Vinod Chandran, MBBS, MD, DM, PhD
Although there are several treatment options for PsA, there have been few head-to-head studies conducted to determine comparative efficacy. Ustekinumab, a biologic agent targeting IL-p40, and therefore both IL-12 and IL-23, has proven efficacy in PsA, but the impression is that this drug is less effective than are TNF inhibitors for the treatment of the peripheral arthritis domain. However, in a prospective, observational study, Gossec and colleagues report that the improvements in patient-reported outcomes were generally comparable between ustekinumab and TNF inhibitor treatments. This study evaluated 437 patients with PsA from the PsABio study who initiated first- to third-line ustekinumab (n = 219) or TNF inhibitors (n = 218) and continued the initial treatment for 3 years. At 3 years, ustekinumab and TNF inhibitors were associated with comparable improvements in the EuroQol-5 dimensions health state visual analog scale scores, Psoriatic Arthritis Impact of Disease 12-item scores, and work productivity, although the improvements were generally greater in the TNF inhibitor–treated group. A randomized trial comparing ustekinumab to TNF inhibitors in PsA is warranted to confirm these findings and inform treatment decisions.
Targeted therapies, such as biologics, are proven to be more efficacious than are conventional therapies; however, only about 60% of patients initiating targeted therapies demonstrate treatment response. Identifying the predictors of treatment response is an active area of research. Linde and colleagues looked at data from 13,369 biologic-naive patients registered with a PsA diagnosis from 13 European registries who initiated a first TNF inhibitor treatment. The study demonstrated that sex, disease duration, C-reactive protein level, age at treatment initiation, and fatigue predicted the achievement of the Disease Activity in Psoriatic Arthritis in 28 joints remission at 6 months.
Could biomarkers help predict response beyond clinical predictors? An interesting study indicates that beta–defensin 2 (BD-2) may serve as a predictive biomarker for clinical response to secukinumab in PsA. BD-2 is an antimicrobial peptide and an important protein in innate immune response. Cardner and colleagues analyzed protein expression data in serum samples from the phase 3 FUTURE 1-5 trials that included 1989 patients with PsA who received secukinumab or placebo. Baseline BD-2 levels were associated with early as well as sustained PsA treatment response to secukinumab, independent of psoriasis severity. BD-2 levels did not predict response to adalimumab in PsA nor was it associated with treatment response to secukinumab in RA. The addition of BD-2 to the clinical prediction model significantly improved the prediction of the 16-week American College of Rheumatology 20 response. Thus, BD-2 seems to be a secukinumab treatment response biomarker and requires further evaluation.