LY2886721 is a BACE inhibitor used for the treatment of Alzheimer's Disease. LY2886721 did not inhibit other aspartyl proteases such as cathepsin D, pepsin, and renin, and reduced Aβ in a dose-dependent manner in HEK293Swe cells and in primary neurons from PDAPP transgenic mice. LY2886721 was the first BACE inhibitor to reach Phase 2 clinical research. Lilly completed six Phase 1 studies of LY2886721’s safety, tolerability, and pharmacology in a total of 150 healthy volunteers and people with Alzheimer’s disease at doses of 1–70 mg. Single and multiple ascending oral dosing was accompanied by repeat CSF sampling in the hours and days thereafter. This was done to assess CSF penetration and target engagement by way of measuring levels of the drug, BACE1 substrate, and BACE1 cleavage products. The compound lowered CSF Aβ40, Aβ42, and sAPPβ concentrations while increasing sAPPα, consistent with expectations for BACE1 inhibition. Fourteen days of daily dosing reduced BACE1 activity by 50–75 percent, and CSF Aβ42 by 72 percent. No safety concerns were apparent in dosing up to six weeks