The companies formed an alliance in 2014 to develop and commercialize AZD3293, an oral beta secretase cleaving enzyme (BACE) inhibitor.
The new milestone means Eli Lilly will pay AstraZeneca $100m under the terms of the deal.
Amaranth, the Phase II/III study of AZD3293, is investigating the safety and efficacy of AZD3293 and testing the hypothesis that it is a disease-modifying treatment for early Alzheimer’s disease.
The study will now continue into phase III after the Amaranth independent data monitoring committee recommended that it could go on without changes following the completion of a scheduled interim safety analysis.
AZD3293 has been demonstrated in phase I studies to reduce levels of amyloid beta in the cerebro-spinal fluid of people with Alzheimer’s disease and healthy volunteers.
AstraZeneca executive vice president of IMED Biotech Unit Menelas Pangalos said: "BACE inhibitors have the potential to target one of the key drivers of disease progression and we are delighted that our combined efforts have resulted in the development of AZD3293 moving into the next phase of study.
"Disease modifying approaches, such as this, have the potential to transform the treatment of Alzheimer’s disease and help patients in this area of large unmet medical need."
Alzheimer’s disease is the most common form of dementia, which accounts for 60% to 80% of dementia cases.
It is estimated that 46 million people live with dementia globally at present, and the number is anticipated to increase to more than 74 million in 2030 and 131 million in 2050.
Image: AstraZeneca and Eli Lilly announce continuation of pivotal clinical trial for people with early Alzheimer’s disease. Photo: courtesy of AstraZeneca.