After multiple failures to develop therapeutics for Alzheimer’s disease, Biogen’s Michael D. Ehlers resigned from his role as head of research and development.

Days after halting Biogen’s BACE inhibitor program for Alzheimer’s disease, the Cambridge-based company stopped a clinical trial in idiopathic pulmonary fibrosis due to safety reasons.

Biogen Inc. and Eisai Co. Ltd. are abandoning two late-stage trials for their Alzheimer’s treatment elenbecestat in a widely anticipated move that comes months after the companies scrapped studies of aducanumab for the memory-robbing disease.

Novartis, Amgen and the Banner Alzheimer’s Institute announced they are halting two pivotal Phase II/III clinical trials in the Alzheimer’s Prevention Initiative Generation Program.