Diagnosing suspected acute nonclassic appendicitis with sulesomab, a radiolabeled antigranulocyte antibody imaging agent

The aim of this study was to investigate the potential role of a technetium 99m-labeled antigranulocyte murine antibody Fab’ fragment (sulesomab) as a diagnostic imaging agent in children with suspected acute nonclassic appendicitis. Serial planar images at 15 to 30 minutes, 1, 2, and 4 hours and single-photon emission computed tomography (SPECT) images were acquired after sulesomab injection. In 40 children with suspected acute nonclassic appendicitis, imaging results were confirmed surgically in 21 patients, whereas 19 nonsurgical patients resolved presenting signs and symptoms and were considered to not have appendicitis. Sulesomab imaging had 95% sensitivity, 90% specificity, 95% negative predictive value, and 90% positive predictive value for acute appendicitis. In 78% of patients, sulesomab accurately detected or excluded acute appendicitis and would have changed management plans. No patients had adverse events, and no human antimurine antibody response occurred in 18 evaluable patients. Sulesomab was well tolerated with no side effects and with no apparent immunogencity. Appendicitis was rapidly and accurately detected. In pediatric patients with suspected nonclassic appendicitis, management decisions incorporating sulesomab imaging provided benefit in separating surgical from nonsurgical patients.