TNF and infection: Biologic agents that act as tumor necrosis factor (TNF) inhibitors—etanercept, adalimumab, infliximab, golimumab and certolizumab—have demonstrated efficacy in improving the signs and symptoms of PsA in large, well-controlled clinical studies [12, 14, 22], but patients sometimes experience waning efficacy over time [13] or rare but serious adverse events (AEs), such as infection and non-melanoma skin cancer [14].