Subcutaneous abatacept (125 mg/week) is a safe and effective treatment for patients with rheumatoid arthritis who have an inadequate response to methotrexate, according to results published in the Journal of Rheumatology.
During the initial 6-month double-blind period, participants with rheumatoid arthritis received intravenous or subcutaneous abatacept plus methotrexate. In the subsequent open-label long-term extension period, all participants received subcutaneous abatacept, 125 mg per week. The researchers assessed 5-year safety, tolerability, and efficacy.
Of 1385 participants who completed the double-blind phase, 1372 entered the long-term extension period and 945 completed ≥5 years of treatment.
During the long-term extension, 7.1% (n=97) of participants discontinued treatment because of adverse events. The incidence rates (event/100 patient-years of exposure) for adverse events were 7.73 for serious adverse events, 38.60 for infection, 1.68 for serious infection, 1.09 for malignancies, and 1.33 for autoimmune disorders. All incidence rates were stable over time.
The researchers did not find an association between immunogenicity and either worsening of abatacept safety or loss of efficacy.
The efficacy of abatacept during the long-term extension period was consistent with the double-blind period, and efficacy was maintained until the study’s end. American College of Rheumatology 20% improvement (ACR20), ACR50, and ACR70 responses at day 169 were 80.1% (1087/1357), 53.2% (724/1362), and 27.2% (371/1362), respectively.
At day 1821, ACR20, ACR50, and ACR70 responses were 84.6% (356/421), 65.5% (277/423), and 44.9% (191/425), respectively.
“The longterm safety and efficacy data in this trial are consistent with previously published data for the [intravenous] and [subcutaneous] formulations of [abatacept], and demonstrate that [long-term subcutaneous abatacept] use has a consistent safety profile and durable efficacy in patients with [rheumatoid arthritis] who continue to receive treatment,” the study authors concluded.
Genovese MC, Pacheco-Tena C, Covarrubias A, et al. Longterm safety and efficacy of subcutaneous abatacept in patients with rheumatoid arthritis: 5-year results from a phase IIIb trial [published online April 15, 2018]. J Rheumatol. doi: 10.3899/jrheum.170344