HIV entry inhibitors.

The need for new classes of antiretroviral drugs has become apparent because of increasing concern about the long-term toxic effects of existing drugs, the need to combat HIV-1 variants that are resistant to treatment, and the frequency of treatment change in drug-experienced patients. Currently, most regimens are combinations of inhibitors of two viral enzymes--reverse transcriptase and protease. Nevertheless, several steps in the HIV replication cycle are potential targets for intervention. These steps can be divided into entry steps, in which viral envelope glycoproteins and their receptors are involved, and postentry steps, involving viral accessory gene products and the cellular proteins with which they interact. New treatment options target viral entry into the cell. These treatments include the HIV fusion inhibitor enfuvirtide, and new HIV coreceptor antagonists in advanced stages of clinical development or in different stages of preclinical development. Here, we review the development of new HIV entry inhibitors, their performance in clinical trials, and their possible role in anti-HIV therapy.