Biological treatment of psoriatic arthritis in the 1st line – results of the SPIRIT-H2H study after 1 year of follow-up
The SPIRIT-H2H study compared the efficacy of ixekizumab and adalimumab, either as monotherapy or with concomitant methotrexate (MTX), in patients with psoriatic arthritis (PsA) who had not been previously treated with biologics. The results of the recent work presented below after one year of follow-up suggest that the efficacy of ixekizumab remains the same regardless of the use of MTX, while the efficacy of adalimumab increases in combination with MTX.
Therapeutic approaches to psoriatic arthritis
Treating PsA remains challenging due to the heterogeneous manifestations of this disease. The European League Against Rheumatism (EULAR) recommends in its 2019 guidelines to start treatment with non-steroidal anti-inflammatory drugs and to proceed with monotherapy with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs), among which MTX is the most commonly used, if the initial response is inadequate.
If patients do not respond adequately, the recommendation is to introduce biological targeted therapy (bDMARDs), either in combination with ongoing csDMARDs therapy or as monotherapy. However, for clinical decision-making on whether to choose combination therapy or monotherapy, we still do not have sufficient valid data. Comparing the efficacy of bDMARDs monotherapy with combination therapy was thus one of the aims of the study published last year.
Current findings from the SPIRIT-H2H study
After 24 weeks of follow-up, ixekizumab demonstrated better efficacy than adalimumab in patients with active psoriatic arthritis who had not yet been treated with biological therapy. The measured parameter was a combined endpoint of at least 50% improvement on the American College of Rheumatology (ACR) scale (ACR50) and a 100% improvement on the Psoriasis Area and Severity Index (PASI100).
Methodology and course of the study
The SPIRIT-H2H clinical study provided a direct comparison of efficacy blinded only to the evaluators. Patients were stratified at randomization according to concomitant use of csDMARDs and moderate to severe plaque psoriasis manifestations. The post hoc analysis presented divided patients into subgroups based on their use of MTX at the time of study entry.
Analysis results
At week 52 of follow-up, ixekizumab provided comparable improvement in the combined outcome of achieving ACR50 and PASI100 (38.9% of patients taking MTX vs. 39.7% on monotherapy), and improvements in other parameters assessing PsA manifestations regardless of concomitant MTX therapy. The efficacy of adalimumab increased with concomitant MTX therapy but was generally lower than that of ixekizumab – the combined endpoint was achieved by 30.2% of patients with MTX vs. 20.2% on monotherapy.
Ixekizumab in monotherapy led to significantly better responses compared to adalimumab as measured by the combination of ACR50 and PASI100 (p = 0.002), reaching minimal disease activity (p = 0.016), and low disease activity (p = 0.037).
The safety profiles of both treatments were consistent with previous observations, regardless of concomitant MTX therapy.
Conclusion
In patients with inadequately controlled PsA, ixekizumab has a consistent effect on various clinical manifestations of the disease regardless of concomitant MTX administration, while the efficacy of adalimumab increases with MTX administration. This fact may be helpful in deciding whether to introduce MTX along with targeted therapy with ixekizumab or adalimumab, whether at the start of therapy or during long-term maintenance treatment.
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Source: Smolen J. S., Sebba A., Ruderman E. M. et al. Efficacy and safety of ixekizumab with or without methotrexate in biologic-naïve patients with psoriatic arthritis: 52-week results from SPIRIT-H2H study. Rheumatol Ther 2020; 7 (4): 1021–1035, doi:10.1007/s40744-020-00250-3.
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