Immunoglobulin variable domains
VH domain, in which: (i) the amino acid residue at position 1 12 is one of K or Q; and/or (ii) the amino acid residue at position 89 is T; and/or (iii) the amino acid residue at position 89 is L and the amino acid residue at position 1 10 is one of K or Q; and (iv) in each of cases (i) to (hi), the amino acid at position 1 1 is preferably V; and in which said VH domain contains a C-terminal extension (X)n, in which n is 1 to 10, preferably 1 to 5, such as 1, 2, 3, 4 or 5 (and preferably 1 or 2, such as 1); and each X is an (preferably naturally occurring) amino acid residue that is independently chosen, and preferably independently chosen from the group consisting of alanine (A), glycine (G), valine (V), leucine (L) or isoleucine (I).
1. A heavy chain immunoglobulin single variable domain (ISVD) in which the amino acid residue at Kabat position 89 is L and the amino acid at Kabat position 11 is V,
wherein the heavy chain ISVD specifically binds to OX40L and comprises four framework regions (FW1, FW2, FW3 and FW4) and three CDRs (CDR1, CDR2 and CDR3), wherein CDR1 comprises the sequence of SEQ ID NO: 209; CDR2 comprises the sequence of SEQ ID NO: 210; and CDR3 comprises the sequence of SEQ ID NO: 211.
2. The heavy chain ISVD according to claim 1 , wherein the C-terminal end of the heavy chain ISVD comprises an amino acid sequence selected from the group consisting of: VTVSS (SEQ ID NO:76), VKVSS (SEQ ID NO: 95), and VQVSS (SEQ ID NO: 96).
3. A fusion polypeptide comprising a heavy chain ISVD according to claim 1 fused to an additional heavy chain ISVD.
4. The fusion polypeptide according to claim 3 , wherein the additional heavy chain ISVD specifically binds to serum albumin.
5. The fusion polypeptide according to claim 4 , wherein the additional heavy chain ISVD has at least 90% sequence identity with Alb-8 (SEQ ID NO:46) or Alb-23 (SEQ ID NO:61).
6. The fusion polypeptide according to claim 4 , wherein the additional heavy chain ISVD comprises a CDR1, CDR2, and CDR3 in which:
CDR1 comprises the amino acid sequence SFGMS (SEQ ID NO:41);
CDR2 comprises the amino acid sequence SISGSGSDTLYADSVKG (SEQ ID NO:42); and
CDR3 comprises the amino acid sequence GGSLSR (SEQ ID NO:43).
7. The heavy chain ISVD according to claim 1 , in which:
the amino acid residue at Kabat position 14 is selected from the group consisting of A or P;
the amino acid residue at Kabat position 41 is selected from the group consisting of A or P;
the amino acid residue at Kabat position 108 is selected from the group consisting of Q or L; and
the amino acid residue at Kabat position 110 is selected from the group consisting of T or Q.
8. A composition comprising a fusion polypeptide according to claim 3 , and further comprising at least one pharmaceutically acceptable carrier, diluent or excipient.
9. The heavy chain ISVD according to claim 1 , which is a VHH domain, a humanized VHH domain, or a camelized VH domain.
10. The fusion polypeptide according to claim 3 , wherein the heavy chain ISVDs are linked directly or via a suitable linker.