Abatacept provides clinically meaningful efficacy, acceptable safety for RA patients, data reveal

Abatacept appears to have an acceptable safety and tolerability profile and provides clinically meaningful efficacy over 6 months for patients with active rheumatoid arthritis who have had an inadequate response to anti-tumor necrosis factor (TNF) therapy, according to recent Phase IIIb data. In the international, open-label trial, 1,046 patients were treated with a fixed dose of abatacept of approximately 10 mg/kg on days 1, 15, and 29, and then every 4 weeks thereafter up to and...

Abatacept appears to have an acceptable safety and tolerability profile and provides clinically meaningful efficacy over 6 months for patients with active rheumatoid arthritis who have had an inadequate response to anti-tumor necrosis factor (TNF) therapy, according to recent Phase IIIb data.

In the international, open-label trial, 1,046 patients were treated with a fixed dose of abatacept of approximately 10 mg/kg on days 1, 15, and 29, and then every 4 weeks thereafter up to and including day 141. The patients had an inadequate response to anti-TNF therapy for 3 months or longer and had a disease activity score in 28 joints (DAS28) of at least 5.1.

The participants were classified into 2 groups based on their use of anti-TNF therapy before enrolling into the study. ''Washout'' patients (n=449) were those who had discontinued anti-TNF therapy 2 months or more before screening while ''direct-switch'' patients (n=597) had received anti-TNF therapy within 2 months of screening, and received abatacept at their next scheduled anti-TNF treatment dose.

The average duration of exposure to abatacept was similar for washout and direct-switch patients (6.2 and 6.1, months, respectively), and the average number of infusions was 6.4 for both groups.

With regard to safety, the washout patients and direct-switch patients had similar rates of adverse events (AEs; 78% vs 79.2%), serious AEs (11.1% vs 9.9%), and discontinuations due to AEs (3.8% vs 4.0%) or serious AEs (2.0% vs 1.3%). Neither group reported any opportunistic infections.

Efficacy was also similar between the 2 groups. Both washout and direct-switch patients had an average 2-point reduction in DAS28 score from baseline. In addition, clinically meaningful improvements in DAS28 score, defined as a decrease from baseline of at least 1.2 units, were reported by 59.5% of patients in the washout group and by 53.6% of patients in the direct-switch group. The groups also had similar results for low disease activity state, defined as a DAS28 score of <2.6 (22.5% vs 22.3%, respectively), and remission rates (12.0% vs 13.7%, respectively).

"[T]hese results support the clinical use of direct switching to abatacept from anti-TNF agents in patients who do not respond to, lose response to, or are unable to tolerate anti-TNF agents," the authors concluded. (Schiff M, et al. Ann Rheum Dis 2009;68:1708-1714.)