STABLE IgG4 ANTIBODIES

1 - 75 . (canceled)

76 . A stabilized IgG4 antibody, comprising a heavy chain and a light chain, wherein each of the heavy chain and the light chain comprises a variable region and a constant region,

wherein the heavy chain constant region is a human IgG4 constant region comprising a substitution of the Arg residue at EU index position 409 selected from the group consisting of: a Lys, Thr, Met or Leu residue, and wherein the antibody does not comprise a Cys-Pro-Pro-Cys sequence in the hinge region,

wherein optionally the heavy chain constant region further comprises:

a) a substitution of the Lys residue at EU index position 370 with a Thr residue;

b) a substitution of the Phe residue at EU index position 405 with an Ala or Leu residue;

c) a substitution of the Phe residue at EU index position 234 with an Ala residue;

d) a substitution of the Gly residue at EU index position 236 with an Ala residue;

e) a substitution of the Gly residue at EU index position 237 with an Ala residue;

f) a substitution of the Asn residue at EU index position 297 with an Ala residue;

g) a substitution of the Glu residue at EU index position 318 with an Ala or Val residue;

h) a substitution of the Lys residue at EU index position 320 with an Ala residue;

and/or

i) a substitution of the Lys residue at EU index position 322 with an Ala or Gln residue,

wherein the antibody has reduced ability to induce Fab-arm exchange in vivo.

77 . The stabilized IgG4 antibody of claim 76 , wherein the antibody has a Cys-Pro-Ser-Cys sequence (SEQ ID NO: 51) in the hinge region at EU index positions 226-229.

78 . The stabilized IgG4 antibody of claim 76 , wherein the Arg residue at EU index position 409 is substituted with a Lys.

79 . The stabilized IgG4 antibody of claim 76 , wherein the antibody comprises a substitution of the Lys residue at EU index position 370 and a substitution of the Phe residue at EU index position 405.

80 . The stabilized IgG4 antibody of claim 76 , wherein the antibody comprises a substitution of the Lys residue at EU index position 370 with a Thr residue and a substitution of the Phe residue at EU index position 405 with an Ala or Leu residue.

81 . The stabilized IgG4 antibody of claim 76 , wherein the antibody comprises a substitution of the Phe residue at EU index position 234 with an Ala residue.

82 . The stabilized IgG4 antibody of claim 76 , wherein the antibody comprises a substitution of the Gly residue at EU index position 236 with an Ala residue.

83 . The stabilized IgG4 antibody of claim 76 , wherein the antibody comprises a substitution of the Gly residue at EU index position 237 with an Ala residue.

84 . The stabilized IgG4 antibody of claim 76 , wherein the antibody comprises a substitution of the Asn residue at EU index position 297 with an Ala residue.

85 . The stabilized IgG4 antibody of claim 76 , wherein the antibody comprises a substitution of the Glu residue at EU index position 318 with an Ala or Val residue.

86 . The stabilized IgG4 antibody of claim 76 , wherein the antibody comprises a substitution of the Lys residue at EU index position 320 with an Ala residue.

87 . The stabilized IgG4 antibody of claim 76 , wherein the antibody comprises a substitution of the Lys residue at EU index position 322 with an Ala or Gln residue.

88 . The stabilized IgG4 antibody of claim 76 , wherein the antibody has reduced effector functions.

89 . The stabilized IgG4 antibody of claim 88 , wherein the heavy chain constant region comprises

a) a substitution of the Phe residue at EU index position 234 with an Ala residue;

b) a substitution of the Gly residue at EU index position 236 with an Ala residue;

c) a substitution of the Gly residue at EU index position 237 with an Ala residue;

d) a substitution of the Asn residue at EU index position 297 with an Ala residue;

e) a substitution of the Glu residue at EU index position 318 with an Ala or Val residue;

f) a substitution of the Lys residue at EU index position 320 with an Ala residue; and

g) a substitution of the Lys residue at EU index position 322 with an Ala or Gln residue.

90 . The stabilized IgG4 antibody of claim 76 , wherein the antibody is selected from the group consisting of: a human antibody, a humanized antibody, and a chimeric antibody.

91 . The stabilized IgG4 antibody of claim 76 , wherein the antibody comprises a human kappa light chain.

92 . The stabilized IgG4 antibody of claim 76 , wherein the antibody comprises a human lambda light chain.

93 . The stabilized IgG4 antibody of claim 76 , wherein the antibody is a full-length antibody.

94 . The stabilized IgG4 antibody of claim 76 , wherein the antibody is linked to a cytotoxic agent; a radioisotope; a prodrug; or a drug.

95 . The stabilized IgG4 antibody of claim 76 , wherein the antibody binds erythropoietin, beta amyloid, thrombopoietin, interferon-alpha (2a and 2b), interferon-beta (1b), interferon gamma, TNFR I (CD120a), TNFR II (CD120b), IL-1 R type 1 (CD121a), IL-1 R type 2 (CD121b), IL-2, IL2R (CD25), IL-2R-beta (CD123), IL-3, IL-4, IL-3R (CD123), IL-4R (CD124), IL-5R (CD125), IL-6R-alpha (CD126), IL-6R-beta (CD130), IL-8, IL-10, IL-11, IL-15, IL-15BP, IL-15R, IL-20, IL-21, TCR variable chain, RANK, RANK-L, CTLA4, CXCR4R, CCR5R, TGF-beta1, TGF-beta2, TGF-beta3, G-CSF, GM-CSF, MIF-R (CD74), M-CSF-R (CD115), GM-CSFR (CD116), soluble FcRI, sFcRII, sFcRIII, FcRn, Factor VII, Factor VIII, Factor IX, VEGF, VEGFxxxb, alpha-4 integrin, Cd11a, CD18, CD20, CD38, CD25, CD74, FcalphaRI, FcepsilonRI, acetyl choline receptor, fas, fasL, TRAIL, hepatitis virus, hepatitis C virus, envelope E2 of hepatitis C virus, tissue factor, a complex of tissue factor and Factor VII, EGFr, CD4, CD28, VLA-1, VLA-2, VLA-3, VLA-4, LFA-1, MAC-1, I-selectin, PSGL-1, ICAM-I, P-selectin, periostin, CD33 (Siglec 3), Siglec 8, TNF, CCL1, CCL2, CCL3, CCL4, CCL5, CCL11, CCL13, CCL17, CCL18, CCL20, CCL22, CCL26, CCL27, CX3CL1, LIGHT, EGF, TGFalpha, HGF, PDGF, NGF, complement, C1q, C4, C2, C3, C5, C6, C7, C8, C9, MBL, factor B, a Matrix Metallo Protease, any of MMP1 to MMP28, CD32b, CD200, CD200R, Killer Immunoglobulin-Like Receptors (KIRs), NKG2D, leukocyte-associated immunoglobulin-like receptors (LAIRs), 1y49, PD-L2, CD26, BST-2, ML-IAP (melanoma inhibitor of apoptosis protein), cathepsin D, CD40, CD40R, CD86, a B cell receptor, CD79, PD-1, or a T cell receptor.

96 . A pharmaceutical composition comprising the stabilized IgG4 antibody of claim 76 .