CHICAGO,  (Reuters) – U.S. researchers have  developed tiny nanoparticle robots that can travel through a  patient’s blood and into tumors where they deliver a therapy  that turns off an important cancer gene.

The finding, reported in the journal Nature yesterday,  offers early proof that a new treatment approach called RNA  interference or RNAi might work in people.

RNA stands for ribonucleic acid — a chemical messenger  that is emerging as a key player in the disease process.

Dozens of biotechnology and pharmaceutical companies  including Alnylam, Merck, Pfizer, Novartis and Roche are  looking for ways to manipulate RNA to block genes that make  disease-causing proteins involved in cancer, blindness or  AIDS.

But getting the treatment to the right target in the body  has presented a challenge.