Sanofi has bought itself rights to Principia BioPharma’s experimental tyrosine kinase (BTK) inhibitor PRN2246, in a deal potentially worth more than $800 million to the latter firm.

The experimental oral therapy, which is designed to access the brain and spinal cord by crossing the blood-brain barrier to impact immune cell and brain cell signaling, has shown promise in multiple sclerosis (MS) and also has potential in other central nervous system (CNS) diseases.

Under the terms of the deal, Principia will grant Sanofi an exclusive, worldwide license to develop and commercialise PRN2246, in return for a $40 million upfront payment and future milestone payments that could total $765 million, a well as royalties on product sales.

Principia also has the option to co-fund Phase III development, in exchange for either increased royalties on worldwide product sales or a profit and loss sharing arrangement in the US.

“Complementing our own internal R&D expertise, external relationships like this may accelerate delivery of new treatments to patients living with these serious diseases,” said Rita Balice-Gordon, PhD, global head of MS/Neuroscience Therapeutic Research Area at Sanofi.

“Sanofi is an ideal partner for PRN2246. 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” added Martin Babler, Principia’s chief executive.