UPDATE 1-La Jolla says in partnership talks on Lupus drug

(Updates with details)

By Toni Clarke

BOSTON, Aug 9 (Reuters) - La Jolla Pharmaceutical Co (LJPC.O) said on Thursday it is in "serious" partnership discussions with big pharmaceutical and biotechnology companies over its experimental drug to treat Lupus.

Chief Executive Officer Deirdre Gillespie said in an interview that the company expects to sign a deal by the end of the first quarter of next year, or even earlier.

Gillespie said La Jolla has "serious discussions going on," based on renewed optimism among potential partners following the release of clinical trial data that suggests the drug -- long in development -- may still have a future.

She said the company is considering two possible deal structures: one being a global partnership with a single company; the other being separate deals covering different regions of the world, depending on which would create most value for shareholders.

Regardless of which option it chooses, "we will keep at least part of the United States for ourselves," she said.

La Jolla has been struggling to win approval for its Lupus drug for years.

In 2004, U.S. regulators declined to approve the drug until the company provided more clinical data proving it works. Now, with a new management in place and a new, more robust clinical trial underway, the company hopes to win back the credibility of investors whose hopes have been dashed more than once.

Earlier this year La Jolla released clinical data from a study of its drug, Riquent, that showed it was well tolerated at higher doses than previously studied. The company is hoping its new trial will show that a higher dose of the drug will improve its efficacy.

Gillespie said the decision to test the drug at 300-milligram and 900-milligram doses, compared with the previously tested 100-milligram dose, was largely a matter of trial and error, but that early data suggests it could work substantially better.

An initial glimpse of efficacy data will be revealed before the end of this year, but Gillespie said potential partners show no sign of waiting for the data to be released.

Many biotech companies these days wait for as much data to be released as possible before signing a deal, because the better the data the better the terms they are likely to win.

But Gillespie said that she is willing to sign a partnership deal early to help rebuild confidence in the drug, in the company's credibility and in the stock.

"That would give me currency to do other things further down the road," she said.