Sanofi sheds billions after program from Principia deal hits clinical snag

Concerns about liver injury have led FDA to place a clinical hold on a Btk inhibitor Sanofi obtained via its $3.4 billion takeout of Principia two years ago, slicing billions from the pharma’s market cap Thursday.

The agency’s hold will pause enrollment of new patients in four Phase III trials of tolebrutinib (SAR422168) to treat forms of multiple sclerosis, as well as a Phase III trial in myasthenia gravis. Patients receiving the brain-penetrant Btk inhibitor for fewer than 60 days will also stop receiving it; those on treatment for at least 60 days may continue...