Gilead Sciences has presented more promising late-stage data on its four-drug HIV treatment which could be filed by the end of the year, earlier than scheduled.

The data comes from a second Phase III trial of Quad, a fixed-dose, single-tablet regimen made up of Gilead’s investigational drugs elvitegravir and cobicistat combined with the two active ingredients in Truvada (emtricitabine and tenofovir). The study compared Quad with ritonavir-boosted atazanavir plus Truvada.

Gilead noted that 90% of patients receiving Quad regimen achieved HIV RNA levels (viral load) of less than 50 copies/ml after 48 weeks' treatment. This compared to 87% in the comparison arm, meeting the trial's goal of non-inferiority.

Some 3.1% of Quad patients discontinued treatment due to adverse events, versus 5.1% in the comparison arm. Gilead R&D chief Norbert Bischofberger said that the 90% response rate observed on the Quad arm "is an unprecedented result and speaks to the potency, safety and convenience of an integrase-based single-tablet regimen".

In August, the first Phase III study of Quad showed that it was as effective as Gilead's big-selling combo Atripla (efavirenz/tenofovir/emtricitabine). Dr Bischofberger said that based on the availability of data from both studies, "we are now working toward filing for US regulatory approval of Quad by the end of the year". Previously, Gilead had been looking at filings in the first quarter of 2012.