A substance being studied in the treatment of breast cancer that has spread to other parts of the body. It is also being studied in the treatment of other cancers and conditions. Fresolimumab binds to a protein called transforming growth factor-beta (TGF-beta), which is found on some cancer cells. Fresolimumab may help keep cancer cells from growing and prevent the growth of new blood vessels that tumors need to grow. It is a type of monoclonal antibody and a type of antiangiogenesis agent.