Long-term abatacept treatment for 48 weeks in patients with primary Sjögren's syndrome: The open-label extension phase of the ASAP-III trial

OBJECTIVE: To investigate treatment efficacy of long-term abatacept treatment in pSS patients. METHODS: The single-centre ASAP-III trial consisted of two phases: the randomised, double-blind, placebo-controlled phase (1:1 randomisation) from baseline to week 24, of which results have been published previously, and the open-label extension phase from week 24 to 48, in which all patients received abatacept. Main inclusion criteria were fulfilment of the AECG criteria, positive gland biopsy, disease duration ≤ 7 years and ESSDAI ≥ 5. Long-term treatment effects of abatacept on clinical, patient-reported, glandular and laboratory outcome measures were assessed in patients treated with abatacept from baseline to week 48. Furthermore, Composite of Relevant Endpoints for Sjögren's Syndrome (CRESS) response (response on ≥3 of 5 items) was analysed. RESULTS: In patients on abatacept treatment for 48 weeks (n = 40), median ESSDAI improved from baseline 14.0 (IQR 9.0-16.8) to 4.0 (2.0-8.0) at week 48 (p < 0.001), with 50% of patients reaching low disease activity (ESSDAI < 5) at week 48. Median ESSPRI improved from 7.0 (IQR 5.4-7.7) to 5.0 (3.7-6.7) (p < 0.001). Significant improvement was also seen in dry eye and laboratory tests. Combining response at multiple clinically relevant items, 73% of patients were CRESS responders at week 48. Additional improvement was seen between week 24 and week 48 of abatacept treatment. CONCLUSION: In the open-label extension phase of the ASAP-III trial, improvement was seen up to 48 weeks of abatacept treatment in clinical, patient-reported, dry eye and laboratory outcomes. The majority of patients were CRESS responders at week 48.