Updated with new information. BOSTON ( TheStreet) -- Gilead Sciences ( GILD) has drawn first blood from Abbott Labs ( ABT) (but just barely) in the battle for hepatitis C pill supremacy. Twelve weeks of treatment with two Gilead drugs plus the immune system booster ribavirin yielded an interim cure rate of 100% in treatment-naive hepatitis C patients. A 12-week regimen consisting of three Abbott drugs plus ribavirin demonstrated a final cure rate of 97% of treatment-naive hepatitis C patients and 93% of "null" responders -- the hardest-to-treat patients because they've failed previous therapy. The score so far: Gilead 100%, Abbott 97%. Close, but Gilead wins, which means shares are likely to move higher when trading opens Monday. The Gilead result is the "best case" scenario, said ISI Group analyst Mark Schoenebaum in an email to clients. In a Monday note to clients, Jefferies analyst Thomas Wei said, "These data make us more confident in Gilead winning a dominant position among
genotype 1 regimens for hepatitis C, with comparable cure rates, fewer side effects and better convenience relative to the Abbott regimen." Gilead shares closed Friday at $65.01. The Abbott and Gilead regimens were not tested against each other in a single study, so declaring a winner and a loser isn't scientific or fair, necessarily. It's important, too, to note that Abbott's phase II study is larger and reported final cure rates after 12 weeks of follow-up. Gilead's phase II study enrolled fewer patients and cure rates are being reported after only four weeks of follow-up. Wall Street investors are comparing the two sets of results directly against each other, nonetheless. Hepatitis C researchers, with investors tagging along, are gathering in Boston at the Liver Meeting, the annual conference sponsored by the American Association for the Study of Liver Disease. The most important data presentations over the next four days will focus on the race to develop new pills, which when used in various combinations, can replace the traditional injections long required to treat and cure hepatitis C. The hepatitis C drug treatment market could grow to as much as $20 billion, some estimates claim, if more people with the viral liver disease seek cures with simpler and more effective all-oral therapies. The new Abbott data announced Saturday come from a large, phase IIb study known as "AVIATOR" that was designed to assess the efficacy and safety of various combinations of oral hepatitis drugs in treatment-naive, genotype 1 hepatitis C patients as well as hard-to-treat null responders.
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), 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