99mTc-anti-TNF-α antibody for the imaging of disease activity in pulmonary sarcoidosis

Infliximab, a monoclonal antibody directed against tumour necrosis factor (TNF)-α, is used in the treatment of refractory sarcoidosis. However, the clinical response is variable and a tool to select responders beforehand is highly desirable. In this study we evaluated scintigraphy with technetium-99m (99mTc)-labelled infliximab for the imaging of disease activity in patients with pulmonary sarcoidosis. 10 patients were studied using single photon emission computed tomography/computed tomography (CT) 6 h and 20 h after intravenous administration of 370 MBq of 99mTc-infliximab. Correlation analysis was performed between tissue accumulation of 99mTc-infliximab and laboratory parameters (including soluble interleukin-2 receptor and angiotensin-converting enzyme), lung function parameters (including forced expiratory volume in 1 s and the diffusing capacity of the lung for carbon monoxide) and 18Ffluorodeoxyglucose (FDG) positron emission tomography (PET)/CT. Analysis showed selective and variable accumulation of 99mTc-infliximab in the target tissue. Accumulation correlated positively with all four laboratory parameters and negatively with all four lung function parameters, yielding better correlations than serum TNF-α levels or 18F-FDG PET/CT. 99mTc-infliximab accumulation reflects the in situ TNF-α expression in an individual patient and therefore provides valuable information on the presence of the biological target for anti-TNF-α therapy.