Gilead’s four drug single dose anti-HIV pill “quad” regimen shows promise

New single dose “quad” pill contains elvitegravir, emtricitabine, tenofovir and a boosting agent to fight HIV

A new once-daily, fixed-dose pill containing four anti-HIV drugs shows promise in clinical studies, Gilead Sciences, Inc. announced.

The new once-daily pill uses investigational integrase inhibitor elvitegravir and two commonly prescribed emtricitabine and tenofovir disoproxil fumarate and GS 9350, a boosting agent to combat HIV infection.

Also called “Quad” regimen, the single dose pill has shown effective in tackling HIV in Phase 2 trials.

A Phase II clinical trial of its investigational integrase inhibitor-based, once-daily, fixed-dose “Quad” regimen of elvitegravir, GS 9350 and Truvada (emtricitabine and tenofovir disoproxil fumarate) for the treatment of HIV-1 infection met its primary objective, Gilead said.

The ongoing study of 71 HIV-infected, antiretroviral treatment-naive adults compares the Quad with Atripla (efavirenz 600 mg/emtricitabine 200 mg/tenofovir disoproxil fumarate 300 mg).

Based on 24-week data, efficacy of the Quad met the statistical criteria of non-inferiority as compared to Atripla based on the proportion of subjects with HIV RNA levels (viral load) of less than 50 copies/mL.

Gilead plans to submit full study results for presentation at a scientific meeting in early 2010.

Elvitegravir is an HIV integrase inhibitor. Unlike other classes of antiretroviral agents, integrase inhibitors interfere with HIV replication by blocking the ability of the virus to integrate into the genetic material of human cells.

Elvitegravir, also known as GS 9137 or JTK 303, was licensed by Gilead from Japan Tobacco Inc. in March 2005.

Under the terms of Gilead’s agreement with JT, Gilead has exclusive rights to develop and commercialize elvitegravir in all countries of the world, excluding Japan, where JT retains rights.

GS 9350 is Gilead’s proprietary potent mechanism-based inhibitor of cytochrome P450 3A (CYP3A), an enzyme that metabolizes drugs in the body.

Gilead is also studying GS 9350 as a stand-alone boosting agent for other antiretrovirals, in particular, protease inhibitors.

A Phase II clinical trial evaluating the safety and efficacy of GS 9350-boosted atazanavir compared to ritonavir-boosted atazanavir, each in combination with Truvada, is ongoing.

Truvada is a fixed-dose combination tablet containing 200 mg of emtricitabine (Emtriva) and 300 mg of tenofovir disoproxil fumarate (Viread).

In the United States, Truvada is indicated in combination with other antiretroviral agents, such as non-nucleoside reverse transcriptase inhibitors or protease inhibitors, for the treatment of HIV-1 infection in adults.

In the United States, Atripla is indicated for use alone as a complete regimen or in combination with other antiretroviral agents for the treatment of HIV-1 infection in adults.

Atripla contains the components Truvada (emtricitabine and tenofovir disoproxil fumarate) and Sustiva (efavirenz), co-formulated as a single tablet.

Headquartered in Foster City, California, Gilead Sciences is a biopharmaceutical company. Gilead has operations in North America, Europe and Australia.