Baricitinib, formerly LY3009104 (INCB28050), is an orally administered selective JAK1 and JAK2 inhibitor that is JAK3-sparing.
In the Phase 2b double-blind study, 301 patients with active RA on stable doses of methotrexate were randomised to receive either placebo or one of four once-daily doses of baricitinib (1mg, 2mg, 4mg or 8mg) for 12 weeks.
The study demonstrated a statistically significant difference in the American College of Rheumatology 20 (ACR20) response between the combined 4mg and 8mg baricitinib groups (76%) compared with placebo (41%) after 12 weeks of treatment, thereby reaching the primary endpoint.
The placebo-controlled dose-ranging study reported that a statistically significant improvement was observed at the first assessment point after two weeks of treatment and was sustained through week 12.
With the 1mg, 4mg and 8mg dose groups compared with placebo, a statistically significant difference in response for the ACR20, ACR50 and ACR70 secondary endpoints was observed.
Infections, with a similar rate observed among patients in the placebo group (12%) and patients receiving baricitinib (14%), were the most common treatment-emergent adverse event class reported.
Seven serious adverse events were reported in six patients (two events in the placebo group, four in the 2mg group and one in the 8mg group), according to the study data.
With greater changes being observed in the 8mg baricitinib group, dose-dependent changes in laboratory tests such as haemoglobin, neutrophil, serum creatinine, LDL and HDL were observed.
Image: Eli Lilly and Company’s global headquarters, in Indiana, US. Photo courtesy of: Guanaco152003.