Diagnosis and therapy of neuroectodermally associated tumours using targeted radiation

Monoclonal antibodies have been proposed as targeting agents for cytotoxic compounds in vivo. We have undertaken a phase 1 study of 131I UJ13A in patients with neuroblastoma as well as a pilot study for the intrathecal use of radiolabelled conjugates for diffuse malignant meningitis. Access to solid tumour deposits appears to be a major problem in targeting sufficient isotope to elicit a therapeutic response. This, however, is overcome in the intrathecal use of antibodies for diffuse disease. Problems have also been identified in changes in the pharmacokinetics of antibody handling that occur on repeated administration of conjugate to patient. This is presumably due to the generation of an anti-mouse Ig response. These studies indicate some of the limitations in using murine antibodies as targeting agents and point to areas where their use may be of maximal effect.