What Did Not Work: The Drug or the Trial?

In this issue of Arthritis & Rheumatology, the paper by Isenberg et al, entitled Efficacy, Safety, and Pharmacodynamic Effects of the Bruton's Tyrosine Kinase Inhibitor, Fenebrutinib (GDC-0853), in Systemic Lupus Erythematosus reports results of a Phase 2 trial of fenebrutinib, an inhibitor of Bruton's tyrosine kinase (BTK). This treatment met expected pharmacodynamic targets, decreasing phosphorylated BTK, dampening plasmablast signals, and lowering anti-dsDNA and IgG. No concerning safety signal was observed.