Emerging role of integrase inhibitors in the management of treatment-experienced patients with HIV infection

Integrase is an essential HIV-1-specific enzyme that is an active target for antiretroviral drug development. Recently, a new class of drugs that specifically inhibits strand transfer, one of the three steps of HIV integration into the host DNA, has been developed. Two drugs in this class have reached late stages of development for use in HIV-1 infected individuals: raltegravir, which has just been approved for use in treatment-experienced patients, and elvitegravir, currently in phase III trials. Both are potent with an IC(50) in the 30 nM range and active in vitro against wild type as well as in strains highly resistant to all other existing classes of drugs. Clinical trials in both treatment-naïve and -experienced patients have demonstrated raltegravir to be highly effective with an excellent tolerability profile and no specific clinical or metabolic side effects. Longer follow up is necessary to ensure this early safety profile is sustained. The rapid rate of viral decay observed with raltegravir challenges the current understanding of HIV-1 turnover and may open new strategies for long term treatment and management of infected patients.