Arena says safety board clears obesity drug trial

LOS ANGELES, March 17 (Reuters) - Arena Pharmaceuticals Inc (ARNA.O: Quote, Profile, Research, Stock Buzz) on Monday said an independent safety review board has cleared the way for a pivotal trial of the company's experimental weight-loss drug lorcaserin to continue.

San Diego-based Arena said the review of patients who completed 12 months of dosing confirmed that differences, if any, between the rate of heart valve problems in patients taking lorcaserin and those given a placebo did not meet predetermined stopping criteria.

Lorcaserin is a serotonin activator like fenfluramine, half of the infamous fen-phen diet pill that was recalled a decade ago after being linked to deadly side effects, including heart valve problems.

The Phase III trial involving 3,200 obese patients is slated to continue for another 12 months, but no further independent safety reviews are planned.

"We believe that this exposure duration, even under a conservative interpretation of the literature, would have been sufficient to observe a fenfluramine-like effect on heart valves if present," said Jack Lief, Arena's chief executive officer.

Based on the safety review, which gave Arena some idea of the rate of valvulopathy in the placebo group, Lief said the company has confirmed that its clinical trial program for lorcaserin is large enough to detect the statistical risk of heart valve problems.

The company says lorcaserin blocks appetite signals in the brain, but is much more selective in the receptors that it targets than fenfluramine, which also binds to a separate cell receptor in the heart.

An earlier study of lorcaserin, without diet and exercise, showed that participants lost an average of 7.3 pounds.

Investors have been closely monitoring whether Arena will secure a marketing partner for lorcaserin. Lief said the company is continually talking with potential partners. "It is just a question of coming to a meeting of the minds ... this is still a work in progress," he said.

Arena is also conducting Phase III trials of lorcaserin in diabetes patients and in combination with diet and exercise. (Reporting by Deena Beasley; Editing by Christian Wiessner)