Modified polypeptides for bispecific antibody scaffolds

1. A bispecific antibody comprising:

(a) an Fc region comprising a modified heavy chain, wherein the CH1 region of the modified heavy chain comprises

(i) a substitution of a native cysteine to a non-cysteine amino acid, and

(ii) a substitution of a native non-cysteine amino acid to a cysteine amino acid;

(b) a modified corresponding light chain, wherein the CL region of the modified light chain comprises

(i) a substitution of a native cysteine to a non-cysteine amino acid, and

(ii) a substitution of a native non-cysteine amino acid to a cysteine amino acid;

(c) a second Fc region comprising a second heavy chain; and

(d) a second corresponding light chain,

wherein the modified heavy chain is directly linked to the corresponding modified light chain, and on a separate target binding arm, the second heavy chain is directly linked to the second corresponding light chain, and

wherein the substituted cysteine of the modified heavy chain, resulting from the substitution of the native non-cysteine amino acid to the cysteine amino acid, and the substituted cysteine of the modified corresponding light chain, resulting from the substitution of the native non-cysteine amino acid to the cysteine amino acid, can form a disulphide bond, wherein the substitutions in the modified heavy chain and modified corresponding light chain are selected from the group consisting of variants V10, V10-2a, V10-2b, V10-3, V10-4, V11, V11-2a, V11-2b, V11-3, V11-4, V12, V12-2a, V12-2b, V12-3 and V12- 4 as provided in Table 4.

2. The bispecific antibody of claim 1 , wherein

(a) the second heavy chain and second corresponding light chain do not comprise a substitution of a native non-cysteine amino acid to a cysteine amino acid and do not comprise a substitution of a native cysteine to a non-cysteine amino acid; and/or

(b) the two light chains each comprise a VL domain and a CL domain, wherein the VL domains have different amino acid sequences and the CL domains have different amino acid sequences; and/or

(c) the two heavy chains each comprise a VH domain, a CH1 domain and an Fc region, wherein the VH domains have different amino acid sequences, the CH1 domains have different amino acid sequences, and the Fc regions have different amino acid sequences, optionally wherein one light chain is a kappa light chain and one light chain is a lambda light chain.

3. The bispecific antibody of claim 2 , wherein the two heavy chains form a heterodimer.

4. The bispecific antibody of claim 1 , wherein the antibody specifically binds to two independent antigens or to two independent epitopes on the same antigen.

5. The bispecific antibody of claim 1 , wherein the Fc region of either or both heavy chains comprises one or more modifications optionally wherein the modifications facilitate heterodimerization of the heavy chains.

6. The bispecific antibody of claim 5 , wherein the modifications in the Fc region are selected from those provided in Tables 5 and 6.

7. The bispecific antibody of claim 5 , wherein the Fc region of either or both heavy chains comprises one or more modifications that alter protein A binding and are only present in one heavy chain,

wherein:

(a) the antibody is an IgG1, an IgG2 or an IgG4 and the modifications in the Fc region that alter protein A binding is the amino acid substitution H435R/Y436F; or

(b) the antibody is IgG3 and the modifications in the Fc region that alter protein A binding is the amino acid substitution R435H/F436Y, and

wherein numbering is according to the EU index.

8. The bispecific antibody of claim 5 , wherein:

(a) the modified heavy chain Fc region comprises the amino acid substitution T366W, and the second heavy chain Fc region comprises the amino acid substitution Y407V/T366S/L368A; or

(b) the modified heavy chain Fc region comprises the amino acid substitution Y407V/T366S/L368A, and the second heavy chain Fc region comprises the amino acid substitution T366W,

wherein numbering is according to the EU index.

9. The bispecific antibody of claim 8 , wherein:

(a) the modified heavy chain Fc region further comprises the amino acid substitution S354C, and the second heavy chain Fc region further comprises the amino acid substitution Y349C; or

(b) the modified heavy chain Fc region further comprising the amino acid substitution Y349C, and the second heavy chain Fc region further comprises the amino acid substitution S354C,

wherein numbering is according to the EU index.

10. The bispecific antibody of claim 5 , further comprising modifications in the Fc region that alter the half-life of the antibody, wherein the half-life depends on FcRn binding affinity and/or modifications in the Fc region that alter the effector function, wherein the binding affinity for an Fc gamma receptor or Clq complement protein is increased or decreased.

11. A composition comprising the bispecific antibody of claim 1 and an excipient.