The invention relates to antibodies which bind to insulin like growth factor receptor-1 (IGF-1R) and uses thereof, in particular in the diagnosis and treatment of cancer. Specific human and murine monoclonal antibodies which inhibit IGF-1R-mediated pro-survival and tumor proliferation pathways, and variants, fragments, and derivatives thereof are provided. Also provided are specific human and murine monoclonal antibodies capable of synergistically inhibiting the ability of the ligands, insulin like growth factor 1 (IGF-1) and insulin like growth factor 2 (IGF-2), to bind to IGF-1R as well as fragments, variants and derivatives of such antibodies. Antibodies of the invention produce such synergistic effects via allosteric and/or competitive inhibition of IGF-1R ligand binding.
