Eli Lilly’s experimental Alzheimer’s drug solanezumab failed to have statistically significant benefits in the primary end points of two phase III trials but showed possible early cognitive benefits in secondary analyses, the company announced Aug. 24.

The two 18-month trials, called EXPEDITION 1 and 2, randomized more than 2,050 patients with mild-to-moderate Alzheimer’s disease to the drug or placebo.

Dr. Richard Caselli

Two secondary analyses of pooled data from the trials found significant slowing of cognitive decline that was driven mainly by patients with the mildest disease, Dr. William Thies said in an interview.

“This is consistent with the idea that treatment is best started well before a patient becomes demented,” said Dr. Thies, medical director of the Alzheimer’s Association.

The studies’ main contribution may be scientific rather than clinical, he said. “This finding [of slowed decline] in a large human trial shows that if you lower amyloid, you can at least partly affect disease course. This is very important. It’s a piece we have not had before.”

Dr. Richard Caselli, a neurologist at the Mayo Clinic in Scottsdale, Ariz., was less enthusiastic.

“The planned secondary analyses of pooled data are certainly of scientific interest, but was this statistically significant effect clinically significant?”

He also suggested that cost could hamper the drug’s real-life impact, should it come to market. “Another monoclonal antibody, rituximab, costs roughly $60,000 per treatment cycle per patient. It seems reasonable to question the potential cost for a drug with clinically minuscule effects, given for a disease that affects 5.4 million Americans.

“Clearly we need an effective therapy, but it must be clinically significant and it must be affordable. Unfortunately, we still have a long way to go to meet this goal.”

The Alzheimer’s Disease Cooperative Study is conducting an independent review of the data from the trials, and will present its findings on Oct. 8 at the annual meeting of the American Neurological Association, according to Eli Lilly.

Neither Dr. Thies nor Dr. Caselli had any relevant financial disclosures.