Accuracy and safety of 99mTc-labeled anti-D-dimer (DI-80B3) Fab’ fragments (ThromboView®) in the diagnosis of deep vein thrombosis: A phase II study

BackgroundThe assessment of patients with suspected deep vein thrombosis (DVT) remains challenging despite current diagnostic algorithms. 99mTc-labelled DI-DD3B6/22-80B3 Fab´ fragments (99mTc-DI-80B3, ThromboView®) is a novel diagnostic test that uses a radiolabelled humanized monoclonal antibody fragment specific for the D-dimer region of cross-linked fibrin to detect DVT. This test has an anatomic component to locate DVT and a functional component to differentiate acute (newly formed) thrombus from inactive (old) thrombus.MethodsIn a multi-centre prospective cohort trial we investigated the diagnostic accuracy and safety of 99mTc-DI-80B3 in consecutive patients with suspected DVT who had the diagnosis confirmed or excluded by venography.ResultsWe enrolled 94 patients with suspected DVT of whom 12 did not have 99mTc-DI-80B3 imaging, leaving 82 patients for the safety analysis. Of these patients, there were 16 with non-evaluable imaging (11 venography, 7 99mTc-DI-80B3, both in two patients) leaving 66 patients for the accuracy analysis. 99mTc-DI-80B3 imaging was well-tolerated: 2 patients developed urticaria; none developed serious adverse events. For proximal DVT, the sensitivity (84.2%; 95% confidence interval [CI]: 62.4–94.5) and specificity (97.6%; CI: 83.3–99.4) were highest when the combined 0.25-hour and 3-hour 99mTc-DI-80B3 images were used. The accuracy was lower for distal DVT, irrespective of the images used. There were insufficient patients to comment on the accuracy of 99mTc-DI-80B3 imaging for suspected recurrent DVT.Conclusions99mTc-DI-80B3 (ThromboView®) is a novel diagnostic modality for patients with suspected DVT with a promising accuracy and safety profile that justifies additional clinical development in diagnostic accuracy and clinical management studies.