Immunoconjugates: applications in targeted drug delivery for cancer therapy.

Monoclonal antibodies can be produced against virtually any molecule, and unlike polyclonal antisera, they are highly specific. There has been great improvement in the monoclonal antibody production technique since its inception in 1975. The idea behind using monoclonals to direct cancer treatments is based on the fact that surfaces of tumor contain a wide variety of proteins, some of which are specific to the tumor type. Monoclonal antibodies that bind to such tumor-specific antigens could be used, either alone or as conjugates of drugs and toxins (immunoconjugates), to selectively seek out and destroy these tumor cells. Targeted drug delivery therapy of tumor using monoclonals or their conjugates has been reported by many investigators, and the early results are quite promising. However, many obstacles still have to be overcome before immunoconjugates become a valuable agent in the treatment of human diseases including cancer.