By Ransdell Pierson and Bill Berkrot
April 23 (Reuters) - AbbVie Inc's experimental hepatitis C treatment cured up to 96 percent of patients in just 12 weeks, according to data released on Tuesday, shoring up its position in the race to deliver a potent oral therapy for the serious liver disease.
AbbVie's treatment, a combination of five oral medications, is expected to be a close contender to a treatment in development by Gilead Sciences Inc. Analysts see the Gilead drug winning regulatory approval as early as 2014, with AbbVie close behind.
AbbVie said on Tuesday that about 88 percent of new patients with hepatitis C were deemed cured after only eight weeks of treatment, while 96 percent of those treated for 12 weeks eliminated the liver virus, as verified by blood tests 24 weeks after completion of treatment. No serious safety concerns were observed by researchers.
If the virus is undetectable 24 weeks after completing treatment - known as sustained virologic response, or SVR 24 - a patient is considered cured.
The latest findings from an ongoing trial sponsored by AbbVie, called Aviator, were unveiled at a meeting of the European Association for the Study of the Liver (EASL) in Amsterdam. Shares of AbbVie rose 2 percent in morning trading on the New York Stock Exchange.
"AbbVie looked good, but I think Gilead is still in the lead," said Tim Nelson, an analyst with Nuveen Asset Management. He estimates that the market for oral hepatitis C treatments would be worth billions of dollars in annual sales.
Hepatitis C affects an estimated 170 million people worldwide, and if left untreated can lead to cirrhosis, liver cancer or the need for a new liver.
Existing treatments must be taken by patients for either 24 or 48 weeks and the most effective have a cure rate as high as 80 percent. Several companies are working to eliminate infusions of difficult-to-tolerate interferon from the regimen, while raising cure rates and shortening the length of treatment.
MORE ROBUST DATA
The latest results from AbbVie confirmed interim data presented in October, which showed a 99 percent SVR rate for patients evaluated 12 weeks after completing a 12-week regimen of the treatment.
"We are pleased that the data remain consistent and robust," lead researcher Dr. Kris Kowdley in said an interview. "The data confirm that the 12-week treatment appears to be optimal, but certainly we are still very pleased with ... data for the eight-week treatment."
AbbVie spokeswoman Tracy Sorrentino said the 8-week data was impressive. But for larger late-stage trials, she said the company plans to test the drug combination for 12 weeks, in order "to help the greatest number of patients achieve virologic cure."
Gilead has been given an edge by many analysts because its experimental regimen involves fewer drugs and may be closer to reaching the market. AbbVie said it is testing regimens with fewer drugs and ones that do not include the older oral drug ribavirin, which can also be difficult for some patients to tolerate.
Bristol-Myers Squibb unveiled data on Tuesday at the meeting from a smaller mid-stage study of its three-drug combination that does not include ribavirin. Its program is behind those of Gilead and AbbVie, but cure rates in excess of 90 percent and a relatively clean safety profile are expected to make it a formidable player in the field.
Bristol-Myers shares were up 1.2 percent.
Patients in the AbbVie Aviator study had the most common, but hardest to treat, genotype 1 variation of the infectious virus.
The AbbVie regimen included three experimental direct acting antiviral drugs that each attack a different target necessary for virus replication. The drugs were the protease inhibitor ABT-450, whose effect was boosted by a widely used antiviral called ritonavir; the polymerase inhibitor ABT-333, and ABT-267 from a class known as NS5A inhibitors. Those were given along with the older medicine ribavirin.
Kowdley, director of the Liver Center of Excellence at Virginia Mason Medical Center in Seattle, said the trial also showed impressive results among patients who had failed to benefit from earlier therapy.
The cure rate after 12 weeks of treatment was 93 percent for those patients, called null responders, assessed both 12 weeks and 24 weeks after completion of their drug regimens. In addition, data showed a cure rate of 95 percent for patients treated for 24 weeks, and then assessed 24 weeks after treatment stopped.
AbbVie said the safety of the tested drugs was similar to that seen in results presented last year. Of the 247 patients evaluated, serious side effects were seen in four patients (1.6 percent), while seven patients had elevated levels of liver enzymes that can be considered a potential sign of toxicity.
Less-serious side effects seen in more than 10 percent of patients included headache, fatigue, nausea, insomnia and diarrhea.