The present disclosure relates to the generation of an antibody that specifically recognizes and binds Endosialin, a cell surface antigen characteristic of tumor pericytes and cells of tumor stroma. The antibody has the ability to become internalized in Endosialin expressing cells and to block the activation of MAPK in PDGF stimulated human pericytes. The antibody is able to block angiogenesis induced by LGALS3BP, a known Endosialin interactor and to inhibit tumor growth alone and in combination with 1959, a humanized antibody against LGALS3BP in human osteosarcoma xenograft. The disclosure is also related to nucleotides encoding the antibodies of the invention and cell expressing the antibodies.