The efficacy, safety and tolerability of i.v. abatacept are well established in patients with active RA. A s.c. abatacept formulation is now available in some countries. Here, we review clinical data for s.c. abatacept. Six trials are presented (Phase II dose-finding study, ACQUIRE, ALLOW, ACCOMPANY, ATTUNE and AMPLE) and issues important to both patients and clinicians are addressed. The primary focus assesses whether the i.v. and s.c. abatacept formulations have similar efficacy, including whether the recommended fixed dose of s.c. abatacept is comparable to the weight-tiered i.v. dosing and whether efficacy is sustained with long-term treatment. Safety and immunogenicity are also discussed, including the short- and long-term safety of s.c. abatacept, and whether immunogenicity is increased following a switch from i.v. to s.c. abatacept, after withdrawal or reintroduction of s.c. abatacept or in the absence of MTX. Year 1 data from the AMPLE study, comparing s.c. abatacept with the TNF antagonist adalimumab, are discussed. Although fewer patient-years of exposure are available for s.c. compared with i.v. abatacept, observations suggest that s.c. abatacept has a similar long-term efficacy to the i.v. formulation, improving the signs, symptoms, disease activity and physical function in patients with RA. With continued treatment, these improvements are maintained over time with high retention rates, similar to i.v. abatacept. s.c. abatacept is associated with low immunogenicity and short- and long-term safety that is consistent with i.v. abatacept. In addition, s.c. abatacept demonstrates comparable efficacy, kinetics of response, safety and radiographic inhibition to adalimumab.
Keywords: abatacept; biologic therapy; rheumatoid arthritis; subcutaneous.