Alzheimer's drug slows down the disease, but comes with risks: study

Another experimental Alzheimer's drug can modestly slow patients' inevitable worsening — by about four to seven months, researchers reported Monday.

Eli Lilly and Co. is seeking U.S. Food and Drug Administration (FDA) approval of donanemab. If cleared, it would be only the second Alzheimer's treatment convincingly shown to delay the mind-robbing disease, after the recently approved Leqembi from Japanese drugmaker Eisai.

"Finally there's some hope, right, that we can talk about," Lilly's Dr. John Sims told reporters Monday at the Alzheimer's Association International Conference in Amsterdam.

"We don't cure the disease," he said. "Diabetes doesn't have a cure either. It doesn't mean you can't have very meaningful treatments for patients."

Lilly announced in May that donanemab appeared to work, but on Monday the full results of a study of 1,700 patients were published by the Journal of the American Medical Association (JAMA) and presented at the Alzheimer's conference.

Both donanemab and Leqembi are lab-made antibodies, administered by IV, that target one Alzheimer's culprit: sticky amyloid buildup in the brain. Both drugs come with a serious safety concern — brain swelling or bleeding that in the Lilly study was linked to three deaths.

Leqembi and donanemab are not approved in Canada. 

In an email to CBC News, a Health Canada spokesperson said that Leqembi is listed as under review on the agency's new drug submission website. The drug's application was accepted for review in May. 

Health Canada says it doesn't comment on drugs that are under review, and that timing of these submissions depends on many factors, including a need for more data, talks with the sponsor and requirements for updates to safety information. 

Meanwhile, donanemab has not been submitted for review, according to Health Canada's website. 

The Alzheimer Society of Canada's CEO Christopher Barry told CBC News in an email that the society is "hopeful that new advancements in research will bring more treatment options to Canadians."

Barry added that long-term trial data will be crucial in understanding the risks and benefits for people living with dementia. 

Scientists say while these drugs may mark a new era in Alzheimer's therapy, huge questions remain about which patients should try them and how much benefit they'll really notice.

"The modest benefits would likely not be questioned by patients, clinicians or payers if amyloid antibodies were low risk, inexpensive and simple to administer. However, they are none of these," Dr. Eric Widera, of the University of California, San Francisco, wrote in a JAMA editorial accompanying Lilly's new data.