Principia Biopharma Inc. announced that the first patient has been enrolled in its partner Sanofi’s Phase 3 clinical trial of SAR442168 in patients with relapsing multiple sclerosis (RMS). Upon dosing, Principia will be entitled to a $50 million milestone payment. SAR442168, discovered by Principia and formerly known as PRN2246, is a Bruton’s tyrosine kinase (BTK) inhibitor that crosses the human blood-brain barrier and modulates immune cell function in both the periphery and in the central nervous system (CNS), which shows promise for the potential treatment of CNS diseases.