27 Feb 2015

Vitae Pharmaceuticals announced on 26 February the temporary suspension of Phase I clinical testing of BI 1181181. This β-secretase (BACE) inhibitor is being developed by Boehringer Ingelheim and evaluated jointly with Vitae. Few details are available, but the decision reflects some kind of skin reaction in trial volunteers. Vitae expects testing of this inhibitor or a backup compound will continue (see company press release). Boehringer had not issued a press release as of today. BACE performs a key cleavage step in the release of Aβ from its precursor protein APP.

BI 1181181 joins BACE inhibitors from other companies, including Roche and Lilly, that stumbled over safety concerns. The side effects may be unrelated to BACE inhibition, though some researchers in the field have concerns about on-target effects since BACE has many substrates, and several known functions thus far (see Jun 2013 news). For example, BACE cleaves PMEL, a protein involved in melanin production, and some BACE knockout mice grow fur coats with “bleached” spots (see Dec 2013 conference news). 

Other BACE inhibitors are in various stages of development, including drugs from Merck (Phase 3), Lilly/Astra Zeneca (Phase2/3), and Biogen/Eisai (Phase 1).—Tom Fagan.