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One year of treatment with biologic drug abatacept (Orencia; Bristol Myers Squibb) delays progression to rheumatoid arthritis (RA) for up to four years in high-risk patients, according to the results of a study.
The results of the randomised, double-blind, placebo-controlled trial, published in The Lancet Rheumatology on 20 January 2026, build on an earlier study — published in 2024 — that followed 213 participants from the UK and the Netherlands for two years.
Now, researchers have analysed data from 143 of those participants over a longer follow-up period, of between four and eight years after they received 52 weekly subcutaneous injections of 125mg abatacept (n=110) or a placebo (n=103).
The longer-term follow-up revealed that at four years, there was still a significant difference in restricted mean arthritis-free survival time between patients who had received abatacept compared with the placebo group (4.9 months; 95% CI, 0.1–9.6; p=0.044), although the magnitude of this difference diminished over time.
Patients with high levels of anti-citrullinated protein antibody (ACPA) responded better to abatacept: at two years, when compared with the overall population, cumulative arthritis-free proportions in those with ACPA titres of at least 340 IU/mL at baseline (n=81) were 73% in the abatacept group and 51% in the placebo group; and at four years cumulative arthritis-free proportions were 41% for abatacept and 33% for placebo.
Abatacept was shown to be even more effective in patients testing positive in all five autoantibody assays (n=50), including rheumatoid factor, Immunoglobulin G ACPA, Immunoglobulin A ACPA, antibodies to acetylated protein antigens and antibodies to carbamylated protein antigens.
In those with an extended autoantibody serotype, the cumulative arthritis-free proportions were 88% for abatacept and 47% for placebo after two years, and 53% for abatacept and 33% for placebo after four years.
Those with an extended autoantibody serotype showed continued response to abatacept after six years (36% in the abatacept group and 24% in placebo), compared with those fewer than five serotypes (25% in the abatacept group and 33% in placebo), results from the latest study suggest.
Individuals at highest risk of developing RA were most likely to benefit from early intervention.
Commenting on the study, Andrew Pothecary, lead pharmacist for rheumatology and biologics at Royal Cornwall Hospitals NHS Trust, said: “[The latest study] highlights the need for better risk stratification so that efforts to prevent or delay RA can be targeted most effectively.
“Patients still experienced a return of pain and fatigue with impaired physical and mental wellbeing in the period after they had completed a one-year course of abatacept, suggesting the need for long-term treatment,” he added.
Lucy Donaldson, director of research at Arthritis UK, said: “[The study] provides valuable insights into which groups of people may be at higher risk of progressing to RA and which groups may respond better to treatment.
“The long‑term findings show that early abatacept treatment did not prevent the onset of RA, as people in the treatment group did progress on this follow-up.
“Overall, further research is needed to identify why early abatacept treatment delays RA in only some people and not others before the NHS could consider it as a targeted treatment to delay disease onset.”
However, Wendy Holden, medical advisor for UK charity Arthritis Action and honorary consultant rheumatologist at North Hampshire Hospitals NHS Foundation Trust, warned: “In this study, participants were not people who had been diagnosed with RA, rather those at risk of RA because of joint pain and a blood test. This means that potentially a medicine that can have serious side effects was given to many people who will never develop RA.
“At the end of the study, almost one-third of all participants including those on placebo had not developed RA. Abatacept was more effective at delaying the onset of RA in some people, but 18 out of 71 patients who received abatacept had a serious side effect.
“Abatacept is an extremely expensive medication and much more research needs to be done before it could ever be available to people who may never develop inflammatory arthritis, especially given the risk of side effects.”
