LONDON--A new once-daily AIDS drug from GlaxoSmithKline PLC (GSK) and its Japanese partner Shionogi & Co (4507.TO) performed better than Gilead Sciences Inc.'s (GILD) blockbuster three-drug HIV pill Atripla in a late-stage clinical trial.
Britain's biggest drug maker and Shionogi said Wednesday that a triple regimen containing dolutegravir, a novel integrase inhibitor, and two older Glaxo drugs did better in newly diagnosed HIV patients than Gilead's oral product.
Results from the Phase III SINGLE trial showed 88% of patients on the dolutegravir regimen had undetectable virus at 48 weeks compared with 81% on Atripla, a combination of Gilead's Truvada with Bristol-Myers Squibb Co.'s (BMY) Sustiva.
Full results of the study will be presented at an upcoming scientific meeting. It is the second of four Phase III studies on dolutegravir due to be reported this year that are designed to support regulatory filing of the experimental product and are keenly watched by experts and investors, as the full picture of the efficacy and safety of dolutegravir hasn't been conclusively determined.
The first set of study results, reported in April, showed dolutegravir was as effective as Merck & Co's (MRK) twice-daily blockbuster Isentress.
Dolutegravir is being developed by a joint venture between Shionogi and ViiV Healthcare Ltd., itself a joint venture established in 2009 by GlaxoSmithKline and Pfizer, Inc (PFE).
Integrase inhibitors represent a promising area of development and commercialization in HIV and dolutegravir has attracted positive attention for a number of reasons, notably its low milligram dosing which could make it easier to include in a fixed-dose combination pill, as well as its potential to minimize side effects because the drug does not require a booster.
Analysts said the latest clinical trial results were clearly a boost for dolutegravir and Glaxo.
"GSK now has the key trials needed for filing and approval of dolutegravir in treatment-naive patients," analysts at Bernstein said. "This trial also provides most of the clinical data needed to support their development, filing and approval of the fixed dose combination with Epzicom [abacavir and lamivudine]"
But the implications for Glaxo were less clear.
Deutsche Bank analyst Mark Clark said "while the SINGLE results are a clear positive, we caution that the impact on GSK will be constrained by several factors: GSK will enjoy only about 40% of the economics of the drug as it arises from a 50:50 joint venture with Shionogi and as GSK's HIV activities have been rolled into the ViiV Joint Venture with Pfizer, which owns 15%. " He also noted that Gilead is attempting to move beyond Atripla by launching its own integrase-based quadruple combination, Quad and is around a year ahead in development.
"Success of the dolutegravir combination would inevitably come partly at the expense of cannibalization of its "backbone" drugs abacavir and lamivudine," Clark added.
Shares in Glaxo were up 0.5% at 1330 GMT, at 1461 pence.
-Write to Sten Stovall at Sten.Stovall@DowJones.com