99mTechnetium-C595 radioimmunoscintigraphy: a potential staging tool for bladder cancer

To assess whether immunoscintigraphy using a conjugate of the anti-MUC1 monoclonal antibody C595 and 99mTc could be used to target transitional cell bladder cancer after intravenous administration to patients.

Twenty-one patients with invasive or metastatic transitional cell carcinoma were recruited. Patients received 1 mg of C595 labelled with 800 MBq 99mTc followed by imaging at 0.5, 6 and 24 h using a combination of planar and single-photon emission computed tomography. Of these patients, 14 subsequently underwent cystectomy, four underwent radiotherapy and the remaining three had histologically confirmed metastatic disease. The results of immunoscintigraphy were compared with surgical findings and conventional radiology.

There were no adverse reactions in any patient. Of the 20 patients who were found to have tumour at the time of the study, positive localization of antibody in tumour was apparent in 16. Of the remaining four patients, false-positive localization of antibody in presumed nodal tissue was detected in two. The remaining scan results were equivocal. In three patients, histologically confirmed pelvic nodal metastases that had not been detected on preoperative computed tomography were identified.

These early results show the potential of 99mTc-C595 immunoscintigraphy for staging bladder cancer. A larger study is needed to fully evaluate the technique.