PRO 140

PRO 140 is a humanized monoclonal antibody targeted against the CCR5 receptor found on T lymphocytes of the human immune system. It is being investigated as a potential therapy in the treatment of HIV infection.

The United States Food and Drug Administration has designated PRO 140 for fast-track approval.

Development
PRO 140 is being developed by Progenics Pharmaceuticals. In May 2007, they announced results from the phase I clinical trial of the drug. The researchers said the results demonstrated "potent, rapid, prolonged, dose-dependent, highly significant antiviral activity" for PRO 140. Participants in the highest dosing group received 5mg/kg and showed a average viral load decrease of -1.83 log10. On average, reductions of greater than -1 log10 copies/ml were maintained for between two and three weeks, from only a single dose of the drug. The largest individual HIV RNA reductions ranged up to -2.5 log10 among patients receiving both the 2 and 5 mg/kg doses.

Mechanism of Action
PRO 140 functions as an entry inhibitor. PRO 140 binds to the CCR5 receptor, and interferes with HIV's ability to enter the cell. Unlike other entry inhibitors, PRO 140 is an monoclonal antibody. As such, it must be injected to be effective. However, once inside the body, PRO 140 binds to to CCR5 for >60 days, which may allow for dosing as infrequently as every other week.