(Reuters) - In the race to find a faster cure for hepatitis C, Bristol-Myers Squibb Co said it will test its experimental antiviral drug combination with Gilead Sciences Inc's blockbuster drug Sovaldi, hoping to cut treatment time to four weeks.

Bristol-Myers disclosed plans for the exploratory 30-patient trial testing its three-drug combination with Sovaldi in an interview with Reuters. Eric Hughes, the leader of Bristol's global hepatitis program, said the details were due to be posted on the clinicaltrials.gov website next week.

Sovaldi's $84,000 price tag for a 12-week treatment has spurred outrage among insurers, state health officials and lawmakers who fear the cost of treating millions of Americans with the progressive liver disease will top $250 billion. Insurers are pushing Gilead's rivals to offer lower prices when their hepatitis C medicines reach the market.

Using the drug for a shorter course of treatment could, in theory, lower the cost, even when combined with Bristol's therapies. Rivals Merck & Co and AbbVie are also racing to develop next-generation hepatitis C treatments that cure most people of the virus in a shorter time frame.

But drug pricing experts expect Gilead and its rivals may still argue that the quicker cure represents a value to patients, buffering any steep price reductions.

"The position and concept of pharma is not ingredient costs or duration of treatment cost. Pharma is looking at it as cost per cure," said John Whang, co-president of Reimbursement Intelligence, which works with pharmaceutical companies and payers to help determine prices for medicines.

The cost could come down, he said, "but it's not going to be proportionate to the degree that the duration of treatment shortens."

The new generation of oral drugs being developed by several companies has raised hepatitis C cure rates to well above 90 percent from about 75 percent without the need for interferon or ribavirin, which caused miserable side effects that led many patients to delay or drop treatment. The drugs in clinical trials have already cut treatment time to 12 weeks from 24 to 48 weeks.

"We got rid of the tolerability problem. We got rid of the efficacy problem. Now there is a tremendous drive to get down to shorter treatment durations," Bristol-Myers' Hughes said in a telephone interview.

REVIVING A SOVALDI COMBO

Bristol's plan essentially revives an effort to test its drugs in combination with Sovaldi. It previously tested a single compound with Sovaldi, achieving cure rates close to 100 percent in 12 weeks. But Gilead scrapped further testing in 2012, as it preferred to develop its own combination without a partner.

Gilead's pill that combines Sovaldi with its ledipasvir is expected to gain U.S. approval this year for therapies of eight or 12 weeks, depending on the patient. The company is also testing the combination as a six-week treatment.

The go-it-alone strategy has already paid off as Gilead was first to market with Sovaldi, breaking pharmaceutical industry sales records with $2.3 billion in sales within a few months.

The new study, set to begin in late July, will test a trio of Bristol drugs with Sovaldi in previously untreated patients with the most common Genotype 1 form of the virus. It will involve two groups of 15 patients each - one getting four weeks of treatment and the other six.

If Bristol can demonstrate cure rates in excess of 90 percent in four weeks, it plans to conduct larger trials with a more diverse patient population.

"We'll see what the data says," Hughes said. "Taking this forward will be a very exciting thing."

With Gilead not involved in the effort, Bristol will pay full price for Sovaldi to conduct the trial.

Bristol would not discuss potential pricing of its regimen, since its drugs are not approved. But if treatment can be cut to four weeks from 12, the Sovaldi portion would be closer to $28,000.

Other rivals are also advancing efforts to compete in what is expected to be a huge market.

Merck this month agreed to pay $3.85 billion to acquire Idenix Pharmaceuticals Inc with the hope that combining the two companies' most promising drugs will produce cures in four to six weeks across the full spectrum of genotypes.

U.S. and European health regulators in the last week said they would accelerate their reviews of AbbVie's four-drug regimen, meaning it could be vying for market share by early next year.

(Reporting by Bill Berkrot; Editing by Michele Gershberg and Douglas Royalty)