RNAi therapy shuts down gene critical to RSV, prevents virus replication

John DeVincenzo, MD, professor and researcher in the Departments of Pediatrics and Molecular Sciences at the University of Tennessee Health Science Center (UTHSC), has proven for the first time that a totally new concept in drug design can be used to treat human disease.  Dr. DeVincenzo, who also serves as a children's infectious diseases specialist at Le Bonheur Children's Hospital, conducted his study at the Children's Foundation Research Center, a UT Health Science Center partner located at Le Bonheur.

The new drug design concept is that a simple chain of sugars called RNA (Ribonucleic Acid) can be easily designed on laptop computers and then synthesized into powerful disease-fighting therapies.  The therapies work by shutting down disease-causing genes through a process known as RNA interference (RNAi).  The discovery of this natural process of RNAi was awarded the Nobel Prize in 2006.  RNAi drugs had shown promise in test tube studies and in animals, but had never been shown to work in humans.  

Realizing the potential power of the new discovery, Dr. DeVincenzo and his team tackled the virus called RSV (Respiratory Syncytial Virus), the most common cause of hospitalization of infants and an infection with no therapy or vaccine.  Healthy adults contract only rare, mild RSV infections that disappear without medical intervention.  The investigator's team infected 88 healthy adults with RSV cultures that he collected and grew from his patients at Le Bonheur Children's Hospital.  He then administered RNAi drug therapy to half the study participants in the form of a nasal spray and a placebo to the other half.  Findings from Dr. DeVincenzo's study proved that the RNAi therapy shut down a gene critical to RSV, thus preventing the virus from replicating itself.  Patients who received the RNAi drug had significantly less infection than those receiving the placebo.  The findings pave the way for this new type of drug therapy to treat a large variety of human diseases including cancers, genetic diseases and viral infections.  In April, the study was published in the Proceedings of the National Academy of Sciences announcing the potential of the RNAi drug therapy.

"The next step in this discovery is already being undertaken," said Dr. DeVincenzo.  "We are in the midst of a clinical trial to test the RNA interference drug in lung-transplant recipients who have become naturally infected with Respiratory Syncytial Virus, which can be deadly for these patients."  The researcher added that the aerosol form of the RNAi drug was proven to be safe in the previous phase of study and the safety is being tested again in the current phase of the clinical trial.  His long-term goal is to test RNAi drug therapies to reduce RSV infections in infants.  

Regarding the possibility of marketing the RNAi drug treatment, Dr. DeVincenzo emphasizes that the drug's commercialization cannot be predicted, but could receive approval as an orphan drug (a treatment for rare conditions) as early as 2013 if the current phase of clinical trials proves to be very successful.  Approval for using RNAi treatment on children who suffer from RSV would take longer.