OBJECTIVES: To assess the cost per response at Week 16 of bimekizumab, a monoclonal IgG1 antibody which selectively inhibits interleukin (IL)-17F in addition to IL-17A, against approved IL-17A inhibitors for axial spondyloarthritis (axSpA) in Sweden.

METHODS: A cost per responder model was developed using clinical response from a network meta-analysis (NMA) at Week 12–16, including patients with non-radiographic (nr-) and radiographic (r-) axSpA. Clinical response was assessed in pre-specified subgroups (predominately biologic-naïve/biologic-experienced to biologic disease-modifying anti-rheumatic drugs). Included treatments were bimekizumab 160 mg every four weeks (Q4W), ixekizumab 80 mg Q4W and secukinumab 150 mg loading dose. Efficacy outcomes assessed were Assessment in SpondyloArthritis International Society (ASAS) 40/Partial Remission (PR), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) 50, and Ankylosing Spondylitis Disease Activity Score (ASDAS) Low Disease Activity (<2.1). Drug acquisition costs for treatments obtained from the Dental and Pharmaceutical Benefits Agency’s (TLV) price database in February 2023 were used to calculate total cost per patient over 16 weeks. Response rates derived from the NMA informed number-needed-to-treat calculations which were multiplied with total cost per patient for each intervention to obtain cost per response at Week 16.

RESULTS: In biologic-naïve nr-axSpA patients, for ASAS40, bimekizumab had the lowest cost per response (7.660€), followed by secukinumab (14.170€) and ixekizumab (12.949€). In biologic-naïve r-axSpA patients, for ASAS40, bimekizumab had the lowest cost per response (7.490€), then ixekizumab (9.442€) and secukinumab (9.784€). Bimekizumab had the lowest cost per response in both nr- and r-axSpA biologic-naïve patient groups for ASAS-PR, BASDAI50 and ASDAS <2.1. In biologic-experienced r-axSpA patients, for ASAS40, bimekizumab had the lowest cost per response (8.426€), then secukinumab (9.132€) and ixekizumab (17.431€).

CONCLUSIONS: Treatment with bimekizumab provided the lowest cost per response across the axSpA disease spectrum (nr-axSpA and r-axSpA), versus approved IL-17A inhibitors in Sweden, for all efficacy outcomes analysed at Week 16.