Steroid-resistant sarcoidosis: is antagonism of TNF-α the answer?

Abstract

Steroid-resistant sarcoidosis has conventionally been treated with various drugs, including methotrexate, azathioprine, cyclophosphamide, cyclosporine, antimalarial drugs and thalidomide, with variable success. There is a compelling need for more efficient and safer alternatives to these agents. Several lines of evidence suggest a critical role of TNF-α (tumour necrosis factor-α) in the initiation and organization of sarcoid granulomas. Inhibition of TNF-α with monoclonal antibodies has therefore received attention as a potential treatment option in therapy-resistant sarcoidosis. A number of case reports and small case series describe successful treatment of refractory disease with infliximab. Preliminary evidence from an RCT (randomized controlled trial) with infliximab in pulmonary sarcoidosis suggests a modest improvement in functional and radiological parameters. In contrast, the results with etanercept have been disappointing, perhaps related to differences in the mechanism of TNF-α blockade. The experience with adalimumab in sarcoidosis is too limited to draw conclusions. An open-label study and an RCT evaluating the efficacy of adalimumab in sarcoidosis with pulmonary and cutaneous involvement respectively, have been initiated. Although TNF-α antagonists appear relatively safe, especially when compared with conventional agents, caution is warranted in view of the increased incidence of tuberculosis, which may be a particular diagnostic challenge in patients with sarcoidosis. Pending publication of the RCTs, the use of TNF-α blockade in sarcoidosis should remain in the realm of experimental treatment.