Accuracy and safety of99m Tc-labeled anti-D-dimer (DI-80B3) Fab’ fragments (ThromboView®) in the diagnosis of deep vein thrombosis: A phase II study

Abstract Background The assessment of patients with suspected deep vein thrombosis (DVT) remains challenging despite current diagnostic algorithms.99m Tc-labelled DI-DD3B6/22-80B3 Fab´ fragments (99m Tc-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. Methods In a multi-centre prospective cohort trial we investigated the diagnostic accuracy and safety of99m Tc-DI-80B3 in consecutive patients with suspected DVT who had the diagnosis confirmed or excluded by venography. Results We enrolled 94 patients with suspected DVT of whom 12 did not have99m Tc-DI-80B3 imaging, leaving 82 patients for the safety analysis. Of these patients, there were 16 with non-evaluable imaging (11 venography, 799m Tc-DI-80B3, both in two patients) leaving 66 patients for the accuracy analysis.99m Tc-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-hour99m Tc-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 of99m Tc-DI-80B3 imaging for suspected recurrent DVT. Conclusions99m Tc-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.