Molecules with extended half-lives, compositions and uses thereof

#The present invention relates to molecules whose in vivo half-lives are increased by modification of an IgG constant domain, or FcRn (Fc Receptor-neonate) binding domain thereof. Specifically, these molecules have amino acid modifications that increase the affinity of the constant domain or fragment thereof for the FcRn. Increasing the half-life of therapeutic and diagnostic IgGs and other bioactive molecules using methods of the invention has many benefits including reducing the amount and/or frequency of dosing of these molecules, for example, in vaccines, passive immunotherapy and other therapeutic and prophylactic methods. The invention further relates to fusion proteins containing all or a portion (a FcRn binding portion) of an IgG constant domain having one or more of these amino acid modifications and a non-IgG protein or non-protein molecule conjugated to such a modified IgG constant domain, where the presence of the modified IgG constant domain increases the in vivo half-life of the non-IgG protein or molecule.

#The use of immunoglobulins as therapeutic agents has increased dramatically in recent years and have expanded to different areas of medical treatments. Such uses include treatment of agammaglobulinemia and hypogammaglobulinemia, as immunosuppressive agents for treating autoimmune diseases and graft-vs.-host (GVH) diseases, the treatment of lymphoid malignancies, and passive immunotherapies for the treatment of various systemic and infectious diseases. Also, immunoglobulins are useful as in vivo diagnostic tools, for example, in diagnostic imaging procedures.

#One critical issue in these therapies is the persistence of immunoglobulins in the circulation. The rate of immunoglobulin clearance directly affects the amount and frequency of dosage of the immunoglobulin. Increased dosage and frequency of dosage may cause adverse effects in the patient and also increase medical costs.

#FIG. 1 shows the structure of the IgG hinge-Fc region indicating the locations of the residues identified to be involved in the interaction with the FcRn receptor (Ghetie et al., Immunology Today, 18(12):592-598, 1997).

#FIG. 2 shows the amino acid sequence of the human IgG1 hinge-Fc region (SEQ ID NO:83) containing a hinge region (SEQ ID NO:82), CH2 domain (SEQ ID NO:80), and CH3 domain (SEQ ID NO:81).

#FIGS. 3(A and B) show the amino acid sequences of (A) human FcRn (SEQ ID NO:84) and (B) mouse FcRn (SEQ ID NO:85), respectively.

#The present invention relates to molecules, particularly proteins, more particularly immunoglobulins, that have an increased in vivo half-life and comprise an IgG constant domain, or fragment thereof that binds to an FcRn (preferably a Fc or hinge-Fc domain), that contains one or more amino acid modifications relative to a wild type IgG constant domain which modifications increase the affinity of the IgG constant domain, or fragment thereof, for the FcRn. In a preferred embodiment, the invention particularly relates to the modification of human or humanized IgGs and other bioactive molecules containing FcRn-binding portions of human IgGs, which have particular use in human therapy, prophylaxis and diagnosis.

#The present invention is based upon identification of amino acid modifications in particular portions of the IgG constant domain that interact with the FcRn, which modifications increase the affinity of the IgG, or fragment thereof, for the FcRn. Accordingly, the invention relates to molecules, preferably proteins, more preferably immunoglobulins, that comprise an IgG constant domain, or FcRn binding fragment thereof (preferably a Fc or hinge-Fc domain fragment), having one or more amino acid modifications (i.e., substitutions, insertions or deletions) in one or more regions that interact with the FcRn, which modifications increase the affinity of the IgG or fragment thereof, for the FcRn, and also increase the in vivo half-life of the molecule. In preferred embodiments, the one or more amino acid modifications are made in one or more of residues 251-256, 285-290, 308-314, 385-389, and 428-436 of the IgG hinge-Fc region (for example, as in the human IgG1 hinge-Fc region depicted in FIG. 4, SEQ ID NO:83), or analogous residues thereof, as determined by amino acid sequence alignment, in other IgG hinge-Fc regions. In a preferred embodiment, the amino acid modifications are made in a human IgG constant domain, or FcRn-binding domain thereof. In a certain embodiment, the modifications are not made at residues 252, 254, or 256 (i.e., all are made at one or more of residues 251, 253, 255, 285-290, 308-314, 385-389, or 428-436) of the IgG constant domain. In a more preferred embodiment, the amino acid modifications are not the substitution with leucine at residue 252, with serine at 254, and/or with phenylalanine at position 256. In particular, in preferred embodiments, such modifications are not made when the IgG constant domain, hinge-Fc domain, hinge-Fc domain or other FcRn-binding fragment thereof is derived from a mouse.

#The amino acid modifications may be any modification, preferably at one or more of residues 251-256, 285-290, 308-314, 385-389, and 428-436, that increases the in vivo half-life of the IgG constant domain, or FcRn-binding fragment thereof (e.g., Fc or hinge-Fc domain), and any molecule attached thereto, and increases the affinity of the IgG, or fragment thereof, for FcRn. Preferably, the one or more modifications also result in a higher binding affinity of the constant domain, or FcRn-binding fragment thereof, for FcRn at pH 6.0 than at pH 7.4. In other embodiments, the modifications alter (i.e., increase or decrease) bioavailability of the molecule, in particular, alters (i.e., increases or decreases) transport (or concentration or half-life) of the molecule to mucosal surfaces (e.g., of the lungs) or other portions of a target tissue. In a preferred embodiment, the amino acid modifications alter (preferably, increase) transport or concentration or half-life of the molecule to the lungs. In other embodiments, the amino acid modifications alter (preferably, increase) transport (or concentration or half-life) of the molecule to the heart, pancreas, liver, kidney, bladder, stomach, large or small intestine, respiratory tract, lymph nodes, nervous tissue (central and/or peripheral nervous tissue), muscle, epidermis, bone, cartilage, joints, blood vessels, bone marrow, prostate, ovary, uterine, tumor or cancer tissue, etc. In a preferred embodiment, the amino acid modifications do not abolish, or, more preferably, do not alter, other immune effector or receptor binding functions of the constant domain, for example, but not limited to complement fixation, ADCC and binding to FcγRI, FcγRII, and FcγRIII, as can be determined by methods well-known and routine in the art. In another preferred embodiment, the modified FcRn binding fragment of the constant domain does not contain sequences that mediate immune effector functions or other receptor binding. Such fragments may be particularly useful for conjugation to a non-IgG or non-immunoglobulin molecule to increase the in vivo half-life thereof. In yet another embodiment, the effector functions are selectively altered (e.g., to reduce or increase effector functions).