Ixekizumab therapy following secukinumab inadequate response in psoriatic arthritis: a case series focusing on axial disease.

There are limited data regarding cycling between interleukin-17 (IL-17) inhibitors in psoriatic arthritis (PsA). We aimed to report the efficacy of an IL-17 inhibitor (ixekizumab-IXE) after inadequate response (IR) of another one (secukinumab-SEC) in patients with PsA. Case series of PsA patients who received IXE after SEC-IR in four rheumatology centers between 1/9/2021 and 1/9/2022 were included. Peripheral arthritis was assessed with disease activity in psoriatic arthritis score (DAPSA) and skin involvement with body surface area (BSA). Axial disease was defined as having both imaging and clinical features and its activity was measured with the ankylosing spondylitis disease activity score (ASDAS). Twenty-four patients (54.2% female, mean [SD] age: 51.6 [14.1]) who were SEC-IR and received IXE either immediately (n = 11) or after ≥ 1 interposed biologic disease modifying anti-rheumatic drug (bDMARD) (n = 13) were included. Patients were followed on IXE for a mean [SD] period of 9.6 [4.9] months. Among patients with peripheral arthritis (n = 24), the mean [SD] DAPSA decreased from 22.8 [8.6] to 13.6 [7.8] during follow-up (p =  0.0001) with 62.5% of patients showing improvement in the DAPSA disease activity categories. For patients with axial involvement (n = 16), a clinically meaningful improvement (Δ ≥ 1.1 in ASDAS) was noted in 50% (8/16), while dactylitis and enthesitis resolution was observed in 60% (3/5) and 83% (5/6) of patients, respectively. Regarding psoriasis, the mean [SD] BSA of involved skin decreased from 8.7 [8.7] to 2.4 [3.3] (p =  0.001). In this case series, treatment with IXE after inadequate response to another IL-17 inhibitor (SEC) was efficacious in a real-world setting in patients with PsA, including axial disease.