Biomarkers to Diagnose, Assess and Treat Chronic Spontaneous Urticaria: Not There Yet

Purpose of Review Biomarkers to identify patients with chronic spontaneous urticaria (CSU), to grade clinical severity of CSU, and to guide therapy selection in patients with CSU have not yet been validated in any large CSU patient population. As such, there is insufficient evidence to recommend routine use of any particular biomarker. This review will summarize ongoing research in the field of biomarker development and how it could 1 day benefit diagnosis, severity grading, and treatment decisions in CSU. Recent Findings Second-generation antihistamines are the accepted first-line therapy in the treatment of CSU. The United States Food and Drug Administration (FDA) has approved omalizumab for use in CSU that is refractory to antihistamines. Multiple alternative pharmacologic therapies have been utilized with varying levels of success, although no others are FDA approved. Of the alternative therapies, cyclosporine is the best-studied. Hydroxychloroquine, sulfasalazine, dapsone, and colchicine are others that are frequently prescribed. While oral corticosteroids can provide symptomatic relief for most patients, using corticosteroids for more than a couple of weeks is not advised due to significant side effects. Regardless of which therapy is chosen, a significant fraction of patients do not respond. With the emerging market of biologic products targeting specific immunologic molecules, additional therapies for CSU are likely to become available in the next 10 years. Identifying biomarkers to assess disease response to therapy and to determine which patients are most likely to benefit from which therapy would greatly benefit the field. Summary The ideal tissue source for biomarker identification in CSU has not been determined. Basophil trafficking has been demonstrated to be abnormal in CSU and would benefit from further exploration. Autoreactive T cells have been recently identified in some CSU patients and combined with autologous serum skin test may be useful as a diagnostic tool. Finally, relative to the search for blood biomarkers, the skin has been a poorly charted territory as a possible source for biomarkers and would likely benefit from additional investigation.