Merck & Co. has completed enrolment of patients into its Phase II/III trial of verubecestat for Alzheimer disease. The drug is the most advanced of the β-secretase (BACE) inhibitors, which prevent the cleavage of amyloid precursor protein. Merck started the 1,960-patient trial in 2012 and now expects trial data in July 2017.

The trial will test the therapeutic potential of a BACE inhibitor in mild-to-moderate Alzheimer disease. The company's ongoing Phase III trial of the drug, which started in 2013, is testing its efficacy in 1,500 patients with prodromal Alzheimer disease.

Two other companies are also in pursuit with BACE inhibitors in Phase II/III trials. They are several years behind Merck, but are looking for efficacy in slightly different patient populations.

In 2014 AstraZeneca started enrolling 2,200 patients into a Phase II/III trial of AZD3293, with a focus on patients with mild Alzheimer disease. AstraZeneca expects final data from the trial in 2019. AstraZeneca is co-developing this drug with Lilly, which dropped its lead BACE inhibitor LY2886721 in 2013 owing to liver toxicity.

In December 2016, Johnson & Johnson became the latest to join the fray, when it started enrolling patients into a Phase II/III trial of JNJ-54861911. The company's 1,650-patient trial will focus on asymptomatic patients who are at risk of developing Alzheimer disease, as assessed by a family history of dementia, the apolipoprotein E (APOE) ɛ4 risk allele and evidence of amyloid accumulation. Johnson & Johnson expects this trial to complete in 2023.

Eisai has a BACE inhibitor in Phase II trials, and Novartis and Lilly both have BACE inhibitors in Phase I trials.