Background The switch from the intravenous (IV) formulation to the subcutaneous (SC) formulation of abatacept (ABA) had been analysed in clinical trials but there are few data regarding the effectiveness and safety of the SC formulation in clinical practice.

Purpose To evaluate the impact of switching from IV to SC abatacept (SC ABA) in patients who were controlled on the IV formulation in a real world setting.

Material and methods Observational retrospective study of patients switched from IV to SC ABA, 125 mg once weekly, between September 2013 and April 2015. Data were collected by reviewing patient clinical records and the database of the local advisory committee for rheumatoid arthritis (RA). Measured parameters were: disease activity score at 28 joints (DAS28), treatment duration, reasons for withdrawal and new biologic agent introduced.

Results 19 patients were included in our study, 17 women (89.5%) and 2 men (10.5%), mean age 59.6 years. All the patients had low RA activity at the beginning of SC ABA treatment (mean DAS28=3.1).

6 patients (31.6%) discontinued; all experienced an arthritic flare (mean DAS28=4.21; p = 0.02 vs baseline) but no adverse effects were described. 5 (83.3%) returned to IV administration after a mean of 7.1 months (range 2.7–10.8). The other patient (16.7%) switched to etanercept. 13 patients (68.4%) have continued SC administration to date with good disease control and no adverse reactions. All five patients that returned to IV ABA also have good disease control to date.

Conclusion In our small case series, SC ABA showed a risk of relapse in 31.6% of cases but reinsertion of IV administration seemed to reinstate disease control. It could be possible that an eventual failure of the SC formulation does not compromise the effectiveness of the ABA therapy itself. Further research with a greater number of patients is needed.

References and/or Acknowledgements

1. Reggia R, et al. J Rheumato. 2015;42:193–5

References and/or AcknowledgementsNo conflict of interest.