BACKGROUND: Secukinumab is the first selective interleukin-17A inhibitor licensed in the United Kingdom (UK) for ankylosing spondylitis (AS), a progressive, irreversible and burdensome disease. Following positive reimbursement decisions, secukinumab is available to National Health Service (NHS) patients with active AS who have responded inadequately to conventional therapy. Current treatment for these patients comprises tumour necrosis factor alpha (TNFα) inhibitors, for two of which (etanercept, infliximab) biosimilar versions offer equivalent efficacy at a lower price than their originator products. However, in order to ensure population health is maximised, comparison of therapies must consider not only drug costs but also relative health impacts and non-drug costs in a full cost-effectiveness analysis. In this context, this research evaluated the cost-effectiveness of secukinumab versus the available biosimilar products for the treatment of biologic-naïve patients with active AS in the UK.
METHODS: A cost-effectiveness model was constructed to capture the health benefit (measured by quality-adjusted life years [QALYs]) and costs associated with secukinumab and TNFα inhibitors over a 40-year time horizon. Treatment response at 12 weeks was assessed via a decision tree; a Markov model captured short-term treatment effects on Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Bath Ankylosing Spondylitis Functional Index (BASFI), and longer-term treatment effects on BASFI. Relative treatment response rates for secukinumab and comparators were informed by a network meta-analysis of randomised controlled trials, including the MEASURE 2 trial for secukinumab. Patient quality of life was based on an algorithm linking BASDAI and BASFI scores, gender and age to utilities. Costs incurred from the NHS and Personal and Social Services perspective, including those of relevant adverse events, were included. All drug acquisition costs were based on UK list prices; reductions in the secukinumab price through the commercially available patient access scheme were therefore not accounted for.
RESULTS: Incremental cost-effectiveness ratios (ICERs) for secukinumab versus etanercept originator and etanercept biosimilar at list price were £10,173 per QALY gained (Δ QALY=0.87; Δ cost=£8,846) and £11,417 per QALY gained (Δ QALY=0.87; Δ cost=£9,928), respectively; well below conventional cost-effectiveness thresholds that value a QALY at £20,000¬—£30,000. Even when assuming the etanercept biosimilar to be associated with a 99.99% discount to the originator, secukinumab was cost-effective at the £30,000 per QALY threshold. In the list price comparison to infliximab originator and infliximab biosimilar, secukinumab was the dominant treatment option (positive health gains at lower overall cost). For anything less than a 50% discount to the list price of the infliximab originator, secukinumab remained cost-effective at a £20,000 per QALY threshold.
CONCLUSIONS: Secukinumab represents a cost-effective first-line biologic treatment in the UK compared to etanercept, infliximab and their lower cost licensed biosimilars for patients with active AS who have an inadequate response to conventional therapy.
