Is it time for Biogen to dump its Alzheimer’s partner?

Biogen’s eagerly awaited quarterly earnings call came and went without answering the existential questions facing the company’s work in Alzheimer’s disease. And, as Biogen perseverates, more and more investors and analysts are convinced the best path forward is getting out of the amyloid business altogether.

But that could be tricky. Biogen’s amyloid-targeting therapies — including the definitely failed aducanumab and the arguably failed BAN2401 — are partnered with the Japanese company Eisai. Under that partnership, Eisai can make decisions that Biogen is obliged to help pay for, and there’s already evidence that the two are not exactly on the same page.

What complicates matters is that the exact terms of the agreement aren’t public. There is presumably a breakup clause that would let Biogen bail, but it might come with a financial penalty.

The future of the Eisai relationship will remain the biggest question facing the company because, as Mizuho analyst Salim Syed put it, “investors generally want to know what the path forward is for Biogen in a post-aducanumab failure world and if the company plans on putting what is likely good money after bad.”