Anti-transferrin receptor antibodies and methods of use

1. An isolated antibody that binds to human transferrin receptor (TfR) and primate TfR, wherein the antibody comprises a heavy chain variable region amino acid sequence of SEQ ID NO: 158 or SEQ ID NO: 159, and a light chain variable region amino acid sequence of SEQ ID NO: 162 or SEQ ID NO: 163.

2. The isolated antibody of claim 1 , wherein the antibody comprises a heavy chain variable region amino acid sequence of SEQ ID NO: 158 and a light chain variable region amino acid sequence of SEQ ID NO: 162, or a heavy chain variable region amino acid sequence of SEQ ID NO: 159 and a light chain variable region amino acid sequence of SEQ ID NO: 163.

3. The antibody of claim 1 , which is a monoclonal antibody.

4. The antibody of claim 1 , wherein the antibody comprises at least one mutation in the antibody Fc region, relative to a wild-type antibody Fc region of the same isotype, that reduces or eliminates the complement activation function of the antibody or the effector function of the antibody, or increases the half-life of the antibody.

5. The antibody of claim 4 , wherein the at least one mutation reduces or eliminates the effector function or complement activation function relative to an antibody comprising a wild-type antibody Fc region of the same isotype.

6. The antibody of claim 4 , wherein the at least one mutation reduces or eliminates the effector function relative to an antibody comprising a wild-type antibody Fc region of the same isotype.

7. The antibody of claim 4 , wherein the at least one mutation increases the half-life of the antibody.

8. The antibody of claim 7 , wherein the half-life is increased by at least one mutation in the FcRn binding domain of the antibody at a position selected from: 252, 254, 256, 434 and 436, wherein amino acid numbering is according to the EU numbering system.

9. The antibody of claim 8 , wherein the FcRn binding domain comprises mutations at positions 252, 254 and 256.

10. The antibody of claim 9 , wherein the FcRn binding domain comprises M252Y, S254T and T256E mutations.

11. The antibody of claim 8 , wherein the FcRn binding domain comprise mutations at positions 434 and 436.

12. The antibody of claim 11 , wherein the FcRn binding domains comprises N434A and Y436I mutations.

13. The antibody of claim 1 , wherein the antibody is of an isotype that naturally has reduced or eliminated effector function.

14. The antibody of claim 1 , wherein the glycosylation of the antibody is reduced by a method selected from: production of the antibody in an environment that does not permit wild-type glycosylation; removal of carbohydrate groups already present on the antibody; and mutation of a glycosylation site of the antibody such that wild-type glycosylation does not occur.

15. The antibody of claim 14 , wherein the antibody is produced in a non-mammalian cell production system, or where the antibody is produced synthetically.

16. The antibody of claim 14 , wherein the Fc region of the antibody comprises a mutation at position 297 such that the wild-type asparagine residue at that position is replaced with another amino acid that interferes with glycosylation at that position, wherein amino acid numbering is according to the EU numbering system.

17. The antibody of claim 1 , wherein the effector function or complement activation function is reduced or eliminated by deletion of all or a portion of the Fc region.

18. The antibody of claim 1 , wherein the antibody comprises at least one mutation is-selected from: a point mutation of the Fc region to impair binding to one or more Fc receptors selected from the following positions: 234, 235, 238, 239, 248, 249, 252, 254, 265, 268, 269, 270, 272, 278, 289, 292, 293, 294, 295, 296, 297, 298, 301, 303, 322, 324, 327, 329, 333, 335, 338, 340, 373, 376, 382, 388, 389, 414, 416, 419, 434, 435, 437, 438, and 439; a point mutation of the Fc region to impair binding to C1q selected from the following positions: 270, 322, 329, and 321; and a point mutation at position 132 of the CH1 domain, wherein amino acid numbering is according to the EU numbering system.

19. The antibody of claim 18 , wherein the antibody comprises at least one point mutation of the Fc region to impair binding to one or more Fc receptors selected from 234, 235, 265, 297 and 329.

20. The antibody of claim 19 , wherein the Fc region comprises a mutation at position 297 or at positions 265 and 297.

21. The antibody of claim 19 , wherein the Fc region comprises mutations at positions 234, 235 and 329.

22. The antibody of claim 19 , wherein the Fc region comprises a N297G mutation; D265A and N297A mutations; or D265A and N297G mutations.

23. The antibody of claim 19 , wherein the Fc region comprises L234A, L235A, and P329G mutations.

24. The antibody of claim 1 , wherein the antibody has a KD for TfR of about 20 nM to 100 nM.

25. The antibody of claim 1 , wherein the antibody is coupled to a therapeutic compound.

26. The antibody of claim 25 , wherein the antibody is a multispecific antibody and the therapeutic compound optionally forms one portion of the multispecific antibody.

27. The antibody of claim 26 , wherein the multispecific antibody comprises a first antigen binding site which binds TfR and a second antigen binding site which binds a brain antigen.

28. The antibody of claim 27 , wherein the multispecific antibody comprises a first heavy chain comprising the sequence of SEQ ID NO: 160 and a first light chain comprising the sequence of SEQ ID NO: 161.

29. The antibody of claim 27 , wherein the brain antigen is selected from the group consisting of: beta-secretase 1 (BACE1), Abeta, epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER2), tau, apolipoprotein E (ApoE), alpha-synuclein, CD20, huntingtin, prion protein (PrP), leucine rich repeat kinase 2 (LRRK2), parkin, presenilin 1, presenilin 2, gamma secretase, death receptor 6 (DR6), amyloid precursor protein (APP), p75 neurotrophin receptor (p75NTR), and caspase 6.

30. The antibody of claim 27 , wherein the multispecific antibody binds both TfR and BACE1.

31. The antibody of claim 27 , wherein the multispecific antibody binds both TfR and Abeta.

32. The antibody of claim 25 , wherein the therapeutic compound is a neurological disorder drug.

33. A method of transporting a compound across the blood-brain barrier (BBB) in a subject comprising exposing the BBB to an antibody of claim 25 such that the antibody transports the compound coupled thereto across the BBB.

34. A method of increasing exposure of the central nervous system CNS of a subject to a compound, comprising exposing the CNS to an antibody of claim 25 such that the antibody transports the compound coupled thereto to the CNS.

35. A method of increasing retention in the CNS of a compound administered to a subject, comprising exposing the CNS to an antibody of claim 25 such that the retention in the CNS of the compound is increased.

36. A pharmaceutical formulation comprising the antibody of claim 1 and a pharmaceutically acceptable carrier.

37. An isolated nucleic acid encoding the antibody of claim 1 .

38. A host cell comprising the nucleic acid of claim 37 .

39. A method of producing an antibody comprising culturing the host cell of claim 38 so that the antibody is produced and optionally further comprising recovering the antibody from the host cell.

40. An isolated antibody fragment that binds to human transferrin receptor (TfR) and primate TfR, wherein the antibody fragment comprises a heavy chain variable region amino acid sequence of SEQ ID NO: 158 or SEQ ID NO: 159, and a light chain variable region amino acid sequence of SEQ ID NO: 162 or SEQ ID NO: 163.