The Abbott drugs studied in AVIATOR were ABT-450, a protease inhibitor that requires blood-boosting with ritonavir; ABT-072, an NS5A inhibitor; and ABT-333, a "non-nuc" polymerase inhibitor. Ribavirin, a current backbone in hepatitis C treatment, was also included in some but not all of the combination regimens.
Gilead's results come from a large phase II study known as ELECTRON, testing two experimental pills, the nucleoside, or "nuc" polymerase inhibitor GS-7977 (also known as sofosbuvir) and GS-5885, an NS5A inhibitor, plus ribavirin. The study also enrolled treatment-naive, genotype 1 hepatitis C patients.
Gilead has already started phase III studies of its oral hepatitis C pill combinations. Positive results could lead to regulatory approval in 2014. Based on the results from AVIATOR, Abbott is moving forward into phase III studies with its three-drug regimen, with and without ribavirin.
In addition to efficacy, convenience may also play a role in which new hepatitis C regimen emerges as the winner. Gilead could have a slight edge because GS-7977 and GS-5885 are being coformulated into single pill taken once per day. With the addition of ribavirin, hepatitis C patients on the Gilead regimen would take two pills in the morning and one at night for 12 weeks.Abbott's combination therapy requires patients to take more pills. With ribavirin added, hepatitis C patients would swallow four pills in the morning and two pills in the evening for 12 weeks. Vertex Pharmaceuticals (VRTX - Get Report), Bristol-Myers Squibb (BMY), Merck (MRK), Idenix Pharmaceuticals (IDIX) and Achillion Pharmaceuticals (ACGN) are also engaged in the race to develop new, combination-pill therapies against hepatitis C. -- Reported by Adam Feuerstein in Boston. Follow @AdamFeuerstein