Presence of anti-CCP, RF antibodies at baseline linked to better clinical response to abatacept

LONDON — Improved clinical response to abatacept was associated with baseline positive status for anti-cyclic citrullinated peptide and rheumatoid factor antibodies, according to results presented at the EULAR Annual Congress.

“Both rheumatoid arthritis (RA) patients and their providers would benefit from a biomarker that would identify the subsets of patients to respond to certain specific treatments. [Anti-citrullinated peptide antibodies] ACPA antibodies can help with that,” Leslie R. Harrold, MD, MPH, of the University of Massachusetts Medical School, said during a presentation. “Our study is the first that we know of to look at ACPA and rheumatoid factor status on RA treatment outcomes in those initiating abatacept and [tumor necrosis factor] TNF inhibitors.”

Using the Corrona RA registry, Harrold and colleagues enrolled 566 patients who started abatacept (ABA) and 1,715 patients who started a TNF inhibitor (TNFi) between June 2002 and January 2015. Participants were limited to those who had anti-cyclic citrullinated peptide (anti-CCP) and rheumatoid factor (RF) testing before initiation of the drug and had a follow-up at 6 months.

Anti-CCP and RF for seropositivity were determined as at least 20 U/mL and at least 40 U/mL, respectively. The primary outcome after 6 months was the mean change in the clinical disease activity index (CDAI). Secondary outcomes included achievement of remission based on the CDAI (≤2.8) in those with low, moderate or high disease activity and low disease activity based on the CDAI (≤10) in those with moderate or high disease activity.

Researchers performed unadjusted and adjusted linear and logistic regression models regarding serologic status. Models were adjusted for age, sex, BMI, CDAI score, comorbidity index and number of prior biologic disease-modifying antirheumatic drugs.

Of the patients who started abatacept, 244 were identified as double positive; 167 were single positive; and 155 were double negative. Of the patients initiating a TNFi, 774 were identified as double positive; 470 were single positive; and 471 were double negative.

Most patients in the study were women in their 50s. Patients in the ABA group had a mean disease duration of 9 years to 11 years, and patients in the TNFi group had a mean disease duration of 6 years to 8 years. Both groups displayed moderate disease activity, with a mean CDAI of 18 to 23 in ABA group and a mean CDAI of 18 to 19 in TNFi group.

Overall, a better clinical response was linked to a double positive result for ABA users, with double seropositivity having the strongest relationship. In addition, for those who initiated ABA, increased remission rates were associated with single positive status. However, in the TNFi group, no major differences were observed within the anti-CCP and RF group responses. Adjusted models also did not show significant differences in the anti-CCP and RF status outcomes among TNFi users, but did show differences for ABA users.

According to a press release, results suggest the predictive value of autoantibodies is reliant on drug mechanism of action due to no apparent relationship between anti-CCP and RF status and response to TNFi.

“These findings are exciting as anti-CCP antibodies are a marker of disease severity and detectable early in the course of the disease. A better understanding of the relationship between anti-CCP antibodies and treatment response has the potential to advance patient care,” Harrold said in the release. “Specifically, patients with RA can spend years trying different treatments until their disease is properly controlled. Therefore, identifying subsets of patients likely to respond to a specific drug or class of drugs is so critical.” – by Alaina Tedesco

References:

Harrold LR, et al. Abstract #OP0178. Presented at: EULAR Annual Congress; June 8-11, 2016; London.

www.eular.org

Disclosure: Please see the study abstract for a full list of disclosures.