Superantibodies that can bind to targets within cells, rather than on their surface, could lead to a new range of treatments for diseases, InNexus Biotechnology of Vancouver claims.

Superantibodies could be used to target bacteria and viruses (including HIV) inside cells, for instance, or abnormal proteins that turn cells cancerous. In theory, they could do everything that the small molecules of most conventional drugs do, and more.

The beauty of a cell-penetrating superantibody is that it would be highly discriminating. Because antibodies can be far more specific than small-molecule drugs, and because they are not inherently toxic, they should have fewer side effects.

As a proof of principle, the company developed a superantibody that binds to and blocks caspase-3, an enzyme inside cells that triggers cell suicide. The superantibody stopped human white blood cells from killing themselves when they were exposed to actinomycin D, a drug that normally triggers cell suicide (Apoptosis, vol 8, p 631). InNexus hopes a superantibody of this kind can be developed to block cell death in people who have just had heart attacks or strokes.

New Scientist news release