Ligand

Abstract

The invention provides a dual-specific ligand comprising a first immunoglobulin variable domain having a first binding specificity and a complementary or non-complementary immunoglobulin variable domain having a second binding specificity.

What we claim is: 
     
         1 . An isolated ligand comprising an antibody single variable domain comprising an amino acid sequence selected from the group consisting of: SEQ ID NO: 232 (dAb7h11) and an amino acid sequence that is at least 95% identical to SEQ ID NO: 232,
 wherein at least one of said antibody single variable domains is an antibody single variable domain that specifically binds serum albumin.   
     
     
         2 . The isolated ligand of  claim 1 , wherein said at least one antibody single variable domain that specifically binds serum albumin binds to Domain II of serum albumin. 
     
     
         3 . The isolated ligand of  claim 2 , wherein said ligand comprises a monomer antibody single variable domain which specifically binds to Domain II of serum albumin. 
     
     
         4 . The isolated ligand of  claim 3 , wherein said monomer antibody single variable domain is conjugated to a drug. 
     
     
         5 . The isolated ligand of  claim 2 , wherein said ligand is a dual specific ligand, wherein said dual specific ligand comprises a first antibody single variable domain, wherein said first antibody single variable domain specifically binds to Domain II of serum albumin. 
     
     
         6 . The isolated ligand of  claim 5 , wherein said dual specific ligand further comprises a second antibody single variable domain, wherein said second antibody single variable domain specifically binds a target other than serum albumin. 
     
     
         7 . An IgG comprising the dual-specific ligand of  claim 6 , wherein said IgG comprises four antibody single variable domains. 
     
     
         8 . The isolated ligand of  claim 1 , wherein said antibody single variable domain comprises a set of four Kabat antibody framework regions (FRs), said set being encoded by human framework germ line antibody gene segments. 
     
     
         9 . An isolated ligand comprising at least one antibody single variable domain which that specifically binds serum albumin and also competes for binding to serum albumin with an antibody single variable domain which comprises the amino acid sequence of an antibody single variable domain of SEQ ID NO: 232 (dAb7h11). 
     
     
         10 . The isolated ligand of  claim 6 , wherein said second antibody single variable domain is selected from the group consisting of: cytokines, cytokine receptors, enzymes, enzyme co-factors and DNA binding proteins, wherein said second antibody single variable domain specifically binds a target other than serum albumin. 
     
     
         11 . The isolated ligand of  claim 9 , wherein said ligand is a dual specific ligand, wherein said dual specific ligand comprises said antibody single variable domain that specifically binds serum albumin and a second antibody single variable domain, wherein said second antibody single variable domain specifically binds a target other than serum albumin. 
     
     
         12 . The isolated ligand according to  claim 1 , wherein at least one of said antibody single variable domains specifically binds an epitope or antigen with a dissociation constant (Kd) selected from the group consisting of: 1×10 −3  M or less, 1×10 −4 M or less, 1×10 −5  M or less, 1×10 −6 M or less, 1×10 −7 M or less, 1×10 −8  M or less, and 1×10 −9  M or less, as determined by surface plasmon resonance. 
     
     
         13 . The isolated ligand of  claim 1 , wherein said ligand is a dual specific ligand, wherein said dual specific ligand comprises said antibody single variable domain that specifically binds serum albumin and a second antibody single variable domain, wherein said second antibody single variable domain specifically binds a target other than serum albumin. 
     
     
         14 . The isolated ligand according to  claim 1 , wherein said ligand further comprises at least one entity selected from the group consisting of: a label, a tag and a drug. 
     
     
         15 . A composition comprising the isolated ligand according to  claim 1 , and a carrier thereof. 
     
     
         16 . The isolated ligand according to  claim 6 , wherein said ligand is a dual specific ligand, and wherein:
 a. each of said antibody single variable domains that specifically binds serum albumin and said antibody single variable domain that specifically binds a target other than serum albumin, is an antibody heavy chain single variable domain; or   b. each of said antibody single variable domains that specifically binds serum albumin and said antibody single variable domains that specifically binds a target other than serum albumin, is an antibody light chain single variable domain; or   c. said antibody single variable domain that specifically binds serum albumin is an antibody heavy chain single variable domain, and said antibody single variable domain that specifically binds a target other than serum albumin is an antibody light chain single variable domain; or   d. said antibody single variable domain that specifically binds serum albumin is an antibody light chain single variable domain, and said antibody single variable domain that specifically binds a target other than serum albumin is an antibody heavy chain single variable domain.   
     
     
         17 . The isolated ligand of any one of the claims according to  claim 6 , wherein said ligand is a dual specific ligand, and wherein:
 a. each of said antibody single variable domains that specifically binds to Domain II of serum albumin and said antibody single variable domains that specifically binds a target other than serum albumin, is an antibody heavy chain single variable domain; or   b. each of said antibody single variable domain that specifically binds to Domain II of serum albumin and said antibody single variable domain that specifically binds a target other than serum albumin, is an antibody light chain single variable domain; or   c. said antibody single variable domain that specifically binds to Domain II of serum albumin is an antibody heavy chain single variable domain, and said antibody single variable domain that specifically binds an antigen other than serum albumin is an antibody light chain single variable domain; or   d. said antibody single variable domain that specifically binds to Domain II of serum albumin is an antibody light chain single variable domain, and said antibody single variable domain that specifically binds an antigen other than serum albumin is an antibody heavy chain single variable domain.   
     
     
         18 . The isolated ligand of  claim 9 , wherein said at least one antibody single variable domain that specifically binds serum albumin binds to Domain II of serum albumin.