What is PRO-542?

• PRO-542 is no longer being studied for the treatment of HIV infection. Progenics is now focusing on the development of PRO-140, an experimental entry inhibitor currently in phase I studies.
   
• PRO-542 mimics a protein (CD4) found on the outside of T-cells. In order for HIV to infected T-cells, it must first grab hold of the CD4 protein. PRO-542 therefore serves as a decoy. If HIV attaches itself to the CD4 proteins found in PRO-542, it will be not be able to attach itself to the real CD4 proteins found on T-cells. This should help prevent HIV from infecting healthy T-cells in the body.
   
• PRO-542 will most likely need to be used in combination with other anti-HIV drugs.

• A dose for PRO-542 has not yet been determined. At the present time, PRO-542 is being studied in an intravenous (IV) form. Progenics Pharmaceuticals is currently exploring the possibility of taking pill forms of PRO-542 by mouth.
   
• PRO-542 remains in the bloodstream for several days after a single IV infusion. This means that PRO-542 might only need to be infused, through an IV line, once a week (or longer).
   
• PRO-542 holds promise for HIV-positive patients who no longer respond to other anti-HIV drugs. Because PRO-542 targets HIV differently than currently available drugs, chances are that most people living with the virus – regardless of which drugs they have tried (and failed) in the past – will likely benefit from using PRO-542.
   
• It is not known if HIV can become resistant to PRO-542. It is not known how quickly resistance to PRO-542 develops if resistance does occur.
   
• PRO-542 might interact with other medications, including those used to treat HIV. It is important that your personal physician and/or the research nurse or study investigator be aware of all drugs you are taking, including those you buy without a prescription.

• Clinical trials looking at the effectiveness of PRO-542 against HIV are now being conducted.
   
• In one small study involving 22 HIV-positive adults, one-time IV infusions of PRO-542, using different doses of the drug, were found to be safe and to lower HIV viral loads – for up to two weeks in some patients. A similar study, involving HIV-positive children, has been conducted. Like the study involving adults, the HIV-positive children did not experience any serious side effects after receiving a single IV infusion of PRO-542 and experienced reductions in viral load that lasted up to two weeks.
   
• Early results from a phase II clinical trial suggest that PRO-542 is effective for HIV-positive people who have tried and failed other anti-HIV medications in the past. In this study, HIV-positive patients who had taken other anti-HIV medications in the past received a single IV infusion of PRO-542. Each patient received 25mg for each kilogram of his or her body weight (i.e., a person weighing 165 pounds would receive 1,875mg PRO-542). Even though these patients had tried and failed other anti-HIV drugs in the past, they were able to reduce their viral loads by up to 80% after one infusion.

• Side effects may occur as a result of taking PRO-542. These have not yet been fully examined in clinical trials and have not yet been reviewed by the FDA.

• It is not known whether PRO-542 will harm an unborn baby. It is very important to treat HIV/AIDS during pregnancy to reduce the risk of infecting your baby. Talk to your doctor about your treatment options.
   
• It is not known whether PRO-542 passes into breast milk and what effect it may have on a nursing baby. To prevent transmission of the virus to uninfected babies, it is recommended that HIV-positive mothers not breast-feed.

• If you would like to find out if you are eligible for any clinical trials that include PRO-542, there is an interactive web site run by ACRIA, the AIDS Community Research Initiative of America.
   
• Another useful service for finding clinical trials is AIDSinfo.nih.gov, a site run by the U.S. National Institutes of Health. They have "health information specialists" you can talk to at their toll-free number at 1-800-HIV-0440 (1-800-448-0440).