consisting of the amino acid sequences of SEQ ID NOs: 31 to 37;
 (ii) having a stronger affinity to a peptide consisting of an extracellular domain of HER2 than to a variant of the extracellular domain of HER2 having one or more amino acid mutations, 
 wherein the extracellular domain of HER2 consists of the amino acid sequence of from position 23 to positon 652, both inclusive, of SEQ ID NO: 2, and 
 wherein the one or more amino acid mutations are selected from the group consisting of W614A, K615A, and F616A with respect to SEQ ID NO: 2; and 
   (iii) having a stronger affinity to HER2 expressed on a cancer cell than to HER2 expressed on a non-cancer cell.   
     
     
         16 . A method for producing, selecting or identifying the antibody or an antigen-binding fragment thereof according to  claim 1 , the method comprising:
 producing, selecting or identifying an antibody or antigen-binding fragment thereof that binds to HER2 or a fragment HER2, from a population of antibodies or antigen-binding fragments thereof that satisfy at least one selected from the group consisting of (i) to (ii) below:   (i) binding to a peptide that comprises any amino acid sequence selected from the group consisting of the amino acid sequences of SEQ ID NOs: 31 to 37; and
 (ii) having a stronger affinity to a peptide consisting of an extracellular domain of HER2 than to a peptide having one or more amino acid mutations, and 
 wherein the extracellular domain of HER2 consists of the amino acid sequence of the position 23 to position 652, both inclusive, of SEQ ID NO: 2, and 
 wherein the one or more amino acid mutations are selected from the group consisting of W614A, K615A, and F616A with respect to SEQ ID NO: 2. 
   
     
     
         17 . The method according to  claim 15 , further comprising producing, selecting or identifying an antibody or an antigen-binding fragment of an antibody that does not significantly react to HER2 expressed on a non-cancer cell, but can specifically react to HER2 expressed on a cancer cell, from the population of the antibodies or a population of antigen-binding fragments of the antibodies, obtained in step (ii). 
     
     
         18 . A method for producing, selecting or identifying an antibody or the antigen-binding fragment thereof according to  claim 1 , the method comprising:
 producing, selecting or identifying an antibody or an antigen-binding fragment thereof that does not significantly react to HER2 expressed on a non-cancer cell, but can specifically react to HER2 expressed on a cancer cell, from a population of antibodies or antigen-binding fragments thereof that have at least one or more amino acid mutations selected from the group consisting of substitutions, additions, insertions, and deletions in at least one of the following CDRs;   (iii) a heavy chain variable region comprising
 a heavy chain CDR1 comprising the amino acid sequence of SEQ ID NO: 18, 
 a heavy chain CDR2 comprising the amino acid sequence of SEQ ID NO: 19, and 
 a heavy chain CDR3 comprising the amino acid sequence of SEQ ID NO: 20, as well as 
   a light chain variable region comprising
 a light chain CDR1 comprising the amino acid sequence of SEQ ID NO: 21, 
 a light chain CDR2 comprising the amino acid sequence of SEQ ID NO: 22, and 
 a light chain CDR3 comprising the amino acid sequence of SEQ ID NO: 23, 
   (iv) a heavy chain variable region comprising
 a heavy chain CDR1 comprising the amino acid sequence of SEQ ID NO: 24, 
 a heavy chain CDR2 comprising the amino acid sequence of SEQ ID NO: 25, and 
 a heavy chain CDR3 comprising the amino acid sequence of SEQ ID NO: 26, as well as 
   a light chain variable region comprising
 a light chain CDR1 comprising the amino acid sequence of SEQ ID NO: 27, 
 a light chain CDR2 comprising the amino acid sequence of SEQ ID NO: 28, and 
 a light chain CDR3 comprising the amino acid sequence of SEQ ID NO: 29.