A reversible, brain-penetrant BTK inhibitor reduces brain lesions in multiple sclerosis (MS). Genentech recently announced that fenebrutinib (GDC-0853), a noncovalent Bruton’s tyrosine kinase (BTK) inhibitor, rapidly reduced new brain lesions in Ph. II clinical trials for relapsing multiple sclerosis (RMS) and would be entering Ph. III. Following the success of BTK inhibitors in oncology, BTK has been a hotly pursued target to treat chronic autoimmune diseases, with multiple companies evaluating BTK inhibitors in a range of clinically and commercially important indications. Other candidates for MS, evobrutinib, tolebrutinib, remibrutinib, and orelabrutinib, are all covalent Btk inhibitors, leaving fenebrutinib as the only...