medwireNews: Open-label extension results from a phase IIb trial suggest that baricitinib continues to be well tolerated and efficacious for up to 2.5 years among patients with rheumatoid arthritis (RA).
The primary trial results showed that a significantly greater proportion of patients receiving baricitinib at a dose of 4 or 8 mg once daily achieved at least a 20% improvement in ACR criteria (ACR20) at week 12 compared with those receiving placebo, and baricitinib was “well-tolerated with no unexpected safety findings” up to week 24, say the study authors in The Journal of Rheumatology.
In the extension study, participants received baricitinib for two additional 1-year periods. In the first year, patients receiving baricitinib 8 mg up to week 24 continued with the same dose, whereas all other participants were allocated to baricitinib 4 mg. And in the second year, all participants who completed the first year received baricitinib 4 mg, giving a total exposure time of 433.9 patient–years.
The incidence of adverse events in the open-label extension period was “generally consistent” with that observed at 24 weeks, report Edward Keystone (Mount Sinai Hospital, Toronto, Ontario, Canada) and study co-authors.
In the first 1-year extension period, 63% of 108 patients receiving baricitinib 4 mg experienced a treatment-emergent adverse event (TEAE), while 16% had a serious adverse event (SAE). A total of 67% of 93 participants in the 8 mg group had a TEAE, with 13% experiencing an SAE. Infections occurred in 35% of patients in the 4 mg group and 40% of those in the 8 mg group, and a corresponding 5% and 3% experienced serious infections.
“Importantly, TEAE occurrence did not increase in frequency with prolonged exposure, and the lowest event rates were generally seen during the second [extension period],” write the study authors.
Indeed, in the second extension period, TEAEs occurred in 52–56% of all participants. No opportunistic infections, cases of tuberculosis, or lymphomas occurred over the whole 128-week study duration.
The researchers also found that the proportion of patients with an ACR20 response was “similar or increased” in the first and second extension periods compared with that in the original 24-week study, suggesting that baricitinib “produced sustained efficacy.”
They caution that the extension study was limited by the lack of a control group, and that “the sample size was subject to the inherent restrictions of phase II development.”
Nevertheless, the team concludes that their findings “support the potential utility of baricitinib as a valuable additional therapy for the treatment of this common and disabling disease.”
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