Sanofi has committed up to $805 million to license multiple sclerosis drug PRN2246 from Principia Biopharma. The French Big Pharma is paying $40 million upfront to pick up the preclinical asset, with $765 million more to follow if it passes all the milestones that await.

Principia has taken BTK inhibitor PRN2246 up to and into IND-enabling studies. Along the way, the biotech has generated data suggesting the drug triggers the effects on immune cell signaling that have made BTK inhibitors hot property in the autoimmune space. Crucially, Principia has also shown PRN2246 crosses the blood-brain barrier, opening the door to use in multiple sclerosis and other neurological disorders. 

That attracted the attention of Sanofi, which has built a significant multiple sclerosis franchise through Aubagio and Lemtrada. The French Big Pharma is putting up a tidy sum, for a preclinical asset, to land a drug that could one day bolster that franchise. 

Interest in BTK, best known as the target of Imbruvica, has broadened in recent years as scientists have generated evidence linking the protein to autoimmune disorders. Merck KGaA is among the companies to respond to the emerging therapeutic opportunity, notably by advancing evobrutinib. The German firm is testing the BTK inhibitor in midphase multiple sclerosis, rheumatoid arthritis and lupus trials.  

Principia tapped into growing interest in BTK inhibitors in 2014 to raise $50 million in a series B round and thinks PRN2246’s ability to cross the blood-brain barrier gives it an edge over its rivals in neurological indications. But the West Coast biotech has decided it is best served by partnering the asset and focusing its resources on its other, more advanced BTK inhibitor.

"The agreement allows Principia to maximize the BTK opportunity in neurology with a strong partner for PRN2246 while focusing internal resources on our lead BTK inhibitor in another therapeutic area," Principia CEO Martin Babler said in a statement.

Principia’s lead BTK inhibitor is PRN1008, which it is developing in pemphigus vulgaris and another indication. The company posted a look at interim phase 2 data in pemphigus vulgaris at an event earlier this year.