New Version of Drug May Assist in AIDS Battle

A new version of an experimental AIDS drug may stay in the bloodstream longer and increase the drug’s ability to fight the deadly human immunodeficiency virus, researchers say.

The genetically engineered drug has yet to be tested in humans, so it is not yet known if it will prove to be a safe and effective AIDS therapy.

The research is described in today’s issue of the British journal Nature by scientists at Genentech Inc. of South San Francisco, the National Cancer Institute and the New England Deaconess Hospital in Boston.

The new drug contains part of a protein, called CD-4, that plays a key role in allowing the AIDS virus to infect immune system cells, as well as part of an antibody molecule, a special protein that helps to defend the body against germs.

The researchers hope that the CD-4 portion of the drug will be able to act as a decoy and latch onto AIDS virus particles. Then, they hope that the antibody portion of the drug will help the body’s immune system destroy the AIDS virus particles.

Several versions of CD-4 are already being tested in individuals infected with the AIDS virus. But the fact that these versions of CD-4 appear to be eliminated from the bloodstream within hours may limit their usefulness, although this will not be known for sure until further tests are completed.

According to the new study, the hybrid molecules--containing both CD-4 and antibody--are likely to stay in the bloodstream longer, and thus be more effective. The researchers based this conclusion on tests in rabbits, which showed that the hybrid molecules stayed in the bloodstream up to 200 times longer than CD-4 molecules.