Identification and engineering of antibodies with variant Fc regions and methods of using same
The present invention relates to molecules, particularly polypeptides, more particularly immunoglobulins (e.g., antibodies), comprising a variant Fc region, wherein said variant Fc region comprises at least one amino acid modification relative to a wild-type Fc region, which variant Fc region binds FcγRIIIA and/or FcγRIIA with a greater affinity, relative to a comparable molecule comprising the wild-type Fc region. The molecules of the invention are particularly useful in preventing, treating, or ameliorating one or more symptoms associated with a disease, disorder, or infection. The molecules of the invention are particularly useful for the treatment or prevention of a disease or disorder where an enhanced efficacy of effector cell function (e.g., ADCC) mediated by FcγR is desired, e.g., cancer, infectious disease, and in enhancing the therapeutic efficacy of therapeutic antibodies the effect of which is mediated by ADCC.
1. An antibody having a variant IgG1 Fc region, or an antigen-binding fragment thereof that comprises said variant Fc region, wherein said variant Fc region contains a CH2 domain and a CH3 domain, and possesses an amino acid sequence that differs from the amino acid sequence of a wild-type IgG1 Fc region by comprising the selected amino acid substitutions R292P and V305I of a wild-type Fc region, wherein said numbering is that of the EU index as in Kabat and wherein said selected amino acid substitutions cause said variant Fc region to bind FcγRIII with an altered affinity relative to that of said wild-type Fc region.
2. The antibody, or fragment thereof, of claim 1 , wherein said variant Fc region also binds an FcγRII with an altered affinity relative to that of a wild-type Fc region.
3. The antibody, or fragment thereof, of claim 2 , wherein said altered FcγRII affinity is an enhanced FcγRIIA binding affinity.
4. The antibody, or fragment thereof, of claim 2 , wherein said altered FcγRII affinity is a decreased FcγRIIB binding affinity.
5. The antibody, or fragment thereof, of claim 1 , wherein said altered affinity for an FcγRIII is an increased affinity.
6. The antibody, or fragment thereof, of claim 5 , wherein said FcγRIII is FcγRIIIA.
7. The antibody, or fragment thereof, of claim 5 , wherein said variant Fc region of said antibody or fragment thereof binds FcγRIIB with decreased affinity relative to that of a wild-type Fc region.
8. The antibody, or fragment thereof, of claim 5 , wherein said variant Fc region of said antibody or fragment thereof binds FcγRIIA with increased affinity relative to that of a wild-type Fc region.
9. The antibody, or fragment thereof, of claim 6 , wherein said variant Fc region of said antibody or fragment thereof binds FcγRIIA with increased affinity relative to that of a wild-type Fc region.
10. The antibody, or fragment thereof, of claim 6 , wherein said variant Fc region of said antibody or fragment thereof binds FcγRIIB with decreased affinity relative to that of a wild-type Fc region.
11. The antibody of claim 1 , wherein said variant Fc region additionally comprises the substitution F243L.