Merck & Co Inc. (MRK) halted a late-stage study of its Alzheimer's drug candidate verubecestat after the drug failed to treat Alzheimer's disease. Verubecestat joins a growing number of drugs that have failed to treat the brain-damaging dementia disease. (See also, Axovant Rival Gives Up On Alzheimer's Drug.)

Drug Shows No Effect

Merck had been evaluating the drug for patients with mild to moderate Alzheimer's disease. An independent data monitoring committee recently concluded that there was "virtually no chance of finding a positive clinical effect," reports Reuters. That assessment led to Merck's decision to halt its Phase 3 study.

Verubecestat is categorized as a BACE1 inhibitor, and works by targeting and blocking an enzyme which is responsible for the build-up of the toxic amyloid protein that transforms into plaques in the brains of Alzheimer’s patients.

Many other drug makers are attempting to develop Alzheimer's drugs based on this concept of blocking the plaque-causing beta amyloid, although with different drug mechanisms. However, success has been hard to find. They include attempts by Biogen Inc. (BIIB), Eli Lilly and Co. (LLY), and Novartis AG (NVS) in partnership with Amgen Inc. (AMGN). (See also, Eli Lilly Tanks on Alzheimer's Drug Failure.)

Prodromal Alzheimer's Study Continues

Merck has another ongoing study for the drug in treating Prodromal Alzheimer's disease, which is the very early form of Alzheimer's, when memory is deteriorating but a person remains functionally independent. The drug will continue to be assessed for Prodromal studies, and the study data is expected by February 2019.

The news of late stage trial suspension lead to a marginal decline in Merck’s stock price. The stock was trading at $64.50 per share during pre-market hours on Wednesday, down by around 1.7% from previous day’s close of $65.66 a share. (See also, Merck Q4 Sales Slip, Promises Better 2017.)

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