Antivirals continue to dominate the 109 products currently in clinical trials or awaiting approval for the treatment or prevention of HIV/AIDS or related conditions in the US.

More than half (57) of the candidate drugs and vaccines listed in the latest development update released by Pharmaceutical Research and Manufacturers of America (PhRMA) to mark the 20th anniversary of World AIDS Day are antivirals.

But there are also 29 vaccines in development – only one of them past the Phase II stage – as well as four cancer treatments, six immunomodulators, two gene therapies and 12 other medicines.

PhRMA quotes Dr Anthony Fauci, director of the US National Institute of Allergy and Infectious Diseases, as saying that a safe and effective vaccine “is critical to the control of HIV globally”. According to the International AIDS Vaccine Initiative, the report notes, without a significant improvement in prevention efforts (including an HIV vaccine), infections could double from around five million a year in 2005 to ten million a year by 2030.

“Conservatively, an effective HIV vaccine could prevent almost 30 million of the 150 million new infections projected in the coming decades,” the PhRMA report adds. “A highly effective vaccine could even prevent more than 70 million infections in 15 years.”

The bulk of the 29 vaccines listed by PhRMA are still in, or have completed, Phase I clinical trials. Three vaccines are in Phase I/II trials and nine are in Phase II. The only HIV vaccine in Phase III development is Sanofi Pasteur’s vCP1521.

Seven of the antivirals on the list are in Phase III trials, a further two are in Phase II/III and one has been filed for US approval – Tibotec Therapeutics’ Prezista (darunavir).