First integrase inhibitor approved by European Union Commission

Merck Sharp & Dohme's Isentress (raltegravir) has been granted a license from the European Union Commission for use in combination with other antiretroviral medicinal products for the treatment of HIV-1 infection in treatment-experienced adult patients with evidence of HIV-1 replication despite ongoing antiretroviral therapy (ART).

Raltegravir is the first approved integrase inhibitor, a new class of ART that works by targeting the integrase enzyme, which is essential for HIV replication.

The Commission's decision, reflecting the positive opinion of the European Medicines Agency, was based on efficacy and safety data from two double-blind, placebo-controlled trials of 24 weeks duration in treatment-experienced patients. In these studies raltegravir, in combination with optimised background therapy (OBT), significantly reduced HIV RNA viral load (p<0.001), and significantly increased CD4 cell counts (p<0.001).

The efficacy and safety of raltegravir have not been established in treatment-naïve adult patients or paediatric patients, although studies in these populations are underway.

"Raltegravir is an important new advancement in the treatment of HIV, because it is the first therapy in a new class of drugs that attacks the virus in a completely different way from other available medicines," said Ken Frazier, executive vice president and president, Global Human Health, Merck & Co., Inc.

Despite the availability of drugs to treat HIV and AIDS, the pandemic continues. In the EU, nearly 250,000 cases of HIV have been reported since 2002, according to the European Centre for the Epidemiological Monitoring of HIV and AIDS. Additionally, resistance to current HIV therapies in treatment-experienced patients has been noted in numerous international studies, suggesting that resistance to at least one class of antiretroviral agents may be as high as 76%. The World Health Organisation (WHO) has called resistance an emerging public health concern and has partnered with the International AIDS Society to develop the Global HIV Drug Resistance Surveillance Network to track emerging resistance patterns in developing and developed countries.

"Treatment-experienced HIV patients have limited options for therapies that are well-tolerated and can reduce viral loads while boosting CD4 counts," said Jürgen Rockstroh, professor of medicine and head of the HIV Outpatient Clinic, University of Bonn, Germany. "The approval of raltegravir in the EU represents a significant scientific advancement, but more importantly, it addresses a much-needed evolution in the treatment of HIV and AIDS."

Raltegravir is being studied in two ongoing Phase III multi-centre, double-blind, randomised, placebo-controlled studies in 699 treatment-experienced adult patients with documented resistance to at least one drug in each of three classes of ARTs.