Progenics Pharmaceuticals, Inc. initiated phase II clinical programme for PRO 140, an investigational drug for the treatment of human immunodeficiency virus (HIV) infection. Two phase II clinical trials in HIV-infected individuals will investigate multiple dose levels of PRO 140 via intravenous and subcutaneous routes of administration.

Intravenous PRO 140 has the potential for infrequent (e.g., monthly) dosing, whereas subcutaneous PRO 140 may enable self-administration as infrequently as every two weeks. The objective of these phase II studies is to identify an optimal dosing regimen of PRO 140 for evaluation in pivotal clinical trials as well as to further assess the investigational drug's safety and tolerability.

PRO 140 is a humanised monoclonal antibody directed against CCR5, a portal that most forms of HIV use to enter immune system cells. PRO 140 is a viral-entry inhibitor that is designed to protect healthy cells from infection. In a recent clinical study, single intravenous doses of PRO 140 significantly reduced HIV viral loads by greater than 90 per cent (1.0 log10) for two-to-three weeks.

"There is an urgent need for new therapies such as PRO 140 to address the limitations of currently available HIV drugs," said Paul J. Maddon, M.D., Ph.D., founder, chief executive officer, and chief science officer, Progenics. "Blocking the viral-entry infection pathway with a monoclonal antibody is a promising new approach to treating people with HIV/AIDS that is designed to be more specific and better tolerated than currently available medications. Following results from these phase II studies, we plan to meet with the US Food and Drug Administration (FDA) with the intention of moving into longer-term, pivotal trials in the first half of 2009."

In February 2006, PRO 140 was designated a Fast Track product by FDA for the treatment of HIV infection. The FDA Fast Track Development Programme facilitates development and expedites regulatory review of drugs intended to address an unmet medical need for serious or life-threatening conditions. With Fast Track designation for PRO 140, Progenics can take advantage of several programmes at FDA to streamline the regulatory review process and to work more closely with FDA on product development plans.

The phase II programme includes two multi-centre, double-blind, placebo-controlled studies that will be conducted in a total of 70 volunteers with early-stage HIV disease and who have not received antiretroviral therapy within the previous three months. The studies are designed to evaluate, separately, PRO 140 dosed via the intravenous or subcutaneous routes of administration. All patients will be screened prior to the study for the presence of virus that utilizes only CCR5 as the entry co-receptor. Patients will then be monitored for approximately two months to assess tolerability, antiviral activity and blood concentrations of PRO 140.

One trial is assessing intravenous PRO 140 up to 10 mg/kg. A total of 30 patients will be randomised into three groups to receive a single dose of placebo, PRO 140 5 mg/kg or PRO 140 10 mg/kg. The second trial will evaluate subcutaneous PRO 140 administered as three weekly doses or two bi-weekly (once every two weeks) doses. A total of 40 patients will be randomised into four groups to receive placebo weekly, PRO 140 162 mg weekly, PRO 140 324 mg weekly or PRO 140 324 mg biweekly. Subcutaneous PRO 140 is being developed as a potential long-acting, self-administered therapy for HIV infection.

Discovered by Progenics' scientists, PRO 140 is a humanised monoclonal antibody that binds to CCR5, a co-receptor that is the principal molecular portal used by HIV to enter and infect immune system cells. In 1996, Progenics and its collaborators discovered the role of CCR5 in HIV infection.

Progenics received development funding for PRO 140 from the National Institute of Allergy and Infectious Diseases of the National Institutes of Health.

Progenics Pharmaceuticals, Inc. is a biopharmaceutical company focusing on the development and commercialisation of innovative therapeutic products to treat the unmet medical needs of patients with debilitating conditions and life-threatening diseases.