Serum albumin binding immunoglobulin single variable domains

1. An immunoglobulin single variable domain (ISVD) capable of binding to serum albumin that comprises:

a CDR1 (according to Abm) that is the amino acid sequence GLTFSSYAMG (SEQ ID NO: 12); and

a CDR2 (according to Abm) that is the amino acid sequence SISRGGGYTY (SEQ ID NO: 13); and

a CDR3 (according to Abm) that is the amino acid sequence ARYWATGSEYEFDY (SEQ ID NO: 14),

optionally wherein the serum albumin is human serum albumin.

2. The ISVD according to claim 1 , that can bind to human serum albumin with an affinity better than 100 nM or better than 50 nM, as determined by surface plasmon resonance.

3. The ISVD according to claim 1 , that is a heavy-chain immunoglobulin single variable domain.

4. The ISVD according to claim 1 , that is a VHH, a humanized VHH or a camelized VH, optionally wherein the camelized VH is a camelized human VH.

5. The ISVD according to claim 1 , wherein the ISVD has a serum half-life in human (expressed as t1/2 beta) that is more than 6 hours, 12 hours, 24 hours, or 72 hours.

6. The ISVD according to claim 1 , that has:

a degree of sequence identity with the sequence of SEQ ID NO: 15 of at least 85%, at least 90%, or at least 95%; or that has:

no more than 7, no more than 5, no more than 3, no more than 2, or no more than 1 amino acid differences with the sequence of SEQ ID NO: 15;

wherein the CDRs are not taken into account for determining the degree of sequence identity or the amino acid differences.

7. The ISVD according to claim 1 , that is a VHH and that contains, compared to the sequence of SEQ ID NO:15, one or more humanizing substitutions.

8. An immunoglobulin single variable (ISVD) domain capable of binding to serum albumin and that is chosen from SEQ ID NO's: 15 to 77, optionally wherein the serum albumin is human serum albumin.

9. A polypeptide that comprises at least one ISVD according to claim 1 .

10. The polypeptide according to claim 9 , that comprises at least one therapeutic moiety or entity.

11. The polypeptide according to claim 9 , that is a fusion protein.

12. The polypeptide according to claim 9 , that has a serum half-life in human (expressed as t1/2 beta) that is more than 6 hours, more than 12 hours, more than 24 hours, or more than 72 hours.

13. The polypeptide according to claim 9 , wherein:

the polypeptide further comprises a C-terminal ISVD, wherein the C-terminal ISVD polypeptide comprises a C-terminal extension (X)n, wherein each X is an amino acid residue that is independently chosen from naturally occurring amino acid residues, and wherein n is 1-10; and/or

the polypeptide further comprises a N-terminal ISVD, wherein the N-terminal ISVD polypeptide comprises a D at position 1.

14. A pharmaceutical composition comprising a polypeptide according to claim 9 .

15. A nucleic acid that encodes an ISVD according to claim 1 , optionally wherein the nucleic acid is a genetic construct.

16. An expression vector that comprises the nucleic acid of claim 15 .

17. A host cell that comprises an expression vector according to claim 16 .

18. A method for preparing a polypeptide comprising cultivating or maintaining a host cell according to claim 17 under conditions such that said host cell produces or expresses the polypeptide, and optionally further comprising isolating the polypeptide.

19. The polypeptide according to claim 10 , that has a serum half-life in human (expressed as t1/2 beta) that is more than 6 hours, more than 12 hours, more than 24 hours, or more than 72 hours.

20. The ISVD according to claim 1 , wherein the ISVD cross-blocks the binding of the amino acid sequence of SEQ ID NO: 15 to human serum albumin.