Anticitrullinated Antibodies Help Predict RA Treatment Response

Key points
• Patients with rheumatoid arthritis (RA) who are positive for anticitrullinated antibodies have a better clinical response to abatacept than those without them.

• Patients with RA and anticitrullinated antibodies did not show better clinical responses to anti-tumor necrosis factor inhibitors.

• Anticitrullinated antibody testing may be useful for selecting treatment options for patients with RA.

Background
Many options have become available for the initial treatment of RA. Leslie Harrold and colleagues at the University of Massachusetts point out that having a reliable biomarker linked to outcomes in RA would make choosing an individualized treatment plan possible.

Anticitrullinated antibody tests are commonly ordered for patients with RA and are very sensitive and specific biomarkers for the disease in general. Patients who are anticitrullinated antibody positive often develop more severe, erosive disease than others with RA, which makes it even more imperative that effective treatment be initiated.

The investigators sought to determine whether anticitrullinated antibody status was associated with a specific treatment effect in RA patients taking abatacept or tumor necrosis factor inhibitors.

The study
In this retrospective observational cohort study, the researchers looked at data from the Corrona RA registry. Clinical Disease Activity Index (CDAI) was used to determine response to either abatacept or tumor necrosis factor inhibitors in subjects with and without anticitrullinated antibody positivity. Included in the study were 566 patients started on abatacept and 1715 on tumor necrosis factor inhibitors.

The results
• Patients started on abatacept who were anticitrullinated antibody positive saw a significantly greater response measured in mean change from baseline in disease activity and disability at 6 months (-8.5; 95% confidence interval [CI], -9.7 to -7.3) than those without these antibodies (-4.0; 95% CI, -5.6 to -2.4; P = .001).

• There was no significant difference in mean disease activity and disability scores among patients treated with tumor necrosis factor inhibitors whether they were positive or negative for anticitrullinated antibodies: -7.4 (95% CI, -8.1 to 6.8) versus -6.4 (95% CI, -7.3 to -5.6; P = .072).

• Patients taking abatacept who had anticitrullinated antibodies had significantly greater remission responses than those who were negative for the antibody (15.2% versus 4.6%; P < .001).

• Patients taking abatacept who had anticitrullinated antibodies met criteria for low disease activity significantly more often than those who were negative for the antibody (15.2% versus 4.6%; P < .001).

• There was no significant difference in achieving low disease activity among patients treated with tumor necrosis factor inhibitors whether they were positive or negative for anticitrullinated antibodies (P = .023).

Implications for physicians
• Routinely screen patients with newly diagnosed RA for anticitrullinated antibodies.

• Anticitrullinated antibody status may be useful when selecting treatment options for patients with RA.

• Because of the increased risk of erosive severe disease, patients with RA who are positive for anticitrullinated antibodies should be identified and treated promptly.

Disclosures:

Bristol-Myers Squibb provided funding.

References:

Harrold LR, Litman HJ, Connolly SE, et al. Effect of anticitrullinated protein antibody status on response to abatacept or antitumor necrosis factor-α therapy in patients with rheumatoid arthritis: a US national observational study. J Rheumatol. 2018;45:32-39.