In the treatment of tumours the use of a targeted drug, such as a monoclonal antibody conjugated to a toxin is under active development. The antibody provides selectivity in the target, but there still remains the problem of interaction with non-target cells during passage to the intended site of action. The alternative approach of encapsulating toxins in liposomes has also been actively researched. The principal difficulty here is to release the selective agent at the right time or location.
