Capromab pendetide, radiolabelled with indium-111, is a radioimmunoscintigraphic imaging agent used in patients with prostate cancer. It consists of a murine monoclonal antibody (7E11-C5.3) covalently jointed to a linker-chelator molecule. 7E11-C5.3 is thought to be directed against the intracellular domain of human prostate-specific membrane antigen (PSMA), a transmembrane glycoprotein expressed by prostate epithelial cells. The diagnostic utility of capromab pendetide has been investigated in 2 distinct patient groups. In patients with untreated prostate cancer at high risk for pelvic lymph node metastases, capromab pendetide imaging had respective sensitivities and specificities of 52 and 96% in 1 study and 62 and 72% in another, as confirmed by pelvic lymph node dissection biopsy results. In patients with suspected occult recurrent or residual disease after prostatectomy, capromab pendetide had respective sensitivities and specificities of 49 and 71% in 1 study and 77 and 35% in another for detection of cancer in the prostate bed. Almost half of these patients also had evidence of lesions outside the prostate fossa (usually in the pelvic and abdominal lymph nodes) according to immunoscintigraphic scans, but too few cases were confirmed to allow an evaluation of capromab pendetide. Four per cent of patients who received single doses of capromab pendetide experienced adverse events. Elevated bilirubin levels, hypertension and hypotension each affected 1% of patients and elevated liver enzymes and injection site reactions < 1% of patients. Detectable human anti-mouse antibodies were reported in 8% of patients after a single dose of capromab pendetide and in 19% of patients after repeat infusions.
Conclusions: Capromab pendetide offers improved sensitivity in the detection of prostate cancer over other noninvasive techniques. When used in conjunction with other techniques, it offers the possibility of defining the extent of localised and metastatic disease, thereby refining patient management.