Eli Lilly and Co experimental drug solanezumab failed to slow loss of cognitive ability in patients with mild Alzheimer's disease in a large trial, a major setback for the U.S. drugmaker and millions of people with the memory-robbing disease.

Based on the failure of the Phase III study, Lilly on Wednesday said it would not seek U.S. approval of the infused drug for mild dementia. Some analysts had predicted solanezumab, if approved, could eventually claim more than $5 billion in annual sales and boost Lilly's earnings for years to come.

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