Rheumatoid arthritis

ACPA a biomarker of response to some biologics but not others

Anti-citrullinated protein antibody (ACPA) positivity in rheumatoid arthritis patients is associated with a better response to treatment with abatacept but not TNF inhibitors.

A study, using the Optimizing Patient outcomes in Australian RheumatoLogy (OPAL) dataset, assessed changes in disease activity over 12 months in more than 2,000 patients who commenced treatment between 2006 and 2017.

Patients with concomitant inflammatory diseases such as ankylosing spondylitis, psoriatic arthritis or IBD were excluded from the analysis.

The majority of patients had baseline CDAI scores in the moderate (≥10 but <22.0) and high (≥22.0) range.

ACPA positive patients comprised 74% of those treated with abatacept and 70% of those treated with a TNFi.

The study found all treatment groups experienced a mean improvement in CDAI score from baseline to 12 months.

“In the abatacept population, ACPA positive patients had a greater improvement in their CDAI score compared to those who were ACPA negative (-19.01 and -10.8, respectively; p=0.011),” the study said.

“Patients receiving treatment in the first line setting had a greater mean change in their CDAI score compared to those receiving treatment in later lines, irrespective of treatment or ACPA serostatus.”

ACPA positivity in both treatment groups was also associated with a better response for the DAS-28-CRP-3 remission measure at 12 months.

“A significantly greater proportion of patients with ACPA positivity treated with TNFi achieved disease remission than those who were ACPA negative (37.7% vs. 29.0%; p=0.003). This was not observed in the CDAI scores of remission (15% vs. 12%, p=0.20).”

The authors said the discrepancy between the CDAI and the DAS23-CRP-3 scores may be due to differences in underlying constructs for each measure.

The overall median persistence on treatment was 4.6 years, and longer in ACPA positive patients compared to ACPA negative patients irrespective of treatment with abatacept or a TNF inhibitor.

“Our study found similar results to those from international studies in Europe and the United States where ACPA status has been noted as being an important factor in determining patients outcomes.”

Lead author Clinical Associate Professor Kathleen Tymms told the limbic while there was definitely a need for more biomarkers, ACPA provided some guidance.

“If we are trying to do personalised medicine for the RA patients in front of us …and they are ACPA positive, I might think of abatacept a bit earlier there.”

“The TNFis still have a good response but abatacept, if ACPA positive, was slightly better if you use CDAI as your outcome measure.”

Associate Professor Tymms, from Canberra Rheumatology, added that longer term studies were warranted.

The study was published in the European Journal of Rheumatology.

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