QUANTITATIVE DISTRIBUTION OF I-131-LABELED MONOCLONAL-ANTIBODIES ADMINISTERED BY THE INTRA-VENTRICULAR ROUTE

In a preliminary study in one patient [111In]DTPA was injected into the lateral ventricle and at the same time [99mT]DTPA into the lumbar sac. The 111In distributed freely throughout the CSF but the concentration of 99mTc in the ventricles remained consistently low. In the second phase of the study three patients with tumours confined to the neuraxis were treated with 20-50 mCi 131I-labelled monoclonal antibodies administered into the lateral ventricle via Ommaya reservoirs. Quantitative distribution of radio-labelled antibody was assessed at intervals up to 8 days post injection. In each case there was rapid distribution to all parts of the neuraxis with 38-68% of total CNS counts remaining in the head and 13-39% in each of the upper and lower half spine areas. The t 1 2 for total CNS counts were 31.5, 19.8 and 15.5 h. There was no clear evidence of tumour localization and no neurological toxicity. These patients demonstrate that radiolabelled monoclonal antibodies can be given safely via Ommaya reservoirs and that in order to obtain optimal distribution throughout the CSF this should be the preferred method of administration. Further trials in patients with minimal disease are warranted. © 1990.