Eli Lilly and Co. said on Thursday it halted a mid-stage study of an experimental Alzheimer's disease treatment due to potential liver toxicity, the latest setback in the quest to find a treatment that can slow or cure the memory-robbing condition.
Lilly said the Phase II study of the drug, LY2886721, from a class known as beta secretase, or BACE, inhibitors, was stopped after safety monitors identified cases of abnormal liver tests.
The Indianapolis-based drugmaker said the liver issues do not appear related to the drug's mechanism, and that it remains interested in developing BACE inhibitors to treat the progressive brain disease.
Oral drugs to block beta secretase, although still unproven, have been one of the biggest hopes for slowing progression of the disease after another class of medicines being developed by Lilly and Pfizer Inc. last summer fell short in big trials.
Those injectable drugs, Lilly's solanezumab and Pfizer's bapineuzumab, directly block beta-amyloid, a protein that forms brain plaques considered a prime cause of Alzheimer's disease.
Solanezumab failed to slow progression of Alzheimer's among patients with mild to moderate disease. It is now being tested in patients with mild disease because it was shown to slow loss of memory in that narrower population. Bapineuzumab has been largely written off by investors after failing to slow progression of Alzheimer's in its late-stage trials.
BACE inhibitors, including rival products being developed by Merck & Co., Roche Holding AG and Eisai Co. Ltd, are meant to prevent buildup of beta-amyloid by blocking an enzyme called BACE1.
Industry analysts have said any of the BACE inhibitors could become huge sellers, with annual sales of $3 billion or more, if they prove effective and are approved. That is because no drugs currently slow progression of Alzheimer's, the biggest cause of dementia, which is believed to affect an estimated 5 million Americans.
Even so, Wall Street is not assuming the drugs will succeed, because they are in relatively early development and there have been few clues on their safety and effectiveness.
An estimated 35 million people worldwide are believed to have dementia, including Alzheimer's disease, and those numbers are expected to rise as more people live longer.
Lilly shares closed up 0.1 percent on Thursday, amid a 1 percent gain for the drug sector.
(Additional reporting by Bill Berkrot; Editing by Kenneth Barry and Dan Grebler)