Prostate cancer imaging with a new monoclonal antibody: a preliminary report.

BACKGROUND

Optimal treatment of prostate cancer depends on accurate staging. Computed tomography (CT) and magnetic resonance imaging have severe limitations, and standard bone scanning can show only destructive osseous metastases. A radiolabeled antibody specific to prostatic adenocarcinoma could theoretically find evidence of soft-tissue metastases and lymph node involvement.

METHODS

An immunoconjugate (CYT-356) consisting of a murine monoclonal antibody against human prostatic adenocarcinoma bound to a linker-chelator and radiolabeled with indium 111 was administered intravenously to seven patients with documented Stage D adenocarcinoma of the prostate. Planar imaging was done on days 1, 2, and 3 after injection. The CYT-356 scans were compared with standard technetium Tc99m sulfur colloid bone scans and CT scans.

RESULTS

Optimal imaging results were obtained on the 72-h scans. All patients had lesions on both the 99mTc-sulfur colloid bone scan and the CYT-356 scan. The location of the lesions correlated to a great extent. Two patients had positive lesions biopsied, and both biopsies showed the presence of metastatic prostatic carcinoma. There were no side effects from administration of the antibody.

CONCLUSION

In this preliminary study, CYT-356 scanning appears to be a promising agent to accomplish specific staging of prostatic carcinoma.