Precision medicine using molecular-target drugs in psoriatic arthritis.

Psoriatic arthritis (PsA) presents various clinical manifestations, including skin lesions, peripheral arthritis, axial involvement, enthesitis, nail involvement, dactylitis, and uveitis. In addition, it causes a high incidence of lifestyle-related diseases and an increase in cerebrovascular and cardiovascular events. As the pathology of PsA has been clarified, molecular-targeted drugs targeting tumor necrosis factor-α, interleukin (IL)-17A, IL-17A/F, IL-17 receptor, IL-12/23(p40), IL-23p19, Cytotoxic T-lymphocyte Antigen-4 (CTLA-4), Janus kinase, and phosphodiesterase-4 have been developed and are widely used in clinical practice. PsA is clinically and molecularly heterogeneous, and it is necessary to improve various clinical symptoms with limited treatment options simultaneously; therefore, rheumatologists sometimes encounter difficult situations in clinical practice. Hence, the development of precision medicine may improve treatment outcomes. Recently, the strategic use of molecular-targeted drugs based on the stratification of patients with PsA by peripheral blood lymphocyte phenotyping and serum cytokine concentrations has been reported to possibly lead to a higher therapeutic response. A randomized controlled trial was initiated to verify the efficacy of this treatment strategy. However, to make precision medicine in PsA feasible, shifting from conventional clinical trials to clinical trials based on biomarker profiles and accumulating further data are necessary.