A total of 92 medicines and vaccines are either in human clinical trials or awaiting approval from the US Food and Drug Administration (FDA) for the treatment or prevention of HIV/AIDS and related conditions.

The figures come from a report published by the Pharmaceutical Research and Manufacturers of America (PhRMA) in advance of the 20th anniversary of World AIDS Day on 1 December. It lists 46 antivirals, 20 vaccines and 26 other compounds that are either in clinical development or awaiting FDA approval, as well as 30 medicines to treat HIV/AIDS that have been approved since the human immunodeficiency virus was first identified more than 20 years ago.

Despite the encouraging number of candidate therapies in development, the bulk of these are still at the Phase I or II stage. The PhRMA report identifies nine compounds and one vaccine in Phase III trials for HIV/AIDS. Three of these are antivirals: Indevus Pharmaceuticals’ PRO 2000 (intravaginal gel) for the prevention of HIV infection; Pfizer’s Selzentry (maraviroc) for HIV infection in treatment-naïve patients; and Schering-Plough’s CCCR5 receptor antagonist vicriviroc, also for treating HIV infection.

Novartis has an immunomodulator, Proleukin (aldesleukin), in Phase III trials for HIV-1 infection, in collaboration with the US National Institute of Allergy and Infectious Diseases (NIAID).

Five compounds in the final stages of clinical development fall into the ‘other’ category: Bayer HealthCare’s Leukine (sargramostim), for the treatment of HIV infection; Pfizer’s Lyrica (pregabalin) for HIV-associated neuropathy; NeurogesX’s NGX-4010, a high-concentration transdermal capsaicin patch for HIV-associated neuropathy; Theratechnologies’ tesamorelin (TH9507) for HIV-associated lipodystrophy; and Celgene’s Thalomid (thalidomide) for AIDS-related cachexia.

In addition, Sanofi Pasteur has a vaccine for the prevention of HIV infection in Phase III clinical trials in Thailand.

There are a further two products awaiting FDA approval for HIV/AIDS: Tibotec Pharmaceuticals’ etravirine (TMC125), a non-nucleoside reverse transcriptase inhibitor for the treatment of HIV infection; and EMD Serono’s Serostim (rDNA somatropin for injection) for HIV-associated adipose redistribution syndrome (this is an orphan drug indication).

Devastating and growing

As the PhRMA report points out, increased availability and use of new medicines has helped to reduce the US death rate from AIDS substantially in recent years. “With HIV/AIDS medicines, a disease that was once a virtual death sentence can now be controlled and treated as if it were a chronic disease,” noted the association’s president and chief executive officer, Billy Tauzin.

Nonetheless, PhRMA adds, AIDS remains a devastating and growing health problem in developing countries, and particularly in sub-Saharan Africa, China, India and the Russian Federation. According to the Joint United Nations Programme on HIV/AIDS, an estimated 32.7 million people worldwide were living with AIDS at the end of 2006. This year the tally has risen to an estimated 33.2 million people living with AIDS, with some 2.1 million people newly infected in 2007.