What is PRO 140?

• PRO 140 is an experimental entry inhibitor being developed by Progenics Pharmaceuticals, Inc. It has not yet been evaluated by the U.S. Food and Drug Administration (FDA) for use by people living with HIV.
   
• PRO 140 contains genetically engineered antibodies, known as monoclonal antibodies. These antibodies bind to the CCR5 coreceptor on CD4 cells (T cells). Once they do this, HIV cannot successfully bind with the surface of these cells, thus preventing the virus from infecting them.
   
• PRO 140 will most likely need to be used in combination with other HIV drugs.

• A dose for PRO 140 has not yet been determined. The drug has been administered intravenously, using a dose that depends on body weight. Future studies will deliver the drug using a subcutaneous injection.
   
• PRO 140 holds promise for HIV-positive patients who no longer respond to other HIV drugs. Because PRO 140 targets HIV differently than most 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 140.
   
• It is not known how quickly resistance to PRO 140 develops if resistance does occur.
   
• PRO 140 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 safety and effectiveness of PRO 140 against HIV are now being conducted.
   
• In one small trial, researchers examined three single intravenous doses of PRO 140: 0.5 milligram per kilogram (mg/kg) of body weight, 2.0 mg/kg and 5.0 mg/kg. A total of 39 HIV-positive patients, none of whom had used antiretrovirals in the past, were enrolled in the study. All patients were screened prior to the study for the presence of virus that utilizes only CCR5 as its entry coreceptor (as opposed to the CXCR4 coreceptor). Of the 13 patients in each dosing group, 10 patients received PRO 140 and three received placebo.
  
  Ten days after receiving single-dose PRO 140, HIV viral loads dropped by an average of 1.7 log in the 5.0 mg/kg group, compared to average reductions of 1.2 log in the 2.0 mg/kg group, 0.58 log in the 0.5 mg/kg group and 0.39 log in the placebo group. And two to three weeks after the injection of PRO 140, patients who received 5.0 mg/kg still averaged viral loads 1.0 log below pretreatment levels. CD4 counts increased, on average, by 129 cells in the 5.0 mg/kg PRO 140 group by day eight. The elevations in all groups persisted for approximately three weeks after the drug was administered.

• Information regarding the safety and possible side effects of PRO 140 in HIV-positive people is not yet available.

• It is not known whether PRO 140 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 140 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 140, 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).