CHICAGO (Reuters)- Keenly awaited details on Elan ELN.I ELN.N and Wyeth’s WYE.N new Alzheimer’s drug bapineuzumab show it raised the risk of a potentially serious side effect, but may help people who do not have a common genetic risk of the disease, the companies said on Tuesday.
Shares of both companies plunged in after hours trade with Elan’s New York shares falling more 18 percent and Wyeth’s dropping more than 10 percent.
“I think the (drug’s) side effects are going to be perhaps significant, but if they are temporary and tolerable and if the drug shows a benefit, the risk-benefit ratio will be worth the side effects,” said Dr. Scott Turner, incoming director of the Memory Disorders Program at Georgetown University Medical Center in Washington.
“This is potentially the first disease-modifying therapy.”
The update on the antibody medicine, also known as AAB-001, has been closely watched by investors. If proven to work, the drug could be the first to modify the course of Alzheimer’s disease, rather than just offering symptom relief.
Some analysts have forecast eventual annual sales of $13 billion.
Twelve people with mild-to-moderate Alzheimer’s who were treated with the drug, developed a build-up of fluid in the brain called vasogenic edema, researchers told the Alzheimer’s Association International Conference on Alzheimer’s Disease in Chicago.
Ten of those cases were in people who have the ApoE4 gene, which significantly raises their risk of developing Alzheimer’s disease.
Preliminary findings released last month showed the drug failed to boost memory and functionality in most of 234 patients over 18 months.
Carriers of ApoE4, 60 percent of those who got the drug and 70 percent who got the placebo, did not show any improvement in their ability to think or function.
But among people who had different versions of the ApoE gene, the companies did find a statistically significant improvement in these measures.
When they looked at people do not carry the gene and who completed the study, “we have absolutely dynamite data,” said Dr. Sid Gilman of the University of Michigan, who helped work on the study.
“There is a very strong signal among non-carriers, suggesting a beneficial effect,” Gilman told the meeting.
Other experts were cautious. “You can’t conclude anything about the efficacy of the drug from this trial,” said Dr Ronald Petersen of the Mayo Clinic in Rochester, Minnesota.
“It’s a secondary analysis. You have to go with what they pre-specified and what their endpoints were, and they didn’t make those,” said Petersen, incoming chairman of the Alzheimer’s Association’s scientific board and chairman of a safety monitoring board for a therapeutic vaccine Wyeth and Elan are working on for Alzheimer’s.
The results “give me pause that the statistical significance that we saw will bear out in the Phase 3 trials,” said David Moskowitz, an analyst at Caris & Co.
“This is still a very risky endeavor,” he said.
The companies decided to conduct larger studies aimed at proving bapineuzumab worked in ApoE4 non-carriers, who make up about half of all Alzheimer’s patients, Dr. Ronald Black, assistant vice president in neuroscience research at Wyeth, said in an interview.
Black said the big difference in vasogenic edema between ApoE4 carriers and non-carriers prompted the companies to analyze the groups separately.
Shares of Wyeth fell 10.1 percent to $40.40 in extended trade on Tuesday, while shares of Elan dropped 18.5 percent to $27.50 in New York.
Additional reporting by Deena Beasley in Los Angeles; Editing by Maggie Fox, Leslie Gevirtz