The present invention relates to antibodies or fragments thereof that specifically bind FcγRIIB, particularly human FcγRIIB, with greater affinity than said antibodies or fragments thereof bind FcγRIIA, particularly human FcγRIIA. The present invention also encompasses the use of an anti-FcγRIIB
antibody or an
antigen-binding fragment thereof, as a
single agent therapy for the treatment, prevention, management, or amelioration of a
cancer, preferably a B-
cell malignancy, particularly, B-
cell chronic lymphocytic leukemia or non-Hodgkin's
lymphoma, an autoimmune disorder, an
inflammatory disorder, an IgE-mediated allergic disorder, or one or more symptoms thereof. The present invention also encompasses the use of an anti-FcγRIIB
antibody or an
antigen-binding fragment thereof, in combination with other
cancer therapies. The present invention provides pharmaceutical compositions comprising an anti-FcγRIIB
antibody or an
antigen-binding fragment thereof, in amounts effective to prevent, treat, manage, or ameliorate a
cancer, such as a B-
cell malignancy, an autoimmune disorder, an
inflammatory disorder, an IgE-mediated allergic disorder, or one or more symptoms thereof. The invention further provides methods of enhancing the
therapeutic effect of therapeutic antibodies by administering the antibodies of the invention to enhance the
effector function of the therapeutic antibodies. The invention also provides methods of enhancing
efficacy of a vaccine composition by administering the antibodies of the invention with a vaccine composition.