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* EnVivo drug acts on nicotine receptors
* Drug showed a benefit on top of current treatments
By Julie Steenhuysen
VANCOUVER, British Columbia, July 18 (Reuters) - An experimental Alzheimer's drug that activates a specific nicotine receptor in the brain improved measures of thinking and memory over a six-month period in patients with mild to moderate disease, U.S. researchers said on Wednesday.
Most drugs being studied for Alzheimer's aim to keep the disease from progressing. But the experimental drug made by privately held EnVivo Pharmaceuticals Inc of Watertown, Massachusetts, is intended to improve Alzheimer's symptoms.
In the phase 2 study, EnVivo's drug called EVP-6124 was tested in 409 patients with mild to moderate Alzheimer's, many of whom were already taking Pfizer Inc's Aricept, known generically as donepezil, or Novartis AG's Exelon, known generically as rivastigmine.
Even so, patients who took the 2 milligram dose of EVP-6124 showed a statistically significant increase in measures of cognitive function after 23 weeks.
"These are very encouraging data," said Dr. Dana Hilt, chief medical officer of EnVivo, who is presenting the study's findings at the Alzheimer's Association International Conference in Vancouver, British Columbia.
He said that even though the drug was used in a mixed group of patients, some of whom were taking additional medications and others who were not, it improved both their thinking skills and their ability to function in daily life.
"It is statistically and clinically significant," Hilt said.
Most current drugs under study to treat Alzheimer's, including Pfizer and Johnson & Johnson's bapineuzumab and Eli Lilly and Co's <LLY.N > solanezumab, are being tested in the hopes of stopping progression of the brain-wasting disease, but they will not necessarily improve existing symptoms.
Researchers say there is still a need for effective drugs to treat the symptoms of Alzheimer's, which affects some 5 million Americans and as many as 35 million people worldwide.
"The idea of developing a drug that improves symptoms that we could use with a disease-modifying agent is very important to me," said Dr. Jeffrey Cummings, who directs Alzheimer's programs at the Cleveland Clinic in Las Vegas and Cleveland and is a paid consultant for EnVivo.
"My patients want to get better. They don't just want to get worse more slowly," Cummings said.
Aricept and several drugs like it work by keeping an enzyme called cholinesterase from breaking down acetylcholine, an important neurotransmitter for memory and thinking that declines as Alzheimer's progresses.
EnVivo's drug works differently, targeting a nicotine receptor in the brain called alpha 7 that is related to cognition and memory.
Cummings said the drug selectively targets just that part of the nicotine receptor that benefits cognition without stimulating the effect that causes dependency.
"It was a relatively small, phase 2 study, but they did see a cognitive benefit that suggests we would want to look further," said Dr. Laurie Ryan, who heads up Alzheimer's clinical trials at the National Institute on Aging, a part of the National Institutes of Health.
The company plans to test the drug in large, phase 3 clinical trials starting next year.
"Every little bit of functionality we return moves patients closer to normal and gives them a higher quality of life," said William Thies, chief medical and scientific officer at the Alzheimer's Association.