Background/Purpose

Abatacept is a selective T cell costimulation modulator indicated for moderately to severely active Rheumatoid Arthritis (RA). Since August 2013 is available in Italy the new subcutaneous (sc) formulation, that consists in a fixed dose of 125 mg of the drug, administered once weekly. Four clinical trials demonstrated an efficacy and a safety profile comparable to those obtained with the intravenous (iv) administration.

Aim of our work was to analyze the clinical response of a series of patients (pts) with RA treated with monthly iv infusion and than converted to the sc formulation.

Methods

We included 48 pts with RA, converted to the sc formulation of Abatacept from October 2013 to April 2014. We divided them into two groups, depending on their need to return to the iv administration for the appearance of a disease flare. The main clinical and serological features of the two groups were compared using the Chi-square, T-test or the Mann-Whitney test when appropriate.

Results

Pts converted to the sc formulation were the 48.5% of all cases receiving Abatacept therapy in our Unit. No pts received the iv “loading dose”. Eleven pts (22.9%) returned to the iv administration due to a disease flare (mean DAS 28: 2.35 vs 3.85, p:0.005), after a mean of 7.3 injections (range 4-14). The remaining 38 (77.1%) continued with the sc formulation. The compared parameters between the two groups are summarized in Table 1.

In pts with arthritis flare, disease activity decreased again (mean DAS 28: 2.45 vs 3.85, p:0.009) after returning to the iv administration of the drug (after a mean of 38.2 days).

One patient discontinued the sc formulation for the onset of related side-effects (headache and nausea) not reported with the iv administration.

Conclusion

although the safety profile of the sc formulation of Abatacept seems to confirm the data previously obtained with the iv use of the drug, a high rate of our patients complained a reduced efficacy and needed the return to the traditional way of administration.

We failed to identify clear risk factors that may help toward the selection of pts to which propose the formulation switch. However, if an arthritic flare occurs, the return to the iv administration seems to ensure a good control of the disease again. Therefore, the efficacy of the molecule does not seem to be compromised by an eventual switch failure.

Tab.1 Comparison between the clinical and serological features of patients with and without the need to return to the intravenous administration of Abatacept after the switch to subcutaneous formulation

Analyzed features	Pts who maintained the sc formulation n=38 (77,5%)	Pts who returned to iv formulation n=11 (22,5%)	p:
Mean age (years)	58.8	55.1	ns
Positivity for Rheumatoid Factor (RF)	n:34; (92%)	n:10; (91%)	ns
Positivity for anti-citrullinated protein antibodies (ACPA)	n:21; (70%)	n:8; (80%)	ns
Mean disease duration (months)	140.3	125.1	ns
Previous iv therapy duration (months)	20.8	17	ns
Body Max Index (BMI)	24.2	26.1	ns
Smokers	n:4; (10.5%)	n:3; (30%)	ns
DMARDs in association	n:33; (89.5%)	n:10; (90%)	ns
Previous use of biological agents	n:25; (65.8%)	n:8; (72.7%)	ns
N’ of different biological agents used in the past: mean; [SD]	1.7; [1.6]	1.7; [2.3]	ns
Abatacept as first biological agent	n:13; (34.2%)	n:3; (27.3%)	ns
Remission of the disease at sc therapy start	n:29; (76.3%)	n:6; (54.5%)	ns
DAS28 at sc therapy start: mean; [SD]	2.07; [1.07]	2.35; [0.98]	ns

iv: intravenous, sc: subcutaneous, DMARDs: disease-modifying antirheumatic drugs, SD: standard deviation, ns: not significant.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/efficacy-of-the-subcutaneous-formulation-of-abataceptorencia-in-rheumatoid-arthritis-a-single-center-italian-experience/