Adolor shares sink after placebo effect scuttles PhIIa pain trial

Shares of Adolor (ADLR) took an 18 percent dive yesterday evening after the company announced that two of its pain meds partnered with Pfizer had failed a mid-stage clinical trial. Pfizer paid $30 million upfront to collaborate on ADL5859 or ADL5747, two therapies that were tested alongside oxycodone for its effectiveness in reducing pain among patients with osteoarthritis.

Exton, PA-based Adolor said that an unusually high placebo response eliminated any statistically significant drug effect, even eclipsing oxycodone's response rate. And that puzzling result left analysts scratching their heads over the top-line data that they had to ponder. "It's neither an indication the drug does work nor an indication that the drug doesn't work," Wedbush Securities analyst Gregory Wade tells Reuters.

The drugs in the Phase IIa trial were delta opioid receptor agonists, which Adolor says can be used without the side effects demonstrated by traditional mu agonists like morphine.

"We obviously are disappointed with the results of this study," said Eliseo O. Salinas, M.D., senior vice president, research and development and CMO of Adolor. "The extent of placebo response was surprising, but unfortunately not unusual in osteoarthritis studies. Pfizer and we expect to fully assess this data set over the coming weeks and make a determination as to whether additional testing of the delta compounds in chronic inflammatory pain indications is warranted. Our Phase IIa clinical study of ADL5747 in post-herpetic neuralgia continues, with top-line data expected in the first quarter of 2011."

- check out the Adolor release
- here's the story from Reuters