A study of Gilead Sciences’ “Quad” fixed-dose combination tablet containing the experimental integrase inhibitor elvitegravir and boosting agent cobicistat, along with tenofovir and emtricitabine, has met its primary objective—“non-inferiority” compared with the popular protease inhibitor–based regimen of Norvir (ritonavir)-boosted Reyataz (atazanavir) plus Truvada (tenofovir and emtricitabine)—according to a September 19 announcement by the company. 

According to Gilead—full results have not yet been presented or published—90 percent of those who took the Quad tablet in the study had undetectable viral loads (less than 50 copies) after 48 weeks of treatment, compared with 87 percent of those who took the Reyataz-inclusive regimen. The clinical trial enrolled more than 700 people living with HIV starting antiretroviral therapy for the first time.

The discontinuation rate due to side effects was higher in the Norvir-boosted Reyataz group (5.1 percent) compared with the Quad group (3.1 percent). This difference was driven primarily by elevated bilirubin levels—a pigment found in the liver that can cause the skin, nails and whites of the eyes to appear yellowish-brown—in the Norvir-boosted Reyataz group. Though increased bilirubin can also be a sign of liver toxicity, this does not appear to be any more common among people taking Norvir-boosted Reyataz.

The Phase III research program for Gilead’s Quad tablet includes two studies (Studies 102 and 103) evaluating the all-in-one regimen versus a standard of care among people starting HIV treatment for the first time. Like the encouraging results from Study 103, highlighted in Gilead’s September 19 statement, data from Study 102 highlighted in an announcement released in August suggest the Quad also has similar efficacy to Atripla.

Gilead plans to submit the results from Study 102 and Study 103 for presentation at a scientific conference early next year.