Safety, Setbacks

Allergan, Sosei halt global development for Alzheimer’s drug following toxic reaction in a non-human primate

Allergan and Sosei have hit the brakes on an international development program featuring a key Alzheimer’s drug following an “unexpected toxicology finding” for one of the non-human primates it tested the therapy on.

The drug is HTL0018318, a muscarinic M1 receptor agonist that Allergan partnered on when it signed a development deal with Sosei’s UK subsidiary Heptares which was worth close to $840 million, plus billions in potential sales bonuses. 

Tim Tasker

According to the companies, they have suspended clinical work, halting a Phase I study Allergan is running in the US and a Phase II trial in Japan centered on dementia with Lewy bodies. Heptares has already completed a Phase Ib European study and that data are being analyzed now.

Researchers did not spell out what kind of toxic reaction was tracked in the animal study.

The US biotech agreed to pay Sosei $125 million upfront — with hundreds of millions in milestones and $50 million for research support — to launch their alliance in 2016. And this drug was spotlighted as one of the most important therapies in the batch. Alzheimer’s in specific and cognition in general, though, remains one of the toughest fields in R&D, featuring frequent breakdowns for ineffectiveness as well as the occasional dangerous side effect.

Sosei now expects the delay will cost the company a major milestone next year as they reset the clock on the development plan — provided they can understand what happened in the primate study and if the drug is still safe for patients.

The jury is still out, though, on this drug, which has now been tested in more than 300 people around the world.

“We were very surprised to see these results given the safety profile HTL0018318 has exhibited across all previous animal and clinical studies,” noted Sosei CMO Tim Tasker. “We are committed to working with clinical investigators, R&D teams and regulatory authorities to understand better the reason for the findings from this animal toxicology study and so enable the human clinical development program with HTL0018318 to continue as soon as possible.”


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