FDA Approves Two Gilead HIV Drugs, Elvitegravir And Cobicistat

Gilead has two new Food and Drug Administration (FDA) approved HIV drugs. Announced in an FDA email update, the approvals come on the heels of positive results of a study that used both agents as part of a drug cocktail. The drugs, Vitekta (elvitegravir) and Tybost (cobicistat), have already been approved by the European Medicines Agency (EMA).

While this is certainly good news for the company and provides patients with much needed new treatment options, there are some mixed perspectives about whether these drugs will be prioritized treatment options for patients with HIV. Paul Sax, MD, Professor at Harvard Medical School, said to Medscape Medical News that the drugs are unlikely to have a major effect on clinical practice. He said of elvitegravir, "As a separate entity, it does not have clear benefits over either raltegravir or dolutegravir. Additionally, coformulated versions of cobicistat with both darunavir and atazanavir are expected to be approved by the FDA soon; they will be more convenient than giving the drugs separately."

Vitekta

Vitekta (elvitegravir) is an integrase inhibitor that prevents HIV-1 DNA insertion into infected cells. The approval is for patients who have previously been treated with antiretroviral treatment. Elvitegravir is not a standalone drug; it is usually given along with a booster like ritonavir and another antiretroviral. The medication is taken once daily along with the other drugs. 

The FDA states that a Phase 3 trial (Study 145) provided the data to support the approval of Vitekta. The study evaluated 712 treatment-experienced adult patients. About half received Vitekta and the other half received raltegravir, with both groups also receiving a fully active protease inhibitor along with ritonavir and other antiretroviral drugs, depending on genotypic/phenotypic resistance testing and prior antiretroviral treatment history. The FDA stated that virologic outcomes were similar across the treatment arms.

Tybost

Tybost (cobicistat) increases the blood levels of the protease inhibitors atazanavir or darunavir. Clinical trials of Gilead’s Truvada, which contains cobicistat, showed non-inferiority to ritonavir and the other two drugs. Another trial compared cobicistat/ darunavir to ritonavir/darunavir, showing justification of cobicistat as a booster drug or pharmacokinetic enhancer with no antiviral activity.

Gilead proved its cobicistat case with the FDA based on phase 2 and 3 trials in treatment-naïve adults. The studies compared atazanavir/cobicistat 300/150 mg to atazanavir/ritonavir 300/100 mg once daily (in combination with Truvada). The cobicistat combination regimen proved non-inferior to the atazanavir/ritonavir based regimen. A multiple dose trial proved that cobicistat with darunavir was as relatively bioavailable as darunavir/ritonavir 800/100 mg.