medwireNews: The beneficial effects of abatacept treatment for patients with psoriatic arthritis (PsA) are maintained for up to 1 year, suggest follow-up results of the ASTRAEA trial presented at the Annual European Congress of Rheumatology (EULAR) 2017.
As reported previously by medwireNews, the 24-week data for this phase III trial showed that a significantly higher proportion of patients receiving 125 mg weekly abatacept achieved at least a 20% improvement in ACR criteria (ACR20) compared with those receiving placebo, at 39% versus 22%.
After 24 weeks of treatment, all patients were switched to open-label abatacept treatment for up to 52 weeks, while those who did not experience at least a 20% improvement in joint counts at week 16 were switched to open-label abatacept for 28 weeks.
At the 44-week follow-up, just over 50% of 424 patients remaining in the study achieved an ACR20 response. These responses were maintained for the 213 patients continuing with abatacept treatment, and improved for the 211 who switched from placebo, Philip Mease (University of Washington School of Medicine, Seattle, USA) told delegates in Madrid, Spain.
When patients were stratified by prior exposure to tumor necrosis factor (TNF) inhibitors, “as expected, the TNF-naïve population does better” said Mease, noting that more than 60% of patients had received TNF inhibitor treatment before study enrolment. Approximately 55% of patients without prior exposure to a TNF inhibitor had an ACR20 response at week 44, compared with around 45% of TNF-exposed patients.
Patients in both groups also experienced continued improvements in Disease Activity Score at 28 joints based on C-reactive protein (DAS28-CRP) and health assessment questionnaire disability index (HAQ-DI) scores after week 24.
However, in accordance with the 24-week results, “abatacept does not work as well in the skin,” noted Mease. Indeed, less than a quarter of patients experienced a 75% reduction in the Psoriasis Area and Severity Index score from baseline to week 44.
Mease also outlined the results of post-hoc analyses conducted at week 24, which found no significant differences in ACR20 responses between overweight/obese versus normal weight patients. Therefore, “[body mass index] does not appear to affect the efficacy of abatacept,” he said.
Additional post-hoc analyses conducted at the 24-week timepoint showed that the “drug works best in those patients that have prognostic markers of more severe disease,” observed Mease. ACR20 response rates were higher among patients with CRP levels above the upper limit of normal compared with those with lower CRP levels, and among those with higher (>5.1) versus lower (≤5.1) DAS28-CRP scores.
No new safety signals were identified in the follow-up study. Over 52 weeks, 20.4% of participants experienced treatment-related adverse events, with 1.8% experiencing serious infections.
Mease concluded that “abatacept has shown maintenance of effect across all endpoints” in the ASTRAEA follow-up study, in “patient populations that we consider potentially relatively refractory.”
By Claire Barnard
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